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UBC Theses and Dissertations

Retrofitting Tokyo’s existing office buildings with natural lighting Urano, Kazu 2003

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R E T R O F I T T I N G T O K Y O ' S E X I S T I N G O F F I C E B U I L D I N G S W I T H N A T U R A L L I G H I T N G by K A Z U U R A N O .Sc., in Oceanic Architecture and Engineering, Nihon University, 1996 A T H E S I S S U B M I T T E D IN P A R T I A L F U L F I L M E N T O F T H E R E Q U I R E M E N T S F O R T H E D E G R E E O F M A S T E R O F A D V A N C E D S T U D I E S I N A R C H I T E C T U R E in T H E F A C U L T Y O F G R A D U A T E S T U D I E S School o f Architecture W e accept this thesis as conforming to the required standard T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A Apr i l , 2003 © Kazu Urano, 2003 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department The University of British Columbia Vancouver, Canada DE-6 (2/88) The objective of this thesis is to propose strategies to increase the market value of Tokyo's existing office buildings, especially those designed in the 1970's and 1980's, using natural lighting as an integral part of office renovation. Value in Tokyo office buildings has traditionally been judged in terms of a limited range of considerations — location, functionality and architectural aesthetics. Recently however, the decision-making factors which drive the market value of Tokyo's office buildings have widely recognized the benefits of a broader range of considerations associated with "environmentally friendly building" which offers higher quality indoor working environments and improved energy efficiency. With such an increased consciousness of environmentally responsible practices, office renovation with natural lighting provides an appropriate response to the demands of the recent Tokyo office market. There is very little published research and design guidelines on office renovation with natural lighting, resulting in limited guidance specific to Tokyo's dense urban situation. It is widely acknowledged that office renovation with environmentally friendly techniques requires the creative integration of various systems and strategies and a more coordinated effort by members of the design team. This thesis reviews existing guidelines and identifies a suitable design process for retrofitting Tokyo's existing office buildings with natural lighting. Current techniques in Tokyo office renovations associated with natural lighting only tend to focus on shading functions to avoid overheating and glare problems. This limited scope fails to recognize the important benefits provided by natural lighting distribution. This thesis offers an innovative office renovation design framework which aims to provide effective natural lighting control solutions which function to enhance interior natural lighting through distribution to the interior while maintaining the shading function. This framework seeks to integrate team decision making and a simplified natural lighting evaluation software with the design process to optimize natural lighting conditions in office environments. Through the design of effective natural lighting control devices, office renovations can provide more comfortable and delightful office environments which have a high potential for increasing worker productivity, while increasing energy efficiency. While environmental assessment tools have become increasingly sophisticated, providing office building owners with ambitious environmental performance goals, office building owners lack sufficient guidance on how to achieve these goals. The framework developed in this study offers guidance on the design of effective natural lighting control devices as a means of renovating Tokyo's older existing office buildings to meet today's high environmental performance standards. This framework emphasizes that increased environmental performance adds value to older existing office buildings, not only in terms of environmental externalities, but in terms of measurable economic performance. iii ABSTRACT ii LIST OF TABLES vii LIST OF FIRGURES viii ACKNOWLEDGMENTS x i 1. PROBLEM ANALYSIS 1 1.1. Potential for Office Renovation with Natural Lighting in Tokyo- 1 1.2. The Current State of Tokyo's Older Existing Office Buildings 4 1.2.1. Decreasing Market Value of Existing Office Buildings 4 1.2.2. Lack of Occupant Satisfaction and Productivity 10 1.2.3. High Energy Consumption for Electrical Lighting Systems 13 1.3. Current Office Renovation Techniques- 15 1.3.1. Structural Improvement for Durability 15 1.3.2. Improvement of the Appearance of Office Buildings 16 1.3.3. Increasing the Productivity of Older Existing Office Buildings 17 1.3.4. Upgrading Energy Efficiency 17 through Electrical Lighting Systems 1.3.5. Green Renovation with Natural L i g h t i n g 1 8 1.4. Current Decision Making for Natural Lighting Within Tokyo's Contexts 19 1.4.1. Decision-Making for Office Buildings with Natural Lighting 19 1.4.2. Lack of Decision Makers for Good Natural L i g h t i n g 2 0 1.4.3. Assessment of Successful Naturally Lit Office B u i l d i n g s 2 1 1.4.4. Regulations and Codes for Natural Lighting 22 1.5. Thesis O b j e c t i v e 2 3 2. FUNDAMENTAL PRINCIPALS OF NATURAL L I G H T I N G 2 5 2.1. Fundamental Principals of Natural Lighting 25 2.1.1. Types of Natural Lighting 25 2.1.2. Basic Natural Lighting C o n t r o l 2 6 2.2 Defining Natural Lighting Strategies 30 2.2.1. Possible Natural Lighting Control Devices 30 2.2.2. Effective Natural Lighting Control Devices 30 2.2.3. Functions of Naturally Lit Office Buildings 31 5 3. FRAMEWORK FOR NATURAL LIGHTING IN OFFICE R E N O V A T I O N S 3 2 3.1. Natural Lighting Design Process 34 3.2. Team Decision- Making 37 3.2.1. Budget of Renovation Process 37 3.2.2. The Involvement of Specialists- 38 3.3. Natural Lighting Design Evaluation Tools '• 39 3.3.1. Pre-Design 39 3.3.2. Preliminary D e s i g n 3 9 3.3.3. Design D e v e l o p m e n t 4 0 3.3.4. Construction Document 40 4. RESERCH TECHNIQUE FOR NATURAL LIGHTING • ' 4 1 4.1. Research S o f t w a r e 4 1 4.1.1. E C O T E C T v 5 . 0 4 1 4.1.2. Desktop Radiance 43 4.2. Research Procedure for Natural Lighting 45 4.2.1. Building Parameters for Evaluation- 45 4.2.2. Evaluation Process 45 5. A HYPOTHETICAL OFFICE B U I L D I N G 4 8 5.1. Configuration for A Hypothetical Office B u i l d i n g 4 8 5.2. A Sampled A r e a 4 9 5.2.1. Inputted Design Parameters for Sampled Area 49 5.2.2. Omitted Design Parameters for Sampled A r e a • 5 1 5.3. Tokyo Contexts for Natural Lighting Evaluation 53 5.3.1. Tokyo Microclimates 53 5.3.2. Tokyo's Dense Urban Situation- 55 5.4. Benchmark for Interior Natural Lighting 60 5.4.1. Benchmark for Direct Sunlighting Performance 60 5.4.2. Benchmark for Interior Natural Lighting Performance 60 6. EFFECTIVE NATURAL LIGHTING FOR TOKYO OFFICE R E N O V A T I O N 6 2 6.1. Step-1 64 6.1.1. Chart for the Percent Reduction of Interior Natural Lighting due to Obstructions 65 6.1.2. Chart for the Number of Available Months for Direct Sunlighting 66 6.1.3. Ratio Analysis for Chart R e a d i n g 6 8 6.2. Step-2 70 6.2.1. Possible Natural Lighting Control Devices 70 v; 6.3. S t e p - 3 7 5 6.3.1. The Key Design Parameters of Effective Natural Lighting Control Devices 77 6.3.2. Internal Natural Lighting Control Devices 80 6.3.3. Internal + External Natural lighting Control Devices 83 6.3.4. Internal + Ceiling Control Devices 87 6.3.5. Internal + External + Ceiling Control Devices • 91 6.4. Site Specific Office Building Design Case Study 95 6.4.1. Designing Effective Natural Lighting Control Devices 96 6.4.2. Interior Natural Lighting Performance 98 6.4.3. Energy Consumption and Operation Cost of Electrical Lighting Systems 101 7. POTENTIAL WIDESPREAD APPLICATION OF NATURAL LIGHTING 104 7.1. Office Renovation with Natural Lighting 104 7.2. Effective Natural Lighting Control Devices within Tokyo Context 107 7.2.1. Internal Control Devices 108 7.2.2. Internal + External or Internal + Ceiling Control Devices 110 7.2.3. Internal + External + Ceiling Control Devices 112 APPENDIX Appendix 6 . 1 . 1 . 1 1 7 Appendix 6.1.2. 118 Appendix 6 . 2 . 1 . 1 1 9 Appendix 6.3.1.-1 123 Appendix 6.3.1.-2 129 Appendix 6 . 3 . 1 . - 3 1 3 2 Appendix 6.3.2. 135 Appendix 6.3.3. 140 Appendix 6.3.4. 145 Appendix 6.3.5. • 150 Appendix 6.4.1. 155 References 163 vi Table 1-1: Stratification of the Tokyo Office M a r k e t 9 Table 3-1: Framework for Office Renovation with Natural Lighting 33 Table 3-2: The Points of Current and Innovative- 35 Office Renovation Design Process Table 7-1: The Lists of Effective Natural Lighting Control 114 Devices within Tokyo Context vii Figure 1-1: The Classification of Tokyo Existing Office Buildings 2 Figure 1-2: The Area of Tokyo Metropolitan A r e a 5 Figure 1-3: The Percentage of Supplied Office Buildings in Tokyo Market- 5 Figure 1-4: Large and More Centralized Newer Office Buildings- 6 Figure 1-5: Current Office Rents 6 Figure 1-6: Occupant Dissatisfaction with Tokyo Existing Office Buildings- 10 Figure 1-7: The Tokyo Gas Kohoku NT Building 12 Figure 1-8: Energy Consumption for Tokyo's Existing Office Buildings 13 Figure 1-9: The Opportunities of Office Renovation or 15 Demolishing for Tokyo's existing Office Buildings Figure 1-10: The Today's Standards of Structural Durability 16 Figure 1-11: The Current Office Renovation with Window Design- 16 Figure 1-12: The Current Office Renovation with Facade Design 16 Figure 1-13: Conventional Office Renovation Process with Natural Lighting 20 Figure 1-14: Current Office Building Facade Design with Natural Lighting 22 Figure 2-1: Monthly Average Temperature in Tokyo 27 Figure 2-2: Simple Control Devices for Direct Sunlighting with Blinds- 28 Figure 2-3: Simple Control Devices for Direct Sunlighting with Overhangs 28 Figure 2-4: Simple Control Devices for Direct Sunlighting with Curtain Walls 29 Figure 3-1: Relationship of Cost and the Decision-Making for Natural Lighting 37 Figure 3-2: Opportunity for Natural Lighting Designs 38 in the Integrated Design Process Figure 4-1: Office Renovation Design Process- 42 Figure 4-2: 3-D Modeling with ECOTECT 42 Figure 4-3: The Evaluation Method with ECOTECT 43 Figure 4-4: The Evaluation with Desktop Radiance- 44 Figure 5-1: The Detail Configuration of Sampled Area 49 Figure 5-2: Tokyo Microclimate Data 53 Figure 5-3: Local Obstruction with Sun Angle 54 Figure 5-4: Local Obstruction Analysis for Natural Lighting Evaluation 56 Figure 5-5: Monthly Available Direct Sunlighting 57 Figure 5-6: The Average of Percent Reduction for 58 Interior Natural Lighting Performance Figure 5-7: The Benchmark of Monthly Available 60 Direct Sunlighting Figure 5-8: The Benchmark of Percent Reduction for 61 Interior Natural Lighting Performance Figure 6-1: The Chart of the Percent Reduction of Interior Natural Lighting 65 Figure 6-2: The Number of Average Month of Direct Sunlighting Performance 66 Figure 6-3: Diagrams of Direct Sunlighting and Interior Natural Lighting with 70 Tokyo Urban Ratio Analysis. Figure 6-4: The Analysis of Possible Natural Lighting Control Devices 71 Figure 6-5: Possible Natural Lighting Control Devices 73 Figure 6-6: Design Diagrams for Natural Lighting Control Devices-. 76 Figure 6-7: The Design Parameters for Internal Devices 78 Figure 6-8: The Design Parameters for External Devices 78 Figure 6-9: The Design Parameters for Ceiling Devices 79 Figure 6-10: Effective Internal Natural Lighting Control Devices- 80 Figure 6-11: The Evaluation of Interior Natural Lighting Performance 81 Figure 6-12: Effective Internal + External Natural Lighting Control Devices 83 Figure 6-13: The Evaluation of Interior + External Natural Lighting Performance 84 Figure 6-14: Effective Internal + Ceiling Natural Lighting Control Devices- 87 Figure 6-15: The Evaluation of Interior + Ceiling Natural Lighting Performance- 88 Figure 6-16: Effective Internal + External + Ceiling 91 Natural Lighting Control Devices Figure 6-17: The Evaluation of Interior Natural Lighting Performance 92 Figure 6-18: The Relationship Between the Direct Sunlighting 96 and the Interior Natural Lighting Chart Figure 6-19: The Percent Increase for the Interior Natural Lighting 98 Performance with Effective Control Devices Figure 6-20: The Percent Reduction for the Interior Natural Lighting ^ 0 Performance with Effective Control Devices 102 Figure 6-21: The Coefficient for Operation Cost and Energy Consumption for Electrical Lighting Systems and Percent Reduction Figure 6-21: The Operation Cost and Energy Consumption for Electrical Lighting Systems and Percent Reduction ix Figure 7-1: The Recommendation of Effective Control Devices -I07 with Tokyo Urban Scenarios Figure 7-2: Tokyo Urban Scenario (a) 108 Figure 7-3: Tokyo Urban Scenario (b), (c), and (d> 110 Figure 7-4: Tokyo Urban Scenario (d) and (e) 112 x I would like to express my gratitude to my thesis committee for their continuous support and encouragement on what seemed, at times, like a never-ending road. I wish to give my deepest thanks to Raymond J. Cole, my advisor, for his incredible patience with the meandering path I took, and his critical thinking, that challenged me to look deeper and reach for a higher standard. I would like to thank Jerzy Wojtowicz for helping me to understand the larger picture of architectural design, and Kaz Fuziki for providing his valuable knowledge of Tokyo's contextual perspective. A special thanks goes to Samuel Sze for sharing his English knowledge and editing my thesis. Finally I would like to thank my family and friends, who supported me during this academic journey. They gave me the strength and determination to keep pushing ahead at times when all I wanted to do was leave it behind. I cannot thank you enough for everything. The objective of this thesis is to propose and explore innovative renovation strategies to increase the market value of Tokyo's existing office buildings. This chapter, as problem analysis, identifies the importance of office renovation and the need for natural lighting as an integral part of renovation techniques for upgrading Tokyo's existing office buildings. Section 1.1 describes the context of Tokyo's current office building market. Sections 1.2, 1.3, and 1.4 discuss the feasibility of office renovation using natural lighting within the context of the following three current issues: > The weakened market position of Tokyo's older existing office buildings (designed in the 1970's and 1980's) in the face of new environmental, energy efficiency, and indoor environmental performance standards > The inadequacy of existing renovation strategies to respond to these new standards > The barriers to effective, informed decision-making for Tokyo's office building with natural lighting. 1.1. P o t e n t i a l f o r O f f i c e R e n o v a t i o n w i th Natura l L i g h t i n g in T o k y o This section describes the context of Tokyo's current office building market within a framework of three general building types: new office buildings designed after 2000, office buildings designed in the 1990's, and older office buildings designed in the 1970's and 1980's. Office workers have become increasingly aware of the emerging constraints and poor indoor environments of older existing office buildings, designed in the 1970s and 1980s. Deep interior spaces and dense surrounding urban conditions create a high demand for electrical lighting systems which produce high energy consumption, increased cooling loads, comparatively poor lighting quality, and potentially poor office productivity. 1 As shown in Figure 1-1, existing office buildings in Tokyo can be classified according to three general types: > Type A — Tokyo's New Office Buildings designed after 2000. Natural lighting is implemented as an integrated approach for designing an environmentally friendly office building to reduce the energy consumption for electrical lighting systems and improve indoor environmental quality. These office buildings tend to be relatively complex to operate require good management. > Type B — Office Buildings designed in the 1990's: Energy efficient electrical lighting systems tend to be installed with very little or no utilization of natural lighting techniques. These office buildings, relatively simple to operate, are controlled with automatic switching or dimming systems. > Type C — Office Buildings designed in the 1970's and 1980's: Energy inefficient electrical lighting systems were installed. These office buildings, relatively simple to operate, are controlled manually without any innovative lighting management systems or natural lighting control. Technological Complexity Building Management Input More Less More Type A Tokyo New Office Buildings Effective, but often costly Type D Rare in Tokyo Context Less Type C ( n , ^ Tokyo 70s and 80s Buildings 'Risky with performance penalties Type B Tokyo 90s Office Buildings Effective, but often small-scale Fig. 1-1: Tokyo existing office buildings belong to the Type c, based on Bordass study. (Source: Japan Facility Management Promotion Association, 2000) Type A and B office buildings are in high demand in Tokyo's office market. Type B (existing office buildings, designed in the 90's) tend to be less energy-intensive than Type A office 2 buildings (new office buildings), but the management of new office buildings provides interaction between optimal office environment and good energy performance. The issue in the current Tokyo context is that the stock of Type C (1970's and 1980's) office buildings greatly exceeds the stock of newer buildings (Types A and B), and Type C buildings do not place a high priority in environmental performance. These buildings, operating on simple manually operated lights, are difficult to manage and the electric lights are often in continuous use. The result is that these older buildings fail to achieve their potential, both for occupant satisfaction and energy efficiency. It is, therefore, of significant importance to upgrade office buildings, especially Type C, using suitable natural lighting techniques. This will enhance office productivity, add value, and reduce energy consumption, and thereby increasing their competitiveness with Type A or B office buildings in the Tokyo market (Bordass, 2000). 3 1.2. T h e C u r r e n t S ta te o f T o k y o ' s O l d e r E x i s t i n g O f f i c e B u i l d i n g s ( T y p e C) This sub-section explores the current issues facing Tokyo's older existing office buildings and examines why office renovation is a preferable alternative to demolition. Three major current problems for existing office buildings in Tokyo's urban context are: > the decreasing market value of existing office buildings > the lack of occupant satisfaction and productivity > the high energy consumption of older electrical lighting systems. 1.2.1. Decreasing Market Value of Existing Office Buildings The market value of Tokyo's existing office buildings designed in the 1980's or before has been decreasing dramatically (Fukao, 2001). These values have traditionally been judged in terms of location, functionality, and aesthetics (Hatanaka and Seino, 2002). However, in the recent Tokyo market, indoor environmental quality is increasingly a key determining factor in the valuation of office buildings. As a result, the demand for newer office buildings, often designed to take advantage of local outdoor environmental conditions to enhance indoor environmental quality, has been increasing. The increasing number of newer environmental-friendly office projects has had a significant impact on the market for office buildings in Tokyo. Effects include: > strong demand for and an increasing supply of new office buildings resulting in a weaker demand for older existing office buildings, > rents in existing office buildings which are competitively weak against the reduced rents in new office buildings > high vacancy rates in existing office buildings caused by a high supply of new office buildings (Sasaki, 2002). Decreasing Demand for Tokyo's Existing Office Buildings Projections suggest that existing office buildings designed in the 1970's and 1980's will continue to represent approximately 44 percent of the total office building stock until 2005 in Tokyo (Tokyo City Hakusyo, 2000). By contrast, new office buildings completed between 2001-2005 will account for 12 percent of Tokyo's office market. Importantly, the 1.7 million square-meters of new office space, which doubled the annual average over the past year, 4 will be provided in the central area, Chiyoda-Ku, Minato-Ku and Chuo-Ku (fig. 1-2), in 2003 (fig. 1-3) (Japan Leasing Update, 2001). Consider ing these projections and the high demand in recent years for high quality office buildings, these office buildings will provide considerable competition in Tokyo's existing office market. Furthermore, the inferior quality of older existing office buildings in terms of indoor environment, structural durability, appearance, and energy efficiency will weaken their competitiveness. A potential glut of new office buildings will lead to a decrease in the value of Tokyo's older existing office buildings. To increase the value of these buildings, renovation is a critical issue. •90 SHirOUKU-KU Sh.nJMku Shinjuku' t- \ "w^1 ua retorts Koshlkawa »• Koraku-en Imperial P«lac« srdens koen Park Jingu Garden* tt Aoyama Cemetery Ham. Rlkyu Delach.d Pal.ce Garrin , Kite 1 To ' '-. •OKoeylartd / filfua f BSom Bunding 5HIBUYA-KU Shiba-Park Centml ODAIBA TOKYO Nature Fig. 1-2: The 1.7 square-meters of new office spaces which doubled the annual average over the past year will be provided the central districts, Chiyoda, Chyuo, and Minato-Ku, with highest in 2003. As new office buildings are large projects, the high vacancy rate for old office buildings is predicted. (Source: Ikoma/CB Richard Ellis.) ( m i l l i o n m 2 ) 3 . 5 3 . 0 2 . 5 2 . 0 1 . 5 1 . 0 0 . 5 44% 9.9 fv lillion m2 43% 9.5 Million m 2 2.4 Million m' 1 9 8 0 S 9 0 9 1 9 2 9 3 9 4 9 5 9 6 9 7 9 8 9 9 0 0 0 1 0 2 0 3 0 4 0 5 Fig. 1-3: the percentage of supplied office buildings in Tokyo market (Source: Japan Leasing Update, 2001.) The demand for Tokyo's existing office buildings will decrease due to their comparatively high rent and poor indoor environment (Sasaki, 2002). Market research performed by the Tokyo Metropolitan Government (TMG) indicates that, with its long history as a political center, Tokyo's central area has a massive concentration of major corporate headquarters and a significant supply of new office buildings whose 5 proximity both adds value to Tokyo's older existing office buildings and contributes to the high-density office situation. However, the recent demand for offices offering advanced telecommunications capabilities and better indoor office environmental quality has resulted in larger and newer office buildings being built in the central district (fig. 1-4). Therefore, upgrading older office buildings located on the central district has become necessary (Japan Leasing Update, 2001). In order to maintain the demand for these existing buildings within the Tokyo market, developers, stakeholders and architects must undertake or plan necessary renovations. Large and More Central o m 12 9 o 6 3 86-90 91-95 96-00 01-05 % large buildings (over 10,000 m 2 ) completed in central 3 Words Average size of all large buildings completed in Tokyo Competitively Weak Rents for Existing Office Buildings in The Tokyo Market The reasonable rents and high indoor environmental quality offered by new office buildings attracts tenants away from older existing office buildings (Sasaki, 2002). Japanese companies are increasingly more cost conscious. There is limited demand for Fig. 1-4: Large and newer office buildings are provided to the central district. (Source: Colliers Halifax Research) Note. 1-1: Tsubo is traditional Japanese measurement of space. 1 tsubo=3.3 square meter and 10,000 yen=$125.00 Fig. 1-5: This table shows a significant difference between the landlord's asking rent and the rent that is actually achieved. Landlord has to provide reduced rent to compete with the rent of new office buildings. (Source: Colliers Halifax Research, 2000) Rents Achievable Central District Asking Area Marunouchl. Otemachl, Hibiya_ Source: Colliers Halifax Research ¥(000's/tsubo/month including CE) 1tsubo=3 3sq.m 0 20 40 60 Chiyoda-ku Bancho. Kojlmaetil Chuo-ku Kudan, Jimbocho Glnza Nlngyocho. Kayabacho. Shlnkawa Nlhombashi. Yaesu Toranornon. Shlmbashl, Kamiyacho Minato-ku Azabu, Mlla Aoyama. Akasaka Shlbaura. Shinagawa, Tennozu Nlshl Shinjuku Skyscrapers Osaki. Gotanda Omori, Kamata Toyocho, Kiba Colliers Halifax's experience Is that after Implementing a carefully constructed negotiating strategy, tenants fta ve been capable of realizing what is often a significant difference between the landlord's asking (higher) rent and the rent that Is actually achieved. 6 Tokyo's existing office buildings space with a monthly rent of over ¥30,000 (per tsubo) and practically no demand for space over ¥40,000 (note. 1-1). By contrast, demand is consistently much greater for the new office building stock at ¥25,000 rent (fig. 1-5). As the currently limited supply of Tokyo office space is relieved by new construction, the shift will give tenants of older buildings incentive to pay lower rents in the currently leased space or relocate to a more suitable office building (Japan Leasing Update, 2001). Owners of older existing office buildings will be forced to reduce rents to compete with new office buildings and to improve the quality of office environments. Innovative office renewal planning is necessary to increase demand and to attract tenants to older office buildings. As the rents for older existing office buildings are expected to decrease by 5% during 2003, impacted by lower rents in the new office building stock, tenants will begin to trade up to office buildings that provide a higher quality indoor environment (Japan Leasing Update, 2001). Although this 5% reduction in rents is beneficial for current tenants, the main reason for losing tenants in Tokyo's existing office buildings tends to be poor indoor office environments. Owners and landlords of existing office buildings must understand their current situation in the market and consider upgrading their office buildings to increase the quality of indoor environments (Japan Leasing Update, 2001). The correlation between cost and value arguments for Tokyo's existing office buildings should be reassessed. Increasing Vacancy Rate for Existing Office Buildings Vacancy rates of existing office buildings are anticipated to rise approximately 10-25% because of the high supply of new office buildings in Tokyo (Japan Leasing Update, 2001). Older existing office buildings in the central Tokyo area have had very low vacancy in recent years, but will be forced into competition with new stock both within their own neighborhoods and in new business areas such as Odaiba and Harumi, shown in Figure 1-2. Increasing vacancy rates for existing office buildings may lead to a higher demolition rate in Tokyo's office market. In response to this common problem, the Tokyo Metropolitan Government (TMG) recently developed the "Environmental-Friendly and Economical Renovation Program", cooperating with financial associations and local governments to provide effective incentive programs to encourage owners to upgrade their buildings (Ministry of Construction, 2001). Impracticality of Demolishing Existing Office Buildings There is a widespread belief that demolishing and redesigning office buildings costs much more than retrofitting existing office buildings. Reducing the initial cost to upgrade the value 7 of existing office buildings, building owners tend to commit funds to office renovation or refurbishment while using existing building structure. However, higher environmental performance goals in energy efficiency and indoor office environment are often dismissed by clients and designers without serious exploration, especially at the initial stage of design practice (Cole, 2000). The need to establish an effective relationship between cost and value to counter these perceptions is one of the most critical factors in promoting office renovation, although it is generally perceived that predicting and assessing the costs and benefits of retrofitted office buildings is a difficult task. The Tokyo Metropolitan Government (TMG) and the Energy Conservation Center (ECC) (note. 1-2) stress that higher initial investment in upgrading office buildings can produce lower long term operating costs. The TMG also suggests in the Tokyo Plan 2000 (note. 1-3) that a long-term use by upgrading existing office buildings is profitable with regard to economic and environmental impacts for the community. This acknowledgement of the relationship between cost and value of office refurbishment has been, recently, termed 'environmentally friendly office renovation' in the Guidelines for Assessment of Environmental Friendliness of Government Building Facilities and Renovation Plan (EFRP) (note. 1-4). Demolishing existing office buildings is, therefore, no longer an anticipated trend in Tokyo. This creates a need for office renovation to comply with today's office standards in terms of energy consumption and quality of indoor work environments. Table. 1-1 describes the relationship between the attributes of Tokyo offices and the market response. Note'.1-2: The Energy' . . ;" Conservation Center (ECC) in ;'; vJapah:; contributes to the efficient3] '.' use of energy, protection of the global environment and sustainable development. ' : Note.1-3: Tokyo Plan 2000:' .••.!.)> proposes an ideal future as ;- • sustainable community for Tokyo, ; • including the'global sustainable' >cdhceptifor office buildings. This *:r; proposal provides the framework for the idea of sustainability to ' • \ other NGO and private >! :;organizations;:,; , ji,.y:• ^ Note.1 -4: Guidelines for Assessment of Environmental ; ' r;riendliness'of Government '•-•'" ~;,', ;Biiilding Facilities and Renovation!? ? Plan suggests improving energy V consumption and indoor office ' , environment oh not only governmental buildings but also.:';;!'4 fCommerciaiibuildingsHffiis ^ . " ' ^ i ^ proposal provides.the. idea'tb create better Tokyo,as sustainable : community with international. /Standard.. •. • , •' 8 t «l 1 o IS ° 1 O 8 >l5 .0 0 ! O | •a re o & l 0 c » i o I e I • •a I i S 3 5 .1 CD c oil ft) o £ o I ! < l F* o i is pi c o I c e M i 1! [SI f> It 1 1 O • * J £ s» "5. » J III TJ ]5 ro •C CD a Q. 0) 2 £ S 8. » Ol n r— »5-to o to s 0) ~ ro g xi 2 0) T3 u 5= £ » o) ro l s f ° 3 ° >< I -ro u _ = o ro til o i i ro -° 55 8 5^ to I f .* is ts; to 1 a. n-2m CD Is ro o yi _ ro " S i ci CL j_ >* 0) I- I- JO TJ 9 1.2.2. Lack of Occupant Satisfaction and Productivity Relationship Between Office Value and Productivity It has gradually been acknowledged in Tokyo's office market that a good working environment can lead to improved occupant satisfaction, and subsequently to an increase in office productivity (Hatanaka and Seino, 2002). This is due to the fact that in Tokyo's existing office buildings, highly controlled by electrical lighting systems, currently provide comparatively poor lighting quality and use energy inefficiently. A s shown in Figure 1-6, office workers are becoming increasingly aware of the emerging constraints and unmanageable indoor environments of existing office buildings in comparison to the improved environments within newer office buildings (Hatanaka and Seino, 2002). Innovative office renovation, which takes advantage of beneficial outdoor environmental elements such as natural light can improve indoor environments of office buildings. Occupant Dissatisfaction with Existing Office Buildings Poor Office Comfort Poor Office Automation (Telecommunications and Networks) Outdated Durability Standards for Building Structure 58.3 | 3 0 . 6 .9 20 40 60 80% Fig. 1-6: The approximately 58 percent of office workers are dissatisfaction for indoor office environment for Tokyo's existing office buildings. Number is multiple answers (Source: Sumitomoshintaku Bank. 1997) Poor Understanding About Lighting Level Despite the availability of natural light, demanded lighting levels for the interiors of existing office buildings (designed in the 1970's-1980's) are so high that electrical lights have to be used at all t imes throughout a year. Such lighting systems produce high levels of energy consumption occupying approximately 45% (described in Section 1.2.3.) of total energy consumption in typical office buildings in Tokyo ( E C C , 2002). Furthermore, in 70s and 80s office buildings, providing sufficient quality for office environments using natural lighting is often ignored. (TOTO, 2001). A study by Ikoma/CB Richard Ellis (note. 1-5) points to the importance of intensity, distribution, and control of interior illumination levels, which has an impact of comfort and stress levels to office workers. Ikoma/CB Richard Ellis' study Note. 1-5: Ikoma/CB Richard Ellis: deals with commercial real estate, based on Tokyo, to increase the value of office buildings. This company provides the reliable research data for strategic, creative, and cost-efficient solutions for Tokyo office buildings. 10 also indicates that office workers with the most demanding tasks are least satisfied with their lighting quality (Hatanaka and Seino, 2002). The improvement of lighting does not denote or imply a simple increase in illumination level. Brighter is not necessarily better for office work and can often create a worse overall lighting quality. Poor light quality is bad for the eyes, and can result in permanent eye damage (Lam, 1986). However, it is generally difficult to judge the quality of interior light because it depends on the requirements of each individual office worker's task. Lighting design should be linked to occupant tasks. As considerations of the quality of interior lighting level become more important, currently installed electrical lighting systems for Tokyo's existing office buildings should be improved. Lack of Interaction Between Office Comfort And Lighting Controls Another major issue which creates poor comfort conditions in offices tends to be the lack of personal controls for interior lighting levels (ECC, 2002). The relationship between control and comfort seems fairly straightforward. Office workers who are uncomfortable adjust ambient conditions until they reach satisfactory levels. However, this relationship between personal control, comfort, and productivity is made more complex by the unique lighting needs for different tasks or for different ages of office workers (Heerwagen, 2000). The majority of existing offices are, however, fully equipped with electrical lighting systems which provide uniform lighting condition to the interior without any personal control systems. Providing increased lighting quantity and work comfort does not always lead to the highest performance outcomes. Sometimes darker or brighter lighting conditions may enhance productivity depending on the circumstance (Wyon, 1996). The critical factors appear to be the nature of the task, the age of the office worker, and the optimal psycho-physiological arousal levels. For instance, office productivity in creative tasks such as architectural drawing is often increased when the lighting is brighter. Different kinds of tasks and different generations may require different kinds of light. As the quality of office environments for Tokyo's existing office buildings traditionally tends to be ignored, improved personal control and illuminance levels become increasingly important (Heerwagen, 2000). 11 Lack of Health And Well Being for Office Workers Little attention has been given to indoor office environments with regards to health prompting research for Tokyo's office buildings. However, more recently, it has been recognized that the factors of health, comfort and productivity can have a significant impact for increasing the value of office buildings. Boyce (1998) suggests that poor lighting leads to increased health problems and discomfort, and fails to meet the needs of recent standards for indoor office environments. On the other hand, high quality interior lighting utilizing induced natural lighting, by Boyce's definition, reduces Sick Building Syndrome (SBS) for office workers (note. 1-6) and also adds an aesthetic element that lifts the spirit. There is growing evidence that 'spirit-lifting' features in the indoor environment may promote positive emotional functioning and serve as a buffer against discomforts or stresses. These features can often involve bringing desirable exterior environmental elements such as natural light and views to the interior (Heerwagen, 2000). Lam (1986) discusses the importance of natural lighting: If natural lighting is applied with consideration to psychological and physiological needs which are lacking in Tokyo's office buildings, it can produce interior environments that are more comfodable, delightful, and productive (Lam, 1986). Thus the effective use of sunlighting and daylighting to improve office indoor environment is critical for Tokyo's existing office buildings. ; Note.1-6: The terrrT'sick building ' syndrome" (SBS) is used to. *; describe,situations' in, which building occupants experience,; ..' acute health and comfort effects' . that appear to bejinked to time * spent in a building, but ho specific jjllnessor cause can.be identified:.,--' * .Thecpmplaints may be localized in a particular'room or zone, or may. ; be widespread throughout the •' • .(building/ In contrast, the term |;:"bu|ld|ng relatedJllness"(B^I);isi;jj.i • ;iiusedlwhen symptomsof diagnosable illness'are identified and can beattributed directly to : airborne building contaminants. . :, ' ':'!:^!/fSWfce;.t?S"£ i^rOTnfenta/-•••,,.„•, Protection Agency, 2002) •Fig. 1-7:The Tokyo'Gas Kohoku NT Building, completed in March 1996, was built as an environmental friendly building. The research in terms of . occupants' satisfaction for interior . lightingperformahceshowsthat C; approximately 90 percent of office ' workers satisfy interior lighting conditions without electrical lighting' systems during daytime, throughout the year. ' ." , ;: , '- / ' • (Source: Laboratory of Building , Environment; Musashi Institute of. •; ! ' Technology. 1998) As shown in Figure 1 -7, a pre- and post- occupancy analysis of a new office building in Tokyo, The Tokyo Gas Kohoku NT Building, found that workers in new buildings have more positive attitudes and better work experiences compared to Tokyo's older existing office buildings. 12 1.2.3. High Energy C o n s u m p t i o n for Electr ical Lighting S y s t e m s The Relationships Between Office Value and Energy Consumption Traditionally, office value in Tokyo has been judged in terms of location, durability and aesthetics. Stakeholders or owners have been keen to invest in any visible marketable qualities to improve their buildings. Improving energy efficiency and indoor office environmental quality tends to be ignored because it is not an immediately visible asset and because the concept of energy efficiency has not been historically readily marketable in Tokyo. However, reducing energy consumption for office buildings has been a major issue in Tokyo contexts because of the Kyoto Protocol which suggests that Japan has committed to reducing greenhouse gas emissions to 6% below 1990 levels (1996) (note. 1-7). The benefits associated with energy efficient buildings and high quality working indoor environments are increasingly desirable in the Tokyo office market (Hatanaka and Seino, 2002). Energy Consumption for Electrical Lighting Systems TMG indicates in the Tokyo Plan 2000 that the commercial building sector represents approximately 57% of the total annual energy consumption in Tokyo. As shown in Figure 1-8, electrical lighting systems represent approximately 40% of the total building energy consumption for typical office buildings especially those designed between the 1970s and the 1980s. The TOTO Journal (2001) suggests that the cause of the high electrical lighting use for existing office buildings can be attributed to: > a deep building plan > poor provision of natural lighting > lack of personal control over ambient conditions > open plan offices (which produce uniform lighting conditions) As described above, the correlation between the design of office configurations and electrical lighting systems tends to be ignored in typical existing office planning. Older Tokyo office buildings were built at a time when standards for acceptable office environments were much lower than the standards of today. Because of this, it has become **- Note. 1 -7: The world's governments \ adapted the. landmark Kyoto Protocol on,11 December 1997. . The Kyoto Protocol proposes new *Jground,with':its legally-binding r constraints 'on greenhouse gas emissions and its innovative , tmechanisms aimed at cutting the •• cost of curbing; emission. Todayv1 • y i 86 countries (including the • f European Community) are Parties "to the Convention, more than most. ' any other environmental treaty, % and the entry.into force of the .'. * "Kyoto Protpcbiis expected. 13 more difficult for these older office buildings to meet today's interior environment standards without significant modification to their building configurations. Energy Consumption for New Office Buildings Recently however, Tokyo's newer office buildings produce considerable energy savings in electrical lighting management with the use of natural lighting. When natural lighting is not involved as a part of lighting management, the energy consumption of electrical lighting systems occupy between 40 and 50% of the total energy consumption for office buildings. On the other hand, when natural lighting is well designed with supplemental electrical lighting systems, this can be as low as to between 7% and 40% of energy consumption (ECC, 2002). Electrical lighting management utilizing natural lighting availabilities can greatly reduce energy consumption and increase occupant satisfaction, enhancing office productivity. 14 1.3. Current Office Renovat ion Techn iques Current occupant satisfaction research performed by Sumitomo Trust & Banking Co. Ltd indicates that approximately 23% of existing office buildings are in the process of planning or performing office building renewal to counter dissatisfaction with current indoor environments. Another 30% of them in the Tokyo office market have a need for either renewal or renovation (fig. 1-9). Thus, more emphasis on office renewal and new economic incentives to encourage building owners to accelerate office renovation is required. Opportunity for Office Renovation or Demolition for Tokyo's Existing Office Buildings In the process of planning for renewal Thinking of renewal or demolition Not considering renewal or demolition Considering renewal or demolition No answer 10 20 30 I I ^ ^ ^ ^ ^ ^ ^ • 2 3 • 41 9 • 3 12 40 50 : . Fig.1-9: Approximately ! .55% of existing office ,/ ;•' buildings is required for office renovation or i demolition. • i. " ':.'•«!,.: V:! ,/' •.; • • i] (Source: Sumitomo '• "• Trust & Banking Co.: Ltd., 2000) Current reasons for office renovation include: > Increasing the structural durability and seismic performance of existing office buildings > Improving the facade image of existing office buildings > Increasing the indoor office environment of existing office buildings > Improving the energy consumption for electrical lighting systems 1.3.1. Structural Improvement for Durability One of the most important objectives of current renovation techniques is to upgrade the structural durability of older existing buildings. As shown in Figure 1-10, these buildings, designed in the 70s and 80s, do not meet today's seismic standards. Improvements for building durability and adaptability may require a higher initial cost investment than that of the new office building construction, but this initial investment often has a beneficial impact in reducing a building's Life Cycle C 0 2 (LCC0 2) and Life Cycle Cost (LCC) by extending the life of existing office buildings. (Miyazawa and Kuwahara, 2002). 15 Reinforcement Structure 1970s 1980s Today Under 30 cm vUnder 15cm Vertical Reinforcement Under 10cm Under 10cm Horizontal Reinforcemant Fig.1-10: The today's standards of structural durability are design to endure horizontal force rather than vertical force. (Source: Kashimakensetu Co. Ltd.) Current construction techniques for increasing the structural durability of existing office buildings often limit the amount of natural lighting to interior. As shown in Figure 1-11, 350mm X 350mm supplemental structures to achieve today's durability standard are employed as an integral part of fenestration improvement. Figure 1-11 also shows that during the initial stage of current office renovation processes, the potential of Fig.1-11: current office renovation techniques improve structural bringing external natural lighting to the interior is currently durability while avoiding the induction of natural lighting to ignored. Therefore, in current office renovations, the term interior. 'energy efficiency' with regards to electrical lighting systems ( S o u r c e : Sumn°moTcrfucfa2ooo) typically refers to installation of energy efficient electrical lights such as fluorescent lap, ignoring natural lighting. 1.3.2. Improvement of the Appearance of Office Buildings Improving the facade using curtain walls is a common practice for upgrading a building's image and value in Tokyo's office market (fig.1-12). The reason is that the building facade facing the street is typically the only opportunity available for upgrading within Tokyo's dense urban constraints, and it is much more economical to improve a single building facade rather than demolishing the entire building. Figure 1-12 indicates that as buildings are located more tightly together, demolishing and redesigning them involves additional concerns including relations with owners of neighbouring buildings. Therefore, reconstruction of the main building facade provides an effective and simple office renovation application within Tokyo's context. Fig.1-12: Current office renovation techniques use curtain walls to improve the facade of office buildings (Source: TOTO Journal; 2001) 16 Currently, renovation of Tokyo's existing office buildings involves primarily installing curtain wall systems, with very little consideration given to Tokyo urban context or the implication of natural lighting. One reason for this is that these curtain wall fagades are economical to build and may have a conspicuous presence as a modern architectural design (Miyazawa and Kuwahara, 2002). From the perspective of good natural lighting, they effectively act to control direct sunlighting during summer time to reduce energy consumption for HVAC operation systems although they may provide insufficient distribution of natural lighting to interior and provide far from delightful environments for office workers. Installation of curtain walls to upgrade building facades without any consideration of Tokyo's urban context often fails to take advantage of the important potential of natural lighting. Alternative renovation methods that enhance both facade design and interior quality through the induction of natural light are necessary. 1.3.3. Increasing the Productivity of Older Exist ing Off ice Bui ld ings One simple means of improving the work conditions in older buildings is to improve office telecommunications and networking systems. This has a positive impact on the productivity of office workers (Miyazawa and Kuwahara, 2002). Although this approach to Information Technology (IT) renewal (note. 1-8) may be a necessary and appropriate response to poor office productivity, IT renewal alone is insufficient to make these older office buildings competitive with newer buildings which possess both advanced telecommunications capabilities, and better interior environmental conditions. Innovative design, which induces natural lighting to the interior, can help to enhance interior environments and increase the market value of existing office buildings. 1.3.4. Upgrading Energy Eff iciency through Electr ical Lighting S y s t e m s Currently, the installation of energy-efficient electrical lighting systems is a common method of upgrading current indoor office environments. New lighting systems effectively integrate energy efficient lights with operating controls such as motion sensors, and automoatic dimming and computer operated controls to provide more flexibility, energy-efficient operation, and a longer service life than conventional lighting systems. Using these efficient lighting systems, buildings can generally reduce their lighting energy by approximately 25 percent and result in an indirect reduction in cooling load. Office buildings located in high-Vf. »•,:•!««<.' iv. p>-u-vsi«r. >»:"• «Note.1-8: Information Technology.;:-; (IT) renewal is commonly \ j)** implemented as an essential part;'3? . of office renovation to improve ; : * % *>. pfflce'productiv'ity. '• The term 'IT' ",;jfll renewal' is to encourage the -L'Xi •"' replacement of energy consuming ..Office Automation (OA) equipment-X ijf'and highperformarice networking^ ; systems. Other electric appliances |> ; with energy efficient such.as , - . . . . • electrical lighting systems-are well ...» integrated!w|th,innovative OA '^«>pjH '^ enVironmehV.)C-'";:-' ' i , ' . 'Li V : . ' h ' t t B i >:i ?'X : ••• .' \ ':.f s (Source: Kenchiku Setubi Navi, • \ - ; ' ^ . v ^ f e ^ ) : ; 17 density areas of Tokyo can reduce energy from electrical lighting by more than 40 percent (ECC, 2002). 1.3.5. Green Renovation with Natural Lighting The Guidelines for Assessment of Environmental Friendliness of Government Building Facilities and Renovation Plan (EFRP) highlight the effectiveness of the coordinated implementation of both natural lighting and electrical lighting control strategies. In some buildings, natural lighting in combination with a dimming system or motion sensor reduces lighting power density by approximately 60% per year. However, the applicability of these innovative electrical lighting systems alone may not work in office buildings located within dense urban conditions due to the limited amount of natural lighting throughout the year. In Tokyo's dense urban context, these innovative systems can provide better performance when combined with natural lighting control devices. Natural lighting control devices enhance the distribution of natural light in the interior due to the increase the capability of an interior natural lighting level. Environmentally friendly office renovations should offer natural lighting control applications appropriate to the specific lighting needs. 18 1.4. C u r r e n t D e c i s i o n M a k i n g f o r N a t u r a l L i g h t i n g W i t h i n T o k y o ' s C o n t e x t s 1.4.1. Dec is ion-Making for Office Bui ld ings with Natural Lighting The issue of energy consumption for the large number of smaller office buildings is more critical than that of a fewer number of larger new office buildings. Taken individually, the energy consumption of these small buildings may not be that significant, but collectively, these buildings represent a tremendous portion of the energy consumption in Tokyo. What is needed are effective office renovation guidelines using natural lighting to address the wide range of urban scenarios facing older existing office buildings (Miyazawa and Kuwahara, 2002). Natural lighting clearly provides considerable opportunities for improving the energy efficiency and comfort-levels of office working environments. However, there are still several major technical and market barriers which hinder the application of natural lighting as a retrofitting strategy which have yet to be overcome. These barriers include: > The lack of knowledge and information regarding new fenestration technologies and lighting control systems and the ability of such systems to enhance natural lighting utilization: Architects, decision-makers and the Tokyo Metropolitan Government tend to be unaware of the potential benefits of natural lighting. > The lack of convincing evidence for tenants that natural lighting can substantially improve energy efficiency and indoor environmental quality in Tokyo's office buildings. > Poor application and understanding of environmental assessment tools for existing office buildings using appropriate natural lighting design techniques applicable to the Tokyo contexts. > The lack of regulations or codes of practice in place to encourage the use of natural lighting for Tokyo contexts and to ensure that it is given due consideration at the design stage for retrofitting existing office buildings. > The lack of documentation of examples of successful implementation of the retrofitting of office buildings with natural lighting, which can raise the owner's 19 awareness of the benefits of natural lighting and encourage a more widespread use of natural lighting for upgrading office buildings in the future. 1.4.2. Lack of Dec is ion Makers for G o o d Natural Light ing The decision to use natural lighting has to be made early on in the renovation design process because natural lighting considerations affect the form and layout of a building, (Balcomb, 1992). However, it is rare that lighting specialists are employed at the beginning of the decision making process for conventional office renovations in Tokyo (fig. 1-13). Furthermore, when architects design the building facade, they often neglect to include any assessment of opportunities for natural lighting to increase interior lighting performance and reduce energy consumption. Relative Number of Delsgn Consultant Involvement (architects, city planner and Government consultant) Natural Lighting Designer' Involvement E o CL •c o Q . o E E tO 0- CL 2 O S. » i f CD ca CD ±z 2 85 <5 1 CD 3 CO n 6 o 3- & < Q « cl CO o N, c CD E CL o CD > CD a -5> E a 8 Q 0 £ E m i 1 S 8 U - C ~ CO 0. CD L > CD C E £ CD > O CD co CD Q . O •o I s § 1 C L ,CD 8 s O 5 In the current process the design team is not properly defined the goal of daylighting performance Daylighting performance is usually an unknown until this point Fig.1-13: Conventional office renovation process with natural lighting ,. •y (Source:.Building Research & Information, 2000) The relationship between initial cost and payback is a primary concern for building owners considering design with natural lighting. Near-term payback, initial cost, and project schedules can help to show the profitability of a building renovation approach, and to convince office building owners that designing for retrofitting is a better alternative than demolition. Typical office buildings with daylight dimming sensors or switching require 3.8 or 4.2 years for payback ( E C C , 2002). If natural lighting strategies are to be effectively implemented, the task is to present owners with convincing evidence of the more short-term 20 paybacks of investment at early stages in the design process. The case for retrofitting office buildings with natural lighting can be strengthened by offering solid demonstration of its enhanced performance relative to typical practice - both through successful case studies, and through the use of simulation techniques during design. 1.4.3. A s s e s s m e n t of S u c c e s s f u l Naturally Lit Office Bu i ld ings in T o k y o Sophisticated environmental assessment systems provide a means for rating environmental efficiency and natural lighting performance. Existing assessment systems, such as the Comprehensive Assessment System for Building Environmental Efficiency (CASBEE) (note. 1-9), allow for performance evaluation comparisons between alternative design options, and between design options and actual buildings or performance standards. Such performance assessment systems may provide a grading system which may create a potential for the benefits of environmentally friendly strategies, such as innovative office renovations with natural lighting, to respond to demand in an increasingly environmentally conscious Tokyo office market (Papamichael, 2000). Note.1-9::CASBEE is comprised of a variety of assessment tools which can.be used'during the.design process.These • si j .include Rre-designAssessment Tool, DfE (Design for Environment)iTool; Eco-labeling Tool and Sustainable Operation . ••: and Renovation Tool." Each CASBEErTool has its own purposes and is intended for,:specific target users as explainedV. V below: , • 'V " ' , • >-' •* ; - i ,i' i i , i. i ; Tool-0: Pre-design Assessment Tool' ' >' \ , f . ?,\Sr ' ' Enable owners and planners to identify the basic context of the project. This tool'will suggest proper site selection and the < '. basic impact of the project. ' ' ; „ . . • . ' '•''' ' Tool-1: DfETool^ •» " , ' ; v ' " -Provide a,simple self-evaluation check system"for designers and engineers for improving the building.environmental* = \ ,; efficiency of relevant buildings dunng the design process. - V1 , ' ','<' -p1"' , - - "*• " • , Tool-2: Eco-labelihg Took., * - • ' , 1 ',• . • • •> - , t, '' , 'Evaluate to rate, buildings in terms of building environmental efficiency aftercompletion. This tool can also be used to,: determine the basic property value of the labelled building in the'market., " i - , -V* . /• 1 >' •' Tool-3: Sustainable Operationand Renovation Tool ' ' -'-^ ' »{* ' • ' l . . ' ' V Provide information/conceminghow'to improve the buildingenvironmental'efficiency of their own building property during . the post-design process for building owners and managers. 1 • „ -'V , J • "* „ v • • • • 1 ( S o u r c e : Japan Sustainable Building Consortium, 2002) •( The accuracy of performance prediction and estimation depends on the simulation software model. Sophisticated models, like DOE-2 (note. 1-10), usually require more detailed input but are more time consuming and open to errors in input data. However, performance prediction can be made more effective by providing a software tool that is fast and relatively easy to use. As an integrated part of the Note.1-10: DOE-2, widely used in North America,'calculates the • ' ' , hourly energy use and energy cost ' s, •pfW.commercial brresidential '.'ibuiidirig given information about •"' * the building's climate, construction; operation, utility rate schedule and • . heating; ventilating, and air-conditioning (HVAC) equipment. •\ (Source: Ernest Orlando Lawrence :: Berkeley National Laboratory, 21 environmental assessment process, such a software tool could help inform designers about what may or may not be possible, and allow them to test proposed design solutions against defined green performance criteria and standards. 1.4.4. Regulat ions and C o d e s for Natural Light ing According to Japanese Building Code, Part 44, "Restrictions on Extended Objects into the Street", only neon signs are permitted as extended objects on the building facade. This creates a significant limitation for current renovation techniques. Reconfiguration of facades to allow for projections into the street requires permission from the TMG. However, the Tokyo Metropolitan Government White Paper 2000 states that these existing building codes or standards may be mitigated or modified to allow for environmentally friendly office building renovations, as long as the renovations are clearly evaluated with existing assessment tools such as CASBEE to provide reliable documentation of the benefits for energy efficiency or for the indoor office environment. With such mitigated approaches, the use of extended facade configurations and objects such external light-shelves to enhance interior environmental performance are made more feasible. The Guidelines for "Environmentally Friendly" Government Building Facilities and Renovation Plans, published by Ministry of Land, Infrastructure and Transport, establishes a set of guidelines for "green" office renovation. To some extent, these guidelines suggest that the integration of natural lighting with energy efficient electrical lighting may help in reducing energy consumption and improving indoor office environments. However, as shown in Figure 1-14, the extent of the discussion on natural lighting control in these guidelines (EFRP) is restricted to shading against excessive direct sunlight. The feasibility of natural lighting control devices for providing an effective light source through strategies of distribution to the interior is largely ignored in these guidelines. Research and Development (R&D) to establish techniques for controlling natural light are critical for demonstrating and communicating the value and economic viability of natural lighting for the Tokyo's office market. The fixed 500mm size of overhang is required for shading direct sunlighting on the south side. Window opening is required for the 60% of total height from floor to ceiling height Fig. 1-14: office building fagade design with natural lighting iQruirr/z; hAini^tn/ rtf Hrtn<;triirtinn 1QQ7\ 22 1.5. T h e s i s O b j e c t i v e The objective of this study is to position natural l ighting strategies as an integral part of office renovation planning and to suggest that natural lighting may provide innovative techniques to increase the market value of Tokyo's existing office buildings. Effective natural lighting control dev ices can take advantage of the benefits of external natural lighting even within Tokyo's dense urban situation and distribute them to office interiors. This thesis argues for analysis at a preliminary stage of renovation, to identify the effective design parameters for installing natural lighting control devices and to evaluate the potential of lighting control devices for improving indoor environmental performance. The structure of the paper is as follows: Chapter 2: Fundamental Principles of Natural Lighting provides an introduction to natural l ighting both generally, and specifically in relation to the Tokyo context. Chapter 3: Natural Lighting Design proposes a set of progressive office renovation guidel ines using natural lighting strategies appropriate to Tokyo's dense urban context. Chapter 4: Evaluation Technique for Natural Lighting suggests a s imple model l ing software that can be used in the initial stages of the office renovation process to generate a 3-D model and test indoor environmental performance against design parameters of control devices. Chapter 5: Hypothetical Office Building defines a hypothetical office bui lding and parameters which will form a model for analysis in Chapter 6. The software identified in Chapter 4 is used to design a typical Tokyo office building, which may have potential for widespread application. This model includes considerations of Tokyo's dense urban context, including Tokyo's microclimate and the configuration of Tokyo's existing office buildings Chapter 6: Effective Natural Lighting for Tokyo Office Renovation defines a method of analysis and des ign for effective natural l ighting within the T o k y o context. The model established in Chapter 5 is analyzed with the evaluation software described in Chapter 4. This analysis involves the following three stages: 23 Direct Sunl ight ing Control (shading): establishes a possible set of control devices according to the minimum design parameters which allow the devices to function effectively as direct sunlighting control devices (provide shade from excessive direct sunlight in the summer, and allow direct sunlight penetration in the winter). The assumption is that direct sunlighting control is a necessary first requirement of natural light control. This part of the analysis therefore establishes the minimum parameters for possible control devices, which can then be modified to meet daylighting needs. Daylighting Contro l (distribution): The key design parameters of natural lighting control devices to enhance the performance of daylighting control for distribution to the interior are developed using modeling software. This provision for the design modification of modified possible control devices is developed with the analysis of available daylighting performance under the conditions of Tokyo's dense situation. Evaluation of Effective Control Dev ices: re-evaluate the interior natural lighting performance of effective control devices which have a high potential for applicability within the context of Tokyo's older existing office buildings. 24 2.1. Fundamental P r inc ipa l s of Natural L ight ing In Japan, architects and lighting designers often undertake office renovations with little understanding of the fundamental principles of natural lighting. Included in these natural lighting fundamentals is an understanding of: > The types of natural lighting > The methods for control of natural lighting Littlefair (1986) argues that understanding the fundamental distinction between the two types of natural lighting, direct sunlighting and daylighting. is critical to designing successful and effective natural lighting control devices. 2.1.1. Types of Natural Lighting The two principle types of natural light, as classified by Lam (1986), are as follows: 1. Direct sunlight: sunlight shining to the interior during clear sky conditions. In general, direct sunlighting is a directional light, determined by the position of the sun in the sky. Within Tokyo's context, the year can be divided into seasons according to the impact of direct sunlighting on building interiors: a) Excessive direct sunlighting occurs in hot seasons, when cooling is needed. In general, the hot season in Tokyo occurs during the months of June, July, Aug and Sept (EFRP, 2001). During the hot season, direct sunlight may negatively impact the interior environment, producing overheating (increasing potential cooling loads) and creating glare problems. Excessive direct sunlighting during hot seasons should be controlled to minimize these negative impacts. b) Beneficial direct sunlighting occurs in mild seasons, when heating is required. The mild season in Tokyo occurs during the months from October to May. During mild seasons, direct sunlight may have a positive impact on the interior environment, potentially reducing heating loads. Beneficial direct sunlighting should be induced during mild seasons to take advantage of this potential. 25 2. Daylight: diffused sunlight that is produced when sunlight is filtered through sky and clouds (such as in overcast sky conditions), or when direct sunlight is reflected from artificial surfaces. Because of diffusion, daylight is an ambient light, more evenly emitted by the sky vault but less intense than direct sunlight. The quality and quantity of natural light (both direct sunlight and daylight) changes in magnitude and pattern with the position of the sun, sky conditions, and the shapes and reflectivity of object surfaces. Direct sunlight provides the highest degree of illumination on a clear day. On a clear summer day in Tokyo, outside light levels are generally in the order of 75,000-80,000 lux, while on an overcast winter day this might fall to around 10,000 lux. Uncontrolled direct sunlighting may not provide a very effective light source. Its intensity can be a significant source of overheating and glare when falling on work surfaces or reflected off computer screens. As a result, in order for direct sunlight to be of use for interior lighting, it must be reflected and distributed from surfaces. On the other hand, daylight, which is diffuse, generally provides a much more effective light source, providing a high quality of light often without reflection. Daylight can act to improve indoor environmental conditions and reduce eye problems or sick building syndrome (see Chapter 1.2.2.). Within Tokyo's dense urban situation, daylight is often more useful than direct sunlight. In cases where streets are narrow, and office buildings are positioned close together, direct sunlight cannot reach the lower stories of buildings and only affects the upper stories. At the same time, daylighting available to lower stories is also greatly reduced. The traditional response to this problem has been to outfit these buildings for an extensive use of electrical lighting systems. Office renovations designed to make use of natural lighting provide a much more energy efficient solution to this problem. 2.1.2. Basic Natural Lighting Control Direct Sunlighting Control Direct sunlighting control employs the following functions: > in hot seasons, shading excessive direct sunlighting from the interior > in mild seasons, inducing beneficial direct sunlighting to the interior Providing solar shading on windows through overhangs, solar control glazing, and internal blinds reduces the amount of solar energy that enters the building interior. However, these 26 devices act only to limit the heat gain from excessive sunlight, but fail to take advantage of effective natural lighting by distributing it to places where needed. These devices depend on electrical lighting to provide sufficient light for interior office work. Three common traditional techniques for currently applying direct sunlighting control with office renovation are: > overhangs > curtain walls > internal blinds a) Overhangs — As shown in Figure 2-1, the E F G B recommends that "shading summer's excessive direct sunlighting is effective to prevent glare and overheating to interior using overhang or louver". These direct sunlighting control devices are externally mounted static elements above windows which prevent the sun from striking the glass, but which do not allow occupant control of quality and quantity of direct sunlighting. Although the function of overhangs and louvers described on the E F G B shades the summer's direct sunlighting while inducing winter's beneficial direct sunlighting to interior, their usefulness is limited in Tokyo's urban space because they fail to effectively redistribute natural light to the interior where it is most needed. Direct sunlighting during summer seasons j Fig. 2-1! Balancing seasonal I j shading devices reduce the j I summer's direct sunlighting ,while|ij j providing winter's one. I r (Source: Tips for Daylighting witti^ | * window, 1997) j b) Curtain walls — Direct sunlighting can also be controlled through the installation of curtain walls which employ reflective (mirrored) or absorptive (tinted) glass which limits the amount of sunlight penetration throughout the year (fig. 2-2). The quality of indoor lighting levels created by curtain walls tends to be uniform because of the lack of occupant control and natural lighting distribution. Curtain walls are quite effective in reducing solar heat gain while allowing for limited natural light penetration. However, curtain walls may be an ineffective solution in many circumstances, as curtain walls reduce direct sunlighting throughout the year without any seasonal consideration (for the potential benefits of direct sunlight for reducing heating loads) and without consideration of the potential of direct 27 sunlight distribution to meet interior lighting needs. Curtain wall strategies are currently used widely in Tokyo office renovations, with little consideration for their limitations. Architects and lighting designers need to weigh the benefits and drawbacks of the curtain wall strategy if they are to make an informed design decision. Direct sunlighting is effectively shaded during summer seasons. Direct sunlighting is also shaded during winter seasons. r^ Flg".^ ''i?-2: 'curtain •' walis*l'br;:':lowSi {transmission glass shade direct j .sunlighting through a year without d^istribution performance: ''?*( if; (Source: TipsforDaylighiingwithY] ' r": window, 1997) c) Internal blinds — In Tokyo's older existing office buildings, internal blinds are often employed as simple direct sunlighting control devices. As shown in Figure 2-3, they are easily mounted to windows to screen interiors from glare and excessive heat gain. However, internal blinds are often post-design solutions to problems of excessive sunlight. Because architects are typically responsible for designing building form and envelope components, design of office renovations which perform the shading function through facade elements give the architect more control over office interiors. Direct sunlighting is controlled by occupants throughout a year Fig. 2-3: Simplecqntrpl devices.for i direct sunlighting currently installed on Tokyo's existing office buildings ; (Source: tips for Daylighting with j - window, 1997) ' Daylighting Control Daylighting control may have more potential for widespread application retrofitting Tokyo's existing office buildings than direct sunlighting control because it creates more uniform 28 distribution of light regardless of sun position and obstructions. Daylighting control strategies can be applied to two types of diffuse light: > direct sunlight which has been reflected from surfaces or diffused > daylight which has been naturally diffused by clouds, or other reflective surfaces As shown in Figure 2-4, diffusion of direct sunlight increases its potential as a useful, reliable, and stable natural light for deep interior spaces (Lam, 1986). In dense urban contexts, direct sunlight is only available in the upper floors of office buildings. In order to make full use of this limited direct sunlight, strategies of reflection and diffusion from the surfaces of installed control device can help to enhance the brightness balance of the interior natural lighting level and increase the potential naturally lit area. Direct sunlighting provides higher performance at window side. (: Fig. 2-4: Curves show indoor light ] ; level both direct sunlighting and ; I? diffused direct sunlighting I |" • *t - » .•. • i • - • ' i J}:f(S6urc^ The amount of daylight available is related to the amount of unobstructed sky visible (Lam, 1986). In general, unobstructed office buildings receive much more illumination than obstructed buildings. However, as most of Tokyo's existing office buildings are located on narrow streets which create constraints for daylight availability, it is necessary to enhance daylighting performance for the interior, especially in lower floors, through innovative daylighting control devices. The objective of daylighting control is to maximize illuminance levels to create comfortable and delightful space using reflected direct sunlighting and daylighting, and to minimize the need for supplemental electrical lighting systems (Bodart and Herde, 2002). Integrated with electrical lighting controls such as automatic switching or dimming systems, daylighting control devices can dramatically reduce energy consumption. Diffused direct sunlighting through natural lighting control devices improves the lighting level of deeper space. 29 2 . 2 . D e f i n i n g Natura l L i g h t i n g S t r a t e g i e s A "natural lighting strategy" is a general term describing a broad building design approach focused on the appropriate application of fundamental principals of natural lighting. Applied, current natural lighting strategies involve "natural lighting control devices" which respond to external natural lighting conditions and control the amount and distribution of light that enters a building. 2 . 2 . 1 . P o s s i b l e Natural Lighting Contro l Dev ices Current renovation techniques in Tokyo are often successful in preventing the admission of excessive direct sunlighting without the use of control devices. This can be achieved through the installation of curtain walls fitted with solar control glazing which limits the amount of direct sunlight which is transmitted to the interior (described in 2.1.2). These control devices are therefore successful regarding the function of solar control. Innovative natural lighting control devices which seek to distribute daylight to the office interior must therefore achieve this same level of solar control before they can seek to improve interior lighting conditions through daylighting. Therefore, for this study, the set of possible natural lighting control devices is defined as the set of control devices which at the minimum are successful in shading the interior from excessive direct sunlight in hot seasons. 2 . 2 . 2 . Effective Natural Lighting Contro l Dev ices In this study, natural lighting control devices are considered effective if they are successful in enhancing the interior illuminance level. Their basic function is described below: Effective natural lighting control dev ices are devices which are installed on existing office building facades to control the admission of natural lighting, both direct sunlighting and daylighting, and manage its penetration to the interior. The following functions are simultaneously performed through these control devices: > Shading against excessive direct sunlight in hot seasons to reduce glare and overheating while allowing for beneficial direct sunlight in mild or cold seasons (described in Section 2.1.2.) > Distributing direct sunlight and daylight to illuminate spaces deep within the interior 30 Older existing office buildings in Tokyo, designed in the 70's and 80's when energy was abundant, were typically designed to maximize office space, and isolate conditioned indoor spaces from the external environment. These buildings tended to rely heavily on electrical lighting systems. On the other hand, naturally lit office buildings (office buildings which are retrofitted with effective natural lighting control devices) can produce better indoor work environments by taking advantage of a higher quality natural light from the exterior. 2.2.3. Funct ions of Naturally Lit Office Bui ld ings There are two main functions of naturally lit office buildings: 1. Effective Indoor Illuminance: Enhancing indoor illuminance by shading direct sunlighting and distributing daylighting to occupied spaces. There is a widely held view sated on the EFRP that the 600 lux interior illuminance on the desk level (800 mm from the floor) and optimal lighting quality lead to better work environments, a higher level of worker satisfaction, and potentially a higher level of worker productivity (Ministry of Construction, 2001). 2. Energy Ef f ic iency: Minimizing the energy consumption of electrical lighting systems and cooling systems. Design optimization is essential to both maximize indoor environmental performance, and to minimize energy consumption. Design optimization involves: a) Controlling natural lighting to reduce energy consumption for electrical lighting systems by effectively distributing direct sunlighting and daylighting to the interior. b) Controlling natural lighting to reduce the cooling load by shading direct sunlight from the interior. Currently, in Tokyo, the primary interest in naturally lit office buildings is their reduced energy consumption relative to those that are primarily electrically lit. What is often overlooked is the potential of naturally lit office buildings to provide higher quality lighting for indoor environments versus electrically lit buildings. Retrofitting existing office buildings to perform both of these functions can add value to these buildings and make them more competitive in Tokyo's office market. 31 This chapter aims to review existing Japanese environmental guidelines, and establish a foundation specifically for retrofitting Tokyo's existing office buildings with natural lighting. Currently, architects who specialize in natural lighting are uncommon in Japan. In order to facilitate opportunities for design with natural lighting, a new Framework for Office Renovations with Natural Lighting in Tokyo is developed. As shown in Table 3-1, the process involves three essential components: > The natural lighting design process > team decision-making > natural lighting design evaluation software tools Although the EFGB and EFRP include discussions of the natural lighting design process, team decision-making, and natural lighting design evaluation software tools, these existing guidelines fail to effectively discuss any approach to integrate these three components. This Framework for Office Renovations with Natural Lighting proposed here offers a recommendation for the relative levels of involvement and impact of these three components. 32 o o I-UJ tt < o CO CO CO LU o o tt. a. z tn ui Q CD z I-X o u. o UJ CO < X O. o z < o CO o UJ o s < UJ UJ CO < TD o '» CD CL CD "> CD DC CD rx cu E c I CO > o CD o 'l CD D_ c a .2 o cn CD c TD TD CO o 3 i_ «> c o o c '<5 CO co c g CD Q. O TD C CO >. o c CO Q. 3 CJ O O cn c 'F CD I s 'E S E •-o <o o 2 The value of office buildings are resolved, (architects, clients, lighting designers, government consultant and government consultant) The full design team is assembled, (architects, clients, lighting designers, government consultant and government consultant) Natural lighting design professionals are added when issues are defined that can be addressed by project, (architects, clients, lighting designers, and government consultant) Core Design Team Selection (architects, clients, and government consultants) CO g Tool lr CD cp i ro "co h_ 3 o CO to c T3 on an —: CO CO <o i_ CD CO O aj 2 c 0_ CD c CO 'co CD CD Q ighi ting •j d_ CO •2 Li a <0 3 -a "co z CO c w 1*: c CO o J° cz •V o o c 'u> Dec CD ti E £ CO 0 O 1— •» .o c «c o •s CO o > no CD CD E L_ (Q CD ,W. O U. i t CO o co iho "o >> UJ CD o .Q (— CO -*-» <0 co jr en f- CD O —^ 2 CO o. CD c CO JD 'to ra CD 1- "O 33 3.1. Natura l L i g h t i n g D e s i g n P r o c e s s The purpose of the proposed framework is to modify the way current office building renovations are managed from the design phase to the operational phase of natural lighting strategies. This framework suggests the advantages of an integrated design approach emphasizing team decision-making, the natural lighting design process and software tool evaluation. The shift from current office renovation techniques to an innovative office renovation process enables office buildings to be environmentally responsive and responsible. This framework suggests an office renovation and design process that may be useful, functional, and cost effective for clients. Table 3-2 presents the basic structure for this Tokyo office renovation framework. Current office renovation methods offer a workable model of how to provide direct sunlighting control using curtain walls. However, there is a lack of documentation on appropriate methods of prediction and assessment of daylighting control devices on indoor environmental performance. 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O •— O) - T T J CO c CO 0 CB to CO 3 V) CD c c .3? =5 CO ~ 0 3 •a xi cz ra 0 — S ~ a.; 3 _ CO *. 5 » -co a 0 (0 t— c CO o 3 x a. 0 I f p P u o u6isaa AjeujuineJd 3.2. Team Dec i s ion- Making As shown in Figure 3-1, innovative renovation projects using natural lighting may require more specialization and greater initial investment than more common office renovation methods, due its more complex and difficult nature. Fig. 3-1: Relationship of cost and the decision-making for natural lighting with office renovation. ' .. (Source: Building Research & • Information, 2000) Opportunities for cost-effective office renovation with innovative team decision-making process Costs raise if daylighting strategies are addressed later in the renovation process Time 3.2.1. Budget of Renovation Process Innovative renovation strategies require building owners to make significant investments. To receive financing and government approval, owners may have to spend additional money on various consultants who can address fundamental interior natural lighting performance through control devices and integration issues of supplemental electrical lighting systems with existing office building structures. Current office renovation processes (using curtain walls) provide few benefits for interior lighting and energy efficiency, and have slow pay-back periods. To provide a better alternative to this current situation, an innovative design process should involve the full design team in the early stages of decision making. While it may be more expensive to perform assessment analyses for accurate natural lighting modeling at an early phase of design process, naturally lit office buildings provide an improved pay-back period due to energy savings and may have increased market value. 37 3.2.2. The Involvement of Specialists Figure 3-2 illustrates that a higher level of involvement of design consultants (clients, architects, government consultants, natural lighting design specialists, facility managers and developers) occurs at the preliminary phase in the innovative design process. What is emphasized is the need for a more complex pattern of involvement by specialists at the various phases of the office renovation process vs. current design processes. Some members of the design team (clients, architects, and developers) are currently involved at the earliest stages, but natural lighting design specialists tend not to be involved until after the site is selected (fig. 3-2). When clients recognize an opportunity or need for building renovation with natural lighting, the idea is tested and analyzed with natural lighting design specialists. This graph stresses the importance of involving natural lighting design consultants at an earlier stage in the renovation process, to provide prediction and assessment of natural lighting opportunities through control devices. Other specialists may focus on environmental concerns at different levels, including office layout, building structure, and electrical lighting systems. As a result, an integrated fc-'Figf' *|j3h ;f Opportunity for natural |, lighting d^esign in the .integrated i design'process .„ (Source: Building Research & Information, 2000) Natural Lighting Design Consultant Involvement Relative Number of Consultant Involvement (architects, city Planners and Goverment Consultant) With daylighting consultant daylighting performance has been achieved The full Design Team is assembled. Including the Builder and Commissioning Authority flighting specialists are added as issues are defined that can be addressed by project Gore Design Team selected 38 approach to natural lighting design should involve collaboration of all specialists and teams from the initial phase of building design is required. 3.3. N a t u r a l L i g h t i n g D e s i g n E v a l u a t i o n T o o l s The proposed framework describes four phases for the evaluation of interior natural lighting performance of natural lighting control devices using software tools. These four phases should be integrated with the phases of the natural lighting design process. 3.3.1. Pre -Des ign The objective of using software tools at the pre-design phase includes two points: > To evaluate current illuminance levels (with no natural lighting control devices) for Tokyo's existing office buildings > To establish the target for obtainable interior natural lighting performance through natural lighting control devices Establishing a target for obtainable interior natural lighting performance through control devices is often ignored at the pre-design phase with current office renovation methods. This reflects a failure to recognize that natural lighting affects the decisions of entire office building configurations. It is therefore critical that natural lighting design specialists provide these goals to the clients and other team members at pre-design stages. 3.3.2. Prel iminary Design There are two key points that the software tool should facilitate as the preliminary design proceeds: > To model design parameters for possible natural lighting control devices (which mainly effect direct sunlighting control) > To the establish a set of possible control devices using evaluation software In the preliminary design phase, the software tool is used to establish a set of proposed poss ib le control dev ices (devices which successfully provide the minimum requirements of sunlighting control) applied to an office building facade under various scenarios in the Tokyo context. 39 3.3.3. Design Development The integration of software tools and design development are used to find suitable control devices of natural lighting within Tokyo's context for producing comfortable, well lit indoor spaces and improve energy efficiency. Effective natural lighting control devices are developed: > To modify the design parameters of possible control devices (which respond to direct sunlighting control requirements) to increase distribution performance > To re-evaluated interior lighting level to ensure effective distribution performance while shading excessive direct sunlighting. In order to find suitable natural lighting control devices for Tokyo office buildings, the optimal design parameters of the modified control devices are developed through the use of the modelling software tool. The interior natural lighting performance achieved by these control devices is also re-evaluated to achieve the provided target at the pre-design stage within Tokyo contexts. 3.3.4. Const ruct ion Documents Well-documented energy and indoor environmental performance levels are required to ensure that the right steps are taken in the office renovation process and to gain financial support from government and financial institutes. This innovative design framework offers a better method for obtaining a well-organized document than current office renovation design processes in that it provides: > A quick, handy software tool which is used consistently throughout the design process > an effective process which integrates the design team, the design process and software tool 40 4.1. Research Software The investigation in Chapter 6 involves an iterative process of modification and evaluation which tests the impact of incremental changes to individual design parameters of proposed natural lighting control devices on the interior lighting levels of a hypothetical Tokyo office building (described in Chapter 5). Therefore, an ideal research software for modeling control devices and evaluating indoor environments should powerful enough to provide a realistic simulation and provide accurate results, while being flexible enough to evaluate simplified models with a limited scope of input data. While environmental evaluation software packages like ENERGY Plus and DOE-2, commonly used in North America or Europe to evaluate lighting performance in buildings, are very powerful and sophisticated evaluation tools, they may be less appropriate as design research tools where frequent evaluation, modification, and re-evaluation is required. These software packages are relatively complex, time consuming and expensive to use, and are more appropriate for use in situations where accurate and detailed input data is available. For this study, a flexible 3-D modeling and environmental evaluation software, ECOTECT v5.0, is used in combination with a more precise sun-ray analysis software, Desktop Radiance, to design natural lighting control devices for the hypothetical Tokyo office building. 4.1.1. ECOTECT v5.0 The advantage of ECOTECT is that it is easy to use, provides quick and relatively accurate results, and can be used to evaluate models of varying complexity (including models with a limited scope of input data). As such, it can be a very useful research tool for testing and modifying designs even at early stages of the design process where only more general input data are available (fig. 4-1). This flexibility makes it well suited for use in an iterative process of modification and evaluation in this study. 41 Performance Prediction Fig. 4-1: ECOTECT v5.0 is flexible and provides a quick and useful problem solving tool in an iterative design process of prediction and assessment (Source: Building Research & Information, 2000) At the same time, ECOTECT also allows for the input of more complex urban scenarios involving local obstructions at specified distances. In this study, ECOTECT v5.0 is used as a pre-design modeling software to: > Construct a 3-dimensional model of a typical Tokyo office building (fig. 4-2) > Construct 3-dimensional models of natural lighting control devices, and allow for modifications to the design parameters > Provide initial evaluation of interior natural lighting level of natural lighting control devices under both clear and overcast sky conditions in terms of (fig. 4-3): 1. Annual average value for specific space for interior natural lighting level (lux) 2. Specific node value for interior natural lighting level (lux) Lighting Analysis Daylig hling LavAis Fig. 4-2: ECOTECT v5.0, environmental design software, was developed by Dr. Andrew Marsh and Caroline Raines of Square One Research and the Welsh School of Architecture at Cardiff University. This figure shows an example of the interior illuminance level with 3D modeling. ECOTECT is used in this study as a software for its data analysis and quick evaluation research accurate relatively time. (Source: Square One <http://www. google, ca/search ?q =ecotect&ie=UTF-8&oe=UTF-8&hl=en&meta=» 42 Lighting Analysis Daylighting Levels Vertical Range. 0.00 - 6000.00 Lux © ECPTECT v5.0 Displays the annual average of natural lighting value at each grid point. This is the sum of all visible point values divided by the number of points summed. 1 2t 4205.79 4213.89 3802.13 g g T o a 454*8-1 4 n o i a? 4 ? i a -i|i S IB 12 1981.18 1995.48 1621.41 5 (7 30 1685 85 1740 72 1463.86 73 3892.51 4159.67 4207.35 3193.65 dhno 7n d»?fi 91 dans m 3JLL5.B5 1767.30 2036 18 2042 39 U 1174.80 1736.09 1565.33 122HHI 061 15 1500 79 1462 70 1307 46 807 64 744 20 1326 39 1497 31 1416 73 1 149.00 922 90*^ 0202 05 1211 25 1107.75 812.02 781 88 1162 78 1210 18 1147.15 900.36 793.93 1020 07 1038 03 1004.75 608.26 739.15 900 48 1105.48 1014.27 807.72 637 53 644 85 941.14 811.43 731.68 658.71 653.09 888.21 797.46 710.51 56991 60648 837 81 746 63 663 59 844 82 739 11 771 20 789.18 658 92 539.13 868 98 714.27 641.89 574.80 648 59 697 56 780 33 710.10 527 92 472.78 581 08 654 3 2 607 67 524 3 0 350.36 584 16 645 84 60089 824 76 464! 119.62 532 625. J Lux 5000* 14500-5000 | 14000-1500 I 3500 4000 3000-3500 | 2500-3000 | 2000-2500 I I 1500-2000 I 1000-1500 ; Average Value: 839.44 Luij Visible Grid Nodes 240 Fig. 4-3: interior natural lighting evaluation (Source: Square One </iftp;/Aww.goc /^e.ca/searc^^ In chapter 6, natural lighting control devices are applied to a hypothetical Tokyo office building and interior illuminance levels are evaluated to determine an optimum configuration. 4.1.2. Desktop Rad iance E C O T E C T is useful in that it provides a 3-dimensional modeling software which allows for easy modification to models and immediate evaluation of the impacts of changes on lighting performance. However, it has a limited degree of distribution evaluation, especially under clear sky conditions, where direct sunlight becomes a factor. A supplementary software is necessary to provide a more precise data set to verify results, especial ly to provide precise direct sunlight calculations to evaluate the models under clear sky conditions. Desktop Radiance is a very precise sun-ray evaluation software developed by the Lawrence Berkeley National Laboratory (LBNL), capable of evaluating the natural lighting performance of 3-dimensional models under both clear and overcast sky conditions (University of 43 California, Berkeley, 2000). It uses deterministic ray tracing techniques to evaluate illuminance levels resulting from interior direct sunlighting and daylighting (Ward Larson, 1998). Figure 4-4 shows the distribution analysis of direct sunlighting using ray-tracing algorithms; each view ray is traced from the point of measurement to the contributing light sources. Fig. 4-4: These figures show the interior natural lighting analysis performed by Desktop Radiance. Above picture shows the analysis under overcast sky condition with internal light-shelves. Below picture is performed under a clear sky condition. Both of them is evaluated under Tokyo open urban situation. Correlative use of both E C O T E C T (to construct models, and allow for easy modification and evaluation) and Desktop Radiance (to obtain more a precise data set for the E C O T E C T models) is effective for analysis of both direct sunlighting distribution and daylighting distribution. 44 4.2. R e s e a r c h P r o c e d u r e f o r Natura l L i g h t i n g 4.2.1. Bui ld ing Parameters for Evaluat ion The following is a summary of key input parameters which are included in the ECOTECT model to evaluate interior natural lighting (described in more detail in Chapter 5): 1) Office Building configuration parameters > Window configuration Size (1,600 mm X 1,200 mm) and position (900 mm height from floor) > Window type Single clear glass (8 mm thickness) > Ceiling height from floor (2,500 mm) > Building height (31 m) 2) Tokyo urban context > Building orientation South > Local obstruction (adjacent buildings) Distance (5 m to 50 m) and height (31 m) > Building position latitude (35.6°) and longitude(139.7°) 3) Sky conditions Interior natural lighting performance is evaluated under two urban sky conditions using the above office building configuration parameters > Clear sky condition > Overcast sky condition 4.2.2. Evaluat ion P r o c e s s This subsection describes the evaluation process for developing effective natural lighting control devices using ECOTECT v5.0 and Desktop Radiance. This evaluation procedure is generated as a component of the innovative office renovation framework described in Chapter 3 for application in Tokyo. 45 Evaluation with ECOTECT v5.0: Stage 1 > Interior natural lighting performance without any control devices, under the clear sky condition, at various adjacent building distances (from 5 m to 50 m). > A target is established for interior illuminance levels on the desk (800mm above the floor) based on a 600 lux level of required interior natural lighting (note. 4-3) Stage 2 > Existing shading devices are applied to the typical existing office building facade to determine the size and position of possible natural lighting control devices, and interior natural lighting performance is evaluated through possible control devices under the Tokyo's dense urban scenarios. | Note. 4-3: the Guideline for Assessment of Environmental Friendliness of Government Building Facilities and ' ; I Renovation Plan states that the 600 lux is an appropriate lighting level on the desk (800 mm from.the floor). The 600.lux, is considered as the criteria for Interior natural lighting performance in this study Evaluation with Desktop Radiance: Stage 3 > Possible natural lighting control devices are modified and evaluated to find the configuration of effective natural lighting control devices which enhances distribution to maximize interior natural lighting level. > Interior natural lighting performance is re-evaluated for effective control devices, and the performance increases are documented. Accuracy of the Evaluation Process: The research process described in this subsection relies on data which is generated by the two evaluation software applications, ECOTECT and Desktop Radiance. The accuracy of the findings is heavily dependent on the ability of these software applications to provide realistic models of natural lighting performance. While these software programs were designed to provide realistic simulations of natural lighting, they nevertheless offer models which are not absolute, but which each emphasize different aspects of natural lighting, and therefore have relative strengths, and present relative uncertainties. In the first two stages, ECOTECT was used to evaluate internal natural lighting performance without any natural lighting control devices (to establish a benchmark and targets) and to 46 evaluate shading (to determine a set of possible natural lighting control devices). The relative weakness of ECOTECT as an evaluation software is its inability to accurately describe distribution performance under direct sunlight conditions. In order to provide a more accurate model of direct sunlight, Desktop Radiance is used in Stage 3 to evaluate the changes in illumination under clear sky conditions. On the one hand, the use of these two software programs allows us to take advantage of the relative strengths of each. But on the other hand, the use of two different software packages at different stages of the research process raises another issue regarding accuracy: in Stage 3, comparisons with the benchmarks established in Stage 1 might be effective only to the extent that the models defined in the two different softwares are the same. In order to provide reliable data, interior natural lighting performance was evaluated in Desktop Radiance under identical input data as ECOTECT. 47 5.1. C o n f i g u r a t i o n f o r A H y p o t h e t i c a l O f f i c e B u i l d i n g Using the ECOTECT modelling software, a hypothetical office building was modelled to explore the potential for the widespread application of effective natural lighting control devices as an integral part of office renovation. This hypothetical office building represents a typical Tokyo office building (designed 1970's and 1980's), a deep open plan multi-story office building. The following is a description of the features of the hypothetical office building: > A 9-storey office building located in an urban environment. > The building height is 31m (note. 5-1). > The building measures 27m long and 25m deep, with the main facade facing south, (note. 5-2). > The floor to ceiling height of each level is 2,500mm. > The building has 1,600 x 1,200mm clear single pane windows, no internal blinds, no overhangs over the windows. > The occupancy schedule is 8:00 a.m. to 6:00 p.m., 5 days per week. > The building is installed with typical electrical lighting systems — having a high lighting density of 20.6 W/m 2 per year and 2,400 hours per year. > The building is surrounded by local obstructions with the same characteristics equal to 31 m height (note. 5-1). This configuration is chosen as a hypothetical office building because it is a common configuration for Tokyo's existing office buildings found in Tokyo. Note. 5-1 Building Height — The height of a hypothetical office building is held within 31m Japanese building code which specifies the building height limitation at the article 56 states that the absolute buildingj*height is restricted to~under^3^mrin ~the"t commercial zone from 1919 until 1963, so in the highly developed ^ districts,, such * as Ginza and Marunouchi office buildings stand side by side very closely along the i S l r e e t Note. 5-2. Deep Office Plan — The modeled building has deep office space assumed to have no internal . partitions. The typical office building's configuration < often - degrades the capability to induce! both "direct sunlighting and daylighting to interior because of the ««p'oor*window'desigmconsideration for natural lighting .Therefore* the ratio of naturally lit area to total floor area Ms extremely low. The high demand for electrical lighting systems to supplement interior lighting 1evel>is required. 48 5.2. Sampled Area A sampled area of the hypothetical office building provides the basic model which is used to study the impact of various assumed natural lighting control devices on interior illumination. A s shown in Figure 5-1, the sampled area is representative of a 2 window width of the building, open an entire 10 m depth from the window. The sampled area is located at the center of the south-facing hypothetical office building to provide a sample area which may potentially experience both direct sunlight and daylight from 8:00 a.m. to 6:00 p.m., 5 days per week. Locating the sampled area at the center of the building allows for a simplified model, which restricts the impact of the party walls to the east and to the west, especially during the early and late hours of the day. L 2,500 mm 10,000 mm 1 l l i i B i i i i The position of sampled area within a hypothetical office building Facade 27 25 Fig. 5-1:The detail configuration of j 'sampled area*- 'I >,X; * (Source: KumeSekkei, 2002) ] 5.2.1. Inputted Design Parameters for Sampled Area This sub-section explains the following key natural lighting design parameters for the sampled area, which are used to achieve suitable natural lighting evaluation conditions using the E C O T E C T modeling software: > The depth of the sampled area > The width of the sampled area > Floor to ceiling height > Window design > Fixed design parameters The Depth of the Sampled Area — The depth of the sampled area is set to 10 m. The depth of the sampled are is limited to 10 m in this study because spaces deeper than this exhibit marginally different performance levels but require a much greater calculation time 49 This depth limit was chosen as an appropriate depth based on a guideline created by the Ernest Orlando Lawrence Berkeley National Laboratory (LBNL): Natural light penetration with typical depth and ceiling height is 1.5 times head height for standard windows, 1.5 to 3.5 times head height with effective natural lighting control devices, for south-facing windows under direct sunlighting conditions (the Ernest Orlando Lawrence Berkeley National Laboratory, 1997). The Width for the Sampled Area — The width of the sampled area is set to correspond to the width of two widows (2,750 mm). A two window segment of the proposed hypothetical office building (which has a total of 17 punched windows) is isolated for study because while existing office buildings may vary in length, the size and spacing of windows in office buildings built in the 1970's and 80's is more or less the same. This two window sampled allows for a model which has potential for widespread application in typical existing office buildings of different sizes. The significance of choosing a two window wide segment rather than a single window segment is that the wall spaces between windows (set to 350mm in the model) can create contrasts of light and dark areas. Although demand for office renovations which make use of "environmental friendly techniques" has been increasing, the construction cost of common office renovations which replace existing building facades with curtain walls is significantly high (TOTO, 2000). This study assumes that window positions on building facades remain in their current positions, in order to provide a fixed condition to examine how the application of effective internal and external control devices alone may improve current indoor lighting conditions. Floor to Ceiling Height — The floor to ceiling height of the sampled area is set to 2,500mm, reflecting the typical height of office buildings designed in the 1970's and 80's. This is considerably lower than the standard ceiling height for new offices (2,800 mm) (TOTO, 2000). Floor Level — The design parameters of natural lighting control devices are modified with floor level. When a building is along a narrow street, obstructions become a significant factor, and the floor level has a critical impact on the effectiveness of installed natural lighting control devices. In this study, floor level will be one of the variable parameters which will be studied. 50 Window Size and Material — The sampled area has a single pane clear glass, 1,600 X 1,200 mm. Such single pane windows may not be energy efficient, but these windows are typical in 70's and 80's office buildings. Detailed window specifications are described in Note 5-3. Ceiling and Wall Material — The ceiling and walls for the sampled area are composed of flat white plaster panels which provide 80 to 85 % reflectivity for natural lighting typically used for Tokyo's existing office buildings. Whether natural lighting levels for deep interior spaces increase or decrease depends to a large extent on the relationship between the lighting distribution from ceiling and walls, versus the design configuration for natural lighting control devices. In the sampled area wall and ceilings shapes are fixed to study the impact of the control devices. 5.2.2. Omitted Design Parameters for Sampled Area The previous subsection outlines design parameters which were inputted into the software simulation to evaluate natural lighting performance in the sampled area. This subsection describes additional parameters which, while they may have a significant impact on natural lighting performance, were omitted from the input data either because they will be variable parameters in the study, or because they vary considerably with each real-world situation and are assumed to be fixed. In the latter case, these parameters should be specifically inputted for each real-world application. Internal Partitions — While internal partitions have a significant impact on natural lighting distribution, for the purpose of this study, the sampled area is assumed to have no internal partitions that inhibit natural lighting across the depth of the building. In real-world applications, internal partitions need to be modeled. However, open offices are a current trend for the Tokyo office market, and the arrangement of partitions is itself an important aspect of natural lighting optimization which extends beyond the scope of this study. Occupant Schedule — The building is basically assumed to have fixed occupant schedule of 8:00a.m. to 6:00p.m., 5 days per week. This leads to a conservative estimation of natural lighting performance because required natural lighting performance occurs while the building is occupied. Although the occupant schedule may be required to evaluate . Note. 5-3: Single pane window specifications: ;• Shading Coefficeint-0 95 '•rTranspareric>-0 88 • Thickness-8mm [Source. Kume Sekkei Architectwe Corporation) 51 the supplemental energy consumption for electrical lighting systems, it is assumed to be fixed for the purposes of this study. Occupant Control of Windows — The windows in the sampled area are modelled as being inoperable. Different scenarios of occupant control may dramatically affect the level of interior natural lighting. However, for in this study, inoperable windows are assumed. Floor Material — The floor for the sampled area uses carpet tiles which approximatelly 10% reflectivity for natural lighting. However, increasing or decreasing the interior natural lighting level through the floor is ignored in this study. Blinds — Blinds are not installed in the sampled area although they are simple and commonly used techniques for control natural lighting. Blinds are typically a "post-design solution" to shading problems. This study seeks to evaluate the effectiveness of natural lighting control devices alone. Occupant Control of Electrical Lighting Systems — Electrical lighting systems to complement natural lighting control devices should consist of dimming or switching systems to enhance energy performance. However, electrical lighting systems are not inputted into the computer simulation, but should be inputted in a study evaluating energy consumption. If it is necessary, simple and easy calculation methods for energy consumption of electrical lighting systems introduced in the Guideline for Assessment of Environment Friendliness of Government Building Facilities and Renovation Plan could be used. 52 5.3. Tokyo Contexts for Natural Lighting Evaluation To evaluate interior natural lighting performance using the ECOTECT and Desktop Radiance simulation program, two important sets of Tokyo urban contextual data were inputted: > Tokyo weather data > Adjacent buildings within Tokyo urban dense space 5.3.1. Tokyo Microclimates The weather data for the computer simulation was based on data from the Tokyo District Meteorological Observatory (TDMO) and the EFGB. The TDMO weather data compiled from all monthly observations in 2001 shows the average amount of clouds, the total sunshine hours, and the percentage of sunshine. An overview of climate characteristics for Tokyo, as they relate to evaluate interior natural lighting performance, are shown in Figure 5-2. Year and Month Average Temperature Average Humidity Average Amount of Clouds (1-10) Sunshine Total Hours Percentage of Sunshine 2001. Jan. 7.6 51 6.0 153.8 50 Feb. 6.0 38 4.2 207.7 66 Mar. 9.4 44 4.7 207.9 56 Apr. 14.5 55 6.7 174.9 45 May 19.8 68 7.4 184.0 42 June 22.5 74 8.0 129.8 30 July Aug. 27.'7 ,;. 6.5* 6.8 210.2 48 , ,28.3 , , 69 185.7 45 Sept. 25.6 .69 7.2 128.9 35 Oct. 18.8 67 8.2 97.7 28 Nov. 13.3 63 7.4 109.7 36 Dec. 8.8 46 4.2 172.2 57 Average 16.8 60 6.4 163.5 45 Fig. 5-2: Tokyo Microclimate Data (Source: Tokyo District Meteorological Observatory, 2001) 53 Sky Conditions — Tokyo's sky conditions are key components for evaluating interior natural lighting performance using the ECOTECT and Desktop Radiance software program. In this study, two scenarios are considered: > The overcast sky condition > The clear sky condition Figure. 5-2 reveals a high potential for direct sunlighting, especially in the summer, even though the percentage of sunshine and total sunshine hours are low (the 39% average sunshine rate in summer). Therefore to increase indoor office illumination, effective direct sunlighting control is also important to distribute diffused direct sunlighting as well as to reduce indoor summer overheating and glare. Therefore, effective natural lighting control devices under Tokyo's weather conditions should function as both direct sunlighting and daylighting controls. As shown in Figure 5-2, Tokyo experiences a considerable amount of the overcast sky condition, as shown by the 6.9 average cloud cover. Therefore to take maximum advantage of daylighting throughout a year, it is also important that natural lighting control devices be designed to distribute daylighting to interior. Temperature — Although temperature data is not directly required to evaluate natural lighting performance, it is used in this analysis to describe the Tokyo climate such as hot and mild seasons (also described in Chapter 2.1.1.). Temperature information can potentially help to understand the negative or positive impacts of direct sunlighting performance to interior environment. As shown in Figure 5-2, during months from June to September, the outside air temperature exceeds approximately 20 °C in June and increases to 28°C in August. The EFRP states that: > June, July, August and September are considered as hot seasons because they are approximately 25% higher energy consumption for cooling load than other months (Ministry of Construction, 2001). Therefore, these identified months are considered hot season months in this study, where direct sunlighting has negative effects of overheating and glare for interiors. During the hot season, direct sunlighting should be reduced or avoided through shading devices or tinted glass. 54 > During the other eight months of the year, when outside air temperature is lower than the 20°C comfort level, direct sunlighting is assumed to have positive impacts on interiors in reducing internal heating load (Ministry of Construction, 2001). Therefore, to take maximum advantage of direct sunlighting for retrofitting office buildings within the Tokyo context, the design parameters for shading devices should ideally be designed to allow direct sunlighting to enter during these mild season months. Humidity — While humidity does not directly impact natural lighting transmission to the interior, it is of significance here, because Tokyo has a 65% humidity rate that is not ideal for natural ventilation. If the technique of natural ventilation were used as part of office buildings within Tokyo's context, filtration systems to reduce humidity or air pollution might be required. It also would mean an increase in the cost of office renovation and a performance limitation for natural ventilation. The building's facade design is therefore ignored in this study. 5.3.2. T o k y o ' s D e n s e Urban Situation The problem of Tokyo's urban space is that in the winter when there is need of more natural lighting (both direct sunlight and daylight), its effects on the horizontal plane are weakest because office buildings are typically tightly surrounded by local obstructions that limit the amount of natural lighting that can reach the interior. In the summer, both direct sunlighting and daylighting are usually available to office building interiors despite their location on narrow streets because of the high sun angle. It becomes necessary to maximize the effectiveness of direct sunlighting and daylighting performance through natural lighting control, given the limited natural lighting available in Tokyo's dense urban context (note: 5-3). i Note. 5-3: Only high angle of direct Wide range of direct i sunlighting is available sunlighting is available When an office building is located along with the When an office building is located along with the wide narrow street, excessive direct sunlighting street, both excessive and beneficial direct sunlighting provided with the high sun angle only tends to be could be available. (Source' Ernest Orlando Lawrence Deikeley NMonal Laboiatory) 55 Obstruction — Lam (1986) suggests that building density strongly affects the quality and amount of interior natural lighting needed to improve indoor environments. As described in Section 5.1, building height is strictly limited to within 31m so that the magnitude and performance of interior natural lighting criteria explicitly depends on the distance between buildings. The interior natural lighting evaluation analysis in chapter 6 is performed with ECOTECT and Desktop Radiance modeling software under overcast and clear sky conditions for the sampled area defined above. Figure 5-4 shows the variation in obstruction distance in this study: natural lighting control device configurations are evaluated for their impact on natural lighting performance under local obstruction distances f rom 5m to 50m for a f ixed 31m bui lding height. With typical 9 story office buildings, the narrower the obstruction distance, the lower the interior luminance level due to limited external natural lighting available from direct sunlighting and daylighting within Tokyo's dense urban space. 31 m 5 m The minimum obstruction distance is defined as 5m in this study because most existing office buildings are usually along over the 10m wide street. 50 m The maximum obstruction distance is defined as 50m in this study because most existing office buildings are usually along under the 50m wide street. Fig. 5-4: Local obstruction analysis for: natural |ightingeyaluation ; (Source: Tokyo White Paper, 2000)"] a) Avai lable Months for Direct Sunl ight ing Available direct sunlighting to the whole facade of existing office buildings are shown in Figure 5-4. As shown, when an office building is located at a 5m obstruction distance, direct sunlighting is only available to the entire facade in June and July for a limited time between 10:00 a.m. to 1:00 p.m. under clear sky conditions (see Appendix. 6.2.1.). This result shows that under very dense situations, to a large extent, only daylighting is available to the interior even under clear sky conditions (other than in June and July). On the other hand, when an office building is located with an over 50m obstruction distance, direct sunlighting is 56 available to the entire facade is expected annually for a period of time between 9:00 a.m. to 3:00 p.m (see Appendix. 6.2.1.).. The criteria of the number of months of available direct sunlighting for the interior are described in Note 5-5. Note. 5-5' direct sunlighting performance criteria "The number of available months for direct sunlighting to interior" is represented in Figure 5-4. During the months presented, direct sunlighting is available to the interior. When the local obstruction distance is extended, the number of months usually increases due to the increasing potential.for*a,lower*angleiofiic1inect sunlighting (during winter seasons). Direct sunlighting performance under the4 Tokyo microclimate is-basically classified with two • •types (described [n Chapter 2.2.1.):' > Excessive direct sunlighting performance that often provides overheating or excessive glare is provided during hot seasons (June, July, August and September) > Beneficial direct sunlighting performance that often decreases heating load is provided 1 during mild seasons (eight months except hot seasons described above) l l i B Excessive d.rect sunlighting Beneficial direct sunlighting availaWe^Renthe' number is greater;-than 4-.-—'.- *- -This criteria help to decide the design parameters of direct sunlighting control dev.ces No Obstruct ion 5m 50m The number of month for available direct sunlighting to interior 12 2 12 |. Fig. 5-5: Benchmark performance for interior natural lighting b) Percent Reduct ion of Interior Natural Light ing The percent reduction to interior natural lighting level depends on the relative urban ratio of an office building height (31m) to obstruction distance. As shown in Figure 5-6, an obstruction distance of 5m produces a 35 percent reduction to the average interior natural 57 lighting level when compared with no obstruction condition. On the other hand, when the obstruction distance increases to 50m, a 10 percent reduction of indoor natural lighting level is observed. No Obstruction 5m 50m Average percent reduction for interior natural lighting performance 100% -35% -10% Fig. 5-6: the average of percent reduction forinterior natural lighting performance In Tokyo context, the negative impact of obstructions in reducing interior natural lighting can be attributed to two factors: 1. Decreased Direct Sunlighting Available to the Interior: Obstructions of greater height (31 m) and at shorter distances block more direct sunlight from floors of office buildings for greater periods during the year. As a result, less direct sunlight is able to enter building windows and provide an interior illumination. 2. Decreased Daylighting Available to the Interior: In addition, obstructions of greater height (31 m) and shorter distance decrease daylighting by reducing the area of the sky vault visible through the buildings' window openings. Daylight is an ambient light which is diffused and distributed across the sky by the volume of cloud cover, and is the key source of natural lighting under overcast conditions. Orientation — Changing building orientation can potentially effect the interior natural lighting performance of both direct sunlighting and daylighting. In south facing buildings, direct sunlighting is generally available to the office building. Solar gains can be easily controlled with the use of overhangs or low-emission glass materials. Orienting the building so that more windows face west increases solar gains in the latter portion of the day, and increases overhangs. These solar gains are also very difficult to reduce with the use of overhangs due to low sun angles. In north facing buildings, only daylighting is available. The four orientation characteristics are described below: 58 North: High quality consistent daylight is available, but thermal loss during heating conditions is the major problem in north side. For the north orientation, daylighting control is critical, as direct sunlighting is not available. South: Good access to both direct sunlighting and daylighting is available throughout a year depending on obstructions. Although increasing shading performance is easy, it is important to distribute direct sunlighting and daylighting to interior. East and West: Shading is possibly needed only for early morning and late afternoon. However, the potential to get direct sunlight on east and west orientations within Tokyo urban spaces is quite low because tight surrounding obstructions reduce the lower angle of direct sunlighting impacting to interior. Therefore, daylighting is only considered an available resource to improve indoor office environment. For office buildings located in the Tokyo dense urban situation, the fact of building orientation is that all four building facades are blocked by adjacent buildings equal to the building height might make orientation in this study less significant that it would seem. Under this Tokyo urban situation, direct sunlight is not so significant, and daylighting control is the more reliable strategy to improve indoor office environments in all four orientations. Developing effective natural lighting control devices (especially daylighting control devices) through this study may have a high potential for application to building facades that facing all orientations. 59 5.4. B e n c h m a r k f o r Interior Natura l L i g h t i n g The benchmark for interior natural lighting performance within the sample area under conditions of no natural lighting control device and no adjacent obstructions was investigated to develop a simple chart for "the number of months of direct sunlighting" and "the percent reduction of interior natural lighting performance (described in Chapter 6-1)". 5.4.1. Benchmark for Direct Sunl ight ing Performance The number of available months of direct sunlighting (detailed in Section 5.3.2.) for the sampled area is used to study the key design parameters of natural lighting control devices shown in Figure 5-7. As shown, excessive direct sunlighting, which has a negative impact on the interior environment occurs during the 4 months of the hot season: June, July, August and September. Beneficial direct sunlighting, which has a positive impact on the interior environment is available during the 8 months of the mild season. Under the benchmark conditions (no obstructions), direct sunlighting is available throughout the year for the interior under Tokyo's urban condition. The number of available months for direct sunlighting to interior Hot Seasons Mild Seasons 4 months 8 months Fig. 5-7: Benchmark performance for direct sunlighting 5.4.2. Benchmark for Interior Natural Light ing Performance A benchmark for interior natural lighting performance for the sampled area is used to estimate interior natural lighting performance under a no adjacent building condition as shown in Figure 5-8. Interior natural lighting performance is measured under the Tokyo urban Clear Sky Condition to investigate the annual average level within a sampled area (see Chapter. 4.1.1.). As shown, the sampled area achieves the 600lux of standard interior natural lighting performance within approximately 3m from the window annually without control devices. 60 10m 9m 8m 7m 6m 5m 4m 3m 2m 1m Average Interior Natural Lighting Level (lux) 100 100 200 200 200 300 400 1000 2700 5100 Fig. 5-8: Benchmark performance for interior natural lighting The following are investigated based on benchmark: > Improvements to shading performance through installed control devices > Improvements to interior natural lighting performance through effective distribution performance by installed control devices > Improvements to the 600 lux performance area (recommended by the EFRP) through installed control devices The above evaluations are performed under both clear and overcast sky conditions. 61 One widely adopted guideline for establishing acceptable indoor environments using natural lighting with office renovations within Tokyo context is the Guideline for Assessment of Environmental Friendliness of Government Building Facilities and Renovation Plan (EFRP) (Ministry of Construction, 2001). This guideline states that "interior natural lighting levels with 600 lux at desk level (800 mm) should adequately provide the effective performance to meet office workers' needs." To achieve this criterion, this office renovation guideline recommends using direct sunlighting control devices such as overhangs, and tinted and low-e glass, and suggests that office buildings refurbished such additions are "environmentally friendly office buildings." A methodology for designing effective natural lighting control devices (both direct sunlighting and daylighting control) for retrofitting Tokyo's existing office buildings was presented in Chapter 3 of this study as a "Framework for Office Renovations with Natural Lighting." This framework included a step-by-step office renovation design procedure which could be used early in the design process to define the parameters for effective natural lighting control devices, and to estimate their natural lighting performance with the ECOTECT simplified evaluation software. In this chapter, the hypothetical office building discussed in Chapter 5 is used to demonstrate this design process. The structure of this chapter is as follows: 1. Step-1 — Provide simple charts to help identify the current indoor natural lighting conditions (available direct sunlighting to the facade and interior natural lighting level) under various adjacent obstruction situations. Using these charts, the design parameters of natural lighting control devices are designed. To increase the potential for widespread application for effective control devices, these charts cover office buildings located in various Tokyo Urban Scenarios using "Tokyo urban ratio analysis" (a ratio of floor number to obstruction distance). 2. Step-2 — Provide architects and lighting designers with the design parameters for possible natural lighting control devices (see chapter 2.2.1. on possible natural lighting control devices) under the different Tokyo Urban Scenarios. 62 Step-3 — Provide architects and lighting designers with the design parameters for effective natural lighting control devices (see chapter 2.2.2. on effective natural lighting control devices) under the different Tokyo Urban Scenarios. 63 6.1. S tep-1 — t h e chart for predict ing interior natural lighting performance In an attempt to clarify for designers and clients the opportunities in developing effective natural lighting control devices, two key diagrams are presented in this section: 1. the percent reduction of interior natural lighting performance due to obstruct ions (discussed in detail in Chapter 5.3.2.-Section (b)) 2. the number of available months of direct sunl ight ing to the facade (discussed in detail in Chapter 5.3.2.-Section (a)) Using ECOTECT software functions which provide an estimation of annual-based average interior lighting performance under a clear sky condition, a diagram for "interior natural lighting performance" was developed for the sampled area without any natural lighting control devices, for a range of obstruction distances from 5m to 50m. The results of this analysis were then converted into a chart of the percent reduction in natural lighting compared with the benchmark analysis investigated in Chapter 5.4. (no obstruction situation). This diagram helps architects and lighting designers to determine a target for interior natural lighting performance achieved through effective control devices. Next, "the number of available months of direct sunlighting performance to the interior" was investigated through a "solar ray analysis" using the ECOTECT modeling software (see Appendix 6.1.2.). This diagram presents the months of potential direct sunlighting in order to help architects and lighting designers to define the design parameters for possible natural lighting control devices (direct sunlighting control devices) which are needed to shade the summer's direct sunlighting while inducing winter's direct sunlighting. 64 6.1.1. Chart 1: Percent Reduction of Interior Natural Lighting due to Obstructions Using ECOTECT, natural lighting performance data for the sampled area was taken under clear sky conditions, for each floor and with varying obstruction distances (Appendix 6.1.1.). This data was then used to establish a diagram showing the percent reduction in interior natural lighting due to obstructions (figure 6-1). A 40 percent maximum reduction for direct (A) Full Exposed (B) -5 - 0% (C) -10~-5% (D) -15~-10% (E) -20--15% (F) -25 - -20% (G) -30 ~ -25% (H) -35 - -30% (I) -40 ~ -35% Fig. 6-1: the chart of the percent reduction of interior natural lighting 0 5 10 15 20 25 30 35 40 45 50 m The distance from adjacent buildings sunlighting is observed within 5 m obstructed distances. Increasing the obstruction distance results in an equivalent increase in interior natural lighting level. Figure 6-1 shows that the lower floors of typical Tokyo office buildings usually receive less interior natural lighting than higher floors for a given obstruction distance. For example, a interior natural lighting performance on the 1s t floor of an office building located on a 5 m wide street is reduced by more than 35 percent vs. the benchmark performance (with no obstructions). By contrast, when adjacent buildings are located along a 45 m street, the percent reduction of interior natural lighting performance is approximately 10 percent vs. the benchmark preformance. As office buildings are typically restricted to within 31 m in height because of Tokyo building code (see Chapter 5.1.), the distance of adjacent buildings is a more significant factor affecting interior natural lighting performance. 65 6.1.2. Chart 2: The Number of Avai lable Months for Direct Sunl ight ing Based on data obtained with ECOTECT for the sampled area under clear sky conditions (Appendix 6.1.2.), a diagram of number of available months for direct sunlighting (Figure 6-2) was developed. This diagram is important for determining the appropriate key design parameters such as position and size for effective natural lighting control devices on the existing building facade. The numbers of months are classified according two important key periods which provide different external natural lighting conditions: 1. When the number of months is more than 4 (defined in the graph by Tokyo Urban Scenarios (a), (b) and (c)): (i) direct sunlighting is available during both hot seasons and mild seasons. (ii) daylighting through overcast sky conditions is available throughout a year. 66 As shown in above chart, these assumed Tokyo Urban Scenarios (a), (b) and (c) are emphasized in the higher floors of an office building located along a narrower street or in an office building located along a wider street. 2. When the number of months is fewer than 4 (defined in the graph by Tokyo Urban Scenarios (d) and (e)): (i) direct sunlighting is available only during hot seasons. (ii) daylighting though overcast sky condition is available throughout a year. As shown in the graph above, if the number of months is fewer than 4, only excessive direct sunlighting is available to the interior (since mild season direct sunlight is eliminated by obstructions). For such scenarios, a shading device which aims only to limit penetration of the summer's direct sunlighting can be simply designed with the use computer analysis and applied to the office building. On the other hand, as both excessive and beneficial direct sunlighting are available when the number of months is greater than 4, a more complicated function of shading devices is required to both shade the hot seasons' direct sunlighting (prevent overheating) while inducing the mild seasons' direct sunlighting (reduce heat load). In a sense, the 4-month line of the available months of direct sunlighting also represents the lower limit under which direct sunlighting is no longer a viable lighting strategy. The need for effective daylighting control is more significant in scenarios (d) and (e) because penetration of direct sunlighting is extremely low throughout the year. On the other hand, both direct sunlighting and daylighting control present useful lighting opportunities for Tokyo Urban Scenarios (a), (b) and (c). This chart showing the number of months of direct sunlighting can help illustrate to architects and lighting designers the idea that the position and size of effective natural lighting control devices should be determined based on specific Tokyo Urban Scenarios (floor level and obstruction distance). 67 6.1.3. Chart Reading — Tokyo Urban Obstruction Ratio In this section, Tokyo Urban Obstruction Ratio, a simple chart reading method for both the number of available months for direct sunlighting and the percent reduction in interior natural lighting diagram, is presented. A series of linear sloped lines which fade out from the origin are overlaid on the diagrams to represent the ratios of floor number to obstruction distance. Figure 6-3 provides examples of two of these diagrams which show the intersections of this "Tokyo Urban Obstruction Ratio" with using ECOTECT modeling software analysis (Appendix 6.1.3.). In a sense, this ratio analysis provides architects, lighting designers and clients with a method for improving the indoor environment of Tokyo's existing office buildings through effective combinations of natural lighting control devices (described in Note 6-2). This may be of particular interest for office building owners in that it suggests an opportunity for retrofitting their buildings in phases, to improve indoor environments and lighting performance gradually, in contrast to the more time consuming and more expensive approach of curtain wall renovations which are typical in Tokyo. Direct Sunlighting Performance Chart Interior Natural Lighting Performance Chart (a) 8 - 1 2 months (d) 2 - 4 months (A) Full Exposed (F)-25--20% (b) 6 - 8 months (e) 0 - 2 months ( B ) - 5 ~ 0 % (G)-30--25% (c) 4- 6 months CO-10--5% (H)-35~-30% (D) -15--10% (I) -40--35% (E) -20--15% Fig. 6-3: diagrams of direct sunlighting and interior natural lighting with Tokyo urban ratio analysis. 68 Note.6-2sTheianalysis of Tokyo Urban Obstruction Ratio In this study, the term 'Tokyo Urban Obstruction Ratio" indicates a ratip«of floor number to obstruction distance (a 5m interval). This variable occurs on the ;graphs for the following ratios:'.1/,10,1/5,-.1/3,1/2, 3/4\r|/1,4/3, 2/1, 3/1% 5/1; ,10/1 •'(described above). Calculation method: Tokyo Urban Obstruction /•?(/.> = Floor number (F) The 5m-interval obstruction distance For example, when an office building is located.on a 25m wide street. Ratio"'at 5F is 1/1 ".Tokyo Urban Obstruction 5F Tokyo Urban Obstruction Ratio = (25m/5 =) 5 = 1/1 The Tokyo Urban ^ Obstruction Ratio, analysis simply provides the potential selection of effective natural,lighting controltdevices to architects, lighting designers and clients for retrofitting Tokyo's . existing office buildings. For example, from, this diagram it is possible to read; Tokyo, Urban Scenario (see Section 6.1.2.);for an entire office^building from 1F to 9Flocated on a 30 m-wide street and propose the installation of .suitable JcontroK devicesto achieve, desired^ interior illuminance level using Table. 7.1.(p.107). Alternatively, it would ;also be possible to propose effective control devices to one specific floor for one.building location. In this way, this diagram may be useful for office owners because individual tenants usually occupy oneJ6r two floors of the entire office building. I . N B merr-ho 4 monttia ^ J V f c ^ - / ; - - / ' - • / - • - - / - ~ \ — 4 month* 2 month* -PJ- -A .f\A-/A-^—\----^-1 - -2 months 1 Kr A X l^' X • 0 month Omanth |"i Y r / \ / ' X i M IrfV /\/\(' -j^'-- mm 8B fU^^Y • — — \ • '• J Currently, architects and lighting designers do not fully appreciate shading and distribution performance through effective natural lighting control devices under specific locations. The charts proposed here may be useful to encourage them to consider taking maximum advantage of natural lighting performance for the interior at a preliminary stage of office renovation. 69 6.2. S t e p - 2 — Possible Natural Lighting Control Devices 6.2.1. P o s s i b l e Natural Lighting Contro l Devices — Design modifications of direct sunlighting control devices The design parameters of possible natural lighting control devices (devices which provide direct sunlighting and daylighting control) are dependent on the available months of direct sunlighting (obtained in section 6.1.2). The parameters for possible natural lighting devices were obtained with the ECOTECT software based on number of months of direct sunlight: a) 8 to 12 month, b) 6 to 8 month, c) 4 to 6 month, d) 2 to 4 month and e) 0 to 2 month. What is of more relevance for this study are the modifications to these parameters and the considerations that were made in determining the optimal possible natural lighting control device. These design parameters, such as the position and size of possible internal natural lighting control devices are adjusted to meet the following requirements: > Shading excessive direct sunlighting > Permitting beneficial direct sunlighting > Creating eye level's clear view for office workers p i Requirements for Possible Natural Lighting BuiidingjFacade Control Devices In Chapter 2, possible natural lighting control devices were defined as those devices which meet the minimum functions (reflect sunlight and provide shade) which could be met by other direct sunlighting control strategies such as typical curtain walls. At the most basic level, possible natural lighting control devices are required therefore to shade excessive direct sunlighting in the hot months (an essential function which could be served by typical renovation methods such as low-emission curtain walls). But on another level, an optimal shading device should also consider the requirements of providing views for | J ' ' j occupants and employing beneficial direct sunlighting ] in the mild season (note. 6-3). _ I Note 6-3: possible control devices are installed inside of the building facade line. Because of the building code, external control devices can not be suitable to install (see Chapter 1.4.4). Internal control devices are more effective to increase distribution by using ceiling as secondary reflector than that of external control devices (Tips for Daylighting with Window, 1997) Window! 2,500 mm 1,600 mm 35amij i i 70 TYPE-Ao T Y P E - B Q Optimal Shading devices 2,200 mm —J1 900 mm 1200 mm 400 mm 1,900 mm Fig. 6-4: the analysis of effective shading control devices with ECOTECT v5.0 In this section, a brief discussion is included to describe the general considerations which were made in determining possible natural lighting control devices (see Appendix 6.2.1.). Figure 6-4 illustrates three shading device scenarios which were considered: 1. Type Ao shading device: a suitable device position and size to shade against excessive direct sunlighting under conditions of the highest sun angle in hot seasons (in June). Because the sun angle is large, the shading device can be smaller (100 mm x 2,200 mm) to and should be positioned higher relative to the eye level. 71 2. Type B 0 shad ing device: a suitable device position and size to shade against excessive direct sunlighting under conditions of the lowest sun angle in hot seasons (in September). As shown in Appendix 6.2.1 this shading device (900 mm wide and positioned 1,200 mm above the floor level) would be effective for shading during hot seasons, June, July, August and September. However such a device would not provide enough view for office workers. 3. Optimal shad ing dev ices : While Type An and Type B 0 shading devices represent devices which shade excessive direct sunlight at high and low sun angles in the hot season, an effective shading device should be suitable for not only shading during all hot seasons, but should also be designed to induce beneficial direct sunlight during the mild season and permit views for occupants. The "effective shading device" (described in figure 6-4 and Appendix 6.2.1.) represents a device whose parameters are a compromise between Type A Q and Type B 0 shading devices. Although this modified shading device does not strictly shade against all excessive direct sunlighting in hot seasons, it is a compromise which also considers the benefits of inducing direct sunlighting in the mild seasons and increasing views for office workers. In the following subsection, this general "optimal shading device" is modified to determine possible design parameters for natural lighting control devices suitable for a range of specific scenarios within Tokyo's urban context. Modif icat ions to Determine Poss ib le Natural Light ing Contro l Dev ices Figure 6-5 presents five possible natural lighting control devices which are designed to increase direct sunlighting control for five given "Tokyo sunlighting scenarios" (based on number of months of direct sunlight.) While Tokyo sunlighting scenarios (a), (b) and (c) (receiving more than 4 months of direct sunlight) all require sunlighting control devices with identical parameters (400 mm X 1,200 mm in size, positioned 1,900 mm from the floor), they are classified separately because these scenarios will form the basis for further modification in the Step-2 and require different design responses for natural light distribution. 72 TYPE-A a) 8 to 12 months TYPE-B b) 6 to 8 months TYPE-C c) 4 to 6 months TYPE-D d) 2 to 4 months TYPE-E e) 0 to 2 months I U S 400 fnm 1,900 mm 400 mm -J 400 mm 150 mm Fig. 6-5: possible natural lighting control devices Tokyo sunlighting scenarios (a), (b), and (c) represent cases in which direct sunlight occurs in both the hot season and the mild season, which requires possible control devices to shade against excessive direct sunlight and glare during the summer months, and to allow for beneficial direct sunlight during the winter months. While the position of the device 1,900mm above the floor accommodates views to the exterior, additional shading devices such as internal blinds may be required to shade against direct sunlighting for August and September. 73 Tokyo sunlighting scenarios (d) and (e) represent cases in which direct sunlighting occurs only during the hot season (where the number of months of direct sunlight is less than 4). Since obstructions prevent direct sunlight from reaching the facade during the mild seasons, daylighting is only available. Type-D natural lighting control devices (150mm X 1,200mm) are installed under the sunlighting scenario to shade direct sunlighting in the months of June and July. For urban scenario (e), the interior receives very little direct sunlight, so Type E represents a case where no sunlighting control device is needed. Increasing the Potential for Natural Lighting Distr ibution For each of the urban scenarios, possible interior natural lighting control devices are positioned at a 1,900mm height above floor level. This height, apart from providing benefits for views, also provides a 600mm gap between the device and the ceiling. Sufficient space between the ceiling and control devices (clearstory) is important for the induction of natural lighting for distribution. Sustainable Architecture in Japan (2000), an interior natural lighting analysis performed by Nikken Sekkei Ltd., states that optimization of natural light distribution in control devices can increase the average interior natural lighting level by approximately 20 to 30%. 74 6.3. Step 3 — Effective Natural Lighting Control Devices In this section, each of the possible natural lighting control devices described in section 6.2 is enhanced for daylighting function through an iterative process of modification (altering parameters, and adding new device components) and evaluation using ECOTECT v5. What is presented in this section are the results of this iterative modification process. These modified control devices are "effective natural lighting control devices" in that they optimize daylighting distribution while meeting the effective sunlighting control requirements. Each of the device types is applied to the sampled area to analyze: 1) the key des ign parameters of effective natural l ighting control dev ices , classified in the following four control device categories: (shown in Figure 6-6): > internal natural lighting control devices > internal + external natural lighting control devices > internal + ceiling natural lighting control devices > internal + external + ceiling natural lighting control devices 2) the percent increase in interior natural lighting per formance over the default case (no natural lighting control devices), for: > clear sky conditions > overcast sky conditions 75 Fig. 6-6 Internal Natural Lighting Control Device Internal.Natural Lighting Control Devices are applied as the standard type of -control devices. Pro ', y»; > Cost effective for construction > Under Tokyo existing building code , C o n .- - -•>' Limited distribution'under the • . limited external light source such as narrow street. Internal + Ceiling Natural Lighting Control Device Internal + External Natural Lighting Control Device • Pro > Enhancing uniformity and increasing naturally lit space'to rear f Additional cost for construction rather . , than the internal control device Pro ' > Increasing the lighting level at the .especially window side of office space > Building code constrains to install - controhdevices to external. Internal + External + Ceiling Natural ' Lighting Control Device -•' This type of innovative control device-is applied with restricted"'^ Mf building code and enough -' •construction cost. This type of control device is appropriate for installing to the situations such as the limited '-external natural lighting performance and the requirement ") ofthebrighter office space. (Source: Sunlightingias Formgiver for Architecture, 1986) Fig. 6-6: Design diagrams for natural lighting control devices. " ' 6.3.1. The Key Des ign Parameters of Effective Natural Lighting Control Dev ices A review of recently published research papers and environmental friendly office renovation design guidelines (EFRP) produces a number of generally accepted criteria which might be considered natural lighting design guideline. These guidelines were intended for general application to provide effective shading to reduce cooling load in summer seasons, but the majority of them might not be suitable for employing the sunlighting distribution to improve interior natural lighting illuminance levels. Very little research into natural lighting control devices as an integral part of office renovation has been carried out in Tokyo. This subsection seeks to provide some simple design guidelines which are specifically for retrofitting Tokyo's typical existing office buildings for natural lighting under open urban situation (no obstructions). These guidelines can be used to provide architects and lighting designers with rough estimates of the parameters for the following three categories of natural lighting control devices: a) Internal devices b) External devices c) Ceiling-mounted devices The design rules included below were developed using the ECOTECT 5.0 environmental modeling software for Tokyo's sun positions (latitude 35.60, longitude 139.70), using the parameters of a typical Tokyo office building (described in Chapter 5), assuming no external obstructions. Design Gu ide 1 — Internal Control Device (see Appendix. 6.3.1-1) For a typical Tokyo office building, internal control devices should be positioned with a gap of approximately 600mm (25% of ceiling height) from the ceiling to distribution of direct sunlighting to the ceiling, while the 1,900 mm height above the floor (75% of ceiling height) allows for views to the exterior. Internal natural lighting control devices should be designed with an at least 1,000 mm total device depth to distribute direct sunlighting and to shade direct sunlighting during hot seasons (fig. 6-7). 77 The optimal position for internal and external natural lighting control devices is just above eye level to allow for views. The 400 mm of the surface of internal control device distributes hot season's direct sunlighting while shading to interior. The 1000 mm of the whole surface of internal control device distributes mild season's direct sunlighting. Beneficial direct sunlighting is permitted below the control device in mild seasons Fig. 6-7: The design parameters of internal controldevice for Tokyo's existing office building. Design Guide 2 — External Control Device (see Appendix 6.3.1-2.) Curved external natural lighting control devices should be designed with a 100 mm total device depth. The function of this control device is to increase reflector surface while maintaining fixed shading performance for internal control device under the Tokyo's urban open space (fig.6-8). 100 mm > The 10% of reflector surface for internal control devices is extended to increase the distribution performance of direct sunlighting to interior. > The design configuration of external devices is practically transformed to catch direct sunlighting and daylighting under various Tokyo urban dense situations. > The external control device is effective for office buildings tightly surrounded by local obstructions to enhance limited daylighting. Note: curved external control devices can be more effective for increasing distribution performance by approximately 10% to 20% than flat external devices (Tips for Daylighting with Window, 1997) Fig. 6-8: The design parameters of external control device for Tokyo's existing office buildings. 78 Design Guide 3 — Ceiling Control Device (see Appendix 6.3.1-3) Ceiling natural lighting control devices should be designed with a depth of 2,000 mm and a height of 2,300 mm from floor to redistribute direct sunlighting and daylighting which is reflected from internal or external control devices (fig. 6-9). mer Winter > The 2,000 mm depth for ceil ing control devices is effective to redistribute direct sunlighting and daylighting reflected from internal or external control devices. > The 15% of the surface of ceiling control devices is effective for the retribution of hot seasons ' direct sunlighting > The 85% of the surface of ceiling control devices is effective for the retribution of mild seasons ' direct sunlighting > The 100% of the surface of ceiling control devices is effective for the redistribution of daylighting Fig. 6-9: the design parameters of ceilingxontrol device for Tokyo's existing office buildings. *j Internal natural lighting control devices are primarily installed on existing office buildings. External and ceiling control devices deal with supplemental control devices or secondary reflectors to enhance distribution and redistribution performance. 79 6.3.2. Effective Internal Natural Lighting Contro l Dev ices Figure 6-10 presents five effective internal natural lighting control devices, which were developed through the modification of parameters of the possible internal natural lighting control devices identified in section 6.2. This set of modified devices represents an optimization of the internal device dimension for sunlighting distribution within each of the five Tokyo Urban Scenarios, given a fixed constant allied area above the self of 600mm. Also included is the increase in the device depth as a percentage of original possible control device depth. TYPE-Ai TYPE-Bi TYPE-C 1 TYPE-Di TYPE-Ei 600 n m 1,000mm 700 mm J 400 mm 270 mm 270 mm J a) 8 to 12 months b) 6 to 8 months c) 4 to 6 months d) 2 to 4 months e) 0 to 2 months I Fig. 6-10: effective internal natural lighting control devices In order to document the benefits, sunlighting distribution and shading, of each added to the natural lighting devices, the change in interior lighting performance (Appendix 6.3.2.) is presented as a percentage increase in interior illumination for clear sky conditions. Interior illuminance performance is also evaluated under overcast sky conditions. According to the weather data provided from Tokyo District Meteorological Observatory (TDMO), Tokyo experiences a considerable amount of the overcast sky condition, the 6.9 average clouds cover (see Chapter 5.3.1.) (Ministry of Construction, 2001). Therefore it is also important to evaluate daylighting distribution performance though designed control devices. 80 Figure 6-11 presents a graphical summary of interior illuminance level which is produced by internal control devices. Clear Sky Condition (m) 10 9 8 7 6 5 4 3 2 1 0 H h T Y P E A , , B , a n d C , T Y P E D, and E, + 1 0 % H h H 1 1 1 h - H -(m) 10 9 8 7 6 5 4 3 2 1 0 Overcast Sky Condition (m) 10 9 8 7 6 5 4 3 2 1 0 H h T Y P E A , , B , and C , 3 0 % T Y P E D, and E, 4 0 % -I 1 1 1 1 1 1 h + (m) 10 9 8 7 6 5 4 3 2 1 0 Current 600 lux line Improved 600 lux line Shading Distribution Current 600 lux line Improved 600 lux line Distribution Note: 600 lux is an appropriate lighting level in the desk (800 mm from the floor) (Source: Ministry of Construction, 2001) Fig. 6-11: the evaluation of interior natural lighting performance a) Shad ing analysis The results in Figure 6-11 show that from a shading perspective, all types of effective internal natural lighting control devices under clear sky conditions are able to provide effective shading against excessive direct sunlighting while maintaining the 600 lux interior natural lighting level. Types Ai , Bi and Ci provide effective shading performance (a 60 percent reduction in interior natural light within 3 m, under clear sky conditions). Type Di and Type E-t also provide a 20 percent reduction within 2 m under the clear sky condition. Even under overcast conditions, a 10 percent reduction is produced by all devices. b) Distribution analys is Interior natural lighting evaluation results show that the internal control devices are effective in increasing distribution performance. Types A 1 t Bi and are especially effective in clear sky conditions, and Type Di and Type Ei are especially effective in overcast sky conditions. The 600 lux standard level for natural lighting increased by approximately 1 m with the addition of Type Bi and Ci control devices. Interior natural lighting performance 81 improved by approximately 40% between 3.5 m to 6.5 m compared with the default case (no installed control device). c) Per formance summary of effective internal control dev ices > Type A-i, Bi and Ci are effective for increasing interior natural lighting level by approximately 40% within 6.5 m from the building fagade while providing a shading function which reduces excessive direct sunlighting by 60% under clear sky conditions. > Type Ai , C 1 t Di and E i , are effective for improving the adequate interior natural lighting level by approximately 40% for building depths between 3.5 m to 6.5 m under overcast sky conditions. > Type A L B^ CI,, D-\ and are effective for increasing the 600 lux performance depth by approximately 1 m. > Type and provide approximately 10% greater improvement to lighting level than Type AL B^ and C i , under overcast sky conditions. Under overcast sky conditions, smaller internal control devices are effective to employ daylighting and increase daylighting distribution. Larger internal control devices (Type A 1 ( B^ and C ^ reduce daylighting from the opening above a control device, and provide less and therefore natural lighting performance. 8 2 6.3.3. Internal + External Natural Lighting Contro l Dev ices In this section, external natural lighting control devices are added to investigate their reflective benefits for natural lighting performance. Optimal design parameters are developed through an iterative process of modification and evaluation with the ECOTECT software package. External control devices are devices which are mounted on the exterior of the building facade to reflect daylight and direct sunlight through the clearstory into the interior. Their function is primarily for distribution of natural light to deeper interior space. Adding these external control devices can dramatically enhance the natural lighting distribution. Within Tokyo's dense urban context, the lower floors of office buildings located on narrow streets receive limited natural light. Under such conditions, the increased need for natural light distribution may require the dimensions of external control devices to become proportionally exaggerated (see figure 6-12). TYPE-Az T Y P E - B 2 T Y P E - C 2 600 mm 1,000mm 700 mm 400 mm a) 8 to 12 months b) 6 to 8 months c) 4 to 6 months The Size of External Control Device 100 (W)mmX20 (H) mm 200 mm X 70 mm 290 mm X 140 mm T Y P E - D 2 270 mh b) 6 to 8 months 340 mm X 350 mm T Y P E - E 2 270 mm c) 4 to 6 months 350 mm X 350 mm Fig. 6-12: effective internal + external natural lighting control devices (Source: ECOTECT Interior Natural Lighting Analysis) 8 3 Figure 6-13 presents a graphical summary of interior natural lighting performance (see Appendix 6.3.3.) which is produced by the combination of internal and external control devices. Clear Sky Condition (m) 10 9 8 7 6 5 4 3 2 1 0 H h TYPE A2, B2 and C 2 20% 40% TYPE D2 and E 2 H 1 1 1 1 1 1 h I 1 (m) 10 9 8 7 6 5 4 3 2 1 0 Current 600lux line ^ | Shading F n — I m p r o v e d 600lux line Distribution Overcast Sky Condition (m) 10 9 8 7 6 5 4 3 2 1 0 H 1 h TYPE A2, B2 and C 2 1 1 • 1 1 20% TYPE D2 1 and E 2 ;• 30% - z&j&? - < H 1 H 1 1 1 1 1 1 V (m) 10 9 8 7 6 5 4 3 2 1 0 Current 600lux line Improved 600 lux line Distribution Note: 600 lux is an appropriate lighting level in the desk (800 mm from the floor) (Source: Ministry of Construction, 2001) Fig.6r13:^ the evaluation of internal + external natural lighting performance" These performance results are presented as a annual average percentage increase in natural light over the default case (no control devices). a) S h a d i n g analys is The installation of external natural lighting control devices to enhance distribution has little effect on shading performance. Figure 6-13 indicates that the internal + external device configurations, Types A2, B2, C 2, D 2 and E2, provide essentially the same shading performance as the internal device configurations shown in Figure 6-10. What figure 6-13 emphasizes is that added external components benefits natural light distribution while maintaining the effective shading function. b) Distribution analys is The addition of the external control devices results in an added distribution area at depths from 8 m to 10 m for Type A2, B 2 and C 2, increasing interior natural light at those depths by approximately 20% under the clear sky conditions. In contrast to internal devices alone, the external devices are shown to reflect direct sunlight from the exterior, deep into the interior space. 84 As shown in Appendix 6.3.3. the effective configuration of an external control devices depends on the available number of months for direct sunlighting. When the number of available months of direct sunlighting is decreased, the configuration of external control devices is extended beyond the facade (Type E 2 350 mm X 350 mm). The result (Figure. 6-13) shows that larger external devices (type D 2 and E2) produce more effective distribution performance than the smaller Type A 2, B 2 and C 2 device configurations under clear sky conditions. External control devices are more effective to employ daylighting to rear spaces in office buildings located on narrower streets. The distribution performance produced by Type D 2 and E 2 tends to provide a uniform increase in interior natural lighting at distances from 3 m to 10 m, especially in the lower floors (1F, 2F or 3F) of the office buildings and all floors of the office buildings under overcast sky conditions. These device configurations are suitable for situations requiring a stable quality of interior natural lighting in all seasons. c) Interior natural lighting performance area The analysis shows that the addition of external devices did not increase the 600 lux standard interior natural lighting area. The previous analysis for internal devices showed that it is possible to extend the 1 m performance depth limit with effective internal devices to between 1 m and 3 m. Although internal and external devices was able to increase the distribution performance at the range from 8 m to 10 m or provide a uniform natural light up to 10 m, the addition of external devices was insufficient to increase the extended illumination to the 600 lux level. d) Per formance summary for Internal + external dev ices > Under clear sky conditions, reflected sunlight through external devices can effectively increase interior natural lighting levels by approximately 20% in the range from 8 m and 10 m from the building facade, in addition to the increased lighting performance provided by internal devices (from 3.5 m to 6.5 m). > In lower floors (1F, 2F and 3F) of the office building under clear sky conditions and all floors of the office building under overcast sky conditions, external devices such as Type D 2 and E 2 can also be effective in providing uniform natural lighting to the interior. 85 > Although external devices are not effective at extending the standard 600 lux interior natural lighting performance depth, their contribution was in their ability to extend the distribution area and improve interior natural lighting level, particularly at rear space deeper spaces of the sampled area. > Type D 2 and E 2 provide approximately 10% greater improvement to lighting level than Type A 2, B2, and C 2 under overcast sky conditions. Under overcast sky conditions, larger external control devices with greater curvature are more effective to increase daylighting distribution. Smaller external control devices (Type A 2, B2, and C 2) provide less reflection of light to the interior and therefore natural lighting performance. 86 6.3.4. Internal + Ce i l ing Contro l Devices This section extends the systematic analysis of effective natural lighting control devices to configurations which combine internal and ceiling devices. Ceiling mounted control devices function as surfaces which redistribute the natural light reflected from internal control devices to enhance the distribution depth. The configurations of effective internal + ceiling natural lighting control devices are shown in Figure 6-14. TYPE-AS TYPE-B, TYPE-C, 2000 m m 1 ,000mm 700 m m 4 0 0 m m a) 8 to 12 months b) 6 to 8 months c) 4 to 6 months TYPE-D3 TYPE-E, 2 7 0 m m 2 7 0 m m b) 6 to 8 months c) 4 to 6 months Fig. 6-14: effective internal + •' J ceiling natural lighting control j devices : ! Unlike the analyses performed for the other natural lighting control devices (where the configuration of the control device is modified under various Tokyo urban scenarios), the ceiling control devices was modelled with fixed parameters to investigate the effect of a given ceiling control device on interior natural lighting performance in each Tokyo urban scenario. The main function of ceiling devices is to increase distributed natural l ighting from the internal control devices. As shown in Appendix 6.3.1-3 (Design Parameters for Ceiling Control Devices) a ceiling control device (2,000 mm) is designed to maximize daylighting, reflect direct sunlight from the sudace of internal devices under the lowest sun angle situation (December 21th). The result (see Appendix 6.3.1-1) shows a ceiling control 8 7 device effectively which enhances the redistribution performance during hot seasons. The Internal + ceiling control device combination, which maximizes the effectiveness of interior components is particularly effective for cases where building code regulations prevent the installation of external devices (see Chapter 1.4.4.). Figure 6-15 presents a graphical summary of the performance of internal + ceiling control device configurations under the Tokyo Urban Scenarios (see Appendix 6.3.4.). The figures represent the percentage increase in average illumination over the default case (no control devices). Clear Sky Condition (m) 10 9 8 7 6 5 4 3 2 1 0 ' -I 1 1 1 h-TYPE A3, B3 and C 3 6 0 ° i TYPE D3 and E 3 20% + H 1 1 h (m) 10 9 8 7 6 5 4 3 .2 Overcast Sky Condition (m) 10 9 ' —I h-8 7 6 5 -I 1 1 h TYPE A3, B3 and C 3 4 3 2 1 ' l l ' 40% ' TYPE D3 and E 3 60% H 1—I 1 1 1 1 1- -I h (m) 10 9 8 7 6 5 4 3 2 1 Current 600 lux line Improved 600 lux line Shading Distribution Current 600 lux line Improved 600 lux line Distribution Note: 600 lux is an appropriate lighting level in the desk (800 mm from the floor) (Source: Ministry of Construction, 2001) Fig. 6-15: the eyaluationof internal *+ ceiling naturaUighting performahce. a) S h a d i n g analys is As shown in above the graph, the internal + ceiling device configurations provide the same shading performance results as the internal device performance shown in Figure 6-11. As ceiling devices are installed under the interior of ceiling surface, they do not affect the shading function of internal control devices. b) Distribution analysis The results show that in ceiling control devices Type A 3 , B 3 and C 3 , the interior + ceiling device configurations produce a 60% increase in the interior natural lighting level for the 88 area between 3.5 m to 7.5 m, similar to individual effective internal device performance under clear sky conditions. Effective internal + ceiling devices can provide the 60 % improvement of interior natural lighting level for office buildings located alongside a narrow street and experiencing significant overcast sky conditions. Ceiling devices are effective for increasing interior natural lighting level at the depth range between 2 m and 7 m. The graph also shows a distinct difference in natural lighting distribution pattern compared to the internal + external device configurations presented in Figure 6-12. Internal + ceiling redistribution device configurations are suitable when higher average interior natural lighting is required within 7 m depths. b) Interior natural l ighting performance area The redistribution performance of ceiling control devices generally depends on the effective distribution of natural light from internal control devices. As a result, the position of ceiling devices relative to internal devices has a significant impact on the effectiveness of these configurations. The results show an extension of the 600 lux standard depth performance area by approximately 2 m in each of the Tokyo Urban Scenarios under both sky conditions. This effective increase in standard performance depth suggests that this configuration uniformly provides high distribution performance to interior. e) Per formance summary for Internal + cei l ing dev ices > Under the clear sky conditions, ceiling devices such as those included in Type A 3, B 3 and C 3 configurations, can be effective for increasing interior natural lighting levels by approximately 60% between 4 m and 7 m from the window, dramatically enhancing the distribution performance of the interior natural lighting control devices > At 1F, 2F and 3F of office buildings under clear sky conditions or all floor of office buildings under overcast sky conditions, ceiling devices can be effective for providing an annually stable interior natural lighting level at distances approximately 2 m to 7 m from the building facade. 89 > Ceiling devices can be effective at extending the 600 lux standard interior natural lighting performance area by 2 m. > Type D 3 and E 3 provide approximately 20% greater improvement to lighting level than Type A 3, B3, and C 3 under overcast sky conditions. Since ceiling control devices simply enhance the effects of interior control devices, the ceiling + internal device configurations provide greater improvement where the internal devices are more effective. Therefore, under overcast conditions, the ceiling devices are most effective for smaller internal device configurations (Type D 2 and E 2). 90 6.3.5. Internal + External + Ceiling Control Devices In this section, the analysis is extended to a category of device configuration combining all three control device types (internal + external + ceiling). The internal devices perform the function of shading against excessive direct sunlighting while distributing incoming natural lighting, and the external and ceiling devices are added as supplemental distribution devices to enhance interior lighting performance. The configurations of possible internal + external + ceiling natural lighting control devices for the different Tokyo Urban Scenarios is shown in Figure 6-16. TYPE-A, TYPE-Bi T Y P E - C , 1,000mm 700 mm 400 mm a) 8 to 12 months b) 6 to 8 months c) 4 to 6 months TYPE-Bi 270 mm b) 6 to 8 months T Y P E - d 270 mm1 c) 4 to 6 months Fig. 6-16: effective internal + external + ceiling natural ^ lighting control devices , (Source: ECOTECTJntengr Natural Lighting Analysis) 91 Figure 6-17 presents the graphical summary of the interior natural lighting performance resulting from these internal + external + ceiling configurations (see Appendix 6.3.5.). The figures represent the percent increase in interior lighting over the default case (no control devices). Clear Sky Condition (m) 10 9 8 7 6 5 4 3 2 1 0 H 1 h + TYPE A,, 3 , and C, 30% 70% i — i — H TYPE D, and E, 20% -I 1 1 1 h H \->-(m) 10 9 8 7 6 5 4 3 2 Current 600 lux line Improved 600 lux line Shading Distribution Overcast Sky Condition (m) 10 9 8 7 6 5 4 3 2 1 0 H h TYPE A,. B, and C, ' • ' l l TYPE D, and E, 60% -I 1 1 1 h H 1 1 (m) 10 9 8 7 6 5 4 3 2 1 Current 600 lux line Improved 600 lux line • Distribution Note: 600 lux is an appropriate lighting level in the desk (800 mm from the floor) (Source: Ministry of Construction, 2001) j Fig. 6-17: the evaluation of internal + external + ceiling natural lighting performance a) Distribution ana lys is For each of the Tokyo Urban Scenarios, the distribution performance for interior natural lighting is significantly increased. Under both sky conditions, the interior natural lighting performance produced by these combined device configurations has the effect of enhancing the uniformity interior natural lighting. Under both sky conditions, Type A 4 , B 4 and C 4 device configurations are able to achieve a maximum of 70% improved interior natural lighting within 7 m. As discussed previously in Section 6.3.2, external distribution devices are effective for an area at a depth range from 8 m to 10 m and ceiling redistribution devices provide an effective area at depths form 4 m to 7 m, within the Tokyo context. As a result, evaluation results for Type A 4 , B 4 and C 4 show a lower percent increase in interior natural lighting around 8 m, representing the transition area between zones of external and ceiling performance. At all floors of office buildings under overcast sky conditions or at the lower floors (1F, 2F and 3F) of office buildings, interior natural lighting performance, enhanced by ceiling devices, 92 is extended to a 10 m floor depth. This produces a more uniform natural lighting within the interior of a sampled area. b) Interior natural l ighting performance area For all urban scenarios and sky conditions, the internal + external + ceiling control device configurations extend the depth limits of interior natural lighting performance areas to approximately two times the natural lighting depths produced by effective internal control devices alone. The design recommendation for good naturally lit office buildings suggests that effective performance depth of natural lighting should be at least 1.5 to 2.0 times the window height (Nikken Sekkei, 2000). This design recommendation would suggest that for the proposed hypothetical office building, effective performance depth should be 3 m. As shown, the performance depth limits achieved through the internal + external + ceiling configurations generally meet this design recommendation even in the worst Tokyo urban scenarios such as on lower floors of office buildings located on narrower streets under overcast sky conditions. Increasing the depth limit for available natural lighting leads not only to an improved indoor office environment but also to a reduced energy consumption for electrical lighting systems (investigated in Section 6.4 with case studies). e) Performance s u m m a r y for Internal + external + cei l ing dev ices > Combined devices such as Type At, B 4 and C 4 configurations can be effective for increasing interior natural lighting levels by approximately 70% at depths between 3 m to 7 m from the window while utilizing the distribution advantage of both external and ceiling devices under the clear sky conditions. > Combined devices can be effective for providing uniform interior natural lighting levels while maintaining the ceiling distribution performance, especially at lower floors of office buildings or under overcast sky conditions. > Combined devices can be effective to extend the 600 lux standard depth limit for interior natural lighting performance by approximately two times the depth of internal devices alone. 9 3 There are complex interactions between the design parameters of the four types of effective control devices that have significant effects on interior natural lighting performance. The benefits of interior natural lighting achieved with effective control devices are summarized below: 1) Configurations employing internal control dev ices are effective for direct sunlighting and daylighting control within a 5 m depth from the window. 2) Configurations employing both internal + external control dev ices are effective for increasing natural lighting within 5 m of the window and at a deeper interior s p a c e 8 to 10 m from the window. 3) Configurations employing internal + ceil ing control dev ices are effective for enhanc ing the performance of internal control d e v i c e s within 5 m from the w indow. 4) Configurations employing internal + ceil ing + external control dev ices are effective for enhanc ing the performance of internal control dev ices within 5 m from the w indow and at a deeper interior s p a c e 8 to 10 m from the w indow. 9 4 6.4. S i t e S p e c i f i c O f f i c e B u i l d i n g D e s i g n C a s e S t u d y For this study, the hypothetical office building was adopted to demonstrate a process of analysis for the design and evaluation of effective natural lighting control devices for office renovations in the Tokyo context. Up until this point, the analysis in this chapter has focused on determining the specific parameters for different configurations of effective control devices for five Tokyo Urban Scenarios representing five general scenarios of fixed number of months of direct sunlight (which are functions floor level and distance of the facing obstructions). In this section, the hypothetical office building will be set in a specific location with a fixed obstruction distance of 10 m, and fixed obstruction height of 31 m. With fixed obstructions, the number of months of direct sunlighting becomes a function of floor level. Current typical office renovation strategies employing curtain walls are inadequate to respond to specific sites because: 1. Curtain walls typically treat all f loor levels the same, ignoring the differences in number of months of direct sunlight which different floors receive; 2. Curtain wal ls only act to limit e x c e s s i v e direct sunl ight by reflection, ignoring benefits of natural light distribution for interiors; By contrast, the site specific case study provided here aims to demonstrate that a renovation strategy employing natural l ighting control dev ices can be a more site responsive because: 1. Natural lighting control dev ices c a n take o n different conf igurat ions for different f loors, responding to differences in the number of months of direct sunlight which different floors receive; 2. Natural lighting control dev ices act to both limit excess ive direct sunl ight a n d distribute natural light to the interior; 95 An office building retrofitted with effective natural lighting control devices is evaluated for the following three indoor environmental performances: > Interior natural lighting performance > Energy consumption for supplemental electrical lighting systems > Operating cost for electrical lighting systems 6.4.1. Designing Effective Natural Light ing Control Dev ices To improve current interior natural lighting performance, internal + external + ceiling control devices are applied to the building facade to enhance natural lighting distribution for each floor. The appropriate design configuration of internal + external + ceiling control devices for each floor (investigated in Section 6.3.4.) is determined using the interior natural lighting chart and direct sunlighting chart. Figure 6-18 presents the number of the months of direct sunlighting and the percent reduction in interior natural lighting performance for each floor, given the fixed obstruction distance of 10 m. Direct Sunlighting Performance Chart Interior Natural Lighting Performance Chart 10/1 5/1 3/1 2/1 4/3 1/1 10/1 5/1 3/1 2/1 4/3 1/1 (a) 8-12 months (d) 2 - 4 months (A) Full Exposed (F)-25--20% (b) 6 - 8months (e)0-2months (B) -5-0% (G)-30--25% (C)4- 6 months (C)-10~-5% (H)-35-30% (D) -15~-10% (I) -40--35% (E) -20--15% Fig. 6-18: The relationship between the direct sunlighting and the interior natural lighting chart 96 The percent reduction in interior natural lighting performance illustrates the effects of the obstruction in reducing the level of natural lighting available at each floor. These figures may be useful to provide clients, architects, and lighting designers with a sense of the varying natural lighting needs of different floors to help them make investment decisions. From the 1st to the 7 t h floor, the percent reduction of interior natural lighting is relatively high (-35% to -25%). On the other hand, the 8 t h and 9 t h floors experience no reduction in interior natural lighting level due to the obstruction. In general, lower floors experience a greater reduction in natural lighting, and may require a greater level of natural lighting distribution (perhaps benefiting the most from an internal + external + ceiling configurations), whereas upper floors experience very little reduction in natural lighting, and may require a less distribution (perhaps the internal configuration alone). In a real situation, budget constraints may prevent building owners from employing all natural lighting components, so this table may help to show the owners and designers the relative natural lighting needs of different floors, and to make decisions on how best to optimize natural lighting. The number of months of direct sunlight is another important consideration for designing effective control devices. As described in Sections 6.2 and 6.3, the appropriate size and position of control device to provide direct sunlighting and daylighting control is often dependent on the number of months of direct sunlight. The results in Figure 6-18 show that the number of months of direct sunlighting is relatively lower (2 to 4 months) at the lower floors of the office building. For the purpose of this study, the assumption is need that the internal + external + cei l ing conf igurat ions which provide the most effective improvement of interior natural lighting performance are implemented on all floors. Majority of 70's or 80's existing office buildings are typically located on the 10 m street urban setting (Tokyo Real Estate Report, 2002). Significant improvement of interior natural lighting performance is expected (the current performance of interior natural lighting is available from the chart of the percent reduction of interior natural lighting performance described in Chapter 6.1.1.) The parameters of these device configurations depend on the floor level (the number of months of direct sunlight) and are determined by our previous analysis in Section 6.3.5. 97 6.4.2. Interior Natural Lighting Per formance Figure 6-19 presents a graphical summary showing the resulting interior natural lighting performance using internal + external + ceiling control devices to retrofit the hypothetical building under the given site context. The figures represent the percent increase in natural lighting: > compared with the default case (no control devices) > compared with typical curtain wall renovations, (8 mm thickness, Shading Coefficient 0.95, Transparency 0.88) This comparison is shown for both clear and overcast sky conditions. What is evident in the figures is that the curtain walls, while very effective in limiting excessive direct sunlighting, also produce a greatly reduced natural lighting level compared to the default case (without any control devices). Clear Sky Condition Comparison with no devices I TYPE-A (8 and 9F) TYPE-B (7F) TYPE-C (4,5 and 6F) TYPE-D (1,2, and 3F)| Comparison with curtain wall 40% 80% 80% I 100% I 80% 100% I 80% I 100 % 150% H 1 1 1 1 h I -I h (m) 10 9 8 7 6 5 4 3 2 1 0 (m) 10 9 8 7 6 5 4 3 2 1 0 Fig. 6-19: the percent increase for the interior natural lighting performance with effective control devices Under clear sky conditions, a comparison of interior natural lighting performance for the internal + external +ceiling device configurations with the default case (without control devices) shows the following results: 9 8 (i) Effective direct sunlighting and daylighting control are performed from the 4 floor to 9TH floor through the use of control devices within 2 m. > Internal + eternal + ceiling control devices are effective in increasing interior natural lighting performance by approximately 80% within 3 m to 7 m from the fagade while maintaining appropriate shading performance. (ii) Effective daylighting control is performed from the 1 s t floor to 3 R D floor through control devices. > Internal + eternal + ceiling control devices are effective in producing a uniform increase in interior natural lighting performance of approximately 40%. > Internal + eternal + ceiling control devices are effective to extend the 600 lux interior natural lighting performance area to twice the depth limit of the default case (without control devices) for all floors. Under clear sky conditions, a comparison of interior natural lighting performance for the internal + external +ceiling device configurations with curtain walls shows the following results: > Internal + eternal + ceiling control devices are effective to extend the 600 lux interior natural lighting performance area up to 6 times the 600 lux depth produced by curtain walls (1m) while providing sufficient shading performance equal to that produce by the curtain wall. > For the lower floors, internal + eternal + ceiling control devices are effective in increasing the interior natural lighting performance by approximately 150% compared with the selected curtain wall within 6 m. 9 9 Overcast Sky Conditions Compared with no device Compared with curtain wall (m) 10 9 8 7 6 5 4 3 2 1 0 (m) 10 9 8 7 6 5 4 3 2 1 0 Fig. 6-20: the percent reduction for the interior natural lighting performance with effective control devices Under overcast sky conditions, a comparison of interior natural lighting performance for the internal + external + ceiling device configurations with the default case (without control devices) shows the following results: Effective daylighting control is performed on all floors (from the 1 s t floor to 9 t h floor) through control devices. Internal + eternal + ceiling control devices are effective in producing a uniform increase in the interior natural lighting performance of approximately 40 to 60%. Internal + eternal + ceiling control devices are effective in extending the 600 lux interior natural lighting standard depth by up to 2 m from the 1st floor to 9th floor. Under clear sky conditions, a comparison of interior natural lighting performance for the internal + external + ceiling device configurations with curtain walls shows the following results: 100 Internal + eternal + ceiling control devices are effective in increasing interior natural lighting performance by approximately 80%. The area which indicates a 100% improvement reflects the impact of positive distribution in contrast to the curtain walls' screening effect. This analysis of interior natural lighting performance under clear and overcast sky conditions suggests that the combined internal + external + ceiling control devices are effective in increasing interior natural lighting performance for all floors under both the clear and overcast sky conditions. The following subsection extension this analysis by examining the benefits of these natural lighting control devices for energy efficiency and operating cost of electrical lighting systems. 6.4.3. Energy C o n s u m p t i o n and Operat ion C o s t of Electrical L ight ing S y s t e m s It could be argued that, aside from improving interior natural lighting, the second main function of inducing natural lighting to the interior is to reduce the energy consumption and operating cost of electrical lighting systems. When interior natural lighting performance is improved, the effective area of natural 600 lux standard lighting level (recommended as the minimum lighting level for desk surfaces) is extended, and electrical lighting systems need only function as supplemental lighting sources to respond to fluctuations through dimming or switching systems. As a result, energy consumption and operation cost are dramatically reduced. As shown in Note 6-5, the energy consumption and operation cost for electrical lighting systems is evaluated using coefficients obtained from the EFRP to illustrate a comparison of: 1. Internal control devices with high energy efficiency electrical lighting systems with the dimming systems 2. Current electrical lighting systems with no natural lighting control devices 3. Curtain walls with high energy efficiency electrical lighting systems The results of the analysis in this section emphasize the benefits of specific effective natural lighting control devices for interior natural lighting performance, energy consumption and operation cost of electrical lighting systems within the context of a typical older existing office building in Tokyo. This innovative approach to office renovation design reveals the 101 potential opportunities in natural lighting control devices, and provides a framework which allows these opportunities to be realized effectively through an organized team decision making process. Energy consumption and operation cost for electrical lighting systems are evaluated according to the following criteria for 1970's and 80's Tokyo's existing office buildings (6,000 (a) Default Case (no lighting control) (b) Curtain Wall Office Renovations (c) Office Renovation with Natural Lighting Types of Electrical Lighting System Conventional Electrical Lighting System Energy Efficient Electrical Lighting System Energy Efficient Electrical Lighting + Dimming System + Natural Lighting Operation Hours per Day 10h (9:00-19:00) 10h (9:00-19:00) 10h (9:00-19:00) Operation Days per year 250 Day/year 250 Day/year 250 Day/year Coefficient for Energy Consumption for Electrical Lighting Systems 20.6 W/m 2 16.9 W/m 2 14.2 W/m 2 Coefficient for Operation Cost for Electrical Lighting Systems 325 Yen/m 2 249 Yen/m 2 214 Yen/m 2 Fig. 6-21: the Guideline for Assessment of Environmental Friendliness of Government Building Facilities and Renovation Plan. 2001) (1) Types of Electrical L ight ing S y s t e m s The chart above describes the evaluation of the energy consumption and operation cost of electrical lighting systems used as an integral pat of office renovation for 6,000 m 2 office buildings. The electrical lighting systems included were taken from the EFRP. (a) Current Situat ion: Conventional electrical lighting systems are not integrated with natural lighting and are continuously used during defined operation hours per day (see above diagram). (b) Curtain Wall Off ice Renovat ions: Energy efficient electrical lighting systems are installed with curtain wall office renovations to increase energy efficiency without the effective use of natural lighting. Office renovations with curtain walls are effective to reduce cooling loads during hot 102 seasons, but are not designed to increase interior natural lighting performance. Energy efficient electrical lighting systems are in con t inuous use during operation hours. (c) Office Renovat ion with Natural Light ing: Natural lighting control devices are installed to increase interior natural lighting performance. In this study effective control devices (internal, internal + external, internal + ceiling, and internal + external + ceiling control devices) are installed on the existing facade. As shown in Chapter 6.3. the result of improved interior natural lighting performance is different. The coefficient for electrical lighting systems integrated with natural lighting and dimming systems is chosen, as discussed in the EFRP, to evaluate energy consumption and operation cost for electrical lighting systems. (2) The Calculat ion Method To calculate the energy consumption and operation cost for each of these situations, an appropriate coefficient (c) given by the EFBGRP is multiplied to the total square footage of the building (6075 m2). This coefficient (c) represents the relative efficiency of each of these situations. For office renovation with natural lighting, the coefficient (c) reflects the relative performance of dimming systems with natural lighting control devices (without any other natural lighting control systems such as the blinds) under overcast s k y condi t ions . The coeff icients (c) presented in this figure is given by the EFRP generally for Tokyo office buildings. The assumption made by the EFRP is that office planning in the 1970s and 80s followed a typical pattern of deep office plan, without the use of external environmental benefits. Our hypothetical 6,000m2 office building facing a 10m obstruction was designed to conform with this typical pattern. 6075 (m2) X 20.6 (W/m2 )= 125,000 6075 (m2 )X 16.9 (W/m2) = 102,000 6075 m2X14.2 (W/m2) = 86,000 The Percent Reduction for Energy Consumption 0% -19% -31% 6075 (m2) X 325 (Yen/m2) =1,974,000 6075 (m2) X 249 (Yen/m2) = 1,513,000 6075 (m2) X 214 (Yen/m2) = 1,300,000 The Percent Reduction for Operation Cost 0% -23% -35% j Fig. 6-22: the evaluation for energy consumption and operation cost with natural i liahtina 103 7.1. O f f i c e R e n o v a t i o n wi th Natura l L i g h t i n g The practical application of natural lighting in Tokyo's more recent office building projects has been driven by goals of improving indoor office environments, and by demands for energy efficiency in green building guidelines such as CASBEE or the TMG green building program. However, natural lighting are not currently implemented in the renovation of Tokyo's older office buildings, as the conditions under which they are meant to apply are either not stated or poorly defined with regards to the Tokyo context. This thesis argues that innovative office renovation techniques using natural lighting provide a means for increasing the market value of existing office buildings. The following were the key intentions of this thesis: > To provide knowledge and information regarding lighting control systems and the ability of such systems to enhance natural lighting utilization; this study aimed to provide an increased awareness of the potential benefits of natural lighting for architects, decision-makers and the Tokyo Metropolitan Government. > To provide evidence for office building tenants that natural lighting can substantially improve energy efficiency and indoor environmental quality in Tokyo's office buildings. > To provide a simple design framework for retrofitting office buildings using appropriate natural lighting design techniques as a response to CASBEE or other existing Tokyo environmental assessment systems. > To suggest that design guidelines governing design practice should encourage the use of natural lighting for Tokyo contexts and to ensure that it is given due consideration at the design stage for retrofitting existing office buildings. > To provide a model for the successful retrofitting of office buildings with natural lighting, which can raise owners' awareness of the benefits of natural lighting and 104 encourage a more widespread use of natural lighting for upgrading office buildings in the future. The objective of this study was to explore the potential of effective natural lighting control devices as an essential part of office renovation within Tokyo's context. The thesis differs from existing office renovation design guidelines in that it focuses on the implementation of "natural lighting strategies" in a framework that integrates ECOTECT simplified evaluation software, and team decision making with the design process. A hypothetical office building was used to demonstrate how this framework might be applied. One of the intentions of applying the framework to a hypothetical model which represents a "typical Tokyo office building" is to suggest that the process of analysis may have potential for widespread application within Tokyo's context. The computer modelling software, ECOTECT v5, was used in this study to design effective control devices and to evaluate the impacts of these devices on interior natural lighting performance. This simplified environmental evaluation software is suitable as a pre-design tool in that it is relatively easy and fast to use, and because it provides default values for many of the detailed design parameters which are unnecessary or unavailable at the preliminary stage of the office renovation process. While the precision of results produced with ECOTECT were not validated by a sophisticated environmental software package such as DOE-2 or field test measurements, the value is in demonstrating the effective relationship between the design parameters of control devices and interior natural lighting performance. Optimal parameters for the devices were obtained through an iterative process of predicting and assessing the performance of the control device models. Results of this study show that sunlighting control techniques in Tokyo's recent office building projects, such as curtain walls are often ineffective when applied as renovation strategies for typical existing office buildings in Tokyo's dense urban spaces. The results of the computer model analysis found that curtain walls could not provide the appropriate distribution to achieve recommended performance (600 lux) of interior natural lighting. The study also found that the parameters of control device configurations, and the control device benefits for retrofitting Tokyo's existing office buildings vary greatly depending on the specific urban situation (such as the position of obstructions, and floor level). As a result, it is more appropriate to develop effective natural lighting control devices that are appropriate for a wide range of contexts, with an understanding of the general characteristics of Tokyo 105 Urban Scenarios. This study employed a "Tokyo Urban Obstruction Ratio analysis address a range of urban scenarios with different natural lighting conditions. 7.2. S u m m a r y f o r E f fec t i ve Natura l L i g h t i n g C o n t r o l D e v i c e s The design parameters for effective natural lighting control devices (internal, internal + external, internal + ceiling and internal + external + ceiling) were developed with a chart of the number of months of direct sunlighting performance (classified as Tokyo Urban Scenarios (a), (b), (c), (d) and (e)). These control devices were evaluated to identify their relative effectiveness in increasing interior natural lighting under clear and overcast sky conditions. A simple diagram was developed from a "number of available months for direct sunlighting chart" and a "percent reduction in interior natural lighting chart' to illustrate current interior natural lighting performance for each of the Tokyo Urban Scenarios. This section revisits the effective natural lighting control devices which were investigated in this study and aims to formulate recommendations as to their usefulness for clients, architects, and designers. Figure 7-1 presents a simple chart illustrating the relationship between the available months of direct sunlighting to the interior and interior natural lighting performance needs. This chart provides a summary which may be useful to the design team, illustrating the relative effectiveness of different device configurations given the percent reduction in interior natural lighting caused by obstructions. Internal + External Devices Internal + Ceiling + External devices Internal Devices Internal + Ceiling Devices 0- -5% -5--10% -10--15% -15--20% -20--25% -25--30% -30--35% -35--40% The percent reduction in interior natural lighting compared with no obstruction situation Fig. 7-1: the recommendation of effective control devices with Tokyo urban scenarios . 107 Figure 7-1 emphasizes that different Tokyo Urban Scenarios (a), (b), (c), (d) and (e) (different natural lighting conditions) (described in Chapter 6.1.2.) may call for different device configurations, and presents recommendations for sufficient control device configurations. A more detailed analysis of these Tokyo Urban Scenarios and Sufficient Natural Lighting Control Devices are described the following sub sections. 7.2.1. Tokyo Urban Scenario (a) — Internal Natural Lighting Control Devices > The number of available month for direct sunlighting: 8 ~ 12 months > The percent reduction in interior natural lighting: 0 ~ -25% Direct Sunlighting Performance Chart 10/1 5/1 3/1 2/1 4/3 1/1 Interior Natural Lighting Performance Chart 10/1 5/1 3/1 2/1 4/3 1/1 0 5 10 15 20 25 30 35 40 45 50m 0 5 10 15 20 25 30 35 40 45 50m (a) 8 -12 months (d) 2 - 4 months (A) Full Exposed (F) -25 - -20% (b) 6 - 8 months (e)0-2 months (B) -5-0% (G)-30--25% (C)4- 6 months (C)-10-5% (H)-35-30% (D) -15~-10% (I) -40--35% (E) -20 - -15% Fig. 7-2: the recommended Tokyo urban context for sufficient use of Internal natural lighting control devices The shaded area in Figure 7.2 represents the achieved area both the number of available months of direct sunlighting 8 ~ 12 months and the percent reduction in interior natural lighting 0 - -25% which internal natural lighting control devices are sufficient. Expected improvements to the indoor office environment through internal control devices are described in detail below: 108 Clear Sky Condi t ions > Shading excessive direct sunlighting in hot seasons, at distances within 3m from window opening while maintaining the 600 lux interior natural lighting level > Increasing the interior natural lighting level by 40% at distances 4 m to 6 m from the window opening through distribution on the surface of control device > Achieving a 600 lux interior natural lighting level for distances within 4 m of the building facade (approximately a i m increase compared that without any control devices) Overcast S k y Condi t ions > Increasing the interior natural lighting level by 30% at distances of 2.5 m to 6 m from the window opening, through distribution from the surface of control device and the ceiling > Achieving a 600 lux interior natural lighting level for distances within 2.5 m from window opening (approximately a 1 m increase compared that without any control devices) 109 7.2.2. Tokyo Urban Scenarios (b), (c), and (d) — Internal + External or Internal + Ceiling Natural Lighting Control Devices > The number of available month for direct sunlighting: 4 ~ 8 months > The percent reduction in interior natural lighting: -30 ~ -25 % Direct Sunlighting Performance Chart 10/1 5/1 3/1 2/1 4/3 1/1 Interior Natural Lighting Performance Chart 10/1 5/1 3/1 2/1 4/3 1/1 10 15 20 25 30 35 40 45 50m (a) 8 - 1 2 months (d) 2 - 4 months (b) 6 - 8 months (e) 0 - 2 months (c) 4 - 6 months 10 15 20 25 30 35 40 45 50m (A) Full Exposed (B) -5-0% (C) -10--5% (D) -15--10% (E) -20--15% (F) -25 - -20% (G) -30 - -25% (H) -35 - -30% (I) -40--35% Fig. 7-3: the recommended Tokyo urban context for sufficient use Internal + External or Internal + Ceiling natural lighting control devices The shaded area in Figure 7.3 represents the achieved area both the number of available months of direct sunlighting 4 - 8 months and the percent reduction in interior natural lighting -30 - -25 % which internal + external or internal + ceiling natural lighting control devices are sufficient. These combined control devices are necessary where obstructions restrict months of available direct sunlighting and significantly reduce interior natural lighting performance. Expected improvements to indoor office environment produced by Internal + External or Internal + Ceiling control device combinations are described below: 110 1) Internal + External Natural Control Device Internal + External control device combinations are particularly effective for improving interior natural lighting performance in deep spaces. Clear S k y Condi t ions > Shading excessive direct sunlighting in hot seasons at distances within 3 m of the window opening while maintaining the 600 lux adequate interior natural lighting level > Increasing interior natural lighting level by approximately 20% at distances between 8 m to 10 m from the window opening Overcast S k y Condi t ions > Providing a uniform natural lighting within a 10 m distance from the window opening while increasing the interior natural lighting level by30% > Increasing the 600 lux performance area within distances approximately 1 m of the window opening 2) Internal + Ceiling Natural Lighting Control Devices Internal + ceiling control devices are particularly effective for increasing the distribution performance of internal devices. Clear S k y Condi t ions > Increasing interior natural lighting level by approximately 60% at distances within 7 m of the window opening while marinating effective shading against excessive direct sunlighting > Extending the 600 lux standard depth limit by approximately 2 m compared with that without control devices Overcast S k y Condi t ions > Increasing the interior natural lighting level by approximately 40% at distances between 3 m to 6 m from the window opening 111 > Extending the 600 lux standard depth limit by approximately 2 m compared with that without natural lighting control devices 7.2.3. Tokyo Urban Scenarios (d) and (e) Control Devices Internal + External + Ceiling Natural Lighting > The number of available month for direct sunlighting: 0 - 4 months > The percent reduction in interior natural lighting: -25 ~ -40 % Direct Sunlighting Performance Chart Interior Natural Lighting Performance Chart 10/1 5/1 3/1 2/1 4/3 1/1 10/1 5/1 3/1 2/1 4/3 1/1 9F 8F 7F 6F 5F 4F 3F 2F IF I / / / ! I ; \ j / JllJU/ V \ \ 1 1 Ilk / X / l l t l l l l l / A a ^ 10 15 20 25 30 35 40 45 50m (a) 8 -12 months (d) 2 - 4 months (b) 6 - 8 months (c) 4 - 6 months (e) 0 - 2 months 10 15 20 25 30 35 40 45 50m (A) Full Exposed (B) -5-0% (C) -10--5% (D) -15--10% (E) -20~-15% (F) -25 - -20% (G) -30 - -25% (H) -35 - -30% (I) -40 - -35% Fig. 7-4: the recommended Tokyo urban context for sufficient use-Internal4 External•• Ceiling natural lighting control devices The shaded area in Figure 7.3 represents the achieved area both the number of available months of direct sunlighting 0 ~ 4 months and the percent reduction in interior natural lighting -25 ~ -40 % which internal + external + ceiling natural lighting control devices are sufficient. These control device combinations are often needed for Tokyo Urban Scenarios where natural lighting is greatly diminished, such as on the lower floors of office buildings located along narrow streets, especially under overcast sky conditions. A configuration combing internal, external, and ceiling control devices is most effective to induce this limited natural light to interior. Expected improvements to the indoor office 112 environment through internal + external + ceiling control device combinations are described below: Clear Sky Conditions > Increasing interior natural lighting level approximately 20% within 10 m while archiving 600 lux standard interior natural lighting performance area within 4 m (increased from the current performance area 1.5 m) Overcast Sky Conditions > Providing uniform natural lighting for distances within 10 m of the window opening while increasing interior natural lighting levels by 60% > Extending the 600 lux performance depth limit by approximately 2 m (from 1m to 3 m) compared to that without any natural lighting control devices Table 7-1 provides a simple chart is also developed for architects, lighting designers and clients to find effective natural lighting control devices under specific Tokyo Urban Scenarios. 113 Table. 7-1 Effective Natural Lighting Control Devices within Tokyo Context Note: Shading Performance. Distribution Performance and 600 lux Interior Natural Lighting Area are evaluated. ^ T Y P E : A . ifiokyoUrbanlScenano(a) .'• A T Y P E - . liTokyo Urban S . » • T Y P E - C !,., Tokyo Urban Scenano (c) " l^lyfbYanlje^ lP i T Y P E - E TokyolUrrSfflScenano (a)' K Intrenal Natural Lighting Control Devices -10% (2m) -50% (2 m) -10% (2m) -40% (2 m) -10% (2m) -20% (2 m) -10% (2m) -10% (2 m) -10% 12m) +40% (3m-7m) +30% (3m-7m) +35% (3 m-7 m) +30% (3m-7m) +30% (3 m-7 m) +30% (3m-7m) +10% (3m-7m) +35% {3 m-7 m) +15% (3m-7m) I^nternal:* External Naturai;LightingCpntrql Devices 100mm(W)X20mm(H) 200 mm (W) X 70 mm (H) 290mm(W)X140mm(H) 340mm(W)X350mm(H) 350 mm (W) X 350 mm (H) Clear Overcast Clear Overcast Clear -60% (2 m) -10% (2m) -50% (2 m) -10% (2m) -10% (2m) -20% (2 m) -10% (2m) -10% (2m) +30% Pm-10m> +30% (3 m-10 m> +10% (3 m-10 m) +35% (3 m- 10 m) + 15% (3 m-10 m) +40% (3m-1Q m) 2.5 m 2m 2m 2m Internal + Ceiling Natural Lighting Control Devices Clear Overcast Clear -60% (2 m) -10% (2m) -50% (2 m) -10% (2m) -40% (2 m) -10% (2m) -20% (2 m) -10% (2m) -10% (2 m) -10% (2m) +60% (3 m-7 m) +40% (3m-7m) +55% (3m-7m) +40% (3 m-7 m) +50% (3 m-7 m) +40% (3m-7m) +10% (3m-7m) +55% p m - 7 m ) + 15% (3m-7m) +60% (3m-flm) 5m 3.5 m 4.5 m Internal + External + Ceiling Natural Lighting Control Devices ; -60% (2 m) Overcast -10% (2m) +40% <3m-10 m) Overcast (2m) +40% (3 m-7IOm) Clear -40% (2 m) Overcast -10% (2m) +40% (3m-10 m) Clear -20% I2m) +20% (3m-IOm) -10% (2m) +35% (3 m-7 m) -10% (2 m) -10% (2m) +60% (3m-10m) 114 The recommendations made in this section were formulated through an assessment of interior natural lighting performance levels and the effectiveness of the device configurations. Interior spaces located in urban scenarios (d) or (e) experience the greatest reductions in natural lighting, and are probably in most need of combined control device configurations (internal + external + ceiling). However, there are factors other than existing natural lighting levels which should be considered when making decisions regarding control device configurations. Occupant Task — Decisions on effective natural lighting control devices should take into consideration the lighting needs of occupant tasks. As described above, different control devices provide different types of interior performance. Interior + external device configurations are very effective in increasing interior lighting levels in deep spaces, while internal + external + ceiling devices provide more uniform interior natural lighting. These unique performance characteristics of the different control device configurations may often be more suitable for different occupant tasks or needs. Although this "occupant satisfaction" factor may not be directly reflected in an increase in energy efficiency or it have benefits in promoting the increased productivity of the staff Energy efficiency — Energy consumed by electric lighting, which makes up a significant proportion of total energy consumption in Tokyo's older existing office buildings, can often be significantly reduced through the effective use of natural lighting. When natural lighting control devices are properly used in combination with supplemental lighting systems such as dimming or sensor systems, a direct relationship between interior natural lighting performance and reductions in energy consumption can be observed. If the major intention of retrofitting existing office buildings is to increase energy efficiency using natural lighting control devices, internal + external + ceiling control devices are perhaps the most effective within Tokyo contexts. Cost effectiveness — Emphasizing the relationship between the construction cost of retrofitting existing office buildings with natural lighting and the pay-back period resulting from reductions in operation cost is important to emphasize the benefits of a widespread application of effective natural lighting control devices within Tokyo contexts. Using environmentally friendly techniques to upgrade existing offices is not always an effective 115 way to increase the value of office buildings because construction budgets are often more expensive than current office renovation techniques. Building codes and regulations — While Tokyo building codes currently restrict the installation of external objects on building facades, the Guideline for Office Renovation states that mitigation of the building code or other regulations could be performed for office renovations which employ strategies that are intended to respond to environmental considerations. Despite this, mitigation of the code costs time and money, so external strategies may not be appropriate for certain contexts. An understanding of the effective roles which each of the different control device configurations play can allow designers to focus their efforts on optimizing their design parameters to provide the best interior natural lighting performance. Armed with this knowledge, architects and lighting designers will have an essential foundation with which to produce effective renovation designs using natural lighting in Tokyo's dense urban context. 116 Append ix (6.1.1.) — Percent Reduction of Interior Natural Lighting Note: interior natural lighting is evaluated by ECOTECT modeling software Benchmark for Interior Natural Lighting No Obstruction (clear sky) 5F | 336.7 100% Natural Lighting Level with Obstruction (lux) 5m 10m 15m 20m 25m 9F 316.6 316.58 316.58 316.58 316.91 8F 247.7 259.42 278.7 300.1 311.5 7F 232.3 244.8 257.45 276.5 292.7 6F 228.95 239.91 249 256.92 269.3 5F 225.76 236.7 243.94 250.8 258.5 4F 225.14 234.9 241.7 248.7 254.2 3F 225.16 232.5 239.6 246.4 249.5 2F 225.12 231.52 238 243.92 244.11 1F 225.19 228.88 237 244.06 244.25 30m 35m 40m 45m 50m 9F 316.91 316.91 316.91 316.91 316.6 8F 316.2 316.6 316.7 317 316.9 7F 305.5 314.2 316.91 317.3 316.9 6F 282 295 306.2 313.2 316.91 5F 266.2 274 284.59 297.4 310.32 4F 258.4 262.92 275.6 284.16 292.8 3F 258.6 261.5 271.2 280.3 285.97 2F 256.87 262.2 270.64 278.46 285.66 1F 251.46 262.34 270.79 278.12 285.82 The Percent Reduction for Interior Natural Lighting Level (%) 5m 10m 15m 20m 25m 9F -4 -4 -4 -4 -4 8F -27 -23 -17 -11 -7 7F -31 -27 -24 -18 -13 6F -33 -29 -26 -24 -20 5F -34 -30 -28 -26 -23 4F -34 -31 -29 -27 -24 3F -34 -32 -29 -28 -26 2F -35 -32 -30 -28 -27 1F -35 -33 -31 -28 -27 30m 35m 40m 45m 50m 9F -4 -4 -4 -4 -4 8F -4 -4 -4 -4 -4 7F -9 -7 -4 -4 -4 6F -16 -12 -9 -7 -4 5F -21 -18 -15 -12 -8 4F -23 -22 -18 -15 -13 3F -23 -23 -20 -17 -15 2F -24 -23 -21 -18 -15 1F -27 -23 -21 -18 -15 117 Append i x (6.1.2.) — The Number of Available Months for Direct Sunlighting Obstruction Distance Floor 5m 10m 15m 20m 25m 9F 11 12 12 12 12 8F 6 11 12 12 12 7F 4 8 8 10 12 6F 3 6 8 9 10 5F 2 6 5 8 9 4F 1 4 4 7 8 3F 0 4 4 6 7 2F 0 3 3 4 6 1F 0 2 2 3 5 30m 35m 40m 45m 50m 9F 12 12 12 12 12 8F 12 12 12 12 12 7F 12 12 12 12 12 6F 12 12 12 12 12 5F 11 12 12 12 12 4F 10 11 12 12 12 3F 9 10 11 12 12 2F 8 9 10 11 12 1F 7 8 9 10 11 Note: the data is evaluated with the Solar Ray Analysis of ECOTECT modeling software Append ix (6.2.1.) — Design Parameters for Possible Natural Lighting Control Devices Input Data Hot Seasons Mild Seasons Periods - . June, July, August and September Rest of other months Obstruction :. NO No Orientation - South South Position latitude / / - " , .,35.6 \ 35.6 longitude 139 7 139.7 Sky Condition >• ' Cloar sky Clear sky Local Terrain Open Urban (no obstruction) Open Urban (no obstruction) Recommendation Performance " : Shading .' - No Shading Distribution Distribution Design Parameter Ana lys is for Shad ing Dev ices Direct Sunlit Performance Depth from Window (mm) 7am 8am 9am 10am 11am 12 13pm 14pm 15pm 16pm 17pm January - - 2,700 3,800 3,700 3,600 3,700 3,700 2,300 - -February - - 2,000 2,700 2,700 2,700 2,700 2,000 2,000 - -March - - 1,500 1,500 1,500 1,500 1,500 1,500 - - -April - - 850 900 900 1,000 1,000 1,000 - - -May - - - 350 350 350 350 350 - - -June - - or.'' I.. 250 280,; • 250 - • - . July - - 200 300 330 270 - - -August - 380 530 • 600 650 600 510 _ - -September - 1.100 1.200 1,200 1,250 1,200 1.150 - -October - - 2,100 2,200 2,200 2,300 2,300 2,200 - - -November - - 3,000 3,000 3,000 3,000 3,000 3,000 - - -December - - 3,000 3,500 3,500 3,800 3,800 3,400 - - -Note: Shading area represents Hot Seasons Shading Performance (percentage) Note: the number represents the percentage of shading area through installed devices Internal Shading devices 100 mm (positioned 2,200 mm from floor) 7am 8am 9am 10am 11am 12 13pm 14pm 15pm 16pm 17pm January - - 0 0 0 0 0 0 0 - -February - - 0 0 0 0 0 0 0 - -March - - 0 0 10 10 0 0 - - -April - - 0 10 20 40 20 10 - - -May - - - 40 60 60 60 40 - - -June - _ - - J 1100 100 100 - ; ; - -July - - - 40 60 70 60 - - - -August - - 10 20 30 . 10 - - -September - - 10 15 15 15 10 10 - -October - - 0 10 10 10 10 0 - - -November - - 0 0 0 0 0 0 - - -December - - 0 0 0 0 0 0 - - -119 Internal Shading devices 200 mm (positioned 2,100 mm from floor) 7am 8am 9am 10am 11am 12 13pm 14pm 15pm 16pm 17pm January - - 5 5 5 5 5 5 5 - -February - - 5 5 5 5 5 5 5 - -March - - 5 ' 5 15 15 5 5 - - -April - - 5 15 25 45 25 15 - - -May - - - 45 65 65 65 45 - - -June 1 - %-:i'"> - ; . V 100 - 100." •%100, - V - - , : , • July , , : - - - >50 • 70 •'•A • 8 0 * 70*-' - r -f- • Aunu - 30 30' • 40 y,3o:-;'.; 20 - - -September - 20 25 25 25 ',£20 ' 20 -October - - 5 15 15 15 15 5 - - -November - - 5 5 5 5 5 5 - - -December - - 5 5 5 5 5 5 - - -Internal Shading devices 300 mm (positioned 2,000 mm from floor) 7am 8am 9am 10am 11am 12 13pm 14pm 15pm 16pm 17pm January - - 10 10 10 10 10 10 10 - -February - - 10 10 10 10 10 10 10 - -March - - 10 10 15 15 10 10 - - -April - - 10 20 30 50 30 20 - - -May - - - 50 70 70 70 50 - - -June - - - - ,;;ioo 100 100 - - - -July - - 60 80 90 80 - - -August : - - 30 , T40 l; 40 . -so r *%40 - 30 -' September- - - -, .-30 35 , 35 3 5 " 30 30 -October - - 10 20 20 20 20 10 - - -November - - 10 10 10 10 10 10 - - -December - • 10 10 10 10 10 10 - - -Internal Shading Devices 400mm (positioned 1,900 mm from floor) 7am 8am 9am 10am 11am 12 13pm 14pm 15pm 16pm 17pm January - - 15 15 15 15 15 15 15 - -February - - 15 15 15 15 15 15 15 - -March - - 15 15 20 20 15 15 - - -April - - 15 25 35 55 35 25 - - -May - - - 55 75 75 75 55 - - -Juno - • 100 100 100 - iisiiiiii - -July - •ills - S a n 90 100 90 - M Q K -August - _ 40 50 50 55 45 35 - - -September - - 40 45 ;*; 45 45 40 40 - - -October - - 15 25 25 25 25 15 - - -November - - 15 15 15 15 15 15 - - -December - - 15 15 15 15 15 15 - - -Internal Shading devices 500mm (positioned 1,800 mm from floor) 7am 8am 9am 10am 11am 12 13pm 14pm 15pm 16pm 17pm January - - 20 20 20 20 20 20 20 - -February - - 20 20 20 20 20 20 20 - -March - - 20 20 25 25 20 20 - -April - - 20 30 40 60 40 30 - - -May - - - 60 80 80 80 60 - - -June - - - " 1 0 0 .100 - - - -July - - - 80 - 100 • • 100 - - -August - - 50 60 60 65 • 45 - - -September • - - 50 55 55 55 50 50 - - -October - - 20 30 30 30 30 20 - - -November - - 20 20 20 20 20 20 - - -December - - 20 20 20 20 20 20 - - -Internal Shading devices 600mm (positioned 1,650 mm from floor) 7am 8am 9am 10am 11am 12 13pm 14pm 15pm 16pm 17pm January - - 25 25 25 25 25 25 25 - -February - - 25 25 25 25 25 25 25 - -March - - 25 25 30 30 25 25 - - -April - - 25 35 45 65 45 35 - - -May - - - 65 85 85 85 65 - - -June - - - - 100 100 100 - - - -July - - - 90 100 100 100 - - - -August - - 60 70 70 75 65 55 - -September - - 60 65 65 65 60 60 - - -October - - 25 35 35 35 35 25 - - -November - - 25 25 25 25 25 25 - - -December - - 25 25 25 25 25 25 - - -Internal Shading devices 700mm (positioned 1,500 mm from floor) 7am 8am 9am 10am 11am 12 13pm 14pm 15pm 16pm 17pm January - - 30 30 30 30 30 30 30 - -February - - 30 30 30 30 30 30 30 - -March - - 30 30 35 35 30 30 - - -April - - 30 40 45 70 50 40 - - -May - - - 70 90 90 90 70 - - -June - - - - 100 100 100 - - - -July - - - 100 100 100 100 - - - -August - - 70 80 80 85 75 65 - -September - - 70 75 75 • 75 70 70 • - -October - - 30 40 40 40 40 35 - - -November - - 35 35 35 35 35 35 - - -December - - 35 35 35 35 35 35 - - -Internal Shading devices 800mm (positioned 1,350 mm from floor) 7am 8am 9am 10am 11am 12 13pm 14pm 15pm 16pm 17pm January - - 35 35 35 35 35 35 35 - -February - - 35 35 35 35 35 35 35 - -March - - 35 35 40 40 35 35 - - -April - - 35 45 50 75 55 45 - - -May - - - 75 95 95 95 75 - - -June * '«.">t-- / - : 100 100"; '100" . " -• - - -July - - ' 100 * -.100, 100 '100 - - - -4 August *80V; ,90 '90 - ' 95"*= *-85 - 75 - - -September ' - T 8 0 ' .'85-* 85 85 80 • 80 ' - - -October - - 35 45 45 45 45 40 - - -November - - 40 40 40 40 40 40 - - -December - - 40 40 40 40 40 40 - - -Internal Shading devices 900mm (positioned 1,200 mm from floor) 7am 8am 9am 10am 11am 12 13pm 14pm 15pm 16pm 17pm January - - 40 40 40 40 40 40 40 - -February - - 40 40 40 40 40 40 40 - -March - - 40 40 45 45 40 40 - - -April - - 40 50 55 80 60 50 - - -May - - - 80 100 100 100 80 - - -June ,''•.100..' '100 • 100 - - - -July - i 100- "•' 100 \ ,",100 .'100' : - "• - -August - 90 ' 100- 100 •;ioo 95 85 - - -September - i 90 & /- '95*? 95 •;'"95', ' 90 90 • - - -October - - 40 50 50 50 50 45 - - -November - - 45 45 45 45 45 45 - - -December • - 45 45 45 45 45 45 - - -Append ix (6.3.1-1.) — Design Parameters for Internal Control Devices Input Data 1 Period December 22th (Lowest Sun Angle in Winter) Obstruction No Orientation South Position longitude 35.6 latitude 139.7 Sky Condition Clear Sky Condition Size: 1100 mm. Position: 1,900 mm from floor Size: 1000 mm. Position: 1,900 mm from floor Size: 900 mm. Position: 1,900 mm from floor 123 Size: 800 mm. Position: 1,900 mm from floor 124 The relationship between the size of internal control devices and reflected direct 1,500 1,400 1,300 1,200 1,100 1,000 900 800 700 600 500 400 (mm) T h e 1 , 0 0 0 m m in terna l d e v i c e p r o v i d e s e f fec t ive d i s t r i b u t i o n in w i n t e r Note: The percentage represents the reflected direct sunlight on the surface of internal control devices. 125 Input Data 2 Period September 22th (Lowest Sun Angle in Summer) Obstruction No Orientation South Position longitude 35.6 latitude 139.7 Sky Condition Clear Sky Condition Size: 400 mm. Position: 1,900 mm from floor Size: 200 mm. Position: 1,900 mm from floor 127 The relationship between the size of internal control devices and reflected direct T h e 400 m m in terna l d e v i c e p r o v i d e e f fec t ive d i s t r i b u t i o n a n d s h a d i n g Note: The percentage represents the reflected direct sunlight on the surface of internal control devices. Appendix (6.3.1-2.) — Design Parameters for External Control Devices Input Data 1 Period December 22th (Lowest Sun Angle throughout a year) Obstruction No Orientation South Position longitude 35.6 latitude 139.7 Sky Condition Clear Sky Condition Size: 0 mm. Position: 1,900 mm from floor Size: 100 (W) mm X 20 (H) mm. Position: 1,900 mm from floor Size: 200 (W) mm X 70 (H) mm. Position: 1,900 mm from floor 129 Size: 290 (W) mm X 140 (H) mm. Position: 1,900 mm from floor 130 The relationship between the size of external control devices and reflected direct % 100 80 60 40 20 E E o X s E o X X I o o CM JE x o m co X co X E E o C M The effective size of external device provides is 100 mm (W) X 20 (H) mm Note: The percentage represents the reflected direct sunlight on the surface of internal control devices. 1 3 1 Append ix (6.3.1-3) — Design Parameters for Ceiling Control Devices Input Data 1 The redistribution ana lys is with s e a s o n Obstruction No Orientation South Position longitude 35.6 latitude 139.7 Sky Condition Clear Sky Condition June 22th (highest sun angle throughout a year) the 15% of the sur face of cei l ing dev ices September 22th (lowest sun angle in summer and highest sun angle in winter) the 35% of the sur face of cei l ing dev ices December 22th (lowest sun angle in winter) the 100% of the sur face of cei l ing dev ices 132 Input Data 2 Period December 22th (Lowest Sun Angle throughout a year) Obstruction No Orientation South Position longitude 35.6 latitude 139.7 Sky Condition Clear Sky Condition Size: 2,000 mm. Position: 2,300 mm from floor Size: 2,000 mm. Position: 2,200 mm from floor Size: 2,000 mm. Position: 2,100 mm from floor 133 Size: 2,000 mm. Position: 2,000 mm from floor The relationship between the position of ceiling control devices and the percentage of redistributed direct sunlight 120 100 80 60 40 20 O o 5= £ o o o 1 ^ E o o o E o o o 5= E o E E o o CO CM" E E o o CM E E o o E E o o o The 100 (W) mm X 20 (H) mm internal device provides effective distribution throughout a year Note: The percentage represents the amount of the redistribute direct sunlight on the surface of ceiling control devices. 134 Appendix (6.3.2.) — Internal Natural Lighting Control Devices Note: the data is evaluated by Desktop Radiance. a) Internal Control Device Type A No natural lie Summer clear sky hting control device 1 2 3 4 5 6 7 8 9 10 m 8500 4720 1000 300 100 100 100 100 100 100 (lux) overcast 1 2 3 4 5 6 7 8 9 10 m 1800 1000 300 100 100 100 100 100 100 100 (lux) Winter clear sky 1 2 3 4 5 6 7 8 9 10m 9000 4270 1100 900 700 500 300 300 200 100 (lux) overcast 1 2 3 4 5 6 7 8 9 10 m 1000 600 245 136 110 100 100 100 100 100 (lux) Internal control devices Summer clear sky 1 2 3 4 5 6 7 8 9 10m 1870 944 600 453 143 129 100 100 100 100 (lux) overcast 1 2 3 4 5 6 7 8 9 10m 1692 1000 447 150 130 100 100 100 100 100 (lux) Winter clear sky 1 2 3 4 5 6 7 8 9 10m 6300 3203 1210 1215 938 630 369 345 200 100 (lux) overcast 1 2 3 4 5 6 7 8 9 10m 950 600 321 188 143 120 100 100 100 100 (lux) Percent Reduction with Internal/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 m -78 -80 -40 51 43 29 0 0 0 0(%) overcast Winter clear sky 1 2 3 4 5 6 7 8 9 10 m -6 0 49 50 30 0 0 0 0 0 (%) 1 2 3 4 5 6 7 8 9 10 m -30 -25 10 35 34 26 23 15 0 0(%) overcast 1 2 3 4 5 6 7 8 9 10 m -5 0 31 38 30 20 0 0 0 0(%) 135 Type B No natural lighting control device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 7080 3280 600 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1700 900 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 4800 2270 810 510 400 300 300 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux Internal control devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1558 918 432 393 127 121 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1598 900 378 124 116 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 3936 1884 891 607 464 339 339 327 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 950 600 279 166 125 110 100 100 100 100 lux Percent Reduction with Internal/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -78 -72 -28 31 27 21 0 0 0 0 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -6 0 26 24 16 0 0 0 0 0 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -18 -17 10 19 16 13 13 9 0 0 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 14 22 14 10 0 0 0 0 % 136 TypeC No natural lighting control device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 5760 2560 600 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1600 800 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 2400 1130 510 500 400 400 300 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux Internal control devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 2592 1536 480 351 119 116 110 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1504 800 447 150 130 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1824 915 561 590 456 448 327 333 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 950 600 321 188 143 120 100 100 100 100 lux Percent Reduction with Internal/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -55 -40 -20 17 19 16 10 0 0 0 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -6 0 49 50 30 0 0 0 0 0 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -24 -19 10 18 14 12 9 11 0 0 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 31 38 30 20 0 0 0 0 % 137 Type D No natural lighting control device Summer clear sky 1 2 3 4 5 6 7 8 9 10 5440 2000 600 300 100 100 100 100 100 100 overcast 1 2 3 4 5 6 7 8 9 10 1700 900 300 100 100 100 100 100 100 100 Winter clear sky 1 2 3 4 5 6 7 8 9 10 1800 1070 520 510 400 500 300 300 200 100 overcast 1 2 3 4 5 6 7 8 9 10 1000 600 245 136 110 100 100 100 100 100 Internal control devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 2176 1300 672 342 111 100 100 100 100 100 overcast 1 2 3 4 5 6 7 8 9 10 1598 900 447 150 130 100 100 100 100 100 Winter clear sky 1 2 3 4 5 6 7 8 9 10 1512 952 572 551 428 525 300 300 200 100 overcast 1 2 3 4 5 6 7 8 9 10 950 600 321 188 143 120 100 100 100 100 Percent Reduction with Internal/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 -60 -35 12 14 11 0 0 0 0 0 overcast 1 2 3 4 5 6 7 8 9 10 -6 0 49 50 30 0 0 0 0 0 Winter clear sky 1 2 3 4 5 6 7 8 9 10 -16 -11 10 8 7 5 0 0 0 0 overcast 1 2 3 4 5 6 7 8 9 10 -5 0 31 38 30 20 0 0 0 0 138 Type E No natural lighting device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 3760 2020 620 300 300 300 300 300 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1700 900 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1670 870 520 520 500 500 300 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux internal control devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 827 404 372 453 429 387 342 300 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1598 900 447 150 130 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1169 653 572 702 670 630 369 345 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 950 600 321 188 143 120 100 100 100 100 lux Percent Reduction with Internal/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -78 -80 -40 51 43 29 14 0 0 0 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) -6 0 49 50 30 0 0 0 0 0 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -30 -25 10 35 34 26 23 15 0 0 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 31 38 30 20 0 0 0 0 lux 139 Append ix (6.3.3.) — Internal + External Natural Light ing Control Dev ices Type A No natural lighting control device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 8500 4720 1000 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1800 1000 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 9000 4270 1100 900 700 500 300 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux Internal + External control devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 2125 1227 610 444 142 128 100 100 124 126 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1674 990 450 145 132 128 126 128 125 113 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 6300 3160 1199 1188 924 640 369 330 248 120 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 950 600 319 180 138 115 102 100 120 110 lux Percent Reduction with Internal + External/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -75 -74 -39 48 42 28 0 0 24 26 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -7 -1 50 45 32 28 26 28 25 13 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -30 -26 9 32 32 28 23 10 24 20 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 30 32 25 15 2 0 20 10 % 140 Type B No natural lighting control device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 7080 3280 600 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1700 900 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 4800 2270 810 510 400 300 300 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux Internal + External control devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1699 984 420 429 138 130 100 100 124 120 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1581 891 435 142 130 125 126 128 121 113 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 3456 1680 851 663 520 375 360 330 242 115 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 950 600 319 177 134 113 102 100 118 110 lux Percent Reduction with Internal + External/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -76 -70 -30 43 38 30 0 0 24 20 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -7 -1 45 42 30 25 26 28 21 13 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -28 -26 5 30 30 25 20 10 21 15 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 30 30 22 13 2 0 18 10 % 141 TypeC No natural lighting control device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 5760 2560 600 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1600 800 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 2400 1130 510 500 400 400 300 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux Internal + External control devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 2995 1485 432 420 132 128 100 100 120 120 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1504 792 435 140 128 122 122 125 118 110 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1728 870 541 640 488 480 345 330 236 115 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 950 600 306 170 134 111 102 100 115 110 lux Percent Reduction with Internal + Extemal/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -48 -42 -28 40 32 28 0 0 20 20 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -6 -1 45 40 28 22 22 25 18 10 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -28 -23 6 28 22 20 15 10 18 15 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 25 25 22 11 2 0 15 10 % 142 Type D No natural lighting control device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 5440 2000 600 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1700 900 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1800 1070 520 510 400 500 300 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux Internal + External control devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 4080 1600 690 354 120 115 110 113 114 115 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1598 891 435 140 128 122 122 125 118 110 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1440 1231 551 653 480 615 354 330 230 110 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 950 600 306 170 134 111 102 100 115 110 lux Percent Reduction with Internal + External/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -25 -20 15 18 20 15 10 13 14 15 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -6 -1 45 40 28 22 22 25 18 10 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -20 15 6 28 20 23 18 10 15 10 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 25 25 22 11 2 0 15 10 % 143 Type E No natural lighting control device Summer clear sky 10 9 8 7 6 5 4 3 2 1 (m) 3760 2020 620 300 300 300 300 300 100 100 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 1700 900 300 100 100 100 100 100 100 100 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 (m) 1670 870 520 520 500 500 300 300 200 100 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 1000 600 245 136 110 100 100 100 100 100 lux Internal + External control devices Summer clear sky 10 9 8 7 6 5 4 3 2 1 (m) 2933 1616 713 354 360 345 330 339 114 115 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 1598 891 435 142 130 122 122 125 115 110 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 (m) 1336 1001 536 650 600 615 348 330 226 110 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 950 600 306 163 134 110 102 100 113 107 lux Percent Reduction with Internal + External/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -22 -20 15 18 20 15 10 13 14 15 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -6 -1 45 42 30 22 22 25 15 10 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -20 15 3 25 20 23 16 10 13 10 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 25 20 22 10 2 0 13 7 % 144 Appendix (6.3.4.) — Internal + ceiling Natural Lighting Control Devices Type A No natural lighting control device Summer clear sky 10 9 8 7 6 5 4 3 2 1 (m) 8500 4720 1000 300 100 100 100 100 100 100 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 1800 1000 300 100 100 100 100 100 100 100 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 (m) 9000 4270 1100 900 700 500 300 300 200 100 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 1000 600 245 136 110 100 100 100 100 100 lux Internal + Ceiling control devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 2380 1180 520 480 158 145 136 120 112 102 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1656 1000 450 155 135 120 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 6300 3203 1210 1278 1015 680 390 354 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 950 600 331 197 150 123 110 100 100 100 lux Percent Reduction with Internal + ceiling/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -72 -75 -48 60 58 45 36 20 12 2 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -8 0 50 55 35 20 0 0 0 0 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -30 -25 10 42 45 36 30 18 0 0 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 35 45 36 23 10 0 0 0 % 145 Type B No natural lighting control device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 7080 3280 600 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1700 900 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 4800 2270 810 510 400 300 300 300 200 100 lux overcast Internal + Ceiling Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux control devices 1 2 3 4 5 6 7 8 9 10 (m) 2124 853 330 465 152 141 133 120 110 103 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1615 900 426 150 130 118 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 3312 1725 883 714 572 405 390 345 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 950 600 331 196 150 120 110 100 100 100 lux Percent Reduction with Internal + ceiling/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -70 -74 -45 55 52 41 33 20 10 3 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 42 50 30 18 0 0 0 0 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -31 -24 9 40 43 35 30 15 0 0 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 35 44 36 20 10 0 0 0 % 146 TypeC No natural lighting control device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 5760 2560 600 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1600 800 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 2400 1130 510 500 400 400 300 300 200 100 lux overcast Internal + Ceiling Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux control devices 1 2 3 4 5 6 7 8 9 10 (m) 3168 1664 330 435 140 138 128 115 110 105 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1520 800 426 148 130 115 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1800 859 561 675 568 524 384 345 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 950 612 326 193 146 123 110 100 100 100 lux Percent Reduction with Internal + ceiling/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -45 -35 -45 45 40 38 28 15 10 5 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 42 48 30 15 0 0 0 0 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -25 -24 10 35 42 31 28 15 0 0 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 2 33 42 33 23 10 0 0 0 % 147 Type D No natural lighting control device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 5440 2000 600 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1700 900 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1800 1070 520 510 400 500 300 300 200 100 lux overcast Internal + Ceiling Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux control devices 1 2 3 4 5 6 7 8 9 10 (m) 2176 1300 678 348 120 115 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1598 900 447 150 145 130 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1512 952 629 673 540 640 330 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 950 600 321 188 143 120 100 100 100 100 lux Percent Reduction with Internal + ceiling/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -60 -35 13 16 20 15 0 0 0 0 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -6 0 49 50 45 30 0 0 0 0 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -16 -11 21 32 35 28 10 0 0 0 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 31 38 30 20 0 0 0 0 % 148 Type E No natural lighting control device Summer clear sky 10 9 8 7 6 5 4 3 2 1 (m) 3760 2020 620 300 300 300 300 300 100 100 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 1700 900 300 100 100 100 100 100 100 100 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 (m) 1670 870 520 520 500 500 300 300 200 100 lux overcast Internal + Ceiling Summer clear sky 10 9 8 7 6 5 4 3 2 1 (m) 1000 600 245 136 110 100 100 100 100 100 lux control devices 10 9 8 7 6 5 4 3 2 1 (m) 3083 1616 713 342 345 345 300 300 100 100 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 1598 900 447 152 144 132 100 100 100 100 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 (m) 1403 783 624 676 675 625 330 300 200 100 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 950 600 321 184 143 122 100 100 100 100 lux Percent Reduction with Internal + ceiling/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -18 -20 15 14 15 15 0 0 0 0 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -6 0 49 52 44 32 0 0 0 0 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -16 -10 20 30 35 25 10 0 0 0 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 31 35 30 22 0 0 0 0 % 149 Appendix (6.3.5.) — Internal + External + ceiling Natural Lighting Control Devices Type A No natural lighting control device Summer clear sky 10 9 8 7 6 5 4 3 2 1 (m) 8500 4720 1000 300 100 100 100 100 100 100 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 1800 1000 300 100 100 100 100 100 100 100 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 (m) 9000 4270 1100 900 700 500 300 300 200 100 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 1000 600 245 136 110 100 100 100 100 100 lux Internal + External + ceiling control devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1870 1086 650 495 172 165 145 120 130 132 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1710 1000 447 150 142 136 135 138 125 112 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 6480 3416 1210 1215 945 725 414 345 230 120 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 950 600 321 188 150 120 100 110 120 110 lux Percent Reduction with Internal + External + Ceiling/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -78 -77 -35 65 72 65 45 20 30 32 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 49 50 42 36 35 38 25 12 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -28 -20 10 35 35 45 38 15 15 20 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 31 38 36 20 0 10 20 10 % 150 Type B No natural lighting control device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 7080 3280 600 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1700 900 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 4800 2270 810 510 400 300 300 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux Internal + External + ceiling control devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1558 820 390 480 165 160 141 118 125 130 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1615 918 435 145 139 132 130 132 120 110 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 3600 1816 891 673 528 420 405 336 230 126 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 960 636 314 184 145 115 100 110 120 112 lux Percent Reduction with Internal + External + Ceiling/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -78 -75 -35 60 65 60 41 18 25 30 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 2 45 45 39 32 30 32 20 10 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -25 -20 10 32 32 40 35 12 15 26 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -4 6 28 35 32 15 0 10 20 12 % 151 TypeC No natural lighting control device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 5760 2560 600 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1600 800 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 2400 1130 510 500 400 400 300 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux Internal + External + ceiling control devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 3456 1664 420 486 155 151 130 110 120 118 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1520 816 429 141 132 125 124 132 120 110 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1800 927 561 660 540 560 405 342 230 124 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 960 612 314 184 145 115 100 110 115 112 lux Percent Reduction with Internal + External + Ceiling/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -40 -35 -30 62 55 51 30 10 20 18 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 2 43 41 32 25 24 32 20 10 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -25 -18 10 32 35 40 35 14 15 24 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -4 2 28 35 32 15 0 10 15 12 % 152 Type D No natural lighting control device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 5440 2000 600 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1700 900 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1800 1070 520 510 400 500 300 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux internal + External + ceiling control devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 2176 1300 678 348 120 115 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1598 900 447 150 145 130 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1512 952 629 673 540 640 330 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 950 600 321 188 143 120 100 100 100 100 lux Percent Reduction with Internal + External + Ceilinc j/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -60 -35 13 16 20 15 0 0 0 0 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -6 0 49 50 45 30 0 0 0 0 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -16 -11 21 32 35 28 10 0 0 0 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 31 38 30 20 0 0 0 0 % 153 Type E No natural lighting control device Summer clear sky 10 9 8 7 6 5 4 3 2 1 (m) 3760 2020 620 300 300 300 300 300 100 100 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 1700 900 300 100 100 100 100 100 100 100 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 (m) 1670 870 520 520 500 500 300 300 200 100 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 1000 600 245 136 110 100 100 100 100 100 lux Internal + External + ceiling control devices Summer clear sky 10 9 8 7 6 5 4 3 2 1 (m) 4324 1616 701 345 348 345 330 330 112 110 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 1598 900 447 148 145 123 112 110 111 109 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 (m) 1403 774 629 686 675 640 330 330 224 106 lux overcast 10 9 8 7 6 5 4 3 2 1 (m) 950 600 321 188 143 120 119 115 111 112 lux Percent Reduction with Internal + External + Ceilinc j/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 15 -20 13 15 16 15 10 10 12 10 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -6 0 49 48 45 23 12 10 11 9 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -16 -11 21 32 35 28 10 10 12 6 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 31 38 30 20 19 15 11 12 % 154 Appendix (6.4.1.) — Site Specific Office Building Design Case Study Note: the data is evaluated by Desktop Radiance. Type A 8 and 9 Floor No natural lighting device Summer clear sky 10 9 8 7 6 5 4 3 2 1 m 8500 4720 1000 300 100 100 100 100 100 100 lux overcast 10 9 8 7 6 5 4 3 2 1 m 1800 1000 300 100 100 100 100 100 100 100 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 m 9000 4270 1100 900 700 500 300 300 200 100 lux overcast 10 9 8 7 6 5 4 3 2 1 m 1000 600 245 136 110 100 100 100 100 100 lux Curtain wall Summer clear sky 10 9 8 7 6 5 4 3 2 1 m 8415 4720 1950 525 184 176 153 146 130 132 lux overcast 10 9 8 7 6 5 4 3 2 1 m 1710 1000 600 195 184 180 165 152 145 140 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 m 8820 3400 600 300 200 100 100 100 100 100 lux overcast 10 9 8 7 6 5 4 3 2 1 m 1000 500 300 100 100 100 100 100 100 100 lux Internal + External + Ceiling control devices Summer clear sky 10 9 8 7 6 5 4 3 2 1 m 1870 1086 650 495 172 165 145 120 130 132 lux overcast 10 9 8 7 6 5 4 3 2 1 m 1710 1000 447 150 142 136 135 138 125 112 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 m 6480 3416 1210 1215 945 725 414 345 230 120 lux overcast 10 9 8 7 6 5 4 3 2 1 m 950 600 321 188 150 120 100 110 120 110 lux Percent Reduction with Internal + External + Ceiling/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -78 -77 -35 65 72 65 45 20 30 32 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 49 50 42 36 35 38 25 12 % 155 Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -28 -20 10 35 35 45 38 15 15 20 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 31 38 36 20 0 10 20 10 % Percent Reduction with Internal + External + Ceiling/curtain Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -1 0 95 75 84 76 53 46 30 32 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 100 95 84 80 65 52 45 40 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -2 0 40 80 75 70 65 60 55 50 % overcast 1 2 3 4 5 6 7 8 9 10 (m) 0 0 100 80 75 75 68 65 55 54 % 156 Type B 7 Floor No natural lighting device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 7080 3280 600 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1700 900 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 4800 2270 810 510 400 300 300 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux Curtain wall Summer clear sky 10 9 8 7 6 5 4 3 2 1 m 7009 3280 1110 522 180 172 150 142 125 128 lux overcast 10 9 8 7 6 5 4 3 2 1 m 1615 900 600 190 184 175 161 148 141 132 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 m 4704 3400 600 300 200 100 100 100 100 100 lux overcast 10 9 8 7 6 5 4 3 2 1 m 1000 500 300 100 100 100 100 100 100 100 lux Internal + External + Ceiling control devices Summer clear sky 10 9 8 7 6 5 4 3 2 1 m 1558 820 390 480 165 160 141 118 125 130 lux overcast 10 9 8 7 6 5 4 3 2 1 m 1615 918 435 145 139 132 130 132 120 110 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 m 3600 1816 891 673 528 420 405 336 230 126 lux overcast 10 9 8 7 6 5 4 3 2 1 m 960 636 314 184 145 115 100 110 120 112 lux Percent Reduction with Internal + External + Ceiling/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -78 -75 -35 60 65 60 41 18 25 30 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 2 45 45 39 32 30 32 20 10 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -25 -20 10 32 32 40 35 12 15 26 % 1 2 3 4 5 6 7 8 9 10 (m) 157 overcast -4 6 28 35 32 15 0 10 20 12|% Percent Reduction with Internal + External + Ceilings/curtain Summer 1 2 3 4 5 6 7 8 9 10 (m) clear sky -1 0 85 74 80 72 50 42 25 28 % 1 2 3 4 5 6 7 8 9 10 (m) overcast -5 0 100 90 84 75 61 48 41 32 % Winter 1 2 3 4 5 6 7 8 9 10 (m) clear sky -2 0 40 80 75 68 62 60 52 45 % 1 2 3 4 5 6 7 8 9 10 (m) overcast 0 0 100 78 75 75 68 61 55 51 % 158 Type C 4, 5 and 6 Floor No natural lighting device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 5760 2560 600 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1600 800 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 2400 1130 510 500 400 400 300 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux Curtain wall Summer clear sky 10 9 8 7 6 5 4 3 2 1 m 5702 2560 1140 540 178 170 148 142 125 125 lux overcast 10 9 8 7 6 5 4 3 2 1 m 1520 800 585 188 184 175 158 148 141 130 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 m 2352 3400 600 300 200 100 100 100 100 100 lux overcast 10 9 8 7 6 5 4 3 2 1 m 1000 500 300 100 100 100 100 100 100 100 lux Internal + External + Ceiling control devices Summer clear sky 10 9 8 7 6 5 4 3 2 1 m 3456 1664 420 486 155 151 130 110 120 118 lux overcast 10 9 8 7 6 5 4 3 2 1 m 1520 816 429 141 132 125 124 132 120 110 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 m 1800 927 561 660 540 560 405 342 230 124 lux overcast 10 9 8 7 6 5 4 3 2 1 m 960 612 314 184 145 115 100 110 115 112 lux Percent Reduction with Internal + External + Ceiling/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -40 -35 -30 62 55 51 30 10 20 18 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 2 43 41 32 25 24 32 20 10 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -25 -18 10 32 35 40 35 14 15 24 % 159 overcast 1 2 3 4 5 6 7 8 9 10 (m) -4 2 28 35 32 15 0 10 15 12 % Percent Reduction with Internal + External + Ceiling/curtain Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -1 0 90 80 78 70 48 42 25 25 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 95 88 84 75 58 48 41 30 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -2 0 38 80 75 65 62 60 55 45 % overcast 1 2 3 4 5 6 7 8 9 10 (m) 0 0 100 78 77 75 68 61 50 48 % 160 Type D 1, 2 and 3 Floor No natural lighting device Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) 5440 2000 600 300 100 100 100 100 100 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1700 900 300 100 100 100 100 100 100 100 lux Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) 1800 1070 520 510 400 500 300 300 200 100 lux overcast 1 2 3 4 5 6 7 8 9 10 (m) 1000 600 245 136 110 100 100 100 100 100 lux Curtain wall Summer clear sky 10 9 8 7 6 5 4 3 2 1 m 5386 2000 810 474 150 150 148 142 142 140 lux overcast 10 9 8 7 6 5 4 3 2 1 m 1615 900 759 225 202 189 180 175 186 180 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 m 1764 3400 600 300 200 100 100 100 100 100 lux overcast 10 9 8 7 6 5 4 3 2 1 m 1000 500 300 100 100 100 100 100 100 100 lux Internal + External + Ceiling control devices Summer clear sky 10 9 8 7 6 5 4 3 2 1 m 2176 1300 678 348 120 115 100 100 100 100 lux overcast 10 9 8 7 6 5 4 3 2 1 m 1598 900 447 150 145 130 100 100 100 100 lux Winter clear sky 10 9 8 7 6 5 4 3 2 1 m 1512 952 629 673 540 640 330 300 200 100 lux overcast 10 9 8 7 6 5 4 3 2 1 m 950 600 321 188 143 120 100 100 100 100 lux Percent Reduction with Internal + External + Ceiling/no devices Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -60 -35 13 16 20 15 0 0 0 0 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -6 0 49 50 45 30 0 0 0 0 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -16 -11 21 32 35 28 10 0 0 0 % 161 overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 31 38 30 20 0 0 0 0 % Percent Reduction with Internal + External + Ceiling/curtain Summer clear sky 1 2 3 4 5 6 7 8 9 10 (m) -1 0 35 58 50 50 48 42 42 40 % overcast 1 2 3 4 5 6 7 8 9 10 (m) -5 0 153 125 102 89 80 75 86 80 % Winter clear sky 1 2 3 4 5 6 7 8 9 10 (m) -2 0 38 60 54 65 62 60 55 45 % overcast 1 2 3 4 5 6 7 8 9 10 (m) 0 0 120 80 80 80 68 65 50 48 % 162 A. 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