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Lifecycle based energy assessment of green roofs and walls Feng, Haibo 2013

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LIFECYCLE BASED ENERGY ASSESSMENT OF GREEN ROOFS AND WALLS by Haibo Feng  B.Sc., Wuhan University of Science and Technology, 2008  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF  MASTER OF APPLIED SCIENCE in THE COLLEGE OF GRADUATE STUDIES (Civil Engineering)  THE UNIVERSITY OF BRITISH COLUMBIA (Okanagan)  September 2013  ? Haibo Feng, 2013ii  Abstract The building and construction industry accounts for 30-40% of natural resource and energy consumption on earth, and it also contributes to 30% of greenhouse gas emissions. Therefore, it is a major cause of environmental pollution. The environmental impact of buildings could be considerably reduced through sustainable building practices. Covering a building envelope with green vegetation, such as a green roof and living walls, is one of these sustainable construction practices.  There are many environmental and operational benefits of green vegetation, such as energy savings by insulation, air quality improvement, reducing greenhouse gas emissions, adaptation to climate change, habitat provision, and aesthetic perfection. However, the sustainability and energy saving performance of green vegetation hasn?t been demonstrated completely. This study conducted a lifecycle assessment to evaluate the sustainability of living walls in air cleaning and energy savings. Furthermore, the energy saving performance of green vegetation in different parameters was analyzed in normal commercial buildings and green buildings. As the first step, a comparative lifecycle assessment of three living wall systems was conducted. Chemical emissions and energy requirements of the living wall materials were evaluated in the full lifecycle, and compared with the chemical absorption and energy savings of operational living walls. The results demonstrated that the felt layer system is not environmentally sustainable in air cleaning and energy saving compared to the indirect greening system and modular panel system. In the next step, a building energy simulation was executed to assess the energy saving performance of green vegetation in commercial buildings. Parameters such as iii  greening scenario, building type, building vintage, weather condition, and building orientation were considered in the simulation. The energy simulation results demonstrated that all these parameters have a significant influence on the energy saving performance of green vegetation. Furthermore, the energy saving performance of green vegetation was analyzed in a LEED certified green building. The simulation model was validated with the actual operational energy consumption. The simulation model was used to analyze the energy saving performance of green vegetation under different scenarios. The results showed that the green vegetation could significantly reduce the negative heat transfer through the building fa?ade in a summer and winter typical week. Moreover, the green vegetation not only delayed the start time of heat gain but also extended the period of heat loss in the summer. Based on the above analysis, a green vegetation application guideline was developed to ensure the installation of green vegetation could achieve the best energy saving benefits with the least environmental impact.         iv  Preface A part of Chapter 2 and 3 has been published under the title ?Energy performance of living walls in commercial buildings?, in proceedings from the 4th Construction Specialty Conference of the Canadian Society for Civil Engineering.  A part of Chapter 3 has been submitted to the Journal of Cleaner Production under the title ?Lifecycle Assessment of Living Walls: Air Purification and Energy Performance?.  A part of Chapter 5 has been submitted to the Energy and Buildings journal under the title ?Energy-based lifecycle assessment of green vegetation in LEED certified building?.  The above papers were written by Haibo Feng under the supervision of Dr. Kasun Hewage.   v  Table of Contents Abstract .................................................................................................................................... ii Preface ..................................................................................................................................... iv Table of Contents .................................................................................................................... v List of Tables ........................................................................................................................... x List of Figures ........................................................................................................................ xii List of Symbols, Abbreviations ........................................................................................... xiv Acknowledgements .............................................................................................................. xvi Chapter  1: Introduction ........................................................................................................ 1 1.1 Background ................................................................................................................. 1 1.2 Research Objectives .................................................................................................... 2 1.3 Thesis Organization..................................................................................................... 3 Chapter  2: Literature Review ............................................................................................... 6 2.1 Types of Green Vegetation in buildings ..................................................................... 6 2.2 Layers of Green Vegetation Systems .......................................................................... 7 2.2.1 Layers of green roof systems ................................................................................ 7 2.2.1.1 Vegetation layer ............................................................................................ 8 2.2.1.2 Growing medium layer ................................................................................. 9 2.2.1.3 Water retention layer..................................................................................... 9 2.2.1.4 Filter layer ................................................................................................... 10 2.2.1.5 Drainage layer ............................................................................................. 10 2.2.1.6 Root barrier layer ........................................................................................ 11 2.2.2 Layers of living wall systems ............................................................................. 11 vi  2.2.2.1 Vegetation layer .......................................................................................... 12 2.2.2.2 Growing medium ........................................................................................ 13 2.2.2.3 Irrigation system ......................................................................................... 14 2.2.2.4 Waterproofing layer .................................................................................... 15 2.2.2.5 Container ..................................................................................................... 15 2.2.2.6 Structural layer ............................................................................................ 16 2.3 Environmental Benefits of Green Vegetation in Buildings ...................................... 17 2.3.1 Thermal performance .......................................................................................... 17 2.3.2 Air quality ........................................................................................................... 19 2.3.3 Urban heat island effect ...................................................................................... 19 2.3.4 Sound absorption ................................................................................................ 20 2.4 Energy Savings and Green Vegetation: Governing Factors ...................................... 21 2.4.1 Reduction of heat flux and solar reflectivity ....................................................... 21 2.4.2 Evaporative cooling ............................................................................................ 22 2.4.3 Thermal performance of building envelope ........................................................ 23 2.4.4 Wind effect on the building ................................................................................ 24 Chapter  3: Lifecycle Assessment of Living Walls ............................................................. 26 3.1 Materials and Method................................................................................................ 26 3.1.1 Basic approach .................................................................................................... 26 3.1.2 Tools ................................................................................................................... 28 3.1.2.1 SimaPro modeling ....................................................................................... 28 3.1.2.2 EnergyPlus modeling .................................................................................. 28 3.1.3 Data inventory ..................................................................................................... 28 vii  3.1.3.1 Manufacturing stage.................................................................................... 29 3.1.3.2 Construction stage ....................................................................................... 31 3.1.3.3 Maintenance stage ....................................................................................... 31 3.1.3.4 Disposal stage ............................................................................................. 32 3.1.3.5 Assumptions ................................................................................................ 32 3.2 Comparative Lifecycle Analysis of Living Walls ..................................................... 34 3.2.1 Chemical emissions vs. Air purification ............................................................. 35 3.2.2 Energy consumption vs. Energy saving .............................................................. 41 3.2.3 Comparative lifecycle analysis of living walls ................................................... 45 3.2.4 Performance indicators of living walls ............................................................... 47 Chapter  4: Energy Performance of Green Vegetation in Commercial Buildings ......... 49 4.1 Materials and Methods .............................................................................................. 49 4.1.1 Greening scenarios .............................................................................................. 51 4.1.2 Building types ..................................................................................................... 52 4.1.3 Weather conditions ............................................................................................. 55 4.1.4 Building vintages ................................................................................................ 55 4.1.5 Building orientations ........................................................................................... 58 4.2 Energy Simulations for Green Vegetation ................................................................ 59 4.3 Energy Performance of Green Vegetation ................................................................ 59 4.3.1 Heating and cooling energy consumptions ......................................................... 59 4.3.2 Energy savings performance ............................................................................... 65 4.3.3 Impacts of growing medium and plant properties .............................................. 66 4.4 Energy Performance of Green Vegetation in Different Building Types ................... 68 viii  4.5 Energy Performance of Green Vegetation in Different Weather Conditions ........... 70 4.5.1 Yearly heating and cooling energy consumption in different climate zones ...... 70 4.5.2 Energy saving performance in different climate zones ....................................... 80 4.5.3 Application of ?green all? scenario in different climate zones ........................... 82 4.6 Energy Performance of Green Vegetation in Different Building Vintages .............. 83 4.7 Energy Performance of Green Vegetation in Different Building Orientations ......... 84 Chapter  5: Energy Performance of Green Vegetation in LEED Certified Buildings ... 89 5.1 Materials and Method................................................................................................ 90 5.1.1 Building information ........................................................................................... 90 5.1.2 Simulation programs ........................................................................................... 91 5.1.3 Green roof ........................................................................................................... 93 5.1.4 Weather data ....................................................................................................... 93 5.1.5 Simulation process .............................................................................................. 94 5.1.6 Scenarios ............................................................................................................. 95 5.2 Energy Simulation for the Sustainable Building ....................................................... 95 5.2.1 Model validation ................................................................................................. 96 5.2.2 Comparison of energy consumptions.................................................................. 98 5.2.3 Impact of green vegetation on heat transfer ...................................................... 101 5.2.4 Impact of green vegetation on the start time and period of heat gain ............... 104 5.2.5 Impact of energy gain and loss distribution of the original green building ...... 105 Chapter  6: Conclusions and Recommendations ............................................................. 109 6.1 Conclusions ............................................................................................................. 109 6.2 Limitations .............................................................................................................. 113 ix  6.3 Research Contributions ........................................................................................... 113 6.4 Future Research ....................................................................................................... 114 References ............................................................................................................................ 115 Appendices ........................................................................................................................... 130 Appendix A: Screen shots of input data for the LCA in SimaPro software. .................... 130 Appendix B: Screen shots of input data for the building energy simulation in Designbuilder software. .............................................................................. 143                 x  List of Tables Table 3.1    Components, material weight (Kg/m2), and service life (years) of living wall (Derived from Ottel? et al. (2011)). ..................................................................... 30 Table 3.2    Amount of substances released due to the production of 1kg of material in different stages (Derived from SimaPro results). ................................................ 39 Table 3.3    The emission released due to the production of 1m2 living walls and years    needed to balance it. ........................................................................................... 39 Table 3.4    Energy needed to produce 1kg of material in different life stages (Derived         from SimaPro results). ......................................................................................... 42 Table 3.5    Energy required due to the production of 1m2 living walls. ................................ 42 Table 3.6    Energy saving for heating and cooling in different climates (Ottel? et al.,       2011; Alexandri and Jones, 2008). ...................................................................... 43 Table 3.7    Years needed to balance the energy consumption. .............................................. 44 Table 4.1    Hydrothermal properties of green vegetation systems ........................................ 52 Table 4.2    The building energy model input characteristics (Deru et al., 2011) .................. 54 Table 4.3    Cities studies in different climate zones of North America (Derived from ASHARE 90.1-2004). .......................................................................................... 55 Table 4.4    U-values for the envelope of reference building model- Large Office (Unit: W/m2-K) (Derived from Deru et al., 2011) ......................................................... 56 Table 4.5    U-values for the envelope of reference building model- Strip Mall   (Unit: W/m2-K) (Derived from Deru et al., 2011) .............................................. 57 Table 4.6    U-values for the envelope of reference building model- Warehouse   (Unit: W/m2-K) (Derived from Deru et al., 2011) .............................................. 57 xi  Table 5.1    Thermal characteristics of the studied green building (Specification of UBC REAP) .................................................................................................................. 91  xii  List of Figures Figure 1.1     Thesis Organization ............................................................................................. 3 Figure 1.2     Research methodology outline ............................................................................ 4 Figure 2.1     The sections of green roof layers (Bianchini and Hewage 2012). ...................... 8 Figure 2.2     Three living wall systems (cited from Loh (2008))........................................... 11 Figure 3.1     General procedure for the calculation of Eco-indicators (cited from Eco-   indicator 99 (2000)). .......................................................................................... 36 Figure 3.2     Comparison of product stages between different materials (Method: Eco-indicator 99 (E) V2.08/Europe EI 99 E/E/Single score). .................................. 37 Figure 4.1     The factors that impact the energy performance of green vegetation. .............. 50 Figure 4.2     DesignBuilder model of the buildings in different greening scenarios ............. 53 Figure 4.3     Monthly heating and cooling energy consumption in different building ages ? Large office ....................................................................................................... 60 Figure 4.4     Monthly heating and cooling energy consumption in different building ages ? Strip mall ........................................................................................................... 62 Figure 4.5     Monthly heating and cooling energy consumption in different building ages ? Warehouse ......................................................................................................... 64 Figure 4.6     Yearly heating and cooling energy consumption in different climate zones- Large office ....................................................................................................... 71 Figure 4.7     Yearly heating and cooling energy consumption in different climate zones ? Strip mall ........................................................................................................... 75 Figure 4.8     Yearly heating and cooling energy consumption in different climate zones ? Warehouse ......................................................................................................... 78 xiii  Figure 4.9     Yearly heating and cooling energy consumption in different orientations and building vintages ............................................................................................... 85 Figure 4.10   Yearly heating and cooling energy consumption in different orientations and   vegetation cover case ........................................................................................ 86 Figure 5.1     Photo of the studied green building ................................................................... 92 Figure 5.2     DesignBuilder model of the studied green building .......................................... 93 Figure 5.3     Weather file applied to the simulation (originated from USDOE (2011)). ....... 94 Figure 5.4     Energy consumption of Purcell building for lighting, heating, and cooling. .... 96 Figure 5.5     Energy consumption of the studied green building for heating in different scenarios (Derived from DesignBuilder/E+ results) ......................................... 98 Figure 5.6     Energy consumption of the studied green building for cooling in different scenarios (Derived from DesignBuilder/E+ results) ......................................... 99 Figure 5.7     Heat transfer through the walls/roof of the studied green building in the  summer typical week in different scenarios (Derived from DesignBuilder/      E+ results) ....................................................................................................... 102 Figure 5.8     Heat transfer through the walls/roof of the studied green building in the     winter typical week in different scenarios (Derived from DesignBuilder/        E+ results) ....................................................................................................... 103 Figure 5.9     Energy gain distribution of the original green building in the summer        typical week (Derived from DesignBuilder/E+ results) .................................. 106 Figure 5.10   Energy loss distribution of the original green building in the winter           typical week (Derived from DesignBuilder/E+ results) .................................. 107 xiv  List of Symbols, Abbreviations ACH ASHARE  CAM CBECS      Air Change per Hour American Society of Heating, Refrigerating and Air Conditioning Engineers Crassulacean acid metabolism Commercial Building Energy Consumption Survey CH4 CoP  Methane Coefficient of Performance CWEC gbXML GJ HDPE HVAC   Canadian weather for energy calculations Green Building Extensive Markup Language Giga Joule High-density Polyethylene Heating Ventilation and Air Conditioning LCA  Lifecycle assessment LDPE LEED  Low-density polyethylene Leadership in energy and environment design MWh NAHB  Megawatt hour National Association of Home Builders NREL N2O NO2 OpenGL   National renewable energy laboratory Nitrous Oxide Nitrogen Dioxide Open Graphics Library xv  O3 PE PVC PV panels REAP Ozone Polyethylene Polyvinyl Chloride Photovoltaic panels Residential Environmental Assessment Program USDOE USEIA USEPA  United State department of energy United States Energy Information Administration  United States Environmental Protection Agency U-value  Thermal conductivity UHI  Urban heat island effect VOCs  Volatile organic compounds WSUD  Water sensitive urban design    xvi  Acknowledgements I would like to express my heartfelt gratitude to my supervisor, Dr. Kasun Hewage. I am reflecting, with enormous respect and admiration, on your immeasurable guidance, wisdom, inspiration and motivation that has influenced me so greatly. I thank you for your generosity with your time, your energy, and your valuable supervision during my studies at the University of British Columbia (Okanagan). It is an honor for me to have Dr. Deborah Roberts and Dr. Rehan Sadiq as my internal advisory committee members. I am thankful for their encouraging words, thoughtful criticism, valuable time, and attention. I would like to extend my sincerest appreciation to the School of Engineering for providing the support and equipment I needed for my research thesis. I am deeply indebted to Ms. Susan Tingstad, Ms. Renee Leboe, Ms. Shannon Hohl, Dr. Spiro Yannacopoulos, Dr. Richard Klukas, Dr. Carolyn Labun, and Mr. John Parry. You surely made my academic experience unforgettable. I have been blessed with a friendly and cheerful environment created by my fellow students at UBC Okanagan. I am very thankful to all my friends and colleagues in the Project Lifecycle Management Laboratory who always supported me. My officemates from EME 3218, my graduate friends from China, Canada, Central America, Iran, Bangladesh, etc., the kind couple John Burns and Wendy Burns, and the friends in undergraduate studies are all the most important parts of my life in Kelowna. My greatest gratitude goes to Luanxia Yang, Qian Zhang, Wendi Zhang, Xian Jin, Fan Yang, Mariel Barrantes, Jessica Buritic?, Rajeev Ruparathna, Navid Hossaini, Courtney Dean, Anant Praghi, Shelir Ebrahimi. Their warm friendship developed a lifelong link. They xvii  definitely made my stay in Kelowna one of the best times of my life. I would like to take the opportunity to thank all my friends in China, who have always cared about me while I was away studying in Canada. To the girl, Yu Cao, who makes me believe life is beautiful! My family made me the person I am today. You allowed me to grow and stay strong! You are the source of inspiration for all my achievements.                   xviii          To Qiu?e Ming  Shunlan& Xuelan Feng      1  Chapter  1: Introduction 1.1 Background It is recognized that construction practices are one of the major contributors of environmental problems in modern society. The United States Energy Information Administration estimated that buildings account for 72% of all electricity consumption, and 38.9% of all carbon dioxide emissions (USDOE, 2012a). In order to address environmental concerns such as global warming, deforestation, and waste generation, the sustainability concept has been brought into the building construction sector. It is demonstrated that sustainable building practices can dramatically reduce a building?s energy consumption. For example, in the United States, a survey of 99 buildings indicated that green buildings consumed 30% less energy than conventional buildings on average (The Economist, 2004). Other case studies proved that building energy consumption could be reduced by as much as 50% if energy-efficient designs were applied (The Economist, 2004). Increasingly, vegetation is being used as an important new construction material to make buildings more sustainable (Eumorfopoulo and Kontoleon, 2009; Fioretti et al., 2010). Integration of green vegetation in buildings, through green roofs or green walls, increases the building?s ecological and environmental benefits (Perini et al., 2011a). Green technology such as green roofs and living walls is becoming more and more popular in sustainable buildings, and it is mainly because of the multiple social and environmental benefits, such as reducing greenhouse gas emissions, adaptation to climate change, air quality improvement, habitat provision, aesthetics perfection, and energy savings by insulation (Cheng et al., 2010; Wolverton and Wolverton, 1993; Liu and Baskaran, 2003; 2  Oberndorfer et al., 2007; McCarty et al., 2001; Santamouris et al., 2007; Currie and Bass, 2008). Since a major part of building energy consumption is to operate the heating and cooling systems to maintain internal building temperatures, the potential building energy reduction benefits of green vegetation systems have become attractive to the construction sector (Castleton et al., 2010). Eumorfopoulo and Kontoleon (2009) stated that the surface temperature of bare wall sections was substantially higher than those of planted-covered wall sections. The effect was up to 10.8?C. Liu and Minor (2005) showed that heat loss through a green roof can be reduced 10-30% in the winter and 70-90% in the summer on average. In different climate types, Alexandri and Jones (2008) indicated that covering the building envelope with vegetation can save energy from 35% to 90%. However, the exact performance of green vegetation depends on building orientation, the roof-to-building envelope ratio, the type of system, and the insulation in each building roof and external fa?ade (Currie and Bass, 2008). All these parameters have to be considered when analyzing the energy saving performance of green vegetation. 1.2 Research Objectives The main objective of this research project is to investigate the energy saving and lifecycle performance of green vegetation in ?Green? buildings. The following are the sub-objectives:  Conduct a lifecycle analysis for living walls in terms of air purification and energy savings performance. 3   Analyze the heating and cooling energy saving performance of green vegetation systems in commercial buildings for different greening scenarios, building types, building vintages, weather conditions, and building orientations.  Analyze heating and cooling energy saving performance of green vegetation systems in LEED certified buildings. 1.3 Thesis Organization As shown in Fig.1.1, the thesis consists of 7 chapters with the following contents:                Figure 1.1     Thesis Organization Chapter 1 Background Research Objectives Chapter 2 Literature Review Chapter 3 Methodology Chapter 4 Lifecycle Assessment of Living Walls Chapter 5 Commercial Building Energy Simulation with Green Vegetation Chapter 6 LEED Certified Green Building Energy Simulation with Green vegetation Chapter 7 Conclusions and Recommendations 4  Figure 1.2 illustrates the outline of the research methodology used to achieve the objectives of this study. The methodology is described in detail in Chapters 3, 4, and 5.  Literature ReviewTypes of green vegetationLayers of green vegetationBenefits of green vegetationData CollectionTechnical reports reviewBuilding projects documents reviewLifecycle AssessmentData InventoryAssumptionsLCA in air cleaning and energy savingsEnergy Efficiency Analysis in Commercial BuildingsIdentify the potential impact factorsEvaluate energy savings in different parametersEnergy Efficiency Analysis in LEED Standard BuildingsImplement the characteristic of the buildingsValidate the model accuracy Assess the energy performance in different scenariosGreen Vegetation Application GuidelineSustainability performance  IndicatorEnergy based evaluation tool Figure 1.2     Research methodology outline As shown in Figure 1.2, the study started with a comprehensive literature review on the main research topic. In order to achieve the research objectives, the data was collected in the second step through technical reports, building specifications, and other published literature. The collected data was used to conduct a lifecycle assessment of living walls d to evaluate the overall sustainability of green vegetation. In addition, an energy efficiency analysis of buildings with green vegetation was conducted to evaluate the impact factors on energy savings. Furthermore, a comparative energy efficiency analysis was carried out to assess the energy saving performance of green vegetation in LEED certified buildings.     5  Finally, an energy based green vegetation application guideline was formulated with relevant sustainability performance indicators.                      6  Chapter  2: Literature Review The literature review is divided into 4 main sections, namely: 1. Types of green vegetation in buildings 2. Layers of green vegetation systems 3. Environmental benefits of green vegetation in buildings 4. Energy savings and green vegetation: governing factors 2.1 Types of Green Vegetation in buildings There are mainly two types of green walls: green fa?ades and living walls. Green fa?ade systems use plants or hanging shrubs as vegetation with special support structures to cover a desired area (P?rez et al., 2011). The plants can be placed in pots at different heights of the fa?ade, at the base of the structure, or directly on the ground. Without the complexity and technification of the living wall system, green fa?ades are simply based on the use of climbing plants (P?rez et al., 2011). Ecological benefits of green facades, such as energy savings, thermal insulation, and building protection, are not as pronounced as they are with living walls (Weinmaster, 2009). Living walls are made of planted blankets, vertical modules, or pre-vegetated panels that are vertically fixed to a frame or structural wall. The plants are supported by panels or geotextile felts, which are generally made out of concrete, metal, clay, synthetic fabric, expanded polystyrene, or plastic (P?rez et al., 2011). There are many commercially available living wall systems, and they can be categorized in terms of different parameters. Loh (2008) classified the living walls into three systems: trellis, modular panel, and felt layer systems. This classification is based on the characteristics of the plant box. Perini et al. (2012) 7  classified living walls with different features of growing medium. The potting soil is used as substrate in the planter box living wall system, the form is used as the growing medium in the form substrate living wall system, and the felt layers are used as substrate and waterproofing in the felt layer living wall system. Green roofs are quite normalized in building systems compared with the complexity of green walls. According to the purpose and characteristics, green roofs can be categorized into extensive and intensive (Czemiel Berndtsson, 2010). Extensive green roofs are designed to be virtually self-sustaining with a relatively thin layer of soil. Therefore, they require low maintenance (Molineux et al., 2009). Intensive green roofs are usually associated with roof gardens, which need a reasonable depth of soil and require skilled labor, irrigation, and constant maintenance (Molineux et al., 2009). There is a third type of green roofs called semi-intensive, which comprise extensive and intensive. However, the percentage of the extensive type should not exceed 25% of the total green roof?s area (Yang et al., 2008). 2.2 Layers of Green Vegetation Systems According to customer requirements and weather conditions, manufacturers develop different green vegetation systems for the market. The layers of green roofs and living walls are totally different because of the structural difference in the building. 2.2.1 Layers of green roof systems As shown in Figure 2.1, green roof systems constitute a vegetation layer, growing medium layer, water retention layer, filter layer, drainage layer, and root barrier (She & Pang, 2010; Palla, Gnecco, & Lanza, 2009; Czemiel Berndtsson, 2010).  8        Figure 2.1     The sections of green roof layers (Bianchini and Hewage 2012). 2.2.1.1 Vegetation layer As the esthetic layer of green roofs, the vegetation layer might be the symbol that marks a green roof as an environmentally friendly product. It is suggested to use Crassulacean Acid Metabolism (CAM) plants since the environmental conditions at roof tops are different from the conditions at ground level. CAM plants exchange oxygen and carbon dioxide by opening their leaves in the darkness, and allow the conservation of water under drought conditions (Getter and Rowe, 2006). Sedums and mosses have become the most popular type used on green roofs because they meet all the requirements of the environmental conditions on the roof, and are easy to maintain (Berghage et al., 2007). As intensive green roofs can create an enjoyable environment within the building by providing an open and accessible space (Molineux et al., 2009), plants like small fruit trees, vegetables, shrubs, herbs, grasses, or small trees in the height range of 10cm to 100 cm are generally applied to this system (Cavanaugh, 2008).   Vegetation Growing medium Water retention Filter Root barrier  Drainage 9  2.2.1.2 Growing medium layer The growing medium layer supplies nutrients and water to the biological functions of the plants (Jim and Tsang, 2011). The growing medium also helps the plant withstand wind force and other rough weather conditions on the roof tops by settling and strengthening the plant roots (Jim and Tsang, 2011). Since the growing medium layer affects the water retention and thermal performance of the green roof system, it is important to guarantee the quality of that layer (Teemusk and Mander, 2007). The natural growing medium is usually regular soil. However, manufacturers developed their own growing medium due to the weight limitations of green roof systems. In order to maintain the balance between weight and performance, a low content of organic matter and a high content of porous minerals are usually applied to these growing mediums (Clark et al., 2008). Nevertheless, the growing medium content could be changed to satisfy the requirements of the selected vegetation and the roof structure. The requirement of vegetation is the criteria for the thickness of growing medium. In Canada, the thinnest growing medium for an extensive green roof system could be 2.5cm. Since intensive green roof systems are used to grow different types of plants, the medium could vary between 20cm and 120cm (Yang et al., 2008). 2.2.1.3 Water retention layer The water retention layer is located above the filter layer, and it is usually made out of mineral wool or polymeric fibers. The main purpose of this layer is to keep the growing medium layer moist and retain water for runoff control (Jim and Tsang, 2011; Teemusk and Mander, 2007). Since intensive green roofs need more water and nutrients to survive and bloom, the vegetation for these systems is usually bigger with stronger roots. The growing 10  medium in extensive green roofs is thinner because these systems need less water holding capacity (Soprema, 2013; Vitaroofs, 2013). The type of green roof, the building?s roofing assembly, the weather conditions, the vegetation, and the previous soil?s saturation are the parameters for the capacity of the water retention layer (Nicholson et al., 2009; Czemiel Berndtsson, 2010; Teemusk and Mander, 2007; Mentens et al., 2006). 2.2.1.4 Filter layer In order to facilitate easy installation, the filter layer is usually bonded with the drainage layer. The filter layer is usually made of materials such as polyolefin or fibers to keep it thin and light (Bianchini and Hewage, 2011). The function of the filter layer is to block the drainage layer and prevent the particles of the upper layers from draining with water runoff. Moreover, the filter layer helps to keep the integrity of the growing medium and vegetation (Tam et al., 2004). 2.2.1.5 Drainage layer With the variance of weather conditions, roofing assembly, and green roof systems, the drainage layer could be shaped differently (Bianchini and Hewage, 2011). The drainage layer in the extensive green roof is approximately 1.0cm to 1.5cm, and it could reach to 4cm or more in the intensive green roofs as they are designed to holder higher loads (Soprema, 2013; Vitaroofs, 2013). The drainage layer could shift the excess water out of the room effictively to avoid the extra weight of water to the roof assembly. It also decreases the risk of water leaks to the roofing assembly (Getter et al., 2007).  11  2.2.1.6 Root barrier layer The root barrier is basically built out of traditional materials like concrete, and it is the first layer above the building?s roofing assembly. The major purpose of this layer is to separate the building?s roofing assembly from the plants? roots, and provide a waterproof membrane to the roofing assembly (She and Pang, 2010; Soprema, 2013; Vitaroofs, 2013).  2.2.2 Layers of living wall systems As shown in Figure 2.2, living wall systems usually have a vegetation layer, growing medium, irrigation system, container, waterproofing layer, and structural support (Loh, 2008; Perini et al., 2011b; P?rez et al., 2011).            Planter box system       Felt layer system         Trellis system Figure 2.2     Three living wall systems (cited from Loh (2008)).   12  2.2.2.1 Vegetation layer The vegetation layer is the aesthetic layer of living walls, and probably the most important part that identifies a living wall as an environmentally friendly product. The vegetation layer is the critical element for all the environmental benefits of living walls (Bianchini and Hewage, 2012). Because of the core role of the vegetation layer in the living walls, it is necessary to understand the requirements for plants? survival, such as light and microclimate, especially in indoor environments.  The plants, if chosen correctly, require attention only 3 to 4 times a year to remove dust, wilting foliage, and dead plants (Nedlaw living Walls, 2008). In different greening systems, the plants should be selected accordingly. When choosing the climbers for the indirect greening system, the height should be considered. Some climbers can grow 5 to 6 meters high, others can grow up to 10 meters, and some species can even reach 25 meters (Dunnett and Kingsbury, 2004). For the modular panel system, the plant type is normally evergreen (Perini et al., 2011b). Eco-regions should also be considered in choosing the appropriate plant. Based on the climate conditions and localized knowledge of other conditions such as altitude, soil type, topography, and climax vegetation, the eco-regions could be defined into districts (Bailey, 1983). North America encompasses a wide range of eco-regions from desert areas with extremely low annual rainfall, to sub-tropical regions in Southern Florida where vegetation is rarely exposed to freezing temperatures, to mountainous areas with mild temperatures and wind conditions (Dvorak and Volder, 2010). Therefore, the eco-regions of living walls vary widely across the continent, and the chosen plants should be adaptable to the local climate. 13  2.2.2.2 Growing medium The growing medium is related to the thermal performance and water retention of green vegetation (Teemusk and Mander, 2007). It also provides water and nutrients that plants need for their biological functions (Franco et al., 2012). The plant roots will permeate and strengthen inside the medium to withstand wind force and other rough weather conditions. In green roof systems, in order to maintain the balance between weight and performance, the growing medium is made with a high content of porous minerals and a low content of organic matter (Clark et al., 2008). The growing medium in living walls has similar properties since it supplies nutrients to the vegetation. The natural growing medium is regular soil. However, soil can have clay and organic particles that may be heavy when saturated, and if the nutrient in the soil is limited, its replacement will increase costs and inconvenience (Bianchini and Hewage, 2012). With that limitation, many manufacturers develop their own growing mediums. Hydroponic systems in living walls can be seen all over the world. Hydroponic systems can be used to grow plants without soil, where the nutrients are added to water in the irrigation system (Weinmaster, 2009). In the hydroponic system, plants excrete microorganisms, which are developed in the rhizosphere and simulated by carbon, into the root zone. The most important hydroponic growing medium characteristics required for root formation are air-filled porosity and water-holding capacity (Schwab et al., 1998). Three porous materials ? growstone, expanded clay, and activated carbon ? were used by Aydogan and Montoya (2011) for a hydroponic growing medium, to test living wall performance in improving indoor air quality. Use of biochar as a 14  hydroponic growing medium was evaluated by researchers in New Zealand and Canada (Nichols et al., 2010). Biochar had positive effects on decreasing the greenhouse gas emissions from soil, such as nitrous oxide (N2O) or methane (CH4), as well as improving the nutrient retention (Lehmann et al., 2011). 2.2.2.3 Irrigation system The irrigation system is critical, because water and nutrients are fed to the vegetation via specific mechanical or natural irrigation systems. It is important to establish control and timing of the irrigation system to ensure a secure and regular water supply (Loh, 2008).  In the market, alternative irrigation systems are available for different living wall systems. Traditionally, people irrigated manually. At present, drip systems (with gravity) are common. Cheng et al. (2010) conducted an experiment with a timer-controlled irrigation system to assess the thermal performance of a vertical living wall. With a fixed irrigation time, the moisture level could be maintained between 20%-45% throughout the experiment to ensure the best cooling effects. The moisture distribution of the growing medium is guided by gravity. In order to ensure the best life condition for plants, it is necessary to install moisture sensors into the growing medium. In the commercial market, there is a different type of irrigation system for each related living wall system. The common systems are computerized vertical drip irrigation systems, individual water drip irrigation systems, and water retaining irrigation systems.   15  2.2.2.4 Waterproofing layer Generally, the waterproofing layer is on the building wall and is used to create a waterproof membrane on the building fa?ade. As the waterproofing layer is normally connected to the structural support, the moisture is not able to go behind the waterproof membrane and affect the building fa?ade (Weinmaster, 2009). Since leakage in an operational living wall system might consequently require the system to be removed completely, the waterproofing layer would ensure that the whole irrigation system operates normally without leakage. Polyethylene (PE), fleece, or low-density polyethylene (LDPE) is utilized as the traditional waterproof layer (Ottel? et al., 2011). Generally, the modular paper system has a waterproofing layer. However, some advanced commercial systems don?t require an extra waterproofing layer because the modular panel of these systems is self-waterproofed (Green over grey, 2009). 2.2.2.5 Container The container in the living wall system is used to support the vegetation and the growing medium. In the trellis system, the plants usually start to grow in flower pots and then climb onto the trellis. The flower pot could be located at different heights of the fa?ade or on the ground beside it (Loh, 2008). In the modular panel systems, the containers, which have different sizes and types, are generally fixed on the wall structure or a vertical support. Generally, there are two major types of modular containers. The first is the true box system, usually an empty square container made of plastic, metal, or some other material. The number of plants in a single box depends on the size of the species and type of box used, but the number usually ranges from six to fifteen. The size of the boxes varies widely 16  depending on the manufacturer, but generally they are about one square foot and a few inches thick (Weinmaster, 2009). The second type is plastic or metal trays, which contain multiple slanted cells. The slanted cells are able to keep the plants in place and facilitate irrigation. These systems are usually placed side by side and stacked to add height (Weinmaster, 2009). In the felt layer system, the felt pocket is usually attached to a waterproofing layer, and then connected to the back of the structure (Loh, 2008). In some cases, the felt layer is rot proofed and its high capillarity allows for homogeneous water distribution (Blanc and Lalot, 2008). Patrick Blanc developed a unique green wall that has two layers of synthetic fabric with felt pockets. The fabric walls are supported by a frame and backed by a waterproofing layer (Greenroofs, 2008). To sum up, the materials normally used for containers are fibre, plastics, felt bag, aluminum, steel, and wood. These materials might have a negative or positive influence on the environmental burden. Due to the durability, cost, profile thicknesses, and weights, the materials might change the functional and aesthetic properties (Ottel? et al., 2011). 2.2.2.6 Structural layer Structural support is the frame of the living wall system. Generally, the components are not the same and vary from outdoor to indoor environments. The loads from all the other layers have to be held by the structural support. The structural support also needs to handle additional rain, wind, or snow loads if the living wall is installed outside. The trellis system usually uses mesh structures, wired structures, or modular trellises to support the climbing plants (P?rez et al., 2011). This system is simple without too many components, thus the support structure does not need to support extra weight in addition to plants. The felt layer 17  system and modular system are similar in structural support since both felt layers and modular panels are attached directly to the structural frame. Weinmaster (2009) pointed out that aluminum, galvanized steel, stainless steel, or some other non-rusting metal can be used as structural support for modular or felt layer systems. Since wood is more environmentally friendly than steel and plastic, hard wood could be a better structural support for both indoor and outdoor environments, as long as the price is reasonable (Ottel? et al., 2011). Commonly used materials for structural supports are wood, plastic, aluminum, stainless steel, and galvanized steel. 2.3 Environmental Benefits of Green Vegetation in Buildings In the recent literature, many claims have been made about the positive influences of green vegetation. The environmental benefits of green vegetation, including green roof and living wall, are: improving air quality, reducing noise pollution, increasing the thermal performance of buildings (lowering energy costs), improving human health and well-being, improving water sensitive urban design (WSUD), increasing urban biodiversity and urban food production, and mitigating the Urban Heat Island effect (UHI) (Getter and Rowe, 2006; Yang et al., 2008; Molineux et al., 2009; Santamouris et al., 2007; Currie and Bass, 2010; Czemiel Berndtsson, 2010; Cheng et al., 2010; Wolverton and Wolverton, 1993; McCarty et al., 2001). 2.3.1 Thermal performance Green roofs and living walls contribute to the cooling and insulating benefits of a building. Green roofs could mitigate heat loss from the building in winter and heat gain into the building in summer; they also add thermal mass to help stabilize internal temperatures 18  year round (Castleton et al., 2010). Niachou et al. (2001) estimated that the energy savings created by the green roofs in non-insulated buildings can reach as much as 37%. The air layer between the fa?ade and the living wall has an insulating effect, which makes the living wall an extra insulation layer for the building envelope (Perini et al., 2011a). The phototropism effect created by the living walls can filter sunlight, ensuring a cooling effect in warmer climates. Of the sunlight falling on the leaves, 5%-20% is used for photosynthesis, 5%-30% is reflected, 20%-40% is used for evapotranspiration, 10%-50% is transformed into heat, and only 5%-30% passes through the leaves (Krusche et al., 1982; Ottel? et al., 2011). The green vertical cladding can affect the indoor environment even after sunset as it could mitigate the potential solar heat impact. Due to the shading created by living walls, the indoor temperatures could be decreased significantly in summer, and as much as 23% of energy costs could be saved (Bass and Baskaran, 2001). Eumorfopoulou and Kontoleon (2009) carried out an investigation in Greece during the winter, to compare the thermal performance of a bare concrete wall and a plant-covered building fa?ade. The results showed that the surface temperature of the bare wall sections was considerably higher than the surface temperatures of plant-covered wall sections. The effect was about 10.8?C. Wong et al. (2010a) also did research on a free standing wall in Hortpark (Singapore). The results showed that the temperature reduction resulting from the vertical greening system reached as much as 11.6?C. Alexandri and Jones (2008) indicated that applying green vegetation to the building envelope is an important method to reduce cooling and heating energy consumption. 19  Depending on the climate type and the amount and position of vegetation on a building, the energy savings can vary from 35% to 90% (Alexandri and Jones, 2008). 2.3.2 Air quality It is evident that vegetation of living walls can clean the air. Wolverton and Wolverton (1993) stated that potted plants can absorb carbon dioxide and release oxygen through photosynthesis, and reduce air-borne contaminants such as nitrogen oxides, volatile organic compound (VOCs), and dust. Thus, plants could improve indoor air quality significantly. At the Delft University of Technology, Ottel? et al. (2010) also determined that green vegetation could reduce the number of particulates (<10?m) that pose a long-term threat to human health. In addition, green vegetation can help improve air quality by absorbing toxic gas emitted by vehicles. In a UK-based study of air quality with an indoor gas heater, Coward et al. (1996) found that six or more potted plants in the house could reduce one third of NO2 levels. In a study of Korean native indoor species, Lee and Sim (1999) showed that indoor plants absorb and metabolize SO2. Some additional studies showed that plants effectively reduced levels of particulate matter, ammonia, formaldehyde, benzene, and nitrogen oxides (Lohr and Pearson-Mims, 1996). Plants could also increase the indoor relative humidity through moisture released into the air, and increase the comfort level in sealed environments (Aydogan and Montoya, 2011). 2.3.3 Urban heat island effect Due to the expansion of urban spaces, city climates have changed due to building materials and lack of vegetation. These changes cause a significant rise in urban temperatures, especially in the central parts of cities. This phenomenon is called the Urban 20  Heat Island effect (McCarthy et al., 2001). In rural areas, this problem does not exist since the evapotranspiration created by trees and plants helps to control the ambient temperature (Sailor et al., 2008). Green vegetation helps to lower temperatures through evapotranspiration, and mitigates the Urban Heat Island effect. In Lleida, Spain, P?rez et al. (2011) confirmed that the temperature of a building fa?ade covered by vegetation is on average 5.5?C lower than a bare building fa?ade, and the difference may reach as much as 17.6?C on the North West side of a building in September. Another study conducted by Alexandri and Jones (2008) measured green vegetation?s performance in the hottest month in Hong Kong, and the results demonstrated that an urban canyon (5-15m wide and 5-10m high) can achieve a maximum 8.4?C temperature decrease, if the vegetation coveres both walls and roofs. 2.3.4 Sound absorption Hard surfaces in urban areas are more likely to reflect sound, whereas plants absorb sound waves based on the nature of the substrate and vegetation (Getter and Rowe, 2006). Plants offer absorption, diffraction, and reflection of sound. The effect might vary with the frequency of the sound and the nature of the space. With sound at lower frequencies, plants may offer diffraction, and with sound at higher frequencies, plants may reflect the sound onto other surfaces that may then absorb the sound (Costa and James, 1999). Van Renterghem and Botteldooren (2011) stated that green roofs could lead to consistent and significant sound reduction at locations where only diffracted sound waves arrive. In Hort Park in Singapore, a research study was conducted to determine the sound absorption coefficient with 8 different living walls (Wong et al., 2010b). The results indicated that vegetation on living walls has 21  one of the highest values of sound absorption, compared to other regular building materials. Furthermore, as frequencies increased, the sound absorption coefficient also increased. In addition, it was observed that the sound absorption coefficient increases with greater greenery coverage (Wong et al., 2010b). By investigating 8 plant sites in Jharia and Raniganj, India, Pal et al. (2000) proved that the total noise attenuation by the green belts is evident, and the excess attenuation for higher frequencies is more than that for lower frequencies. 2.4 Energy Savings and Green Vegetation: Governing Factors  There are many governing factors related to energy performance of buildings with exterior green vegetation.  2.4.1 Reduction of heat flux and solar reflectivity The surface temperature of a building can be evaluated by the surface reflectance of the roof and the walls, and it is a primary indicator of the urban heat island effect (Brown and Gillespie, 1995). Green vegetation can significantly mitigate the effect, as it can improve the reflectivity of incident solar radiation and reduce the temperature through latent heat loss. It was demonstrated that the exposed area of a black roof can reach up to 80oC in summer, while the equivalent area beneath a green roof is only 27oC (Facer et al., 2007). Liu and Minor (2005) conducted an experiment with a green roof, and a reference bare roof, with heat flux transducers. The results showed that the heat loss through the green roof was about 10%-30% in the summer and 70%-90% in the winter.  Castleton et al. (2010) presented that the overall temperature under a green roof is slightly lower than a standard roof, and the internal temperature peak is slightly delayed. The temperature peak delay is mainly due to the thermal mass effect of green roofs.  22  In green walls, the magnitude of the heat flux reduction effect relies on the density of the foliage. Ivy is the species that provides the maximum cooling effect in the traditional green fa?ade, and the difference in indoor temperature can reach up to 3?C (K?hler, 2008; Stec et al., 2005). In the double-skin fa?ade, replacing the blinds with plants could generally lower the interior temperature. Stec et al. (2005) mentioned that installing plants inside a double skin fa?ade could reduce the energy consumption for the air conditioning system up to 20%.  2.4.2 Evaporative cooling Plants generate evaporative cooling through the evapotranspiration process. The plant types and exposure both impact the evaporative cooling effect, same as the climatic conditions. Furthermore, plants perform evaporative cooling better in dry environments and with the effect of the wind (P?rez et al., 2011). A mathematical model was used by Feng et al. (2010) to analyze the evaporative cooling effect of a green roof in a typical summer in China. The results demonstrated that 58% of the heat of the green roof was lost by evapotranspiration. It is also proved by Castleton et al. (2010) that wet green roofs have more than twice heat losses, through evapotranspiration, than dry green roofs. The dry green roof reduces the incoming heat flux up to 60% compared to a traditional roof. The additional evapotranspiration of the wet roofs not only acts as a passive cooler by actually removing heat from the building, but also prevents the heat flux into the building.  It was noted that evapotranspiration cooling of a green wall can dramatically reduce the peak temperatures of a building, with daily temperature fluctuation being reduced by as much as 50% (Dunnett and Kingsbury, 2004). Through evapotranspiration, large amounts of 23  solar radiation can be converted into latent heat, which does not cause temperature rise. Depending on the amount and type of greenery, a building fa?ade fully covered by green vegetation can reflect or absorb the received radiation by 40% to 80% (Climate booklet for urban development, 2008). Through shading and heat flow reduction by evaporative cooling, vertical greenery systems could significantly reduce incoming solar energy into the interior, which saves energy used for cooling (Wong et al., 2010; Wong et al., 2009). 2.4.3 Thermal performance of building envelope Green vegetation can reduce the annual energy consumption by improving the insulation properties of a building (Castleton et al., 2010). Green vegetation can help increase the thermal mass and stabilize internal temperatures over a full year, since it reduces not only the heat gain from a building in summer, but also the heat loss from a building in winter (Castleton et al., 2010).  Green roofs are suitable for reducing heat gain due to the large thermal mass determined by their drainage and soil layer. The thermal mass of a green roof has a positive effect on the stabilization and reduction of the internal surface temperature. In summer, the thermal mass can reduce the peak cooling loads in a building by storing a large part of the indoor heat gains and delaying the heat transfer from outside to inside (Fioretti et al., 2010). For a planted roof with thermal insulation and U-Value 0.4W/m2 K, the temperature difference across the roof section does not exceed 2.5oC, even when external temperatures range from ?10oC to 40oC (Castleton et al., 2010).  The heat transfer of two green roofs with different thickness of growing medium was measured by Liu and Minor (2005), and the result demonstrated that thicker substrate could improve the thermal performance of green roofs. Del Barrio (1998) found that the relative 24  density of soil also influenced the thermal conductivity of a soil medium, as the insulating properties could be increased by the additional air pockets in the less dense soil. Green walls change the humidity and temperature of the space between the building wall and the green screen. In green fa?ades, the density of the foliage, the design of the openings of the fa?ade, and the renewal of air in this space influence the insulation properties. For the living walls, the substrate thickness is another factor for the insulating capacity (P?rez et al., 2011). If a concrete wall is externally coated with green vegetation, the heat transfer through it could be significantly lower. Hoyano (1988) reported that 0.24 KWh/m2 energy transfer could be reduced by a living wall. 2.4.4 Wind effect on the building In winter, the temperature inside buildings could be reduced critically by the cold winds. Therefore, blocking the cold wind could be one way to increase the energy efficiency. By acting as a wind barrier, green vegetation systems of buildings could block the wind effect on building fa?ades. This effect depends on the direction and velocity of the wind, the orientation of the fa?ade, as well as the density and penetrability of the foliage (P?rez et al., 2011). The thermal transmittance of a structure is also dependent on the wind that passes along the surface of that structure. Green fa?ades could change the wind velocity on the underlying exterior of a construction material, as the leaves of plants create an almost stagnant layer of air or reduce the wind strength (Eumorfopoulo and Kontoleon, 2009). Dinsdale et al. (2006) also claimed that vegetation (green roofs and green walls) could protect a building from cold wind and reduce the heating demand by 25%. 25  McPherson et al. (1988) simulated the effects of wind reduction and irradiance due to vegetation in similar residences in four different climates. However, it is necessary not to favor the air circulation in winter and obstruct the ventilation in summer when considering using the vegetation to mitigate wind effect (P?rez et al., 2011).  26  Chapter  3: Lifecycle Assessment of Living Walls Since there are many commercially available living wall systems, product costs could vary for different designs and functions. In this LCA research, three living walls systems are adopted from the greening systems presented by Ottel? et al. (2011). The first one was an indirect greening system, where the climber is planted on the ground, and grown on the stainless steel mesh. The second one was a planter box living wall system, and the third one was a felt layer living wall system. The materials data of the living walls required for the inventory analyses were obtained from the information provided by the manufacturers and project construction documents. 3.1 Materials and Method By performing the LCA, the environmental impacts of the living walls could be assessed. The main stages of an LCA study are raw material acquisition, materials manufacture, production, use/reuse/maintenance, and waste management (USEPA, 2012). 3.1.1 Basic approach As mentioned above, three living wall systems were chosen from Ottel? et al. (2011) to conduct the LCA. 1) The Indirect Greening System: The indirect greening system is composed of evergreen climbing plants and a steel frame (which is used as the support). The plants are directly grown on the ground. 2) The Planter Box Living Wall System: The planter box living wall system is made with the plastic modules, which are made out of high-density polyethylene (HDPE). The box 27  is filled with soil and planted with evergreen species. Water and nutrients for the planter box living wall system are supplied by an irrigation system. 3) The Felt Layer Living Wall System: The felt layer living wall system is based on several felt layers as substrate, supported by a polyvinyl chloride (PVC) sheet. A separate irrigation system is attached to felt layers to supply water and nutrients for the plants. In this comparative LCA, chemical emissions and energy consumption were calculated by considering the following lifecycle phases of the three living wall systems: 1) raw material depletion, 2) manufacturing, 3) transportation, 4) installation, 5) maintenance, and 6) disposal. A functional unit for LCA must be set to do the basic comparison between different greening alternatives. In this research, the functional unit is selected as 1m2 of living wall. As the basis for calculating the products and materials involved in each selected system, a building fa?ade of 200 m2 was considered. The following steps were undertaken to assess the benefits of living walls: The chemical absorption data presented by Yang et al. (2008) was referred to quantify the air cleaning potential. Energy savings of three typical living wall systems were estimated in three steps: Step 1: Calculated the percentage of energy savings (with the use of living walls) based on the information from Ottel? et al. (2011); Step 2: Evaluated the energy consumption of a standard building in different climatic conditions with the EnergyPlus simulation; and  Step 3: Obtained the total energy savings of a building, due to living walls, by multiplying the results of step one and step two above. 28   With the energy savings in the operational phase, the balance years of the initial energy usage in the material production were calculated with the results of step three. 3.1.2 Tools The following tools were used for data analysis. 3.1.2.1 SimaPro modeling SimaPro modeling (7.3.3) was applied to assess the chemical emissions and energy consumptions of living wall materials, in the manufacturing process. The chemical emission results of SimaPro were compared with the chemical abatement values of the living walls presented by Yang et al. (2008). 3.1.2.2 EnergyPlus modeling Subject to user-specified construction, internal loads, schedules, and weather, EnergyPlus software could be used to model hourly building energy consumption (Kneifel, 2010). EnergyPlus V7.1 (EnergyPlus, 2012) was used to run the building energy simulations to obtain the annual electricity bill for heating and cooling. After the multiplication between the data from EnergyPlus and the energy saving percentage of Ottel? et al. (2011), the results were compared with the energy consumption results of SimaPro to gain the balance years. The results of energy savings, which were calculated with the multiplication between the data from EnergyPlus and the energy saving percentage of Ottel? et al. (2011) were compared with the energy consumption results of SimaPro to attain the balance years. 3.1.3 Data inventory For the LCA, all the components of the living wall systems were examined. The indirect greening system only has a stainless steel support for the plant. The planter box 29  living wall system has planter boxes, which are filled with potting soil. The felt layer living wall system has several layers for rooting, waterproofing, and supporting. The materials of the three living walls used for the inventory were cited from Ottel? et al. (2011). 3.1.3.1 Manufacturing stage In this stage, the raw material depletion, product fabrication, and related transportation were all covered. As shown in Table 3.1, the materials used for the inventory were based on Ottel? et al. (2011). Since the bare fa?ade, where the living wall is attached, is not considered in this LCA analysis, the components of the bare fa?ade are not listed in Table 3.1.            30  Table 3.1    Components, material weight (Kg/m2), and service life (years) of living wall (Derived from Ottel? et al. (2011)). System Name Components Material Weight Distances Service Life (Kg/m2) (km) (years) Indirect greening system Bolts Stainless steel 0.015 18 50 Spacer brackets Stainless steel 0.045 18 50 Structural support member Stainless steel mesh 1.55 18 50 Vegetation H.helix 2.7 30 50 Planter box living wall system Bolts Steel S235 0.27 15 50 Spacer brackets Steel S235 0.315 15 50 Supporting U section Steel S235 4.62 15 50 Planter boxes HDPE 13.2 15 50 Growing material potting soil 75.6 30 50 Vegetation Pteropsida 8 30 10 Watering system PE 0.26 35 7.5 Felt layer living wall system Bolts Steel S235 0.13 65 50 Spacer brackets Steel S235 0.19 65 50 Supporting U section Steel S235 4.62 65 50 Foam plate PVC 7 65 10 White fleece Polypropylene 0.3 65 10 Wool fleece Polyamide 0.6 65 10 PE fleece Polyethylene 0.045 65 10 Black fleece Polypropylene 0.27 65 10 Vegetation Pteropsida 7.5 30 3.5 Watering system PE 0.09 35 7.5 31  3.1.3.2 Construction stage In the construction stage, transportation and machine usage in the installation process are the major contributors of chemical emissions and energy consumption (Zabalza Bribi?n et al., 2009; Baek et al., 2013). In terms of the living wall installation, once the materials are delivered to the construction site, only simple tools such as a drill and screwdriver are needed to fasten the components of the living wall systems. In this research, chemical emissions and energy consumptions of the machines were not considered because of their minor influence. For the material transportation, all the distances from the manufacturing factories to work sites for transporting vegetation, steel components, planter boxes, and felt layers were estimated for the City of Delft, where the living walls were installed. These data were cited from Ottel? et al. (2011) and listed in Table 3.1. Chemical emissions and energy consumption in the transportation process were calculated with the SimaPro software, and a 3.5-ton truck was chosen for the analysis. 3.1.3.3 Maintenance stage Horticultural work to repair and replace vegetation is the major work in living wall maintenance. Therefore, the impact of chemical emission and energy consumption in the maintenance stage is negligible. The nutrients supplied in the maintenance stage should be calculated as the nutrient producing process. This process creates chemical emissions and consumes energy (Berndtsson et al., 2006). VegTech (2002) estimated that the total fertilizer applied to a 1m2 vegetation roof is 17.24g/year. As the vegetation has a similar performance, either in the living wall or in the green roof, the same amount of nutrient consumption is assumed to calculate the nutrient requirement of a living wall. 32  3.1.3.4 Disposal stage In the disposal stage, materials could be recycled, reused, or landfilled. The steel components can be reused, and the planter boxes can be recycled. However, many cities do not have the required facilities to undertake the recycling process. Therefore, the worst-case scenario was considered in this analysis: i.e. the living wall components have to be landfilled. The steel materials were assumed to be disposed of in inert material landfill, and the plastics, such as the planter boxes and felt layers, in a sanitary landfill. The vegetation and soil were assumed to be naturally disposed of as they are mostly organic. The transportation process in the disposal stage makes a significant contribution to the chemical emissions and energy consumptions. In this study, all the waste materials were considered to be delivered to the landfill center in Amsterdam, which is about 66km away from the city (ICOVA, 2013). 3.1.3.5 Assumptions The assumptions made in this analysis are mainly about the service life of living wall components. The living wall system is a newly developed green technology. Scientific research on green fa?ades is relatively new and peaked in the 1980s (K?hler, 2008), and the stainless steel cable system for green fa?ades was first introduced in 1988 (GREENROOFS, 2008). Patrick Blanc, the grandfather of green walls, invented the first hydroponic system for living walls only about 20 years ago (Weinmaster, 2009). Therefore, the actual service life of living walls has not been confirmed yet. Heffernan (2013) from Ambius declared that the hardware, the panels and the growth media of the living wall can last up to 25 years, however plants? survival duration in difficult to establish. Stav (2008) estimated that the lifespan of the intensive green roof could reach as 33  much as 90 years, while Saiz et al. (2006) stated it as 50 years. Kosareo and Ries (2006) also noted that the expected operating life of green roofs as 45 years. Therefore, the lifespan of green vegetation, either green roof or living wall, varies, and it depends on the product quality, maintenance rate, and weather conditions, etc.  Since the service life of a conventional bare wall is about 50 years, the service life of steel components were assumed as 50 years, and the lifespan of the vegetation in the indirect greening system was also assumed as 50 years. The replacement frequencies of plants in planter box and felt layer living wall systems were assumed as 10 and 3.5 years respectively. The life expectancy for the plastic planter box (HDPE) was assumed as 50 years (Ottel? et al., 2011). As per the analysis performed by Riedmiller and Schneider (1992), the lifespan of PVC layers in the felt layer system is about 10 years. The life expectancy of the felt layers is similar to the PVC, which was also assumed as 10 years. The irrigation system for the planter box and felt layer living walls was assumed to be replaced every 7.5 years due to the crystallizing of salts (Ottel? et al., 2011). The service periods of all the components were listed in Table 3.1. In terms of the benefits of the green layer, the indirect greening system performs differently than the living wall systems. The vegetation chosen in this system is Hedera helix (H. helix) for their rapid growth, high vegetative mobility, large leaf area and climb characteristic. H. helix is a woody evergreen vine, which may climb 15 m or more by adhesive tendrils or small rootlets attaching to supports. It grows well in a wide variety of soil types and resists environmental stress, such as infertility, high heat and drought. They can make a fine green cover for vertical surface (Wang et al. 2009). For the indirect greening 34  system, the full covering of the fa?ade by H. helix is estimated after 20 years (Ottel? et al., 2011). For both living wall systems, the benefits could be calculated after the installation due to the material layers and amount of plants. The input data for the LCA in SimaPro software is shown in Appendix A. The importance of this chapter relies on determining the sustainability of living walls from a new perspective. Since the two major quantitative benefits of living walls are energy savings and air cleaning (Bass and Baskaran, 2011; Eumorfopoulou and Kontoleon, 2009; Coward et al. 1996; Lee and Sim, 1999), this study not only considers the energy savings benefit, but also the air cleaning benefit of living walls, which makes the investigation more comprehensive. Furthermore in this study, the environmental burden, energy consumption and chemical emission, is based on the burden created by all the components of the living wall, in its entire lifecycle. This chapter has two main objectives: (1) Evaluate the environmental performance of living walls in manufacturing, constructing, maintaining, and disposing of 1m2 living walls. (2) Quantify the air cleaning and energy saving performance of living walls, in the product lifecycle, with comprehensive statistical analysis. 3.2 Comparative Lifecycle Analysis of Living Walls Comparative analysis of chemical emissions and energy consumption of living walls in their entire lifecycle, and air purification and energy savings in the operations phase, are discussed in this section. In the manufacturing process, the chemical emissions include all the 35  emissions from raw material depletion, transportation to the factory, and fabrication. In the construction stage, chemical emissions of different components are due to the transport emissions, where the weight of the component and the transport distance are the key factors. In the maintenance stage, nutrients are applied twice a year to the living walls, and the chemical emissions are mainly due to the manufacturing of fertilizer. In the disposal stage, transportation to the landfill and the landfilling process both create emissions. It is the same in energy consumption. 3.2.1 Chemical emissions vs. Air purification The Eco-indicator 99 was used to conduct the impact assessment of the living wall components. The Eco-indicators express the total environmental load of a product or a process. The standard Eco-indicator values can be regarded as dimensionless figures. The scale 1Pt means one thousandth of the yearly environmental load of one average European inhabitant (Eco-indicator 99, 2000). As shown in Figure 3.1, three steps are needed to calculate the Eco-indicator score.      36   Figure 3.1     General procedure for the calculation of Eco-indicators (cited from Eco-indicator 99 (2000)). The damage model for these flows (shown in Figure 3.1) is assessed in three categories: 1: Damage to resources is expressed as the surplus energy needed for future extractions of minerals and fossil fuels. 2: Damage to ecosystem quality is expressed as the loss of species over a certain area during a certain time. 3: Damage to human health is expressed as the number of year life lost and the number of years lived disabled. These are combined as Disability Adjusted Life Years (DALYs), an index that is also used by the World Bank and the WHO. The impact assessment (SimaPro based) of different living wall materials (presented in Table 3.1) is shown in Figure 3.2. Based on the comparison results in Figure 3.2, PVC foam has the highest environmental impact compared to other materials, mainly because of the higher carcinogen emissions. Steel and stainless steel have high respiratory inorganic 37  emissions. Further, PE pipes, HDPE plastics, and fleece consume more fossil fuels. It is evident that the PVC foam layer is the least environmentally friendly material.  Figure 3.2     Comparison of product stages between different materials (Method: Eco-indicator 99 (E) V2.08/Europe EI 99 E/E/Single score). According to the inventory results, around 900 emissions were noted in the full lifecycle of a living wall, and the detail of the emissions from SimaPro software is attached in Appendix B. In order to match the chemical absorption data of Yang et al. (2008) with the inventory results, Nitrogen Dioxide (NO2), Sulphur Dioxide (SO2), Ozone (O3) and Particulates (<10?m) were considered. Table 3.2 shows the amount of substances that are 0.100.200.300.400.500.600.700.800.Steel stainlesssteelpvc foamplatePE pipe HDPEplasticFleecemPt Comparing product stages; Method: Eco-indicator 99 (E) V2.08 / Europe EI 99 E/E / Single score Fossil fuelsMineralsLand useAcidification/ EutrophicationEcotoxicityOzone layerRadiationClimate changeRespiratory inorganicsRespiratory organicsCarcinogens38  released to the environment (air, water, and/or solid) by producing 1kg of each component of living walls. By multiplying the weight of each component in Table 3.1 with the emissions per kilogram of the relevant component in Table 3.2, chemical emissions for creating 1m2 of living wall can be attained. Ottel? et al. (2011) noted that the expected operating life for the indirect greening system and the planter box living wall system is about 50 years. Therefore components of both systems that have an operational life of less than 50 years, such as the watering system with a 7.5 year service life, needed to be replaced during the living wall?s lifetime. Therefore, the emissions of those components were multiplied by the number of replacement cycles. With the air purification rate cited by Yang et al. (2008), years required to balance the chemical emissions created by the living walls in the whole lifecycle was calculated. Table 3.3 lists the total emissions released in different stages by 1m2 of living wall system. Table 3.3 also presents the number of operational years needed to balance the emission.39  Table 3.2     Amount of substances released due to the production of 1kg of material in different stages (Derived from SimaPro results). Process Unit Emission/kg Steel Stainless steel PVC foam plate PE pipe HDPE plastic Fleece Vegetation Growing material Fertilizer Manufacture g 12.24 28.53 16.74 7.96 7.77 10.41 0.00 0.00 0.00 Construction g/km 1.66 1.66 1.66 1.66 1.66 1.66 1.66 1.66 0.00 Maintenance g 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 22.04 Disposal g 0.08 0.08 0.13 0.13 0.13 0.13 0.00 0.00 0.00 g/km 1.66 1.66 1.66 1.66 1.66 1.66 0.00 0.00 0.00   Table 3.3    The emission released due to the production of 1m2 living walls and years needed to balance it. System Emission (g/m2) Total of Pollutants (g) Air cleaning ability Balance Years Manufacture Construction Maintenance Disposal Indirect greening system 45.93 0.05 19 0.15 65.14 8.46g.m-2.yr-1(Cited from Yang et al. (2008) 8 Planter box living wall system 180.8 1.78 19 2.12 203.69 24 Felt layer living wall system 191.7 0.73 3.8 1.44 197.7 23 40  Analysis of total pollutants released in the living wall manufacturing process shows that the felt layer system releases 3 times more toxic substances to the environment than the modular panel system and indirect greening system (Table 3.3). Additionally, the felt layer system needs as many as 23 years to balance the pollution (emissions). As the expected operating life of a felt layer living wall is about 10 years, the pollution removal benefit of the felt layer system cannot offset the pollution it initially created. Indirect greening systems and modular panel systems could easily balance air pollution with purification, as their life expectancy is estimated as 50 years (Ottel? et al., 2011). Therefore, among the three typical living wall systems evaluated, the felt layer system is the least environmentally friendly living wall system in terms of air pollution abatement. As shown in Table 3.3, the number of years needed to balance the pollutants emitted by the modular panel system is 3 times higher than that of the trellis system. The reason can be found in Table 3.1; i.e. the trellis system only has one simple layer to support the climber, while the modular panel system has three layers. However, the trellis system uses stainless steel as a structure support, which has the highest pollutant emission rate in the manufacturing process (Table 3.2). Ottel? et al. (2011) conducted an environmental burden analysis for different materials that can be used as living wall supporting systems. Their results showed that stainless steel support has roughly 10 times more pollutant emissions than recycled plastic (HDPE) supporting systems, hard wood, and coated steel. Therefore, stainless steel might not be a sustainable choice even though it has a life span of 50 years or longer.  41  3.2.2 Energy consumption vs. Energy saving Based on SimaPro inventory results, Table 3.4 lists all the energy required in different lifecycle stages to make 1kg of different components of living walls. By multiplying the weight of each component in Table 3.1 with the energy requirement per kilogram of the living wall components in each lifecycle stage, the energy requirements for 1m2 of living wall was calculated and summarized (Table 3.5). Similar to the chemical emissions calculations, materials that have a service life of less than 50 years in the indirect greening system and planter box living wall system, and less than 10 years in the felt layer living wall system, needed to be replaced. Therefore the initial energy consumption of these materials was multiplied by the number of replacement cycles.          42  Table 3.4     Energy needed to produce 1kg of material in different life stages (Derived from SimaPro results). Process Unit Energy Consumption/kg  Steel Stainless Steel PVC foam plate PE pipe HDPE plastic Fleece Vegetation Nutrient Manufacture KJ 1450 29210 69110 72110 900 1890 0 0 Construction KJ/km 6.07 6.07 6.07 6.07 6.07 6.07 6.07 0 Maintenance KJ 0 0 0 0 0 0 0 1181.61 Disposal KJ 1.46 1.46 5.2 5.2 5.2 5.2 0 0 KJ/km 6.07 6.07 6.07 6.07 6.07 6.07 0 0  Table 3.5    Energy required due to the production of 1m2 living walls. System Energy Consumption (KJ/m2) Total of Energy Consumption (KJ) Manufacture Construction Maintenance Disposal Indirect greening system 47,028.10 0.19 1,018.55 2.54 48,049.38 Planter box living wall system 150,667.45 6.61 1,018.55 88.06 151,780.66 Felt layer living wall system 506,209.15 2.67 203.71 51.95 506,467.48   43  In order to estimate the balance years of energy consumption for a living wall in its lifecycle, the energy savings of living walls were compared. Alexandri and Jones (2008) estimated the energy saving percentages in Mediterranean and temperate climates by conducting an energy simulation of a building (40m x 10m x 5m), by installing a 200m2 living wall (Table 3.6). In order to calculate the energy saving percentages (in Table 3.6), the same building dimension was assigned for EnergyPlus simulation. According to the eco-region map created by USEPA (2006), Los Angeles, California was selected for weather inputs in a Mediterranean climate; and Albany, New York was selected for weather inputs in a temperate climate. Other parameters, such as building activity (people density, electrical plug intensity, etc.), building fenestration, and HVAC system were defined with the smart default models in EnergyPlus. Results show that the total heating and cooling energy consumption for a Mediterranean climate is 6.7GJ/year and 23.9GJ/year respectively, and the total heating and cooling energy consumed for the temperate climate is 70.77GJ/year and 17.59GJ/year respectively. Table 3.6    Energy saving for heating and cooling in different climates (Ottel? et al., 2011; Alexandri and Jones, 2008). Living wall system Benefit Mediterranean climate Temperate climate Indirect greening system Energy saving for heating 1.20% 1.20%  Energy saving for cooling 43% \ Planter box living wall system Energy saving for heating 6.30% 6.30% Energy saving for cooling 43% \ Felt layer living wall system Energy saving for heating 4% 4% Energy saving for cooling 43% \ 44  By multiplying the energy consumption data from EnergyPlus results with the energy saving percentages in Table 3.6, the annual energy saving values for different living wall systems, in different climates, were calculated. The total energy required for an area of 200m2 living wall in the full lifecycle was calculated with the data in Table 3.7. With the annual energy savings value, the number of years needed to balance the initial energy consumption of living walls was calculated (Table 3.7). Table 3.7    Years needed to balance the energy consumption. Living wall system Saved Value(GJ/year) Total energy required  for the system (GJ) The balance year Mediterranean climate Temperate climate Mediterranean climate Temperate climate Indirect greening system 10.36 0.85 9.61 1 11 Planter box living wall system 10.7 4.46 30.36 3 7 Felt layer living wall system 10.55 2.83 101.29 10 36 Analysis of the total energy required shows that the felt layer system consumes over 11 and 4 times more energy than the trellis and modular panel systems respectively (Table 3.7). Furthermore, the felt layer system needs nearly 10 years of energy savings to balance the energy used in the Mediterranean climate, which is the full operational lifespan of the system. In a temperate climate, the balance years are 3.6 times longer than the lifespan of the felt layer system. Therefore, it is evident that among the three typical living wall systems, the felt layer system is the least environmentally friendly living wall system in terms of energy saving performance. 45  As shown in Table 3.7, in a Mediterranean climate the modular panel system needs 3 times longer than the indirect greening system to balance the energy spent in the manufacturing process. In a temperate climate, however, the indirect greening system needs more time than the modular panel system, which has a more complex structure. Table 3.6 shows that the indirect greening system makes a low contribution to the heating energy savings, which is less than 20% of the energy savings in the modular panel system. The containers and the growing medium of the modular panel system affect the insulation properties of the building facade and lead to higher energy saving for heating. The indirect greening system just has the climber attached to the mesh and covers the wall, which will not make any significant change in energy savings for heating. However, the cooling effects of living wall systems are mainly due to the shade and evapotranspiration created by the vegetation (P?rez et al., 2011), which gives the modular panel system and felt layer system the same influence of energy savings in cooling. 3.2.3 Comparative lifecycle analysis of living walls In the product lifecycle, the manufacturing process emitted the majority of the chemical pollution and consumed most of the energy. As shown in Tables 3.3 and 3.5, nearly 85% of the chemical emissions were in the manufacturing stage, and the manufacturing process contributes to 99% of energy consumption. As described in the SimaPro database, the manufacturing stage includes raw material extraction, storage, transportation, material fabrication, waste treatment, etc. In order to make the living wall system more sustainable, the materials with fewer manufacturing processes should be considered. 46  In the construction stage of a living wall, the major contributions to chemical emissions and energy consumptions are due to material transportation. A 3.5-ton van was chosen for the analysis, and the chemical emission and energy consumption for transporting 1m2 of living wall for 1km was calculated. In reality, the vehicle is hardly fully loaded in delivering the components to the site, since different components might come from different companies, and the amount also depends on the size of the living wall. Therefore, the pre-planning in material procurement could decrease the environmental impact of the living wall system. Since the transporting distance is another key factor to mitigate the environmental impact, material resources that are close to the construction site should be given priority. Since the living wall installation is simple and only basic tools are needed to assemble the layers, it is not taken into account in this study. The maintenance requirement for a green roof is mostly dependent on the type of plants used and where the plants are located (Peri et al., 2012). The similar phenomenon could apply to the living wall system. Watering, fertilizing, and vegetation replacement are the major works in the maintenance stage. Watering is not considered in the calculation due to its minor impact on the environment. However, fertilizer in living wall systems has a significant impact in chemical emissions (in Table 3.2). The service life for vegetation in the indirect greening system is about 50 years, which means no replacement is required during the lifespan. However, the service life of the vegetation in the planter box and felt layer living wall systems are 10 years and 3.5 years respectively, which means a few replacements, are needed during the lifespan. This process needs extra transportation and construction activities. Therefore, vegetation that can survive with low maintenance and less fertilizer requirements should be considered for living wall systems. 47  In the disposal stage, all the materials are generally landfilled without recycling or reuse. For example, the plastic materials such as planter boxes and felt layers could be used as raw materials in manufacturing new plastic materials, and the structure materials such as stainless steel and bolts could be reused in another living wall system. Thus, the materials that can be recycled or reused after the lifecycle of a living wall should be promoted as sustainable. 3.2.4 Performance indicators of living walls Based on these results, the felt layer system can be classified as environmentally unsustainable from an air cleaning and energy savings points of view. The materials used in the felt layer system are the main reason for its low performance. As shown in Table 3.1, the container and waterproofing are the only differences between the modular panel system and the felt layer system. The HDPE planter box and the PVC foam plate are the containers in the two systems. Table 3.2 shows that pollutants emitted by 1kg of PVC in the manufacturing process are around 2.2 times more than pollutants emitted by HDPE. In addition, Table 3.4 shows that the energy consumed to produce 1kg of PVC in the manufacturing is over 76 times more than that for HDPE. Since containers have the highest weight density in the system (Table 3.1), the emission differences of the two living walls is also mainly based on the containers. Therefore, the material chosen for the container is extremely important in living wall systems. As shown in Figure 3.2, it is evident that the PVC foam plate has the highest environmental burden. If other materials, like PE or steel, can be applied in the felt layer system, the balance years needed for pollutant emission and energy consumption would be changed significantly. 48  The performance of living walls is intimately impacted by the climatic conditions. As shown in Table 3.7, for all three living wall systems, the energy saved in a Mediterranean climate is more than the energy saved in a temperate climate. Since the temperature is relatively cool in the temperate climate, no additional cooling load is needed, even before the vegetation (living walls) is applied to the building (Ottel? et al., 2011). Alexandri and Jones (2008) stated that the living walls could save 68% of energy in a tropical climate (Brasilia), and 37% in a cold climate (Beijing). Therefore, the living walls could be applied to the warmer climates to save cooling energy. In terms of the cooler climate, a modular panel system is better than the indirect greening system since more heating energy could be saved. The final construction cost could also be influenced by the maintenance, durability, location, and building fa?ade. In Europe, Perini et al. (2011b) summarized that a felt layer system costs 350-750?/m2, a modular panel (HDPE) system costs 400-600?/m2, and a trellis system costs 40-75?/m2. The landscape architects from BC Canada estimated that living wall systems cost $70-$150 per square foot (SORENSEN, 2009). Although living wall systems have been proven as a cost-effective method to improve the environment, the application of living walls is still impacted by the high price (K?hler, 2008). Starting on 31st January 2011, the city of Toronto passed a by-law to green the urban area with green roofs. All industrial buildings have to cover 10% or 2000m2 of the roof with green vegetation (Lewington, 2009). In order to ensure the proper maintenance and use, Vienna, Austria provides subsidies and grants for green roof installations. In Stuttgart, Germany, all flat-roofed industrial buildings require the installation of grass roofs after a municipal by-law was passed in 1989 (Peck et al., 1999). Therefore, if green wall installation is guaranteed by government policy or program support, the popularity of living walls would be changed gradually. 49  Chapter  4: Energy Performance of Green Vegetation in Commercial Buildings  This chapter evaluates the heating and cooling energy saving performance of green vegetation systems with the alternations of different parameters. The aim of this chapter is to investigate the optimal options for installing green vegetation systems, in different types of buildings and climates, to achieve the best energy savings.  4.1 Materials and Methods Energy performance of green vegetation varies depending on many characteristics, such as: the combination of different green vegetation systems, the locations of green vegetation systems in a building, the orientation of a building, the geometry and property of a building, the weather conditions, the building vintage, etc. (Gratia and De Herde, 2007; USEIA, 2008; Alexandri and Jones, 2008; Andersson et al., 1985). As shown in Figure 4.1, the factors that might have impacts on the energy performance of the green vegetation will be analyzed in this paper: 50  Impact factorsBuilding OrientationWeather conditionvery Hot Humid1ACold humid6AVery Cold7Hot/Warm Dry2B/3BMix marine4CCool humid5ABuilding typeGreening scenarioPre-1980Post-1980New 2004Building vintageLarge OfficeStrip MallWarehouse?0 degree?Align to the northOffset every 30 degree Green roof caseLiving wall caseGreen all case Figure 4.1     The factors that impact the energy performance of green vegetation. In order to evaluate the energy performance of green vegetation with the influence of all these factors and optimize the energy savings of a building, the software DesignBuilder version 3.1.0.068 was applied to conduct simulations. DesignBuilder is the first comprehensive user interface to the EnergyPlus dynamic thermal simulation engine. Building geometry can be created within DesignBuilder?s OpenGL modeler, or it can be imported as a gbXML file from an architectural modeling program. DesignBuilder can be used to evaluate a range of fa?ade options for the effect on energy use and visual appearance, and calculate heating and cooling loads using the ASHRAE-approved 'Heat Balance' method implemented in EnergyPlus (DesignBuilder, 2010).   51  4.1.1 Greening scenarios Gratia and De Herde (2007) demonstrated that buildings have different solar gains in different surfaces, and Radhi (2010) concluded that the energy savings by PV panels vary on different surfaces of a building. In order to investigate the energy performance of green vegetation on different surfaces of a building, four types of vegetation covering the building envelope are examined: (a) A base wall case, where no green is applied to the building, referred to as the ?no-green? case, (b) The ?green-roof? case, where the roof is covered with vegetation, (c) The ?living-wall? case, where four fa?ades of the building are covered with vegetation, (d) The ?green all? case, where both roof and four facades of the building are covered with vegetation. Based on the green roof model created by Sailor (2008), which has been integrated into the EnergyPlus building energy simulation program (Crawley et al., 2004) to allow energy modelers to investigate vegetative roof design options, the hydrothermal properties of the materials and vegetation considered in the building facades are created and listed in Table 4.1. The data for green roof is cited from the ?green roof example? in the template library of DesignBuilder software (DesignBuilder, 2012). In order to eliminate the variance of energy performance created by the difference of plants and growing mediums, and to clearly focus on the evaluation of the impact factors described in Figure 4.1, the same growing media and plants properties of green roof are chosen for the living wall. However, the green roof usually has the drainage and water 52  retention layers, which the green wall doesn?t (She and Pang, 2010; Perini et al., 2011a). The average thickness for these layers is around 5cm (Bianchini and Hewage, 2011). Therefore, the thickness of the living wall is assumed as 0.15m. Table 4.1     Hydrothermal properties of green vegetation systems Property Green roof Living wall System Thickness (m) 0.2 0.15 Growing medium  Properties Conductivity (W/M-K) 0.3 0.3 Specific Heat (J/Kg-K) 1000 1000 Density (Kg/m3) 1000 1000 Thermal absorbance (emissivity) 0.9 0.9 Solar absorbance 0.7 0.7 Visible absorbance 0.7 0.7 Roughness Rough Rough Plant Properties Height of plants (m) 0.1 0.1 Leaf area index (LAI) 5 5 Leaf reflectivity 0.22 0.22 Leaf emissivity 0.95 0.95 Minimum stomatal resistance (s/m) 100 100 Max volumetric moisture  content at saturation 0.5 0.5 Min residual volumetric moisture content 0.01 0.01 Initial volumetric moisture content 0.15 0.15 Thermal  Properties R-Value (m2-K/W) 2.057 1.89 U-Value (W/m2-K) 0.486 0.529  4.1.2 Building types In the Commercial Building Energy Consumption Survey (CBECS), conducted by the US Energy Information Administration in 2003 (USEIA, 2008), all the buildings were categorized into 14 types based on the building?s principal purpose. The top three building types are Office, Mercantile, and Warehouse and storage, which accounts for 46.7% of the total floor space. Large offices, strip malls, and warehouses, which are the major components 53  of the top three building types, were chosen for the energy simulation in this paper. As shown in Figure 4.2, the three types of buildings were performed in Designbuilder software.  Figure 4.2    DesignBuilder model of the buildings in different greening scenarios In order to create detailed building energy models, several pieces of information are required to represent the typical performance. The National Renewable Energy Laboratory (NREL) divided the model inputs into program, form, fabric, and equipment (Deru et al., 2011). In this study, the detailed information of the building energy models for all three top building types are cited from Deru et al. (2011), and listed in Table 4.2 as the input of the building energy simulation in this study. 54  Table 4.2    The building energy model input characteristics (Deru et al., 2011) Building Characteristic Building Types Large office Strip mall Warehouse Program Total floor area (m2) 46320 2090 4835 Plug and process loads (w/m2) 10.76 4.3 2.6 Ventilation requirements (L/s/m2) 0.51 1.52 0.25 Occupancy (m2/person) 18.6 6.2 0 Service hot water demand (l/h) 80.6 6.6 0 Form Number of floors 12 1 1 Aspect ratio 1.5 4 2.2 Window fraction 0.38 0.11 0.006 Floor height(m) 3.96 5.18 8.53 Fabric Exterior walls Mass wall Steel frame wall Metal building wall Roof Insulated Entirely  Above Deck Insulated Entirely  Above Deck Insulated Entirely  Above Deck Infiltration (ACH) 0.3 0.31 0.19 Equipment Lighting (w/m2) 10.76 23.99 9.68 HVAC system types Heating Boiler Furnace Individual space  heater, furnace Cooling Chillier Packaged air- conditioning unit Packaged air- conditioning unit 55  4.1.3 Weather conditions As per the data of the reference building in the NREL technical report (Deru et al., 2011), seven major climate zones in North America, which are categorized in ASHARE 90.1-2004, were studied in this simulation to analyze the energy performance of green vegetation in different weather conditions (ASHRAE, 2007). The seven representative cities, which are cited from the U.S. Department of Energy (USDOE) (2012b) and the relevant climatic types are summarized in Table 4.3. All cases are examined for a fiscal year, and the hourly weather data are obtained from the weather data of EnergyPlus Simulation software, arranged by World Meteorological Organization (USDOE, 2011). Table 4.3    Cities studies in different climate zones of North America (Derived from ASHARE 90.1-2004). Climate zone Name Representative city Location 1A Very hot humid Miami, Florida 25?48? N, 80?08? W 2B Hot dry Phoenix, Arizona 33?27? N, 112?04? W 3B Warm dry Las Vegas, Nevada 36? 06' N, 115? 10' W 4C Mixed marine Seattle, Washington 47? 36' N, 122? 19' W 5A Cool humid Chicago, Illinois 41? 52' N, 87? 37' W 6A Cold humid Toronto Ontario 43? 42? N, 79? 24? W 7 Very cold Calgary, Alberta 51? 02' N / 114? 3' W  4.1.4 Building vintages A U value is a measure of heat loss in a building element such as a wall, floor or roof. It can also be referred to as an ?overall heat transfer co-efficient? and measures how well parts of a building transfer heat. This means that the higher the U value the worse the thermal performance of the building envelope. A low U value usually indicates high levels of insulation (RIBA, 2013). As the building assembly U-values varied with the building 56  vintages and climate zones, the overall U-values of reference building facades have to be determined based on the different vintages and climate zones. According to the U-factor requirements from different versions of ASHARE standard, Deru et al. (Deru et al., 2011) summarized the envelope U-values of the reference building models in different vintages and climate zones and listed in NREL technical report. Three vintages of reference buildings are categorized in the report: ?Before 1980? (the buildings constructed before 1980s), ?Between 1980 and 2004? (the buildings constructed between 1980 and 2004), ?After 2004? (the buildings constructed after 2004). The U-values of the wall, roof, and window that are involved with the green vegetation energy performance are selected to do the building energy simulation in this study. Tables 4.4-4.6 list all these U-values in different vintages, climate zones, and building categories. Table 4.4    U-values for the envelope of reference building model- Large Office (Unit: W/m2-K) (Derived from Deru et al., 2011)       Envelope Wall Roof Window Climate Pre 1980 Post 1980 New 2004 Pre 1980 Post 1980 New 2004 Pre 1980 Post 1980 New 2004 1A 1.306 5.678 3.293 0.568 0.420 0.358 6.927 6.927 6.927 2B 1.306 2.328 3.293 0.568 0.261 0.358 6.927 6.927 6.927 3B 1.306 1.647 3.293 0.568 0.273 0.358 6.927 6.927 3.237 4C 0.994 0.568 0.857 0.483 0.363 0.358 6.927 4.088 3.237 5A 0.886 0.568 0.857 0.409 0.301 0.358 3.521 3.350 3.237 6A 0.823 0.403 0.698 0.341 0.256 0.358 3.521 2.953 3.237 7 0.772 0.346 0.698 0.341 0.227 0.358 3.521 2.953 3.237    57   Table 4.5    U-values for the envelope of reference building model- Strip Mall (Unit: W/m2-K) (Derived from Deru et al., 2011)        Envelope Wall Roof Window Climate Pre 1980 Post 1980 New 2004 Pre 1980 Post 1980 New 2004 Pre 1980 Post 1980 New 2004 1A 1.306 5.678 0.704 0.568 0.420 0.358 6.927 6.927 6.927 2B 1.306 1.363 0.704 0.568 0.261 0.358 6.927 6.927 6.927 3B 1.306 0.909 0.704 0.568 0.273 0.358 6.927 6.927 3.237 4C 0.994 0.522 0.704 0.483 0.363 0.358 6.927 4.088 3.237 5A 0.886 0.466 0.477 0.409 0.301 0.358 3.521 3.350 3.237 6A 0.823 0.369 0.477 0.341 0.256 0.358 3.521 2.953 3.237 7 0.772 0.329 0.363 0.341 0.227 0.358 3.521 2.953 3.237  Table 4.6    U-values for the envelope of reference building model- Warehouse (Unit: W/m2-K) (Derived from Deru et al., 2011)        Envelope Wall Roof Window Climate Pre 1980 Post 1980 New 2004 Pre 1980 Post 1980 New 2004 Pre 1980 Post 1980 New 2004 1A 1.306 5.678 0.704 0.568 0.420 0.358 6.927 6.927 6.927 2B 1.306 1.363 0.704 0.568 0.261 0.358 6.927 6.927 6.927 3B 1.306 0.909 0.704 0.568 0.273 0.358 6.927 6.927 3.237 4C 0.994 0.522 0.704 0.483 0.363 0.358 6.927 4.088 3.237 5A 0.886 0.466 0.477 0.409 0.301 0.358 3.521 3.350 3.237 6A 0.823 0.369 0.477 0.341 0.256 0.358 3.521 2.953 3.237 7 0.772 0.329 0.363 0.341 0.227 0.358 3.521 2.953 3.237   58  4.1.5 Building orientations It is suggested that building orientation can significantly influence the energy consumption of a well-insulated building (Andersson et al., 1985). In order to find the building?s optimal orientation for energy saving, different scenarios were examined in the simulation. In Figure 4.2, the ?0 degree? orientation is where the north direction is. The direction of north offsets in every 30 degrees counter-clockwise from 0 degree to 360 degree to simulate the effect of changing the building?s orientation toward the sun. After the energy consumption data is captured for all orientations, the best orientation estimate can be found. Green vegetation systems have potential building energy reduction benefits (Eumorfopoulo and Kontoleon, 2009; Alexandri and Jones, 2008; Liu and Minor, 2005). However, the energy performance of green vegetation might be impacted by the building orientation, the roof-to-building envelope ratio, type of the system, and the insulation in each building roof and external fa?ade (Currie and Bass, 2008). This chapter estimates the impacts of these parameters on the energy performance of green vegetation systems with technical regulations and software simulations. This chapter discusses the heating and cooling energy saving performance of green vegetation systems with consideration of the following parameters: greening scenario, building type, building vintage, weather condition, and building orientation. The aim of this chapter is to investigate the optimal options for installing green vegetation systems, in different types of buildings and climates, to achieve the best energy savings.   59  4.2 Energy Simulations for Green Vegetation As shown in Figure 4.2, the model was built in DesignBuilder Software based on the information described in the methodology section, and 378 simulation cases were executed to cover all the combinations of the impact factors in Figure 4.1. All of these cases were simulated in EnergyPlus software to demonstrate the cooling and heating energy saving performance of green vegetation systems with the influence of building type, building vintage, weather condition, and building orientation. Figures 4.3-4.10 display the energy consumptions of three types of buildings in different building vintages, orientations, and weather conditions. The various energy savings created by green vegetation in different cases demonstrated that the impact factors (shown in Figure 4.1) have an apparent effect on the energy saving performance of green vegetation. 4.3 Energy Performance of Green Vegetation Figures 4.3-4.5 depict the monthly heating and cooling energy performance of the green vegetation systems in different building types and vintages. Since the simulations for Figures 4.3-4.5 are conducted in the 1A climate zone, which is in very hot humid weather, the energy consumed for heating was negligible. 4.3.1 Heating and cooling energy consumptions As shown in Figure 4.3, the monthly energy consumption of the large office in different building vintages is similar. The major energy consumption happened in the warmer time from May to October, where the green vegetation has a positive energy performance. The highest energy required for cooling is in July, where the green vegetation has the best energy saving performance.  60   Figure 4.3    Monthly heating and cooling energy consumption in different building ages ? Large office 200300400500600700800900100011001200Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecUnit: Mwh Before 1980 Bare wallGreen roofLiving wallGreen all200300400500600700800900100011001200Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecUnit: Mwh Between 1980 and 2004 Bare wallGreen roofLiving wallGreen all200300400500600700800900100011001200Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecUnit: Mwh After 2004 Bare wallGreen roofLiving wallGreen all61  In the large office built before 1980, 1139.6MWh of energy was used in July for cooling in the bare wall case; 6.4MWh and 19.9MWh of energy were saved by the performance of green roof and living wall respectively. In the green all case, 20.1MWh of energy was saved because of the green vegetation. In terms of the other months from May to October, the energy savings created by the green vegetation are slightly lower than the savings in July. In the cool months from November to April, the building cooling energy requirement is not as much as it is in the warm months, and the energy saving performance of the green vegetation is negligible. In the large office built between 1980 and 2004, 1167.8MWh of energy was consumed in July for cooling in the bare wall case. 4.3MWh, 57.2MWh and 57.7MWh of energy were saved due to the performance of green roof, living wall, and green all respectively. The green vegetation has a better energy saving performance in the building constructed between 1980 and 2004 than in the building constructed before 1980. The living wall has a better energy saving performance than the green roof in all months. In the large office built after 2004, 1163.2MWh of energy was utilized in July for cooling in the bare wall case; 9.5MWh, 45.8MWh, and 46MWh of energy were saved by the performance of green roof, living wall, and green all respectively. Other than July, the monthly energy saving performance of the green vegetation in the rest of the year is not obvious. As depicted in Figure 4.4, the monthly energy consumption of the strip mall is over 10 times less than the energy consumption by the large office due to the size of the building. However, the energy saving performance of green vegetation in the strip mall is better than the performance in the large office.  62   Figure 4.4    Monthly heating and cooling energy consumption in different building ages ? Strip mall 2030405060708090100110Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecUnit: Mwh Before 1980 Bare wallGreen roofLiving wallGreen all2030405060708090100110Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecUnit: Mwh Between 1980 and 2004 Bare wallGreen roofLiving wallGreen all2030405060708090100110Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecUnit: Mwh After 2004 Bare wallGreen roofLiving wallGreen all63  Among the three building ages, the green roof has better performance in the strip mall built before 1980. In the warmer time from May to October, the monthly energy savings created by green roof in the strip mall built before 1980 is 3.6MWh in average, and reaches the highest (4.6MWh) in July. The living wall has better performance in the strip mall built between 1980 and 2004. The monthly energy savings created by the living wall in the strip mall built between 1980 and 2004 is as much as 12.3MWh, which is more than 12% of the average monthly energy consumption, and reaches 13.2% in the hottest month, July. The energy savings created by green vegetation in the strip mall built after 2004 is not evident. Due to the better insulation of the building, the monthly energy consumption of the strip mall built after 2004 is lower than the value of the strip mall built before 2004. Therefore, the energy saving performance of green vegetation in the building constructed after 2004 is not as good as the one in the other two building ages. As illustrated in Figure 4.5, the energy saving performance of green vegetation in the warehouse is much better than the performance in the large office and strip mall.  64   Figure 4.5    Monthly heating and cooling energy consumption in different building ages ? Warehouse 2030405060708090100110120130140Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecUnit: Mwh Before 1980 Bare wallGreen roofLiving wallGreen all2030405060708090100110120130140Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecUnit: Mwh Between 1980 and 2004 Bare wallGreen roofLiving wallGreen all2030405060708090100110120130140Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecUnit: Mwh After 2004 Bare wallGreen roofLiving wallGreen all65  In the warmer time from May to October, the average monthly energy savings created by the green roof in the warehouse built before 1980 is around 8.6MWh, and it reaches 11.7MWh in July, which is more than 10% of the energy consumption in that month. The energy saved by the living wall in the warehouse built before 1980 is around 6.4MWh. The performance of the living wall in the warehouse built between 1980 and 2004 is the best among all the building vintages. The average monthly energy savings created by the living wall in the warehouse built between 1980 and 2004 is as much as 26.3MWh, which is 23.2% of the average monthly energy consumption from May to October. In July, the monthly energy savings rise up to 25.6% by the living wall built between 1980 and 2004. The energy saving performance of the green roof is less tangible than the performance of the living wall in the warehouse built between 1980 and 2004. The monthly energy consumption in the warehouses built before 1980 and after 2004 is similar, while the energy savings created by the green vegetation is slightly larger in the warehouse constructed before 1980 than in the house constructed after 2004. In the warmer months from May to October, the green roof has a slightly better energy saving performance than the living walls. On average, 6.4MWh energy was saved by the performance of the green roof, while 4.8MWh energy was saved by the performance of the living walls. 4.3.2 Energy savings performance The green roof scenario, living wall scenario, and green all scenario all create energy savings compared with the bare wall scenario, in which no vegetation is applied to the building. However, their performance varies in different cases. As shown in Figures 4.3-4.5, in the large office, the living wall has a better energy saving performance than the green roof in the three buildings constructed before 1980 and 66  between 1980 and 2004, while in the warehouse and strip mall, the green roof has a slightly better energy saving performance than the living wall in the buildings constructed before 1980 and after 2004. Therefore, there is no definite conclusion as to which one is better at energy savings between the green roof and living wall. It depends on the conditions of the buildings, the environments, the properties of the green vegetation, etc. According to Figures 4.4 and 4.5, the green roof has a better energy saving performance than the living wall in the strip mall and warehouse constructed before 1980 and after 2004, but the living wall performs much better than the green roof in the strip mall and warehouse built between 1980 and 2004. One of the reasons could be found in the U-values of the building fa?ade in Tables 4.5 and 4.6. As the monthly heating and cooling energy consumptions of the strip mall and warehouse in Figure 4.4 and 4.5 were calculated based on the climate zone 1A, the U-values of the walls for the strip mall and warehouse are the same in three building vintages. As shown in Tables 4.5 and 4.6, the U-values for the strip mall and warehouse in three different building vintages are 1.306, 5.678, and 0.704 in climate zone 1A. It is evident that the thermal transmittance of the walls in the warehouse or strip mall built between 1980 and 2004 is much higher than the ones built before 1980 or after 2004. It is evident that the walls of the warehouse or strip mall built between 1980 and 2004 are not well insulated. Therefore, covering the building fa?ade that is not well insulated with living wall could dramatically save the energy consumption of the building, and the less insulated the wall is, the better performance the living wall will have. 4.3.3 Impacts of growing medium and plant properties In terms of the properties of the green roof and living wall, they are set the same in this study (shown in Table 4.1) except for the thickness. However, the growing medium 67  properties and plant properties could be different because of the various types of green roofs and living walls. In terms of growing medium, the extensive green roof has a much thicker dimension than the intensive green roof, which could reach 1.2m (Yang et al., 2008). However, the growing medium of a living wall not only changes in thickness, but also in materials. The most common living wall systems use hydroponic technology to support the plants with a separate irrigation system (Dunnett and Kingsbury, 2004), and some of the living wall systems even use rock wool, coco coir, or peat as growing medium (Weinmaster, 2009). All of these different growing mediums can make the properties of living walls completely different from the properties of the green roof. Therefore, the properties of the growing medium for the green vegetation system, like conductivity, density, thermal absorbance, etc. should be analyzed separately according to the categories of the green vegetation. Regarding the plant properties, the green roof and living wall have different choices. In the extensive green roof, sedums and mosses are the most popular type of vegetation (Berghage et al., 2007), and the plants do not exceed 10cm in height. However, trees and shrubs could be used in the intensive green roof. On the other hand, the living wall has different plant types as well. The trellis system just has a climber to cover the wall, the felt layer system grows plants vertically, which could be flowers or potted plants. Only specific plants are suitable for different weather conditions as well. Therefore, the properties listed in Table 4.1, such as height of plants, leaf reflectivity, and moisture content, etc. vary from one type to the other, and all of these should be categorized and included in an energy consumption analysis. In summary, the growing medium and plants in different green 68  vegetation systems are different, and these parameters have a great impact on the energy saving performance of green vegetation. 4.4 Energy Performance of Green Vegetation in Different Building Types As shown in Figures 4.3-4.5, the energy saving performance is different among these buildings. The large office constructed before 1980 in Figure 4.3 has better energy saving with a living wall than with a green roof, while the strip mall and warehouse constructed before 1980 in Figures 4.3 and 4.4 have better energy saving with a green roof than with a living wall. The reason is that the large office is a high rise building with 12 floors, where the area of the roof is much smaller than the total area of the walls, while the strip mall and warehouse are both low rise buildings, where the roof area is close to or even larger than the total area of the walls (shown in Figure 4.2). Therefore, if it is a high rise building, the application of the living wall to the building should be an automatic choice. On the other hand, if it is a low rise building, the application of green roof should be considered first as an energy saving solution. In terms of the three buildings constructed between 1980 and 2004, the thermal transmittances are also the same for the walls, roof, and windows in climate zone 1A. But the energy saving performance for these buildings is not the same as the performance for the building constructed before 1980. No matter if it?s the large office (high rise building), strip mall, or warehouse (low rise building), the energy saving performance of the living wall is always better than the green roof due to the weak insulation properties of the wall (U-wall= 5.678W/m2K, U-roof= 0.42W/m2K). Therefore, besides the concept of a high rise or low rise building, the thermal properties of the building facades are always a key factor to consider when applying the green vegetation to the building. 69  Regarding the green roof, the building structure has to be calculated in the low rise building before applying the green roof. In the high rise building, the roof is sometimes occupied with HVAC systems or cleaning systems, which will impact the application of a green roof. These are all direct factors that should be considered regarding the building types. As shown in Figures 4.3-4.5, in the same weather conditions the energy saving percentage among the three types of buildings is totally different. In the large office case, the highest monthly energy saving percentage reaches 4.9% in the building constructed between 1980 and 2004. In the strip mall and warehouse cases, this value reaches as much as 14.1% and 27% respectively. However, the energy saved by the large office in that month is around 57.7MWh, which is only 35.6MWh by the warehouse. The reason is that the yearly energy consumed by the large office in the climate zone 1A is around 10 times more than in the strip mall or warehouse in the same climate zone.  There are many other factors that might impact the building energy consumption. As shown in Table 4.2, the differences between ventilation requirements and occupation will impact the building energy consumption since the higher requirement or occupation rate will lead to more output from the HVAC system. Similarly, in regards to the lighting value, more heat will be released to the indoor air the higher the lighting requirement is set. The HVAC system types also change the total building energy consumption. The higher Coefficient of Performance (CoP) the HVAC equipment has, the less energy is consumed to meet the building requirement. Therefore, if the major percentage of the building energy consumption is created by factors other than the building fa?ade, the necessity for applying green vegetation to the building fa?ade should be investigated clearly. The benefits might be minor compared with 70  the total energy consumption, or the money spent on installing the green vegetation might create a better energy saving if it applies to an alternative optimization. 4.5 Energy Performance of Green Vegetation in Different Weather Conditions  Figures 4.6-4.8 present the yearly heating and cooling energy consumption in different climate zones, with different building vintages and types. In the colder climate zones, more energy is consumed for heating, and more energy for heating is saved due to the performance of green vegetation. In three types of building vintages, the yearly energy consumption in the building constructed after 2004 is generally lower than the other two building vintages. Among three building types, the green vegetation has a better performance of heating energy savings in the large office, and better performance of cooling energy savings in the warehouse. 4.5.1 Yearly heating and cooling energy consumption in different climate zones In Figure 4.6, the energy used for heating in different climate zones is presented in ?a1?, ?b1?, and ?c1?. It is evident that the large office rarely requires heating energy in the climate zone 1A, 2A, and 3B. The yearly energy consumption for heating starts at the mix marine climate (4C), and the value is higher in the large office built before 1980 than the other two building vintages. 71   Figure 4.6    Yearly heating and cooling energy consumption in different climate zones- Large office    01002003004005006007008001A 2A 3B 4C 5A 6A 7Unit: Mwh (a1) Before 1980 - Heating Bare wallGreen roofLiving wallGreen all0100020003000400050006000700080001A 2A 3B 4C 5A 6A 7Unit: Mwh (a2) Before 1980 - Cooling Bare wallGreen roofLiving wallGreen all01002003004005006007008001A 2A 3B 4C 5A 6A 7Unit: Mwh (b1) Bewteen 1980 and 2004 - Heating Bare wallGreen roofLiving wallGreen all0100020003000400050006000700080001A 2A 3B 4C 5A 6A 7Unit: Mwh (b2) Between 1980 and 2004 - Cooling Bare wallGreen roofLiving wallGreen all01002003004005006007008001A 2A 3B 4C 5A 6A 7Unit: Mwh (c1) After 2004 - Heating Bare wallGreen roofLiving wallGreen all0100020003000400050006000700080001A 2A 3B 4C 5A 6A 7Unit: Mwh (c2) After 2004 - Cooling Bare wallGreen roofLiving wallGreen all72  Regarding the large office in ?a1?, the living wall has a much better energy saving performance than the green roof. The yearly heating energy required for the ?bare wall? scenario is 192.2MWh in the climate zone 4C, and 29.8% of the heating energy consumption was saved due to the performance of the living wall. In climate zone 5A, 530.2MWh energy was consumed for the yearly heating requirement, and 23.4% was saved by the performance of the living wall. In climate zones 6A and 7, 655.9MWh and 770MWh energy were used for the yearly heating requirement respectively, and 21% and 18.6% energy were saved separately by the performance of the living wall. The average energy saving percentage created by the green roof in the climate zones 4C, 5A, 6A, and 7 is around 4.6%. The energy saving performance in the ?green all? scenario is better than the performance in the living wall scenario. In ?b1? of Figure 4.6, the yearly energy consumptions in different climate zones are lower than the corresponding consumptions in ?a1? and ?c1?. In climate zones 4C and 5A, 80.6MWh and 351MWh energy were required for yearly heating by the large office respectively, and 6% and 17.4% of the energy was saved by the influence of the green roof and living wall on average. In climate zones 6A and 7, 365.7MWh and 450.3MWh heating energy were consumed yearly by the large office separately, and 3% and 9.7% of the energy were saved due to the performance of the green roof and living wall on average. The yearly energy consumption and energy saving performance of the green vegetation in ?c1? of Figure 4.6 is similar to ?a1?. Yearly consumption to satisfy the heating requirement of the large office in climate zones 4C and 5A was 75.2MWh and 455.4MWh, and 33.5% and 23.4% of the energy was saved by applying the living wall to the building. In climate zones 6A and 7, 537.2MWh and 672.5MWh of energy were consumed yearly for 73  heating respectively, and around 18.4% and 16.6% of energy was saved due to the performance of the living wall. The heating energy saving performance of green roof in the large office built after 2004 is not as efficient as the living wall. As shown in ?c1? of Figure 4.6, only 5% of the energy was saved on average in these climate zones due to the benefit of the green roof. As presented in ?a2?, ?b2?, and ?c2? of Figure 4.6, the cooling energy consumption of the large office in different building vintages is similar. The cooling energy requirement decreases gradually from the hot, humid climate of 1A to the very cold climate of 7, except for the energy consumption in climate 4A where the sudden decrease happened. The energy saving created by the green vegetation is not evident compared with the large amount of yearly energy consumption, especially in the climate zones 4C, 5A, 6A, and 7 where the energy savings are mostly negligible. In the climate zone 1A (Figure 4.6), more than 8000MWh of energy was consumed yearly by the large office to satisfy the cooling requirement, and 35MWh and 90MWh energy were saved on average by the green roof and living wall respectively in different building vintages. The energy saving performance of the living wall runs better in climate zone 2A. Over 6000MWh of cooling energy was required yearly by the large office, and 267MWh, 392MWh, and 522MWh of energy were saved by applying the living wall to the building constructed before 1980, between 1980 and 2004, and after 2004 respectively. In climate zone 3B, an average of 4400MWh of energy was consumed by the large office in different ages, and 188MWh, 211MWh, and 364MWh of energy were saved by applying the living wall to the building constructed before 1980, between 1980 and 2004, and after 2004 74  respectively. The energy saved by the green roof in climate zone 2A and 3B is similar to the performance in 1A. Figure 4.7 displays the yearly heating and cooling energy consumption of the strip mall in different weather conditions and building vintages. The heating energy required by the strip mall starts from climate zone 2A, and it reaches the maximum in climate zone 7. The heating energy requirement of the strip mall built before 1980 is higher than the strip malls built in the other two ages. The energy saving performance of the green vegetation is similar in different climate zones, and it is more efficient in the strip mall made before 1980. In terms of cooling consumption in ?a2?, ?b2?, and ?c2? of Figure 5.5, the energy saving performance is only evident in the warmer climate zones 1A, 2A, and 3B, and it runs better in the strip mall built between 1980 and 2004. 75   Figure 4.7    Yearly heating and cooling energy consumption in different climate zones ? Strip mall As shown in ?a1? of Figure 4.7, the yearly heating energy required for the strip mall in climate zones 3B and 4C are 38.4MWh and 127.1MWh, and the average energy saving percentage created by the green roof or the living wall is around 11%. With the energy 0501001502002503003501A 2A 3B 4C 5A 6A 7Unit: Mwh (a1) Before 1980 - Heating Bare wallGreen roofLiving wallGreen all01002003004005006007008009001A 2A 3B 4C 5A 6A 7Unit: Mwh (a2) Before 1980 - Cooling Bare wallGreen roofLiving wallGreen all0501001502002503003501A 2A 3B 4C 5A 6A 7Unit: Mwh (b1) Between 1980 and 2004 - Heating Bare wallGreen roofLiving wallGreen all01002003004005006007008009001A 2A 3B 4C 5A 6A 7Unit: Mwh (b2) Between 1980 and 2004- Cooling Bare wallGreen roofLiving wallGreen all0501001502002503003501A 2A 3B 4C 5A 6A 7Unit: Mwh (c1) After 2004 - Heating Bare wallGreen roofLiving wallGreen all01002003004005006007008009001A 2A 3B 4C 5A 6A 7Unit: Mwh (c2) After 2004 - Cooling Bare wallGreen roofLiving wallGreen all76  consumption increased in the colder climates 5A, 6A, and 7, the energy savings percentage decreases to 5%.  In ?b1? of Figure 4.7, the highest yearly heating energy consumption in climate zone 7 is 265.5MWh, which is 54MWh lower than the consumption in the strip mall in ?a1?. The average energy saving percentage created by the green roof in ?b1? is around 4.7% in the cold climates 5A, 6A, and 7, and 3.3% by the living wall.  In ?c1? of Figure 4.7, the energy consumptions and energy savings in different climate zones are similar to the performance in ?b1?. The only difference is that the average energy saving percentage of the green roof in climate zones 5A, 6A, and 7 reaches 6%, which is better than the performance of the living wall in ?b1?. In terms of energy consumption for strip mall cooling in ?a2?, ?b2?, and ?c2? of Figure 4.7, the green roof has better energy saving performance in the strip mall built before 1980, while the living wall runs better in the strip mall built between 1980 and 2004.  In ?a2? of Figure 4.7, the highest yearly cooling energy, 781.5MWh, was consumed by the strip mall in the hottest climate zone 1A, and 4.3% of that was saved by applying the green roof to the building. In the climate zones 2A, 3B, and 4C, averages of 11% and 9% of the energy were saved by the green roof and living wall respectively.  In ?b2? of Figure 4.7, the energy savings created by the living wall in climate zone 1A is over 13%, which is 111.6MWh. In climate zone 2A and 3B, the energy savings percentages are 9% and 5% due to the benefits of the green roof and the living wall separately.  In ?c2? of Figure 4.7, the green roof and living wall have similar energy saving performance, which is around 2.5% in the climate zone 1A, and 8% in the climate zones 2A, 77  3B, and 4C. As with the performance in Figure 5.4, the cooling energy consumption in climate zone 4C is not in the declining trend from 1A to 7; it is much lower than 3B and 5A. Figure 4.8 shows the yearly heating and cooling energy consumption of the warehouse in different climate zones and building vintages. It is apparent that the energy saving performance of the green roof and living wall in the warehouse is better than the ones in the large office and strip mall. The energy consumption for heating in the climate zone 1A, 2A, and 3B is negligible due to the low requirement in warm weather. The heating energy savings created by green vegetation starts from the climate 4C, and the energy saving percentage achieved by green vegetation is higher in the warehouse built before 1980 than in the other two building vintages. In terms of cooling energy, the green vegetation has a better performance in the warm climate 1A, 2A, and 3B, and the energy required for cooling in the cool climate is much lower than the one in warm climate. 78   Figure 4.8    Yearly heating and cooling energy consumption in different climate zones ? Warehouse As presented in ?a1? of Figure 4.8, the green vegetation creates an apparent energy savings in the warehouse built before 1980. Heating energy of 51.1MWh was used in the climate zone 4C, 29% of it was saved by the green roof, 36% of it was saved by the living wall, and 54.5% of it was saved by applying the green roof and living wall together. Yearly 0501001502002503001A 2A 3B 4C 5A 6A 7Unit: Mwh (a1) Before 1980 - Heating Bare wallGreen roofLiving wallGreen all01002003004005006007008009001A 2A 3B 4C 5A 6A 7Unit: Mwh (a2) Before 1980 - Cooling Bare wallGreen roofLiving wallGreen all0501001502002503001A 2A 3B 4C 5A 6A 7Unit: Mwh (b1) Between 1980 and 2004- Heating Bare wallGreen roofLiving wallGreen all01002003004005006007008009001A 2A 3B 4C 5A 6A 7Unit: Mwh (b2) Between 1980 and 2004- Cooling Bare wallGreen roofLiving wallGreen all0501001502002503001A 2A 3B 4C 5A 6A 7Unit: Mwh (c1) After 2004 - Heating Bare wallGreen roofLiving wallGreen all01002003004005006007008009001A 2A 3B 4C 5A 6A 7Unit: Mwh (c2) After 2004 - Cooling Bare wallGreen roofLiving wallGreen all79  heating energy consumption of 183.2MWh, 203.7MWh, and 258.3MWh was used by the warehouse in the climate zones 5A, 6A and 7, and an average of 12%, 19%, and 27% of that was saved by the green roof, living wall, and green all respectively.  The performance of green vegetation in the warehouse constructed between 1980 and 2004 in ?b1? is not as good as the one shown in ?a1?. The highest yearly energy consumption is 157.3MWh in climate zone 7, and the average energy saving percentage created by the green roof and living wall is 11.7% and 9.3% separately in the climate zones 5A, 6A, and 7.  The energy consumption for heating by the warehouse constructed after 2004 in ?c1? is close to the one shown in ?b1?. On average, 15.4%, 9.8%, and 19.8% of energy was saved due to the performance of the green roof, living wall, and green all in the climate zones 5A, 6A, and 7. In climate zone 4, the energy consumption is much lower than the consumptions in 5A, 6A, and 7. However, the energy saving performance is much better than the other three climates. In terms of cooling energy consumption shown in ?a2?, ?b2?, ?c2? of Figure 4.8, the warehouse built between 1980 and 2004 requires more energy than the other 2 building vintages in climate zone 1A, and energy saving performance of green vegetation runs better in the warehouse built before 1980.  In ?a2?, 825.3MWh of energy was consumed for cooling in climate zone 1A, and 8% of that was saved by applying the green roof or living wall to the warehouse. In climate zones 2A and 3A, over 21% and 24% of the energy was saved by the performance of the green roof or living wall respectively, which is 140MWh in climate zone 2A and 109.4MWh in climate zone 3A. The energy saving performance in the ?green all? scenario is even better than the other scenarios.  80  In ?b2? of Figure 4.8, the energy saving performance of the living wall is better than that of the green roof. In climate zone 1A, 21% of the cooling energy was saved by the living wall, while only 5% is saved by the green roof. In climate zones 2A and 3B, 24.6% and 20% of energy was saved by the living wall, while 10.6% and 14.2% of the energy was saved by the green roof respectively.  In ?c2? of Figure 4.8, the energy saving created by the green roof or living wall is around 5.8% in climate zone 1A, and approximately 17% and 20% in climate zone 2A and 3B. Regarding the other climate zones from 4C to 7, the cooling energy consumption is much lower than in the warm climate. However, more than 16% of cooling energy was saved by the green roof in the climate zone 4C, and around 10% in the climate zones 5A, 6A, and 7. 4.5.2 Energy saving performance in different climate zones As presented in Figures 4.6-4.8, in the warmer climate zones 1A, 2A, and 3B, most of the energy spent on the HVAC system is for the building cooling. On the other hand, most of the energy spent on the HVAC system in the cooler climate zones 5A, 6A, and 7 is for building heating. Because of that, the green vegetation has a better cooling energy saving performance in the summer and heating energy saving performance in the winter. Thus, in the warm climate zones, the green vegetation should be installed in the building fa?ade that is exposed to the longest hours of sunshine. In the cool climate zones, the green vegetation should be installed in the building fa?ade where the negative wind could be blocked. In terms of climate zone 4C, the heating and cooling energy consumptions for the three types of buildings are not regular in this weather condition. It is obvious that the cooling energy consumption is lower than the consumption in climate zone 3B and 5A (in Figures 4.6-4.8). It is because climate zone 4C is in a mix marine weather near the coast. The 81  weather is not very hot in the summer, and not very cold in the winter. In addition, it is very humid all year. Because of the humidity, the evaporation effect of green vegetation does not have an apparent cooling energy saving performance. Since not too much heating energy is required in the winter, the heating energy saving created by the green vegetation is not efficient compared with the installation cost. Therefore, the green vegetation is not an efficient method to improve the building energy performance in this type of weather condition. From the climate zone 5A to 7 in Figure 4.6, the amount of yearly heating energy consumption by the large office increases, while the energy saving percentage created by green vegetation decreases. From climate zone 1A to 3 in Figure 4.6, the amount of yearly cooling energy consumption by the large office decreases, while the energy saving percentage created by the green vegetation increases. The strip mall and warehouse have the same performance as the large office in the energy consumptions and energy saving percentages.  Moreover, from climate zone 5A to 7 in ?b1? of Figure 4.8, the energy consumption increases from 121.9MWh to 157.3MWh, while the energy saving percentages created by living walls decrease from 12.7% to 11.4%. From climate zone 1A to 3B in ?b2? of Figure 5.6, the energy consumption decreases from 917.9MWh to 403.3MWh, while the energy saving percentage created by the green roof increases from 5.1% to 14.2%.  Therefore, there is no direct connection between the energy saving percentage of the green vegetation and the climate zones, since the building wall and roof are not key factors for the energy consumption increment created by the weather changes. The heating energy 82  saving percentage is not the highest in the coolest weather condition, and the cooling energy saving percentage is not the highest in the warmest weather condition. 4.5.3 Application of ?green all? scenario in different climate zones In terms of the ?green all? scenario, where the building is covered with the green roof and living walls, most of the buildings have the best energy saving performance in Figure 4.6 to 4.8. However, the energy saving percentage varies in different cases. In ?a1? of Figure 4.6, an average of 25% of the energy used for the large office heating is saved by the ?green all? scenario in the climate zones 5A, 6A, and 7, while 4.6% and 23% of the energy was saved separately by the green roof and living wall. In ?b1? of Figure 4.7, 4.7%, 3.3%, and 6.1% of the heating energy for the large office were saved by the green roof, living wall, and ?green all? respectively in the same climate zones. Although the energy saving performance in the ?green all? scenario is higher than the green roof or living wall in the above two cases, the ?green all? scenario should only be applied to the building when the thermal properties of the building walls and roof are both low. Otherwise, it is not worthwhile to gain the small amount of savings, shown in ?a1? of Figure 4.6 and ?b1? of Figure 4.7, with the high initial cost. Besides the energy saving performance, the initial cost of the green roof and living wall should also be considered when applying the ?green all? scenario to the building. In ?a1? of Figure 4.6 and ?a1? of Figure 4.8, the heating energy saved by applying the ?green all? scenario to the large office and warehouse are 154MWh and 67MWh respectively. However, it is still hard to say that the ?green all? scenario works better in the large office, since the large office has a larger building fa?ade area than the warehouse, which costs more to cover with green vegetation. In summary, the ?green all? scenario could create a better 83  energy saving performance for the building in most cases. However, the energy saving difference between the ?green all? scenario and ?green roof?/?living wall? scenario should be evaluated with the initial cost of the green vegetation. 4.6 Energy Performance of Green Vegetation in Different Building Vintages  As shown in Figures 4.6-4.8, it is apparent that the cooling or heating energy consumption in the old building constructed before 1980 is always higher than the new building constructed after 2004.  As shown in ?a1? of Figure 4.6, 770MWh of yearly heating energy is required for the large office built before 1980, while 672.5WMh of yearly heating energy is required for the large office built after 2004. This is because the new buildings usually have a higher insulation standard than the old ones. The green vegetation also has a better energy saving performance in the old buildings than in the new buildings.  As shown in ?a2? of Figure 4.8, 18% and 17.9% of the cooling energy are saved by the performance of the green roof and living wall, respectively, in the large office built before 1980. These values go down to 13.7% and 14.6% in the large office built after 2004 separately. The U-values in the new buildings are lower than the ones in the old buildings, which mean the new buildings have better insulation properties.  Thus, the thermal properties of the new building fa?ades could not be improved as dramatically by the green vegetation as in the old buildings. Especially in the sustainable buildings developed presently, the requirement for the building insulation is even higher than in regular buildings. The possibility of applying the green vegetation to these types of sustainable buildings has to be considered cautiously. 84  However, the building is not always less insulated than the one built after that; it all depends on the requirement at the design stage. For example, in climate zones 1A, 2B, and 3B, the energy saving created by the green vegetation has a better performance in the building constructed between 1980 and 2004 than in the building constructed before 1980. In Figure 5.6, 13% of the cooling energy was saved by the living wall in the strip mall constructed between 1980 and 2004, while only 3% was saved by the living wall in the strip mall constructed before 1980. To sum up, the application of green vegetation should be focused on the old buildings, and the thermal properties of the buildings have to be considered together with the building vintage to decide the optimized building for the green vegetation. 4.7 Energy Performance of Green Vegetation in Different Building Orientations Figures 4.9 and 4.10 depict the relationship between energy consumption and the building orientations in different parameters. Figure 4.9 displays the relationship between energy consumption and building orientation in different building vintages. It is evident that the three types of buildings all consume the least energy for heating and cooling when the north offsets 90 degrees counter-clockwise, no matter when the building was constructed. Figure 4.10 shows the energy consumption in different orientations with 4 greening scenarios, and the conclusion is the same as the ones in Figure 4.10. However, among three building types, the energy consumption variance because of the orientation is more obvious in the large office than in the strip mall and warehouse.  85   Figure 4.9    Yearly heating and cooling energy consumption in different orientations and building vintages   800080508100815082008250830083500?30?60?90?120?150?180?210?240?270?300?330?Unit: Mwh Large office 7507707908108308508700?30?60?90?120?150?180?210?240?270?300?330?Strip mall Before 1980Between 1980 and 2004After 20047507707908108308508708909109300?30?60?90?120?150?180?210?240?270?300?330?Warehouse 86   Figure 4.10    Yearly heating and cooling energy consumption in different orientations and vegetation cover case8000805081008150820082508300835084000?30?60?90?120?150?180?210?240?270?300?330?Unit: Mwh Large office 7007107207307407507607707807900?30?60?90?120?150?180?210?240?270?300?330?Strip mall bare wall green roofliving wall green all7007207407607808008208400?30?60?90?120?150?180?210?240?270?300?330?Warehouse 87  In Figure 4.9, three vintages of large offices have similar energy savings in different building orientations. When the north offsets 90 degrees counter-clockwise, all the large offices get the highest energy savings, and the percentage reaches around 1.8% on average. In different vintages of strip malls and warehouses, the highest energy savings also happened when the north offsets 90 degrees counter-clockwise.  In terms of energy performance of the three types of buildings in different vegetation greening cases shown in Figure 4.9, the highest energy savings due to changes of building orientation also happened when the north offsets 90 degrees counter-clockwise. In Figure 4.10, the energy savings created by the changes of building orientations are different among the three building vintages. When the north offsets 90 degrees counter-clockwise, 25.9MWh of heating and cooling energy was saved by the strip mall built between 1980 and 2004, while only 14.5MWh was saved by the strip mall built after 2004. At the same building orientation, 33.2MWh of heating and cooling energy was saved by the warehouse built between 1980 and 2004, while only 7.4MWh was saved by the warehouse built after 2004. Thus, it is evident that the building orientation has a larger influence on old buildings with a less insulated building fa?ade.  As presented in Figure 4.2, the north direction is originally 0 degree offset. Therefore, when the north offsets 90 degrees counter-clockwise, the building fa?ades with smaller area will be the east and west orientation. In that case, the building will have a lower sunshine exposure rate. At the same time, since fewer windows will be in the small-area building fa?ade, less heat will be transmitted into the building through the windows. Thus, in the rectangular building, the best energy performance, regardless of the building type, building vintages, or vegetation greening cases, happens when the small-area building fa?ades face to 88  the east and west orientation. In terms of general building analysis, the fa?ade with less area, fewer windows/curtain walls, or higher insulation properties should face to the east and west orientation. In terms of the relationship between the energy saving performance of the green vegetation and the building orientation, Kontoleon and Eumorfopoulou (2010) stated that the green vegetation has better energy saving performance when installed on the east- and west-oriented surfaces. Since the east- and west-oriented building fa?ades have longer sunshine exposure hours, installing the green vegetation on these building fa?ades will definitely improve the energy performance of the building. Thus, the best orientation for covering the green vegetation is on the east- and west-oriented building fa?ades.             89  Chapter  5: Energy Performance of Green Vegetation in LEED Certified Buildings Energy savings is the main benefit that could balance the initial capital cost of green vegetation in buildings. A few research studies focused on calculating the energy savings of green roof and living walls. Liu and Minor (2005) demonstrated that the heat flow through a roof could be reduced by 70%-90% in summer and 10%-30% in winter with the use of green roofs. Another study conducted by Liu and Baskaran (2003) reported a 95% heat gain reduction and 26% heat lost reduction in a 22 month observation period of a green roof. Castleton et al (2010) summarized the energy saving potential of green roofs in buildings with different insulation levels, and the annual energy savings of green roofs are not significant in well insulated roofs. Di and Wang (1999) also agreed that green vegetation reduced 28% of the cooling load transferred through a green wall. However, the reference building in the research is an old library built in 1919, and the wall insulation was not efficient compared to current standards. There is rarely published analysis available on the energy performance of green vegetation in LEED certified buildings. This chapter focuses on the energy performance of a LEED Gold certified high occupancy building with green vegetation. It is divided into four parts: First, background information of green vegetation in terms of the energy performance is introduced. Second, the simulation process of the studied green building is described. Technical drawings, specifications, daily operation records, and official governmental data are discussed in this step. Third, the selected green building is simulated using the DesignBuilder software, and the energy consumption data is calculated using the EnergyPlus 90  software (DesignBuilder, 2010). The simulated model was validated with the actual operational energy consumption in the building. Fourth, the energy saving performance of green vegetation with different scenarios was simulated and discussed. Then the annual and hourly energy consumption for heating and cooling were evaluated for the selected scenarios. 5.1 Materials and Method The published literature has already theoretically analyzed the energy performance of buildings with green vegetation, either with a green roof or a green wall, using models generated in various thermal simulation software programs. However, the energy savings of LEED certified buildings has rarely been validated with actual case studies. In order to obtain actual information on the energy performance with green vegetation, a building with a green roof at the University of British Columbia (UBC), Okanagan, Canada was selected for this study. The actual monthly energy consumption data for the building?s heating and cooling was collected and then compared with the results of energy simulations. Furthermore, the comparative analysis was conducted in different scenarios of green vegetation by considering the same building with different greening scenarios.  5.1.1 Building information The studied building is a five storey high green building. It was completed in 2011, and it is located in Kelowna, British Columbia, Canada. The building has an overall size of 68,000 square feet, which could accommodate 212 student residents. The building features a rooftop terrace, solar heating panels, occupancy and window sensors, heat-recovery ventilators, and a geothermal heating/cooling system. It was built to achieve LEED Gold Standard, and awarded UBC Residential Environmental Assessment Program (REAP) Gold 91  Certification. According to the requirement of the REAP, the building was built with the thermal characteristics listed in Table 5.1. Table 5.1     Thermal characteristics of the studied green building (Specification of UBC REAP) Thermal characteristics of the studied green building  (Specification of UBC REAP) Roof Insulation R>=40 External Wall Insulation R>=18 Energy Star Windows U<=0.31 Floor Insulation R>=20 Domestic Hot Water EF=0.94 Boiler Management EF>=0.96 Heat Recovery System >=50% efficiency  Besides the relevant data in Table 5.1, the values of the occupancy rate and the set point temperature for heating and cooling were derived from the daily operation data of the studied green building. Other features of this building, such as lighting systems and plug loads (computers, room supplies) were characterized as default values through the university dormitory template of the DesignBuilder software. 5.1.2 Simulation programs EnergyPlus and DesignBuilder were selected to do the energy simulation in this study. Currently, most of the thermal simulation programs that are used to calculate the energy transfer through green vegetation simply neglect the effects of evapotranspiration and time-varying soil thermal properties (Barrio, 1998; Kumar and Kaushik, 2005). However, Sailor (2008) generated a green roof energy balance model for the US Department of Energy, 92  and combined it into EnergyPlus as the ?Eco-roof? model option. Therefore, EnergyPlus could be used to add a green roof as the outer roof layer on any roof construction. Moreover, the radiant heat exchange, convective heat transfer, soil heat conductance and storage, moisture effects, and evapotranspiration from soil and plants are all accounted for in this model (Sailor, 2008). DesignBuilder is the first comprehensive user interface to the EnergyPlus dynamic thermal simulation engine. Building geometry can be created in the DesignBuilder?s OpenGL modeller or imported as a gbXML file from an architectural modeling program. Moreover, DesignBuilder can be used to evaluate a range of fa?ade options for the effect of energy use and visual appearance. It can calculate heating and cooling loads using the ASHRAE-approved 'Heat Balance' method, implemented in EnergyPlus (DesignBuilder, 2010). Figures 5.1 and 5.2 show the actual photograph and the DesignBuilder model of the studied green building respectively.   Figure 5.1      Photo of the studied green building         93   Figure 5.2    DesignBuilder model of the studied green building 5.1.3 Green roof The green roof is installed around the rooftop terrace (Figure 5.2) of the building with an approximate area of 2400 square feet. It is a modular system supplied by NATS Nursery, which is the licensed owner of Live Roof in Western Canada. The soil is composed of an engineered proprietary blend, such as sand and pumice, which is about 92% inorganic. The soil depth is an average of 4 inches. The plants used in the green roof are different kinds of sedums.  5.1.4 Weather data The weather data for Kelowna (in Figure 5.3) was derived from the EnergyPlus climate file database of the U.S. Department of Energy (USDOE, 2011). The outside Dry-Bulb Temperature in the database is the normal pattern of the months from multiple years (DesignBuilder, 2013), and it matches with the mean temperature of Kelowna recorded by Environment Canada (2013). 94   Figure 5.3    Weather file applied to the simulation (originated from USDOE (2011)). 5.1.5 Simulation process The following steps were followed in this study: 1. Input the building geometry layout data to the DesignBuilder software. This data was extracted from the design drawings and technical specifications; 2. Characterized the building architectural elements (roofs, external walls, windows, ceilings, internal partitions, and doors, etc.) and then elaborated their thermal properties; 3. Specified the building utility supplies and thermal equipment in the energy model; 4. Performed the monthly energy simulations for the studied green building;  5. Performed the hourly energy simulations for a typical week in summer (July 7th 00:00 a.m. to 13th 00:00 a.m.) and winter (January 13th 00:00 a.m. to 20th 00:00 a.m.) according to the weather data translator in DesignBuilder.    -15-10-5051015202530351/1 2/1 3/1 4/1 5/1 6/1 7/1 8/1 9/1 10/111/112/1Temperature (oC)  Month Air Temperature ?COperativeTemperature ?COutside Dry-BulbTemperature ?C95  5.1.6 Scenarios In order to estimate the impact of green vegetation on energy savings, 3 more scenarios were simulated with the same building geometry. Only the locations of the green vegetation were changed in these scenarios. Scenario 1: Green building without a green roof or green wall.  Scenario 2: Green building with a full green roof. In this scenario, the building is considered fully covered with a green roof. Scenario 3: Green building with a full green wall. In this scenario, green vegetation was not applied to the roof, but the vertical fa?ades of the building were fully covered with green walls.  The same properties of the green roof?s grown media, plant, and thermal conductivity were applied for the green wall simulation. In order to analyze the detailed energy performance of green roof and green walls on a daily basis, the hourly heat transfer value through the roof and walls was simulated for the selected typical weeks in the summer and winter.  5.2 Energy Simulation for the Sustainable Building In the first part of the analysis, annual energy consumptions for heating and cooling were derived from the EnergyPlus software, and then the simulation results were compared with the actual monthly energy consumption of the building. The selected study period is from January 2012 to December 2012. In the second part of the analysis, detailed energy consumption and saving performance of green vegetation under different scenarios were simulated.  96  5.2.1 Model validation In order to assure the validity of the simulation results of the EnergyPlus software, the simulated annual energy consumption for heating and cooling of the studied green building was compared with the actual monthly energy consumption of the building. The comparative results are depicted in Figure 5.4.  Figure 5.4    Energy consumption of Purcell building for lighting, heating, and cooling. As per Figure 5.4, it can be concluded that the simulation results largely match with the actual energy consumption of the studied green building. A noticeable difference between the simulation results and the actual energy consumption is in the coldest months of the year: November, December, and January. Energy fluctuations in the geothermal system and the solar panel system in the building could be the main reason for the shown deviation.  As Kelowna (in British Columbia, Canada) is in the cool, dry climate zone (ASHRAE, 2007), a considerable amount of energy is consumed for the building heating in winter months. The studied green building added a geothermal heating/cooling and solar panel system to support the heating system in winter. However, the heat transferred from the 0102030405060708090100Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecMwh Energy Consumption from Simulation ResultsActual monthly building energy consumption97  geothermal system and solar panel system to the building varies with the daily weather conditions, and the building is not equipped with any device to measure these variations. In addition, the input weather data for the simulation was based on the EnergyPlus database of the US Department of Energy?s Canadian Weather for Energy Calculations (CWEC) database. CWEC represents normal weather conditions in a region (USDOE, 2011). According to the daily data report of Environment Canada, the actual temperatures in January, November, and December of 2012 were slightly higher than the temperature selected in the EnergyPlus database (Environment Canada, 2013). Moreover, as shown in Figure 5.4, the actual energy consumption is slightly higher than the simulation results in April and May and lower in June and July. This deviation could be explained by the changes of the schedule and occupancy rate in the building. The schedule input data for the simulation is set according to the common data listed in the software template (DesignBuilder, 2010). However, in a university residential building, the actual schedule has a significant difference in April and the beginning of May. Due to the final exams and the extra activities by the end of the semester (April), the lighting energy consumptions, and the plug and process loads increase significantly. In June and July, the building occupancy and activities decrease substantially due to the summer break. In addition, the real lighting energy consumptions and the plug and process loads also decrease simultaneously. Based on the above mentioned justifications and reasons, it can be concluded that the simulated building energy consumption is reliable and valid. Therefore, the same energy model was used to evaluate the other defined scenarios.  98  5.2.2 Comparison of energy consumptions The annual energy consumptions for heating and cooling for defined scenarios (refer to section 5.1.6) were derived from the DesignBuilder simulations. The results are presented in Figures 5.5 and 5.6.    Figure 5.5     Energy consumption of the studied green building for heating in different scenarios (Derived from DesignBuilder/E+ results) As shown in Figure 5.5, the energy consumption for heating in Scenario 1 is higher than the other scenarios. However, this value doesn?t have an obvious decrement with the impact of green vegetation. In the warmer season, from April to October, where heating is not a functional requirement for the building comfort, the energy consumption values of the 3 scenarios are almost the same. The highest difference appears in December and January where 275.98GJ and 292.24GJ of energy were consumed respectively. In the same months, 0.6% and 2.1% of the average energy savings were achieved by fully covering the roof and walls with green vegetation respectively.  050100150200250300Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecEnergy Consumption (GJ) The original green buildingScenario 1: The green building without green roofScenario 2: The green building with full green roofScenario 3: The green building with full green wall99  With respect to the cooling energy consumptions, Figure 5.6 depicts a better performance of green vegetation on energy savings.   Figure 5.6     Energy consumption of the studied green building for cooling in different scenarios (Derived from DesignBuilder/E+ results) During the colder season from November to April, the energy consumptions for cooling, under the defined scenarios, are almost the same. A difference in the energy consumption for cooling starts to appear in May when the weather becomes warmer, and it reaches the peak in July. Cooling energy of 52.84 GJ was consumed by the building under the scenario 1 (without a green roof). In July, 5.4% of the energy was saved by the green roof (scenario 2), and 8.4% of the energy was saved by the green wall (scenario 3).  Compared with the original green building, the annual energy consumptions for heating and cooling under scenarios 1 and 2 have minimal differences. The heating energy requirements for scenarios 1, 2, and 3 are 1454.1GJ, 1446.1GJ, and 1431.1GJ, respectively. The energy consumptions for cooling in scenarios 1, 2, and 3 are 207.6GJ, 201.0GJ, and 01020304050Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecEnergy consumption (GJ) The original green buildingScenario 1: The green buildingwithout green roofScenario 2: The green buildingwith full green roofScenario 3: The green buildingwith full green wall100  192.4GJ, respectively. The energy consumption for heating in scenario 1 is over 7 times higher than the annual cooling energy consumption. The energy used for heating in January is higher than the energy consumed for cooling in the entire year. According to the data from ASHRAE standard (ASHRAE, 2007), the Okanagan weather is categorized as zone 5 (Cool dry). Therefore, it is advisable to improve the annual energy performance of the studied green building by improving the heating system. In zones 1 to 4, where the climatic conditions are either hot or warm, more attention should be given to the cooling system. As shown in Figures 5.5 and 5.6, 1.19GJ and 1.1GJ of energy were saved in heating and cooling respectively in every year, with the addition of the green roof in the original building. However, the total energy savings are insignificant if the capital cost of the green vegetation is compared with the savings. According to the green roof construction company, the capital cost of the green roof in the studied green building is about $10 per square feet, and the maintenance cost is about $480 per year. With the expectation of a 50 year lifespan (Bianchini and Hewage, 2011), the 2400 square foot green roof in the studied green building costs $960/year without considering inflation and time value of money. However, only $20.80/year could be saved from the energy savings of the green roof. Therefore, it is not economically viable to install this green roof in the studied green building, from an energy point of view. Although the energy savings created by the full green roof in scenario 2 have better performance than the studied green building ($215.20/year), the benefits are still not sufficient to balance the cost of the green roof construction and maintenance. Nevertheless, the energy saving percentage for cooling is higher than the energy saving percentage for heating in scenarios 2 and 3. Cooling energy of 3.2% and 7.3% was 101  saved in scenario 2 and 3 respectively. The cooling energy saving performance is better in the summer period (Figure 5.5 and 5.6). In terms of heating load reduction, the influence of green vegetation is negligible. Green vegetation has a better performance in the warmer climate where the major part of the energy is used for the building?s cooling. The wall and roof material properties of the studied green building might be another reason to explain the insignificant energy saving performance of green vegetation. Although there is published literature that confirms the excellent energy saving performance of green vegetation in different buildings, the relationships between the properties of the building fa?ade and the energy saving performance were not well considered in those publications (Liu and Minor, 2005; Liu and Baskaran, 2003; Castleton et al., 2010; Di and Wang, 1999). The studied green building is a newly constructed building with the LEED Gold standard. Thus, the building fa?ade has already been constructed to earn LEED points in energy savings. This research confirmed that the green vegetation has no significant impact on the energy savings in a LEED certified building, such as the studied green building. 5.2.3 Impact of green vegetation on heat transfer In order to investigate the accurate impact of green vegetation on the roof and walls of the studied green building, the heat transfer through the roof and walls in the summer and winter typical weeks were derived from the simulation results. These results are presented in Figures 5.7 and 5.8. 102   Figure 5.7     Heat transfer through the walls/roof of the studied green building in the  summer typical week in different scenarios (Derived from DesignBuilder/E+ results) As per Figure 5.7, the heat gain and loss in scenario 1 and 2 are almost the same. On average, for scenarios 1 and 2, 0.916GJ of heat was gained through the walls in the summer typical week, and 0.803GJ heat was lost. In scenario 3, where the walls are covered with green vegetation, only 0.032GJ of heat was gained through the walls in the summer typical week, which is around 30 times less than the other two scenarios. The heat loss through the wall in scenario 3 is also 1.8 times more than the heat loss in the other two scenarios. -1.5-1.2-0.9-0.6-0.300.30.60.9Heat gain Heat lostEnergy transfer (GJ) Walls The original green buildingScenario 1: The green building without green roof-1.5-1.2-0.9-0.6-0.300.30.60.9Heat gain Heat lostEnergy transfer (GJ) Roof Scenario 2: The green building with full green roofScenario 3:  The green building with full green wall103  As shown in Figure 5.7, the influence of green vegetation on heat transfer through the roof, in the summer typical week, is also significant. In scenario 1, where no vegetation covered the roof, 0.442GJ of heat gain and 0.338GJ of heat loss happened through the roof in the summer typical week. In the original green building, where a part of the roof is covered with green vegetation, the heat gain through the roof is 24% lower than the bare roof (in scenario 1). In scenario 2, where the entire roof is covered with green vegetation, the heat gain through the roof (01.41GJ) is merely 32% of the heat gain in scenarios 1 and 3, and the heat loss is 1.5 times more than the heat loss in scenarios 1 and 3.   Figure 5.8     Heat transfer through the walls/roof of the studied green building in the  winter typical week in different scenarios (Derived from DesignBuilder/E+ results) Figure 5.8 displayed the heat transfer of the studied building through the walls and roof, in the winter typical week. The heat loss over the walls is the same in scenario 1 and 2 with the average value of -7.64GJ in the winter typical week. When all the walls were covered with green vegetation (in scenario 3), the heat loss decreased to -6.085GJ, which is over 20% less than the heat loss in the other two scenarios. The heat loss through the roof in -8-7-6-5-4-3-2-10Walls RoofHeat transfer (GJ) The original green buildingScenario 1: The green buildingwithout green roofScenario 2: The green building withfull green roofScenario 3: The green building withfull green wall104  the winter typical week varies in the 3 scenarios. The heat loss in scenario 1 and 3 are nearly the same with the mean value of -2.63GJ. When the entire roof was covered with green vegetation (in scenario 2), the heat loss through the roof decreased to -2.09 GJ, which is more than 20% lower than scenarios 1 and 3. According to Figures 5.7 and 5.8, it is obvious that the green vegetation has a prominent influence on heat transfer in the summer and winter typical weeks. Heat gain over the walls is reduced by 96.5% and 68% respectively by covering the walls and roof with green vegetation. The same amount of heat loss (20%) is reduced by covering the walls or roof with green vegetation. 5.2.4 Impact of green vegetation on the start time and period of heat gain The green vegetation also has a great influence on reducing the period of heat gain and delaying the start time of the heat gain in the summer. According to the simulation analysis, the heat loss through the roof and walls usually starts at 3-4 a.m. and finishes at 1-2 p.m. The time period for heat gain is around 11-13 hours per day on average. The warmer the temperature is, the later the heat loss starts, and the longer the period is. In summer, the building starts to heat up after the sunrise because of the solar gain through the glass, windows, air infiltration, etc. This heat loss delay is helpful in reducing cooling loads, especially in the period after sunrise.   With the influence of green vegetation, the start time and the period of heat loss in the original green building merely have variation. However, when the whole roof is covered with green vegetation in scenario 2, the heat loss through the roof starts at 4-6 a.m. and ends at 9-11 p.m. The time period for heat gain through the roof is only 5-6 hours per day on average. In scenario 3, where the whole wall is covered with green vegetation, the heat loss through 105  the wall starts at 4-6 a.m. in the morning and ends at 1-3 a.m. in the morning. The time period of the heat gain through the walls is shortened to only 2-4 hours per day on average. On some days, there is even no heat gain through the green walls. It can be concluded that the green vegetation has an enormous impact on the start time and the period of the heat loss through the roof and walls. The daily heat gains through the walls or roof in the summer could be delayed by 1-3 hours on average, and the period could be shortened to 5-6 hours per day. On some days, the green vegetation can even help the walls to avoid heat gains. The heat loss through the walls in the typical summer week is 1.5 times more than the heat gains (Figure 5.7). 5.2.5 Impact of energy gain and loss distribution of the original green building However, there is a considerable difference between the annual energy consumption of the building (Figures 5.5 and 5.6) and the heat transfer through the roof and walls. There might be some other factors that lead to immense heat gain in the summer or heat loss in the winter. In order to investigate the reasons behind it, the energy gain/loss distribution of the original green building in the summer/winter typical weeks were analyzed with the DesignBuilder software. The results are sorted and displayed in Figures 5.9 and 5.10. 106   Figure 5.9     Energy gain distribution of the original green building in the summer typical week (Derived from DesignBuilder/E+ results) As shown in Figure 5.9, the building energy gains in the summer are mainly from the building fa?ades (exterior windows, glazing, walls, and roof), lightings, occupancy, and room supplies (computer, equipment, etc.). The solar energy gains through the building fa?ades account for 42% of the total building energy gains, however, only 5% is transferred through the walls and roof.  In the winter, the building energy loss distribution (Figure 5.10) is different from the energy gains in summer. Twenty-six percent (26%) of the energy was lost through the building facades (glazing, walls, and roof), 3% through the ground floor, and the major part (69%) through the external infiltration. In this case, the walls and roof together contribute 12% of all the energy loss in the winter. Based on the information in Figure 5.9, general lighting is the highest indoor heat emitting source in the summer typical week, followed by the glazing and exterior windows. These 3 factors produce 70% of the heat gains in the studied green building. In order to Glazing 19% Walls 4% Roofs 1% General Lighting 32% Computer + Equip 15% Occupancy 11% Solar Gains Exterior Windows 18% 107  improve the energy performance of the building, an energy efficient lighting design should be considered. It would not only reduce the cooling energy requirement but also the power use for artificial lighting (Li and Lam, 2001; Lam et al., 2006). For the heat gain through the glazing and windows, shading devices and a double-skin fa?ade could be utilized to mitigate the impact. Gratia and De Herde (2007) stated that solar protection devices, such as blinds, could substantially reduce the solar energy gains through the glazing and windows, and Chan et al. (2009) also demonstrated that the double skin fa?ade system could provide around 26% annual savings of building cooling energy.   Figure 5.10     Energy loss distribution of the original green building in the winter typical week (Derived from DesignBuilder/E+ results) In Figure 5.10, the walls and roof together contribute 12% of the building heat loss in the winter typical week. The biggest part of the heat loss is caused by the external infiltration, which is more than 2/3 of the total heat loss. According to the definition of DesignBuilder Help Desk (DesignBuilder, 2013), ?external infiltration? is the heat gain/loss through air infiltration (unintentional air entry through cracks and holes in building fabric). Based on Glazing -14% Walls -9% Ground Floors -3% Roofs -3% External  Infiltration -69% 108  research data from the National Association of Home Builders (NAHB) Research Center, the heat exchange through air infiltration could be mitigated by applying interior and exterior air barriers to the building fa?ade (NAHB, 2012). Therefore, the designers have to pay more attention to the external infiltration of the building fa?ade to develop green buildings with high energy efficiency. The energy savings created by the green vegetation did not balance the capital cost due to the low contribution of the building fa?ade in energy consumption. As described in section 5.2.2, from the energy point of view, more than 200 years is required to balance the capital cost if the building is fully covered with the green roof. However, the green vegetation still has economic and social benefits, such as air cleaning, urban heat island effect mitigation, and noise pollution reduction (Currie and Bass, 2008; Oberndorfer et al., 2007; McCarty et al., 2001) that could be calculated to balance the capital cost. Bianchini and Hewage (2012) estimated the dollar value for all the benefits of the green roof, and the results demonstrated that installing a green roof is still valuable in the long run. Thus, the green vegetation is still valuable to the green building if all the economical and social benefits are considered.        109  Chapter  6: Conclusions and Recommendations In this chapter of the thesis, conclusions and contributions of this study are presented, limitations of this study are illustrated, and recommendations are provided for potential future research directions. 6.1 Conclusions As urbanization increases, it is critical to find a balance between human development requirements and environmental concerns. This thesis has identified important characteristics that should be taken into account to maximize the benefits of green vegetation in energy savings. This study represents a contribution to creating a guideline for applying green vegetation to commercial buildings. The following conclusions can be derived from the lifecycle assessment of the living walls. 1. The felt layer system is not environmentally sustainable from an air cleaning and energy savings point of view, compared to the indirect greening system and modular panel system. The indirect greening system has the best performance in air cleaning and energy savings.  2. The LCA also indicated the need for environmentally-friendly materials for sustainable living walls. Materials available closer to the site, with shorter delivery distance, should also be considered in the construction stage. In addition, materials that could be recycled or reused should be applied to the system as much as possible. Vegetation that consumes less fertilizer and has a lower replacement rate should be used.  110  3. The comparative analysis showed that the climatic conditions, building types, and plant categories might impact the energy saving and air cleaning performance. Government policies and programs should focus on reducing the cost barrier to constructing living walls. The following conclusions can be derived from the energy performance of green vegetation in commercial buildings. 1. The simulation results showed that greening scenario, building type, building vintage, weather condition, and building orientation, have a significant influence on the energy saving performance of green vegetation. 2. Among the three greening scenarios (i.e.  green roof scenario, living wall scenario, and ?green all? scenario), there is no definite conclusion as to which one has better energy savings. However, the green roof and living wall both have better performance in buildings with poorly insulated facades. The ?green all? scenario could provide better energy savings for the building in most cases, but the initial cost might be a concern. 3. Regarding the building types, the thermal properties of the building facades are always a key factor to consider when applying the green vegetation to the building. The green roof should be considered in low rise buildings like warehouses and strip malls, and the living wall should be considered on high rise buildings like large offices. Moreover, the green vegetation is not suggested for buildings where the major energy loss happens somewhere other than in the building fa?ades. 111  4. In warm climate zones, green vegetation should be installed in the building fa?ade that is exposed to the most hours of sunshine. In cool climate zones, green vegetation should be installed on the building fa?ade where the negative wind can be blocked. However, the green vegetation is not an efficient method to improve a building?s energy performance in mix marine weather.  5. In terms of building vintages, application of green vegetation should be focused on old buildings. However, the thermal properties of buildings have to be considered together with the building vintage to decide the optimal building orientation for the green vegetation. 6. The building orientation has a larger influence with an old building that has poorly insulated building fa?ade. The building facade with less area, fewer windows/curtain walls, or higher insulation properties should face to the east and west orientation, and the best orientation for covering the green vegetation is on the east- and west-oriented building fa?ades. The following conclusions could be derived from the energy performance of green vegetation in LEED certified buildings. 1. The results of energy simulation of the studied green building showed that 3.2% and 7.3% of the annual cooling energy can be saved by fully covering the roof and walls respectively with green vegetation. The energy savings in the winter, with the use of green vegetation, are negligible in the studied green building.  2. In the summer typical week (July 7th 00:00 a.m. to July 13th 00:00 a.m.), 96.5% of the heat gain through the walls can be reduced by covering the walls with green 112  vegetation. In addition, 68% of the heat gain through the roof can be reduced by covering the full roof with green vegetation. During the winter typical week (January 13th 00:00 a.m. to January 20th 00:00 a.m.), about 20% of the heat loss through the walls and roof can be saved by fully covering the walls and roof with green vegetation. 3. The simulation results also proved that the green vegetation delays the start time of heat gain by 1-3 hours and shortens the period of heat gain by 5-6 hours. In summer, general lighting and solar gain through the windows and glazing contribute to 70% of the heat gain through the fa?ade of the studied green building. In winter, external infiltration alone contributes to more than 2/3 of the heat loss through the fa?ade of the studied green building. 4. The analysis demonstrated that green vegetation is not cost-effective to apply to the studied green building, and similar LEED certified buildings, due to the low energy savings performance. The studied green building was constructed with high insulation standards for cold weather conditions. Nevertheless, the lifecycle benefits of the other economic and social factors might make the green vegetation feasible in green buildings. 5. However, the green vegetation has other economic, environmental, and social benefits, such as air cleaning, urban heat island effect mitigation, noise pollution reduction, etc. that could be contributed to balance the capital cost. Furthermore, from a broader perspective, the application of green vegetation could efficiently mitigate the greenhouse gas emission issue and reduce the temperature of the urban city in the hot summer in a beautiful way.  113  6.2 Limitations  The following are the main limitations of the research presented in this thesis: 1. Due to the lack of published data, only one type of vegetation (plant type) was identified and analyzed. 2. The operational cost analyses, such as durability, aesthetical value, and social factors needed to be quantified and evaluated with the related economic benefits. These factors were not included in the analysis due to data limitations. 3. Due to the time and data limitations, chemical absorptions and energy savings of living walls in different weather conditions, building types, and plant categories were not included in the lifecycle analysis. Only the benefits of air cleaning and energy savings from the green vegetation were considered in the lifecycle analysis. 4. In the building energy simulation, the properties of the growing medium were not considered due to the unavailability of published data. The properties of the growing medium, such as conductivity, density, thermal absorbance, etc. should all be analyzed as individual impact factors. 5. In the LEED certified building simulation, the geothermal system, solar panel system, and the HVAC system could not be incorporated completely into the model due to data measurement limitations in the studied building. 6.3 Research Contributions 1. This research is a key contribution to evaluating the sustainability of living walls in terms of chemical emissions and energy savings. There is no other known published literature on this topic to date. 114  2. The application guideline developed in this study could support the green roof and living wall industries in Canada. At present, there are no such application guidelines in North America. 3. The results of the energy saving performance of green vegetation in LEED certified buildings could help to update LEED regulations related to green technologies. 4. This study evaluated the energy saving performance of green vegetation with a consideration of the cumulative impact of most of the impact factors. The published research mostly considered a single impact factor. Therefore, this study provides reliable verification of energy saving performance of green vegetation. 6.4 Future Research 1. There is a need to develop an asset management tool for green vegetation in building. With this tool, the appropriate green vegetation system could be selected according to the building location, building type, customer requirement, etc. to achieve the best benefits with the lowest cost. This tool can further be used for green vegetation maintenance purposes. 2. A full lifecycle cost assessment of green vegetation should be conducted with all social and environmental benefits. This will provide an accurate evaluation of the sustainability of green vegetation in buildings. 3. A database for green vegetation systems should be established with detailed layer and material information, vegetation information, and thermal properties. This database could then be used for future building studies and simulations. 4. More building types should be analyzed to evaluate the energy saving performance of green vegetation in different climate settings. 115  References Alexandri, E., Jones, P., 2008. Temperature decreases in an urban canyon due to green walls  and green roofs in diverse climates. Building Performance Simulation 43, 480?493. Andersson, B., Place, W., Kammerud, R., Scofield, M.P., 1985. The impact of building orientation on residential heating and cooling. Energy and Buildings 8, 205?224. ASHRAE, E., 2004. ANSIASHRAE/IESNA Standard 90.1 -2004-Energy standard for buildings except low-rise residential buildings. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. 2004. Aydogan, A., Montoya, L.D., 2011. Formaldehyde removal by common indoor plant species and various growing media. Atmospheric Environment 45, 2675?2682. Baek, C., Park, S.-H., Suzuki, M., 2013. Life cycle carbon dioxide assessment tool for buildings in the schematic design phase. Energy and Buildings 61, 275?287. Bailey, R.G., 1983. Delineation of ecosystem regions. Environmental management 7, 365?373. Barrio, E.P. Del, 1998. Analysis of the green roofs cooling potential in buildings. Energy and Buildings 27, 179?193. Bass, B., Baskaran, B., 2001. Evaluating rooftop and vertical gardens as an adaptation strategy for urban areas. Berghage, R., Long, A.J., Beattie, D., Kelley, K., Husain, S., Rezai, F., Long, B., Robert, C., Negassi, A., 2007. Quantifying evaporation and transpirational water losses from green roof and green roofs media.  116  Berndtsson, J.C., Emilsson, T., Bengtsson, L., 2006. The influence of extensive vegetated roofs on runoff water quality. The Science of the total environment 355, 48?63. Bianchini, F., Hewage, K., 2011. How ?green? are the green roofs? Lifecycle analysis of green roof materials. Building and Environment 48, 57?65. Bianchini, F., Hewage, K., 2012. Probabilistic social cost-benefit analysis for green roofs: A lifecycle approach. Building and Environment 58, 152?162. Blanc, P., Lalot, V., 2008. The vertical garden: from nature to the city. W W Norton & Company Incorporated. Brown, R.D., Gillespie, T.J., 1995. Microclimatic landscape design: creating thermal comfort and energy efficiency. Wiley. Castleton, H.F., Stovin, V., Beck, S.B.M., Davison, J.B., 2010. Green roofs; building energy savings and the potential for retrofit. Energy and Buildings 42, 1582?1591. Cavanaugh, L., 2008. Redefining the green roof. Journal of Architectural Engineering 14, 4?6. Chan, a. L.S., Chow, T.T., Fong, K.F., Lin, Z., 2009. Investigation on energy performance of double skin fa?ade in Hong Kong. Energy and Buildings 41, 1135?1142. Cheng, C.Y., Cheung, K.K.S., Chu, L.M., 2010. Thermal performance of a vegetated cladding system on facade walls. Building and Environment 45, 1779?1787. Clark, C., Adriaens, P., Talbot, F.B., 2008. Green roof valuation: A probabilistic economic analysis of environmental benefits. Environmental Science and Technology 42, 2155?2161. 117  Climate booklet for urban development. Ministry of Economy Baden-Wu? rttemberg in Cooperation with Environmental Protection Department of Stuttgart; 2008. Costa, P.R., James, R.W., 1999. Air conditioning and noise control using vegetation. In: Proceedings of the 8th International Conference on Indoor Air Quality and Climate. 3, 234-239. Coward, M., Ross, D., Coward, S., Cayless, S., Raw, G., 1996. Pilot study to assess the impact of green plants on NO2 levels in homes. Building Research Establishment Note N154/96, Watford, UK. Crawley, D.B., Lawrie, L.K., Pedersen, C.O., Winkelmann, F.C., Witte, M.J., Strand, R.K., Liesen, R.J., Buhl, W.F., Huang, Y.J., Henninger, R.H., others, 2004. EnergyPlus: new, capable, and linked. Journal of Architectural and Planning Research 21, 292?302. Currie, Beth Anne, Bass, B., 2010. Using green roofs to enhance biodiversity in the city of toronto. Currie, B.A., Bass, B., 2008. Estimates of air pollution mitigation with green plants and green roofs using the UFORE model. Urban Ecosystems 11, 409?422. Czemiel Berndtsson, J., 2010. Green roof performance towards management of runoff water quantity and quality: A review. Ecological Engineering 36, 351?360. Del Barrio, E.P., 1998. Analysis of the green roofs cooling potential in buildings, Energy and Buildings 27, 179?193. 118  Deru, M., Field, K., Studer, D., Benne, K., Griffith, B., Torcellini, P., Liu, B., Halverson, M., Winiarski, D., Rosenberg, M., 2011. U.S. Department of Energy Commercial Reference Building Models of the National Building Stock. DesignBuilder, 2010. DesignBuilder Features-simulation and design. Available at  http://www.designbuilder.co.uk/content/view/6/14/; [accessed at 26.06.2013]. DesignBuilder, 2012. Downloads-DesignBuilder 3.0.0.105. Available at http://www.designbuilder.co.uk/component/option,com_docman/task,cat_view/gid,11/Itemid,30/; [accessed at 26.06.2013]. DesignBuilder, 2013. Designbuiler help. Available at http://www.designbuilder.co.uk/helpv3.0/index.htm; [accessed at 26.06.2013]. Di, H.F., Wang, D.N., 1999. Cooling effect of ivy on a wall, experimental heat transfer. A journal of thermal energy generation,transport, storage, and conversion 12, 235?245. Dinsdale, S., Pearen, B., Wilson, C., 2006. Feasibility study for green roof application on Queen?s University campus. Documento interno. Queens University. Kingston, ?. Dunnett, N., Kingsbury, N., 2004. Planting green roofs and living walls. Timber Press Portland, OR, U, S, A. Dvorak, B., Volder, A., 2010. Green roof vegetation for North American ecoregions: A literature review. Landscape and Urban Planning 96, 197?213. Eco-indicator 99, 2000. Eco-indicator 99 Manual for designers, Ministry of Housing, Spatial Planning and the ?. The Hague Netherlands. 119  EnergyPlus, 2012. EnergyPlus example file generator. Available at  http://apps1.eere.energy.gov/buildings/energyplus/cfm/inputs/; [accessed at 26. 06.2013]. Environment Canda, 2013. Daily data report for January 2012. Available at http://climate.weatheroffice.gc.ca/climateData/dailydata_e.html?timeframe=2&Prov=BC&StationID=48369&dlyRange=2009-09-03|2013-07-18&Year=2012&Month=1&Day=01[accessed at 17th July 2013]. Eumorfopoulo, E.A., Kontoleon, K.J., 2009. Experimental approach to the contribution of plant-covered walls to the thermal behaviour of building envelopes. Building and Environment 44, 1024?1038. Facer, J., Kendall, C., Fenner, R.A., Brown, S., 2007. Can greenery make commercial buildings more green? Cambridge University Press, Cambridge. Feng, C., Meng, Q., Zhang, Y., 2010. Theoretical and experimental analysis of the energy balance of extensive green roofs. Energy and Buildings 42, 959?965. Fioretti, R., Palla, A., Lanza, L.G., Principi, P., 2010. Green roof energy and water related performance in the Mediterranean climate. Building and Environment 45, 1890?1904. Franco, A., Fernandez-Canero, R., Perez-Urrestarazu, L., Valera, D.L., 2012. Wind tunnel analysis of artificial substrates used in active living walls for indoor environment conditioning in Mediterranean buildings. Building and Environment 51, 370?378. Getter, K.L., Rowe, D.B., 2006. The role of extensive green roofs in sustainable development. HortScience 41, 1276?1285. 120  Getter, K.L., Rowe, D.B., Andresen, J. a., 2007. Quantifying the effect of slope on extensive green roof stormwater retention. Ecological Engineering 31, 225?231. Gratia, E., De Herde, A., 2007a. Greenhouse effect in double-skin facade. Energy and Buildings 39, 199?211. Gratia, E., De Herde, A., 2007b. Guidelines for improving natural daytime ventilation in an office building with a double-skin facade. Solar Energy 81, 435?448. Greenovergrey, 2009. What are living walls. Availabe at http://greenovergrey.com/living-walls/what-are-living-walls.php; [accessed at 25.02.2013]. GREENROOFS, 2008. Introduction to green walls technology , Benefits & Design Available at http://www.greenscreen.com/Resources/download_it/IntroductionGreenWalls.pdf; [accessed at 26. 06.2013]. Heffernan, S., 2013. The ultimate guide to living green walls. Ambius. Available at http://blog.ambius.com/ultimate-guide-to-living-green-walls/ [accessed at 12.09.2013]. Hoyano, A., 1988. Climatological uses of plants for solar control and the effects on the thermal environment of a building 11, 181?199. ICOVA, 2013. Available from http://www.icova.nl/web/Contact-met-Icova.htm; [accessed 20.05.13]. Jim, C.Y., Tsang, S.W., 2011. Biophysical properties and thermal performance of an intensive green roof. Building and Environment 46, 1263?1274. 121  Kneifel, J., 2010. Life-cycle carbon and cost analysis of energy efficiency measures in new commercial buildings. Energy and Buildings 42, 333?340. Kontoleon, K.J., Eumorfopoulou, E. a., 2010. The effect of the orientation and proportion of a plant-covered wall layer on the thermal performance of a building zone. Building and Environment 45, 1287?1303. Kosareo, L., Ries, R., 2006. Comparative environmental life cycle assessment of green roofs. Building and Environment 42(7):2606e13. Krusche, P., Krusche, M., Althaus, D., Gabriel, I. 1982. ?kologisches bauen, Heraus- gegeben vom umweltbundesamt, Bauverlag. Kumar, R., Kaushik, S.C., 2005. Performance evaluation of green roof and shading for thermal protection of buildings. Building and Environment 40, 1505?1511. K?hler, M., 2008. Green facades?a view back and some visions. Urban Ecosystems 11, 423?436. Lam, J.C., Tsang, C.L., Yang, L., 2006. Impacts of lighting density on heating and cooling loads in different climates in China. Energy Conversion and Management 47, 1942?1953. 122  Lee, J.H., Sim, W.K., 1999. Biological absorption of SO2 by Korean native indoor species. In, M.D. Burchett et al. (eds) ?Towards a New Millennium in People-Plant Relationships, Contributions from International People-Plant Symposium?, Sydney, 101-108. Lehmann, J., Rillig, M.C., Thies, J., Masiello, C. a., Hockaday, W.C., Crowley, D., 2011. Biochar effects on soil biota ? A review. Soil Biology and Biochemistry 43, 1812?1836. Lewington, J., 2009. Council approves stringent green-roof rules. Global and Mail Canada. Available at http://www.theglobeandmail.com/news/national/council-approves-stringent-green-roof-rules/article4211599/; [accessed at 05.02.2013]. Li, D.H.W., Lam, J.C., 2001. Evaluation of lighting performance in office buildings with daylighting controls 33. Liu, K., Baskaran, B., 2003. Thermal performance of green roofs through field evaluation. 1?10. Liu, K., Minor, J., 2005. Performance evaluation of an extensive green roof. Greening Rooftops for Sustainable Communities, Washington, D.C. 1?11. Loh, S., 2008. Living walls - A way to green the built environment. BEDP Environment Design Guide ACT 1?7. Lohr, V.I., Pearson-Mims, C., 1996. Particulate matter accumulation on horizontal surfaces in interiors: Influence of foliage plants. Atmospheric Environment 30, 2565?2568. 123  McCarthy, J.J., Canziani, O.F., Leary, N.A., Dokken, D.J., White, K.S., 2001. Climate Change 2001. Impacts, Adaptation, and vulnerability. McCarthy, J.J., Canziani, O.F., Leary, N.A., Dokken, D.J., White, K.S., 2001. Climate change 2001: Impacts, adaptation, and vulnerability. Mcpherson, E.G., 1988. Impacts of vegetation on residential heating and coohng 12, 41?51. Mentens, J., Raes, D., Hermy, M., 2006. Green roofs as a tool for solving the rainwater runoff problem in the urbanized 21st century? Landscape and Urban Planning 77, 217?226. Molineux, C.J., Fentiman, C.H., Gange, A.C., 2009. Characterising alternative recycled waste materials for use as green roof growing media in the U.K. Ecological Engineering 35, 1507?1513. NAHB, 2012. Building envelope & air sealing design. Available at http://www.homeinnovation.com/trends_and_reports/trends/building_envelope_and_air_sealing_design; [accessed at 28.02.2012]. Nedlaw living Walls, 2008. Available at http://www.naturaire.com/about-us; [accessed at 26. 06.2013]. Niachou, A, Papakonstantinou, K., Santamouris, M., Tsangrassoulis, A, Mihalakakou, G., 2001. Analysis of the green roof thermal properties and investigation of its energy performance. Energy and Buildings 33, 719?729. Nichols, M., Savidov, N., Aschim, K., 2010. Biochar as a hydroponic growing Medium. Practical Hydroponics and Greenhouses 39. 124  Nicholson, N., Clark, S.E., Ph, D., Wre, D., Long, B. V, Spicher, J., Steele, K.A., 2009. Rainwater harvesting for non-potable use in gardens?: A comparison of runoff water quality from green vs . traditional roofs 1478?1487. Oberndorfer, E., Lundholm, J., Bass, B., Coffman, R.R., Doshi, H., Dunnett, N., Gaffin, S., K?hler, M., Liu, K.K.Y., Rowe, B., 2007. Green roofs as urban ecosystems: ecological structures, functions, and services. BioScience 57, 823. Ottel?, M., Perini, K., Fraaij, A.L. a., Haas, E.M., Raiteri, R., 2011. Comparative life cycle analysis for green fa?ades and living wall systems. Energy and Buildings 43, 3419?3429. Ottel?, M., Van Bohemen, H.D., Fraaij, A.L. a., 2010. Quantifying the deposition of particulate matter on climber vegetation on living walls. Ecological Engineering 36, 154?162. Pal, A.K., Kumar, V., Saxena, N.C., 2000. Noise attenuation by green belts. Journal of Sound and Vibration 234, 149?165. Palla, A., Gnecco, I., Lanza, L.G., 2009. Unsaturated 2D modelling of subsurface water flow in the coarse-grained porous matrix of a green roof. Journal of Hydrology 379, 193?204. Peck, S., Callaghan, C., Kuhn, M., Bass, B., 1999. Greenbacks from green roofs: forging a new industry in Canada. Peri, G., Traverso, M., Finkbeiner, M., Rizzo, G., 2012. The cost of green roofs disposal in a life cycle perspective: Covering the gap. Energy 48, 406?414. 125  Perini, K., Ottele, M., Fraaij, A.L.A., Haas, E.M., Raiteri, R., 2011a. Vertical greening systems and the effect on air flow and temperature on the building envelope. Building and Environment 46, 2287?2294. Perini, K., Ottel?, M., Haas, E.M., Raiteri, R., 2011b. Greening the building envelope, fa?ade greening and living wall systems. Open Journal of Ecology 01, 1?8. Perini, K., Ottel?, M., Haas, E.M., Raiteri, R., 2012. Vertical greening systems, a process tree for green fa?ades and living walls. Urban Ecosystems. P?rez, G., Rinc?n, L., Vila, A., Gonz?lez, J.M., Cabeza, L.F., 2011. Green vertical systems for buildings as passive systems for energy savings. Applied Energy 88, 4854?4859. Radhi, H., 2010. Energy analysis of fa?ade-integrated photovoltaic systems applied to UAE commercial buildings. Solar Energy 84, 2009?2021. RIBA, 2013. U-Values. Sustainability Hub. Available at http://www.architecture.com/SustainabilityHub/Designstrategies/Earth/1-1-1-10-Uvalues%28INCOMPLETE%29.aspx [accessed at 12.09.2013]. Riedmiller, J., Schneider, P., 1992. Maintenance-free roof gardens: new urban habitats. Naturwissenschaften 79, 560?1. Sailor, D.J., 2008. A green roof model for building energy simulation programs. Energy and Buildings 40, 1466?1478. Sailor, D.J., Hutchinson, D., Bokovoy, L., 2008. Thermal property measurements for ecoroof soils common in the western U.S. Energy and Buildings 40, 1246?1251. 126  Saiz, S., Kennedy, C., Bass, B., Pressnail, K.. 2006. Comparative life cycle assessment of standard and green roofs. Environmental Science Technology 40(13):4312e6. Santamouris, M., Pavlou, C., Doukas, P., Mihalakakou, G., Synnefa, a., Hatzibiros, a., Patargias, P., 2007. Investigating and analysing the energy and environmental performance of an experimental green roof system installed in a nursery school building in Athens, Greece. Energy 32, 1781?1788. Schwab, A.P., Al-Assi, A., Banks, M.K., 1998. Adsorption of naphthalene onto plant roots. Journal of environmental quality 27, 220?224. She, N., Pang, J., 2010. Physically based green roof model. Journal of Hydrologic Engineering 15, 458. Soprema, 2013. Sopranature ? Green roofing system. http://www.soprema.ca/en/content/10/sopranature.aspx [accessed at 24.01.2013]. Sorensen, J., 2009. Cost concerns for increasingly popular green walls. Daily Commercial News. Available at http://dcnonl.com/article/id35275; [accessed at 05.02.2013]. Stav, Y., 2008. Living Walls and Their Potential Contribution to Sustainable Urbanism in Brisbane. Queensland University of Technology. Available at http://www.academia.edu/1326234/Living_Walls_and_Their_Potential_Contribution_to_Sustainable_Urbanism_in_Brisbane [accessed at 12.09.2013]. Stec, W.J., Van Paassen, A.H.C., Maziarz, A., 2005. Modelling the double skin facade with plants. Energy and Buildings 37, 419?427. 127  Tam, C.., Tam, V.W.., Tsui, W.., 2004. Green construction assessment for environmental management in the construction industry of Hong Kong. International Journal of Project Management 22, 563?571. Teemusk, A., Mander, U., 2007. Rainwater runoff quantity and quality performance from a greenroof: The effects of short-term events. Ecological Engineering 30, 271?277. The Economist, 2004. The rise of the green building. Economist. USDOE, 2011. EnergyPuls energy simulation software-weather data. Available at http://apps1.eere.energy.gov/buildings/energyplus/weatherdata_about.cfm [accessed at 24.06.2013]. USDOE, 2012a. 2011 Buildings energy data book. Available at http://buildingsdatabook.eren.doe.gov/docs%5CDataBooks%5C2011_BEDB.pdf [accessed at 24.06.2013]. USDOE, 2012b. Building technologies program-reference buildings by building type. Available at http://www1.eere.energy.gov/buildings/commercial/ref_new_construction.html; [accessed 20.01.2013]. USEIA, 2008. 2003 CBECS detailed tables . Available at http://www.eia.gov/emeu/cbecs/cbecs2003/detailed_tables_2003/detailed_tables_2003.html#buildingchar03; [accessed 28.06.12] 128  USEPA, 2006. Ecoregions of north america. Western Ecology Division, U.S Environmental Protection Agency. Available at http://www.epa.gov/wed/ pages/ ecoregions /na_eco.htm #Downloads; [accessed 28.06.12]. USEPA, 2012. Life cycle assessment Available at http://www.epa.gov/nrmrl/std/lca/lca.html; [accessed at 24.01.2013]. Van Renterghem, T., Botteldooren, D., 2011. In-situ measurements of sound propagating over extensive green roofs. Building and Environment 46, 729?738. VegTech, 2002. Montering och skftsel av takvegetation Moss-Sedum, Sedum-O? rt och Sedum-O? rt-Gr7s (in Swedish). (Assembling and care of roof vegetation type moss?sedum, sedum?herbs, and sedum?herbs?grass), Veg Tech AB. Fager3s, Vislanda, Sweden. Vitaroofs, 2013. 1000 living roofs installations and counting. Available at http://www.xeroflora.com [accessed 24.01.2013]. Wang, Z.Q., Wu, L.H., Liu, T.T., 2009. Revegetation of steep rocky slopes: Planting climbing vegetation species in artificially drilled holes. Ecological Engineering 35(7): 1079-1084. Weinmaster, M., 2009. Are green walls as green as they look? An Introduction to the Various Technologies and Ecological Benefits of Green Walls. Journal of Green Building 4, 3?18. 129  Wolverton, B., Wolverton, J., 1993. Plants and soil microorganisms: removal of formaldehyde, xylene, and ammonia from the indoor environment. Journal of the Mississippi Academy of Sciences 38, 11?15. Wong, N.H., Kwang Tan, A.Y., Chen, Y., Sekar, K., Tan, P.Y., Chan, D., Chiang, K., Wong, N.C., 2010a. Thermal evaluation of vertical greenery systems for building walls. Building and Environment 45, 663?672. Wong, N.H., Kwang Tan, A.Y., Tan, P.Y., Chiang, K., Wong, N.C., 2010b. Acoustics evaluation of vertical greenery systems for building walls. Building and Environment 45, 411?420. Wong, N.H., Tan, A.Y.K., Tan, P.Y., Wong, N.C., 2009. Energy simulation of vertical greenery systems. Energy and Buildings 41, 1401?1408. Yang, J., Yu, Q., Gong, P., 2008. Quantifying air pollution removal by green roofs in Chicago. Atmospheric Environment 42, 7266?7273. Zabalza Bribi?n, I., Aranda Us?n, A., Scarpellini, S., 2009. Life cycle assessment in buildings: State-of-the-art and simplified LCA methodology as a complement for building certification. Building and Environment 44, 2510?2520.  130  Appendices Appendix A: Screen shots of input data for the LCA in SimaPro software.  131     132     133     134    135     136     137     138    139     140     141     142     143  Appendix B: Screen shots of input data for the building energy simulation in Designbuilder software.   144   145    146    147    148    149     

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