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Living skins : an attribute framework for green façades Laurenz, Jon 2007

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LIVING SKINS A N ATTRIBUTE FRAMEWORK FOR GREEN FACADES by Jon Laurenz Architect, University of Navarre, Spain, 2001 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF A D V A N C E D STUDIES IN LANDSCAPE ARCHITECTURE in THE FACULTY OF GRADUATE STUDIES THE UNIVERSITY OF BRITISH COLUMBIA October 2007 ®Jon Laurenz, 2007 ABSTRACT. LIVING SKINS An Attribute Framework for Green Facades The thesis critiques the current practice of green facades in terms of a broader range of opportunities they might realize. It analyses the current practice of green facades as to the different types, construction systems, and relationship with the immediate context. It also identifies a series opportunities related to six areas: human comfort; expressive capacity; air & water quality; indoor-outdoor relationship; urban biodiversity; and carbon neutral architecture. This thesis develops a green facades framework that enables the critique and evaluation of the different existing types of green facades in terms of the extent to which they accomplish such opportunities, facilitating a determination of their appropriateness to different conditions, solar orientations, and user needs. This same framework also intends to improve the current practice of green facades by assisting designers to define a particular green facades. L I V I N G S K I N S : A n Attr ibute F r a m e w o r k for G r e e n Facades TABLE OF CONTENTS Abstract ii Table of Contents iii List of Tables vi List of Figures viii Acknowledgements xii 1- Introduction: Living Skins 1 1.1 Questioning the current use of Green Facades 1 1.2 Research Objectives and Contribution to the Body of Knowledge 6 1.3 Methodology 7 2- The Current Practice of Green Facades: Classification of the types of Green Facades 11 2.1 Green Facades as natural responsive facades 12 2.2 Types of Green Facades 17 2.2.1 Attached to an opaque wall 18 2.2.1.1 Green Facade Type 1.1: Green Facade composed of steel wires 2.2.1.2 Green Facade Type 1.2: Green Facade as moss walls 2.2.1.3 Green Facade Type 1.3: Green Facade composed of green vertical panels 2.2.2 Attached to a transparent wall 33 2.2.2.1 Green Facade Type 2.1: Green Facade between two transparent layers 2.2.2.2 Green Facade Type 2.2: Green external layer and glazed internal layer 3- Green Facades Framework: An Attribute Framework for Green Facades 45 3.1 Human Comfort 47 3.1.1 Comfort Temperature and Reduction in Energy Demand 3.1.2 Acoustic Insulation 3.1.3 Visual Comfort 3.1.4 Humidity 3.1.5 Psychological Benefits 3.2 Expressive Capacity 75 3.3 Air & Water Quality 78 3.3.1 Air Quality 3.3.2 Water Quality 3.4 Indoor and Outdoor Relationship 84 3.4.1 The relationship with the immediate context 3.4.2 Flexibility and Permeability 3.4.3 Accessibility 3.5 Urban Biodiversity 88 3.5.1 Plant diversity 3.5.2 Location 3.5.3 Coverage 3.6 Carbon Neutral Architecture 93 3.7 Overview of the framework 97 4- Application of the Green Facades Framework Application to existing types of Green Facades 99 4.1 Case Study of Rue des Suisses apartment complex [Green Facade composed of steel wires] 100 4.2 Case Study of Quai Branly Museum [Green Facade as moss wall] 104 4.3 Case Study of Seedorf House [Green Facade composed of vertical panels] 107 4.4 Case Study of Arts and Human Science Bldg [Green Facade between two transparent layers]... 110 4.5 Case Study of Gymnasium in the Retiro Park [Green Facade as the external layer] 113 4.6 Overview of the Application 116 5- Conclusion: Envisioning the Future Practice of Green Facades 120 5.1 Overview of the thesis 120 5.2 Thesis Usefulness, Limitations and Further Research 122 Bibliography 127 LIST OF TABLES Table 2.1 Green Facade Type 1.1 composed of steel wires attached to an opaque wall 20 Table 2.2 Summary of the green facade type 1.1 22 Table 2.3 Green Facade Type 1.2 as moss walls 25 Table 2.4 Summary of the green facade type 1.2 27 Table 2.5 Green Facade Type 1.3 composed of green vertical panels 30 Table 2.6 Summary of the green facade type 1.3 32 Table 2.7 Green Facade Type 2.1 36 Table 2.8 Summary of the green facade type 2.1 37 Table 2.9 Green Facade Type 2.2 39 Table 2.10 Summary of the green facade type 2.2 42 Table 2.11 The five major types of green facades 43 Table 3.1 Contribution of green facades to comfort temperature and reduction in energy demand 56 Table 3.2 Contribution of green facades to comfort temperature and reduction in energy demand 58 Table 3.3 Contribution of green facades to acoustic insulation 62 Table 3.4 Contribution of green facades to visual comfort 65 Table 3.5 Contribution of green facades to humidity 67 Table 3.6 Contribution of green facades to psychological benefits 73 Table 3.7 Contribution of green facades to improve human comfort 74 Table 3.8 Contribution of green facades to the expressive capacity 77 Table 3.9 Contribution of green facades to air and water quality 83 Table 3.10 Contribution of green facades to indoor - outdoor relationship 87 Table 3.11 Contribution of green facades to urban biodiversity 92 Table 3.12 Contribution of green facades to carbon neutral architecture 96 Table 4.1 Evaluation of the green facade of the rue des Suisses apartment complex 102 Table 4.2 Evaluation of the green facade of the Quai Branly Museum 105 Table 4.3 Evaluation of the green fagade of the Seedorf House 108 Table 4.4 Evaluation of the green facade of the Arts and Human Science Building 111 Table 4.5 Evaluation of the green facade of the Gymnasium in the Retiro Park 114 Table 4.6 Overview of the evaluation of the five selected green facade buildings 119 LIST OF FIGURES Figure 1.1 Recent examples of green facades 2 Figure 1.2 The green facades of the Quai Branly Museum and Prada Store 3 Figure 1.3 Green Facades 4 Figure 1.4 7 Figure 1.5 Thesis Questions 7 Figure 1.6 The Current Practice of green facades 8 Figure 1.7 Opportunities in green facades 8 Figure 1.8 The Green Facades Framework 9 Figure 1.9 Scheme of the Thesis 10 Figure 2.1 Responsive Facades 12 Figure 2.2 A Green Facade changing overtime 13 Figure 2.3 Arab World Institute, Paris 1988 [® G N U Free Documentation License 14 Figure 2.4 Tower of Winds, Yokohama 1986 14 Figure 2.5 Times Squares, New York 14 Figure 2.6 T-Mobile Headquarters, Bonn 2006 15 Figure 2.7 Aperture interactive Facade 15 Figure 2.8 The image of the Thesis 16 Figure 2.9 Recent and older Green Facades designed by Nouvel and Herzog & de Meuron 16 Figure 2.10 Types of Green Facades 17 Figure2.11 Green Facade type 1.1 18 Figure 2.12 Rue des Suisses Apartment complex, Herzog & de Meuron, Paris 2000 19 Figure 2.13 Stainless steel wires of the Jakob AG/SA Company 21 Figure2.14 Examples of green facades of the company greenscreen 21 Figure 2.15 Green Facade type 1.2 23 Figure 2.16 Cartier Foundation, Jean Nouvel, Paris 1998 24 Figure 2.17 Quai Branly Museum, Jean Nouvel, Paris 2005 „„ 24 Figure2.18 Quai Branly Museum, Jean Nouvel, Paris 2005 „„ 24 Figure 2.19 Examples of green facades as moss walls 26 Figure 2.20 Verdir Green Facade System 27 Figure 2.21 Green Facade type 1.3 28 Figure 2.22 Gordillo Studio extension, Madrid 28 Figure 2.23 Seedorf House, Madrid 28 Figure 2.24 Intemper's Green Vertical Panel 28 Figure 2.25 West School Complex in Obernai, France 2006 29 Figure 2.26 Green Panels at the Aichi Expo, Japan 2005 29 Figure 2.27 Aquarium extension Vancouver, Canada 2006 31 Figure 2.28 Prada Store, Herzog & de Meuron, Tokyo 2005 31 Figure 2.29 Intemper's Green Vertical Panel 32 Figure 2.30 ELTS company's Green Walls 32 Figure 2.31 Green Facade type 2.1 34 Figure 2.32 Fine Arts School, Lacaton & Vassal, Grenoble France 2001 34 Figure 2.33 Casa Barcelona 05 35 Figure 2.34 Casa Barcelona 05 35 Figure 2.35 Green Facade type 2.2 38 Figure 2.36 Gymnastic pavilion, Abalos & Herreros, El Retiro Park, Madrid 2002 38 Figure 2.37 Consorcio Building & House in Paul Harris St. E. Browne 40 Figure 2.38 Consorcio Building facade detail 40 Figure 2.39 Pergola Building and J&R Building Bruno Stagno 40 Figure 2.40 Holiday Houses in Jupilles 41 Figure 2.41 Holiday Houses in Jupilles 41 Figure 2.42 Thiais School, Edouard Francois, France 1996 41 Figure 2.43 Thiais School, Edouard Francois, France 1996 41 Figure 2.44 Projects of Green Facades with Jakob company system 42 Figure 3.1 Contribution of green facades to indoor comfort temperature 48 Figure 3.2 Green facades as lungs for the cities 49 Figure 3.3 Various environment albedos 50 Figure 3.4 Surface temperatures for different colours on facade 50 Figure 3.5 Contribution of Green Facades to the outdoor temperature 51 Figure 3.6 Range of values for the evaluation 52 Figure 3.7 The scale considered by the framework 55 Figure 3.8 The spider graph used by the framework 57 Figure 3.9 Contribution of green facades to comfort temperature and reduction in energy demand 59 Figure 3.10 Contribution of green facades to the acoustic insulation 60 Figure 3.11 Range of values for the evaluation 61 Figure 3.12 Contribution of green facades to the indoor visual comfort 64 Figure 3.13 Range of values for the evaluation 65 Figure 3.14. Contribution of Green Facades to Psychological Benefits [from inside] 69 Figure 3.15 Contribution of Green Facades to Psychological Benefits [from outside] 71 Figure 3.16 Contribution of Green Facades Air and Water Quality 79 Figure 3.17 Intemper's Ecological Roof 79 Figure 3.18 Casa Barcelona 05 80 Figure 3.19 Range of values for the evaluation 81 Figure 3.20 Simulation of natural changes of green facades from inside 84 Figure 3.21 Natural adaptation of green facades to surrounding stimuli 84 Figure 3.22 Adaptation of green facades by the user 85 Figure 3.23 Range of values for the evaluation 86 Figure 3.24 Contribution of green facades to urban biodiversity 88 Figure 3.25 Greening Grayfields vs Graying Greenfields 89 Figure 3.26 Range of values for the evaluation 90 Figure 3.27 Range of values for the evaluation 95 Figure 4.1 Rue des Suisses apartment complex 100 Figure 4.2 Rue des Suisses apartment complex 101 Figure 4.3 Quai Branly Museum 104 Figure 4.4 Quai Branly Museum 104 Figure 4.5 Seedorf House 107 Figure 4.6 Seedorf House 107 Figure 4.7 Arts and Human Science Building 110 Figure 4.8 Arts and Human Science Building 110 Figure 4.9 Gymnasium in the Retiro Park 113 Figure 4.10 Gymnasium in the Retiro Park 113 Figure 5.1 The contribution of green facades to human comfort from the four orientations 124 Figure 5.2 The expressive capacity of green facades 125 Figure 5.3 The opportunity to treat grey water and retain rain water 126 Figure 5.4 The possibility of introducing flexibility in green facades 126 Figure 5.5 Vertical Farm project 127 Figure 5.6 Green Facades carbon footprint 127 ACKNOWLEDGEMENTS I would like to thank all of my committee members, and especially my thesis advisor, Ron Kellett, who has been very helpful in leading and guiding the thesis toward its final result, even sometimes understanding the central aims of the proposal better than myself. Without his enormous contribution, this thesis would not have been realized as it is today. And a special thanks also to Ray Cole, whose clarity of ideas and sharp view contributed to the direction of the thesis and helped to focus on the themes that are essential to the topic. And also a remarkable thanks to Doug Paterson, who supported me in uncovering the ethereal meaning of the thesis by paying attention to the poetical dimension that this work demands. I should like to thank Patrick Mooney, the MASLA program director, who made it possible for me to be at UBC attending the MASLA. I would also like to thank Peter Jolliffe and Douglas Justice who helped me understand how plants work in green facades, their growth, metabolism and evapotranspiration process as well as the carbon cycle within them. Thanks also to Sherry McKay who helped me refine the topic in the beginning phases of the thesis, as well as Daniel Roher whose critical view enriched the quality of the thesis. This thesis is certainly more comprehensible thanks to the editing of Stephanie Bonic. I can not forget to thank all the friends I had the opportunity to meet during these two years of the MASLA program, especially the MLA students, as well as my family back home, my parents Miguel and Gemma, and my sisters and brother, Angela, Nerea and Mikel who have always comforted me and made me feel closer to home. Finally it would not be fair to finish this moment of gratitude without the biggest THANKS to the person who has always been close to me, always with constructive critiques, adding a full range of positive comments to enhance the thesis, and also to improve my English. A big THANKS to the person who has always been encouraging me, especially in those difficult moments when I was about to leave everything behind. THANK YOU VERY MUCH - MILA ESKER - JONE. 1 INTRODUCTION. LIVING SKINS. Bu i ld ing facades constitute the l ine of d iv i s ion between the indoor and the outdoor, participating in the spaces of both sides. Initially, the main role of facades was to prov ide protection from the c l imate ' s inc lemenc ies as we l l as f rom other humans or animals ' . As technology made progress these thick facades became more permeable, a l l ow ing air and light to pass through them, leading them to the very thin facades of g laz ing bui ldings. Parallel to this, the facades ' requirements became more and more comp lex in order to improve indoor comfort condit ions. Today 's bu i ld ing facades demand to express the not ion of variabi l i ty and changeabil ity, wh i ch introcude the factor of t ime. This seems to be the main purpose of current green facades. 1.1 Questioning the Current Practice of Green Facades Contemporary architecture is exper ienc ing an increasing and emerging practice of green facades. Mo re and more architects are exper iment ing w i th diverse ways of introducing greenery to bu i ld ing facades, p rov id ing a w i d e spectrum of different types of green facades. This practice, wh i ch one might cal l a boom of green facades, is spreading all around the wo r l d as the fo l l ow ing recent examples reflect: f rom Jupil les, France to Reston, US to Tokyo, Japan, to Madr id , Spain [Fig1.1]. 1 Herzog, Krippner, Lang. Facade Construction Manual. Birkhauser publisher Munich 2004 I 1. Introduction 2 images waiting for ® permission Figure! .1 Architecture is experiencing a boom of green facades around the world. Houses in Jupilles [France, 1996]; National Wildlife Federation [Reston, 2001]; Prada store basement [Tokyo, 2005]; Gymnastic Pavilion [Madrid 2002]. In this context, leading architects, such as Jean Nouvel and Herzog & de Meuron, seem to find in green facades a natural response to the current accelerated information society, one which demands a changeable architecture, as well as to the emerging need for a carbon neutral architecture, one which demands an environmentally sensible architecture. Architects are exploring the changeable and expressive capacity of vegetation in the facade, fascinated by its faculty to naturally introduce the notion of time, providing an ephemeral dimension: "The ephemeral dimension infers a rapport between architecture and ephemeral elements. Vegetation is one of these and is of course very fleeting, very sensitive and very changeable"2 An interview with Jean Nouvel available on his office website: www.jeannouvel.com 1. Introduction Recent buildings illustrate this. In the case of Nouvel, the green facade of the Quai Branly Museum in Paris [2006], achieves a spectacular explosion of different plant species, transmits the thickness and heaviness of 'living walls', and "creates diverse green tapestries rich in texture and tonalities of green, and often punctuated by flowers" 3. In the case of Herzog & de Meuron, the green facade of the basement of the Prada store in Tokyo [2005] uses the same moss-type plant to take different inclinations as if it was "the sponge, grass-covered topography of the yard" 4. Figure l .2 The Green Facades of the Quai Branly Museum in Paris [Nouvel] and the basement of Prada store in Tokyo [Herzog and de Meuron] explore the expressive capacity and plasticity of green facades. But, do these green facades really realize the full range of opportunities they embody? On a closer look at these two examples, it seems striking, for instance, to find both green facades respond in such a similar way - attached to opaque walls - to the very different conditions they face: Quai Branly Museum's faces north-west to a main street and the Seine river, while the green facade at the basement of Prada faces south-east and north-east to the "front yard" of the store. At the same time both green facades are still relatively hermetic. Although they express the changeability that occurs naturally by the passing of time, which is a key aspect of green facades, this thesis understands there are many other qualities in green facades that are ignored or underestimated. 3 L'Atelier Vert www.frenchgardening.com Pedro Arroyo, Prada Tokyo. Architecture is architecture. Website: www.architettura.supereva.com 1. Introduction This thesis argues that green facades could and should respond in a different manner to different orientations as a means of really understanding the variability of their surroundings. Green facades could and should show different faces according to the movement of the sun. The opacity or transparency of the walls that they are attached to should play a key role in this sense. In addition, this could significantly reduce the energy demand of buildings, refreshing the facade in summer, and allowing for solar energy gain in winter through transparent green facades, or insulating from the cold through opaque green walls. Green facades could also incorporate flexibility and movement to the enclosure skin, by rotating or sliding systems. This would allow the users to create their desired relationship with the outdoor space, by moving these sorts of green lattices. Green facades can also act as water storage, reducing the runoff, and can even purify the grey water used by the building. In a similar manner they can purify the air of their surroundings by trapping pollutants, such as CO2. In this sense green fagades appear to be the only building material through which the carbon load can be positive considering its life cycle', contributing to carbon neutral architecture. They can significantly improve the urban biodiversity, especially when located in green network edges, enhancing the activity of living organisms. They can even increase the urban agriculture, acting as cultivated green surfaces, where vegetables can grow. This thesis argues that green facades today are in a rather preliminary stage, given that their designs are relatively intuitive and based more on exploring their expressive capacity than on maximizing the whole range of opportunities they provide. Consequently, designers are often unaware of the larger range of opportunities in green facades. In this sense, this thesis is driven by the following two consecutive questions: Does the current practice of green facades realize the full range of opportunities they embody? If not, what are the attributes that would enable designers to determine the most appropriate green facade for a given context? * This means that while the rest of building materials always have a "CO2 load" due to the one created during their fabrication process; for the case of green facades this could be opposed by the CO2 they trap in their life cycle. I 1. Introduction Figure 1.3 Green Facades This leads the thesis to develop and propose a framework in order to provide a set of attributes to assist designers in defining the green facades that appropriately satisfy a project's needs. To do so, the thesis: Classifies the current types of green facades and undertakes a preliminary critique of these; Identifies a broader range of opportunities within green facades; and Develops a green fagades framework to enable a deeper critique and to evaluate the appropriateness of the current practices of green facades in terms of the accomplishment of the attributes; the aim is to give feedback for and improve on the current practices of building green facades. 1. Introduction 1.2 Research Objectives and Contribution to the Body of Knowledge The main goal of the thesis is to develop a green facades framework to facilitate designers determine the most appropriate green facade for a particular project, through a critique and evaluation in terms of the accomplishment of a broader set of attributes. The contribution to the body of knowledge consists of bridging the gap between the current practices in building green facades and the accomplishment of the opportunities they embody, in terms of improving human comfort and water & air quality, providing expressivity and changeability to building facades as well as flexibility to the indoor-outdoor relationship, and contributing to urban biodiversity and carbon neutral architecture. Research objectives 1. To analyse and critique the current practice of green facades in terms of the different types, construction and management systems, and relationship with their immediate context. 2. To identify the opportunities of green facades in six areas: Human Comfort; Expressive Capacity; Air & Water Quality; Indoor-Outdoor Relationship; Urban Biodiversity; and Carbon Neutral Architecture. 3. To develop a green facades framework to facilitate the critique and evaluation of green facades in terms of the accomplishment of the identified attributes; and consequently to suggest better practices in relation to different conditions, orientations, and user needs. 4. To apply the green facades framework to existing case studies in order to identify its usefulness and limitations. 5. To ultimately improve the current practice of green facades. 1. Introduction Contribution to the body of knowledge This thesis classifies the current types of green facades into two main categories: attached to opaque walls and attached to transparent walls. It develops a green facades framework, which aims to clarify the broader range of opportunities within the current types of green facades. Within this new framework, a deeper critique and evaluation of green facades is enabled, and hence the framework helps to determine the appropriateness of the different types of green facades to different conditions, orientations, and user needs. Overall, the framework intends to assist designers in the definition of a particular green facade type that better satisfies a project's needs in order to improve the current practices of green facades. :. Current Practice of green facades I V ' ,GAP: lack of criteria I Accomplishment of the <• J bpportunities'in'green facades ! ' * '• \ Figure 1.4 1.3 Methodology In order to respond to the thesis questions [Figure 1.5], the methodology begins with a preliminary analysis of the current practices of green facades, which reveals a series of deficiencies and the need to identify a broader set of opportunities in green facades. These have been condensed into six areas: human comfort, expressive capacity, water & air quality, indoor-outdoor relationship, urban biodiversity, and carbon neutral architecture. This serves as the basis for the development of a green facades framework, which is then applied to existing case studies in order to reveal its usefulness and limitations. •jDoes'theeurrentpractice of,greens.* facades realize the full range of opportunities they embody? , If not, what are the criteria that ' *would>.enableidesigners"„delermme» '.IK most appropriate green facade' n for a giyen context?p 'JL.J Fieure 1.5 Thesis Questions 1. Introduction The Current Practice of Green Facades This chapter frames the current practice of green facades wi th in the context of a contemporary type of facade that reacts to the st imuli of its immediate environment, wh i ch the thesis understands as responsive fagades. G reen facades represent a natural alternative with in this type of facade, they are l iv ing skins, w h i c h change and react naturally to surrounding st imuli. The chapter then proceeds to identify and classify the different types of current green facades. These are separated into f ive main types, w h i c h are organized into two major categories: those attached to an opaque wa l l , and those attached to a transparent wa l l . This analysis detects some prel iminary defic iencies in green fagades, suggesting the need for a deeper study on the opportunities avai lable in creating green fagades. Green Fagades Framework This chapter identifies the opportunit ies in green fagades condens ing them into the fo l l ow ing six areas: the improvement in Human Comfort; the explorat ion of their Expressive Capacity; the inf luence in Air & Water Quality; the enr ichment of the Indoor-Outdoor Relationship; and the contr ibut ion to Urban Biodiversity and Carbon Neutral Architecture. 1. Introduction Broader Context: > / ' h 1 Creen facades as natural ! responsive fagades Types of green fagades. .Attached to aniopaque^wall-i.d Attached'to a transparent wall J Figure 1.6 The Current Practice of green fagades lmprove lhuman comfort / I •'Explore the expressive capacity, j v -'' •> , , • i i i Influence in water & air quality •< :-'Enruch mdodr^)utdoor.-relationship<j Contribute to urban biodiversity Contribute to carbon neutral ' V , ^architecture (, Figure 1.7 Opportunities in green fagades 8 The comb inat ion of the two previous f indings - the types of green facades on the one hand, and a broader range of opportunit ies on the other - lays out the foundation for development of the green facades f ramework. This f ramework enables the cr it ique and evaluation of the different types of green facades in terms of the extent to w h i c h they accompl i sh the identified opportunities; and, w i th this, it helps to determine their appropriateness to different condit ions in an effort to improve the current practices for bu i l d i ng green facades. Application of Green Facades Framework The green facades f ramework is app l ied to exist ing examples of green facades to evaluate their appropriateness to their particular condit ions. Five case studies are analysed, corresponding to the prev ious ly identif ied f ive main types of green facades. The appl icat ion of the framework reveals its usefulness and l imitations in assessing h o w designers select and define more appropriate types of green facades for specif ic projects. i ', ; Types of green .facades 1 I •A { | Opportunities in green facades j l Critique: ' '< . Are'the opportunities fulfilled? r l l |f IStfiJE H 1 Appropriateness: ' >' i [ i ' WhicH type is the"most ' i», appropnatejor a specific • condition? i *s <j Figure 1.8 The green facades framework 1. Introduction Develop the GREEN FACADES FRAMEWORK Types ""'•is'"" 1 Current practice of • i Green Facades " Based on related research ?F i How I ' K T l l l l V till id Enable tin V OPPORTUNITIES > CRITIQUE \'i „*>in Green Fagades ' of Green Facades j i ' ,! Determine the ' f; 1 >, APPROPRIATENESS | of Green Facades %*' J Which type fulfil which opportunity I l I . J »-i,V !_'••* 5 r • '•' 1 ,_I IMPROVING JHE CURRENT. -> «. -i j >"^PRAcVlCE OF GREEN FACADES I " " " ' s-tVi Figure 1.9 Scheme of the Thesis 1. Introduction 10 2 THE CURRENT PRACTICE OF GREEN FACADES. The following analysis of the current practice of green facades attempts to find some deficiencies or missed opportunities within them. It collects a series of existing examples of green fagades undertaking a preliminary critic study, which shows, for instance, current green fagades do not consider the different characteristics of the orientation of the fagade, since none of them respond to different orientations with different systems. It also shows today's green fagades are very static and rigid systems which do not afford any flexibility to the fagade. These findings, among others, reveal the need to create a framework to provide a series of attributes that enable to evaluate green fagades with better criteria. This is detailed in the next chapter. This analysis facilitates the classification of the current variety of green fagades. All the studied examples suggest that existing green fagades can be divided into two major categories: those attached to an opaque wall, and those attached to a transparent wall. In addition, this chapter begins by framing the current practice of green fagades within the broader context of building fagades. In this sense, green fagades present a natural alternative as responsive fagades, since they change and react naturally to the stimuli of their immediate context, becoming living skins. 2. The Current Practice of Green Fagades 2.1 Green Facades as natural responsive facades Building facades have always been related to their surrounding environment. As a result many different types of buidlings and facades have adapted to the different characteristics of their surroundings as a means of controlling them. "The problem of controlling his environment and creating conditions favorable to his aims and activities is as old as man himself"5. In an accelerated culture6 and information era7, the relationship of buildings to their surroundings has become more complex, demanding more variability and dynamism in building facades. In a desire to introduce the factor of TIME into building facades, leading architects today are exploring and experimenting with different ways in which building facades can change their properties by responding to surrounding stimuli. These perform as responsive interfaces between the indoor and the outdoor, and seek an innovative integration with their surroundings by adapting or reacting to its changes, such as traffic noise, wind, and seasonal changes. These changes may be activated mechanically or naturally. Different types of facades exist in the category of mechanically activated changes. These include interactive facades, [multimedia facades, switchable facades, and changeable facades, among 5 Victor Olgyay. Design with climate. Princeton University Press. New Jersey1963. 6 Steve Redhead. Paul Virilio. Theorist for an accelerated culture. Edinburgh university Press, Edinburgh. 2004 7 Wil l iam J. Mitchell, e-topia. Urban life, lim-But not as we know it. The MIT Press, Cambridge, Ma, 1999. I 2. The Current Practice of Green Facades others. Mechan i ca l l y activated responsive facades are usually composed of different layers int roduc ing mechan ica l elements to produce reactions or to adapt to outdoor st imul i . Mechan ica l elements are usually Light-Emitting D iodes [LED] l ighting elements and e lectrochromic or thermotrop ic glazing, contro l led by computer systems. Electrochromic systems can alter the radiation transmission by app ly ing integrated charges, wh i l e thermotropic g laz ing systems metamorphose from a fu l ly transparent into a m i l ky wh i te skin as temperature rises 8. In naturally activated chang ing facades, the reaction or adaptation to the surrounding stimuli is induced naturally by, for instance, changes in plants through the seasons. These particular types w i th in responsive facades, where vegetation is introduced as a facade material, behave as green fagades. In this sense, green fagades represent a natural alternative w i th in these types of responsive fagades, w h i c h respond by chang ing their properties, such as co lour texture and density, to surrounding st imul i . They behave as l i v ing skins. Recent examples of responsive fagades O n e of the earliest examples of responsive fagades in recent architecture is Jean Nouve l ' s Arab W o r l d Institute in Paris, 1988. The fagade introduces mechanisms, similar to diaphragms in photographic cameras, w i th in the g laz ing fagade, and reacts differently accord ing to external dayl ight condit ions, open ing and c los ing the incorporated devices in the same way as the d iaphragm in a camera [Fig 2.3]. Schittich, Christian, in Detail Building Skins. Birkhauser publisher, Kempten. 2001 2. The Current Practice of G reen Fagades Figure 2.3 Jean Nouvel, Arab World Institute, Paris (1988). The facade opens and closes its devices reacting to the intensity of daylight. The fagade of Toyo Ito's Tower of Winds consists of a metallic mesh with a variety of sources of light such as neon tubes and light bulbs. It uses these to respond to different environmental conditions such as traffic, wind, and noise. A computer controls the different light sources [Fig. 2.4]. Another example of mechanically activated responsive fagades is those surrounding New York's Times Square, in which screens are continually changing and serving as information transmitters [Fig. 2.5]. 1 image waiting for ® permission Figure 2.4. Toyo Ito, Tower of Winds, Yokohama, 1986. Figure 2.5. New York's Times Square 2. The Current Practice of Green Fagades A c c o r d i n g to Jean Nouve l , in his current architecture he tries to create ephemeral bu i ld ing facades 9 : changing and react ing facades. Arguments for the hermetic and static facades of the past are not va l id anymore, there is an emerging advocacy for facades that react to the st imuli of the surrounding environment. The more recent vers ion of these responsive fagades is achieved by incorporat ing LED [Light-Emitting Diodes] l ighting in bu i ld ing fagades. The T -Mob i le Headquarters bu i l d i ng in Bonn, G e r m a n y 1 0 , presents an example of these [Fig 2.6]. image wai t ing for ® permiss ion Figure 2.6. T-Mobile Headquarters with LED fagade in Bonn, Germany 2006. A particular type of responsive fagade, an interactive fagade, reacts and interacts wi th ne ighbour ing movement, such as the passing of people. Aperture fagade installations with interactive fagade display modes represent a prototype of these interactive fagades" [Fig 2.7]. image wa i t ing for ® permiss ion Figure 2.7. Aperture interactive fagade. The fagade reacts to surrounding movement, such as passers by. 9 An interview to Jean Nouvel available at his office website: www.jeannouvel.com 1 0 www.mediaarchitecture.org " The information on the Aperture fagade can be found at http://www.fredericeyl.de/aperture/index.php?main = 2&sub I 2. The Current Practice of G reen Fagades Within the context of the current kinds of responsive facades, and together with an emerging demand for environmentally conscious architecture - carbon neutral architecture, leading architects find in green fagades a natural alternative to these responsive fagades. Green fagades are an innovative type of responsive fagade which incorporate vegetation as a means of reacting naturally to surrounding stimuli, by changing their colour and density over time. Leading architects such as Jean Nouvel and Herzog & de Meuron have been exploring green fagades. Both firms have a series of built examples in which green fagades play an important role. In the case of J. Nouvel, these are Quai Branly Museum [2006] and the Cartier Foundation [1994J, both in Paris. In the case of Herzog & de Meuron, the projects are the CaixaForum Building in Madrid [2007], and the Rue des Suisses apartment complex in Paris [2000]. Figure 2.8 The image of the thesis 3 images waiting for c permission Figure2.9 Recent and older Green Fagades designed by J. Nouvel: Quai Branly Museum, Paris 2006 and Cartier Foundation, Paris 1994; and Herzog & de Meuron: CaixaForum building, Madrid 2007 and Rue des Suisses Apartment Building, Paris 2000. However, despite this enthusiasm for green fagades to participate in such highly particular, responsive and interactive architecture, some of the other aspects that green facades offer are commonly ignored. Green fagades are typically treated in a superficial manner, underestimated as living beings with ecological and hydrological needs. The implications of working with a living construction material are being ignored. Therefore, this thesis attempts to present a series of fundamental characteristics of green fagades that must be considered in order to design them more thoughtfully in the future. I 2. The Current Practice of Green Fagades | 16 2.2 Types of Green Facades One very important aspect for designers of green fagades to understand is how green fagades are being built. In order to provide a series of different systems for constructing green fagades, this chapter studies very diverse examples of existing fagades. It identifies and classifies them in different types of systems of construction. This study also provides a preliminarily critique of the current practice of green fagades by illustrating deficiencies and missed opportunities in their construction. Most of the green fagades currently being designed belong to one of the two major categories: attached to an opaque wall and attached to a transparent wall. These, in turn, split into the five types described in this section: green fagades composed of steel wires, as moss walls, composed of green vertical panels between two transparent layers, and, as a green external layer and a glazed internal layer. i > ,,,Types of j Green Facades -„, r_,....,,^^^S^^^ft^^^^^^^^,,„ , •> W , V" >-t" I '%Green Fagades composed'ofrsteel wires - Green'Fagade type 1 1 ' -i , 1 lAttached to an opaque wall Green Fagades as moss walls - Green Fagade type 1.2 i T , . ' Green'Facades romnosed of erppn vertical Danels - Gn 2 Attached to a transparent wall ::,Gr eniFaga scompose  f green- rti l "panels'- reen Fagade type 1.3 T*Green Fagades between two transparent layers Green Fagade,type 2.11 '*: Green external layer and glazed internal layer - Green,Fagade type 2 2'' , Figure2.10 Types of Green Fagades 2. The Current Practice of Green Fagades 2.2.1 Green Facades attached to an opaque wall. M o s t green facades be long to the category of attached to an opaque wall. These range f rom the typical image of an o ld house cove red by ivy, to more advanced technolog ies where the plant is gu ided by steel w i res anchored to an opaque w a l l . T h e category also compr ises meta l l ic or w o o d e n meshes fastened to the w a l l , w i th the purpose of gu id ing the plant. Other innovat ive systems inc lude those deve loped by the French botanist Patr ick B lanc : a 'vegetal w a l l ' insp i red by moss wa l ls f rom the rain forests. G reen facades attached to an opaque wa l l inc lude three speci f ic types: green fagades composed of steel wires, green fagades as moss walls, and green facades composed of green vertical panels. 2.2.1.1 G reen Facade Type 1.1 G r e e n Facades c o m p o s e d of steel w i res Description. The const ruct ion system consists of a substructure of steel wi res, w h i c h are punctua l ly attached to an opaque w a l l by different types of meta l l ic e lements. The substructure creates a meta l l ic gr id that gu ides the plant. The p lant g rows from the ground c lose to the opaque wa l l cover ing the meta l l i c grid [Fig. 2.11]. It grows in wha t is cons idered as a l inear plant pot, f o l l ow ing the l ine of the bu i l d i ng facade. The irr igation system waters the l inear plant pot on the ground by a conven t iona l d r ip irr igation system. Examples. A representat ive examp le of this type of green facade is the Rue des Suisses apartment bu i l d ing des igned by H e r z o g & de M e u r o n in Paris, 2000. The use of steel w i res creates a rhombo ida l grid to gu ide the plants, w h i c h g row f rom the ground [Fig. 2.12]. Figure 2.11 GF Type 1.1 Steel wires attached to an opaque wall 2. The Current Pract ice of G r e e n Facades 2 images waiting for ® permission Figure 2.12 Herzog & de Meuron. Rue des Suisses housing, Paris, 2000.12 Comment. This type of green facade illustrates a subtle manner in which plants are guided through an almost unnoticeable system of steel wires punctually fastened to blank walls. However, the system makes difficult accessibility for maintenance requirements to many parts of the facade. Furthermore, the height of the green facade is limited by the height of the plant. 1 2 El Croquis. Herzog & de Meuron 1998-2002. Issue # 109-110 El croquis editorial. Madrid, 2002 I 2. The Current Practice of Green Facades 1 image waiting for • permission CONSTRUCTION SYSTEM Plants grow from the ground, guided by steel wires punctually attached to the opaque wall Section IRRIGATION SYSTEM Drip irrigation system placed in the ground Section COMMENT Unnoticeable steel wire system guides vines subtly forming a rhomboidal shape, which help create an overgrown, unkempt ambience to the landscape areas 1 3. Yet, one of the shortcomings is that the vines limit the height of the green facade and the system makes difficult the accessibility for maintenance. Table 2.1 Green Fagade Type 1.1 composed of steel wires attached to an opaque wall 3 Roger Sherwood, Rue des Suisses. www.housingprototypes.org 2. The Current Practice of Green Facades Manufacturers. The chief company providing this kind of steel wire system worldwide is Jakob A G / S A 1 4 . It provides the stainless steel wires as well as different options for the fastening system and the shape of the grid, among other things. 3 images waiting for ® permission Figure 2.13 Stainless steel wires of the Jakob AG/SA Company The company "greenscreen" provides a similar system15,that uses metallic mesh instead of stainless steel. Below are some examples of the system. 3 images waiting for ® permission Figure 2.14 Some examples of the green facades by the "greenscreen" company [Marketplace at Oviedo, Florida; California State University, Fullerton, California; National Wildlife Federation, Reston Virginia] 1 4 www.lakobstainlessteel.com Check the green solutions G1 section. 1 5 www.greenscreen.com I 2. The Current Practice of Green Facades Summary Green Fagade type 1 . 1 WSy'ijA WIS 4 I i j • 1 ! • Description: Green fagade composed of steel wires or metallic mesh attached to opaque walls. Examples: Rue des Suisses Apartment complex [Herzog & de Meuron]; Parking buildings in Oviedo, Florida; Fullerton California; and Reston, Virginia. Comment: Unnoticeable steel wires or metallic mesh systems guide vines subtly. However, plants limit the height of the green facade, and the system makes accessibility for maintenance difficult. Table 2.2 Summary of the green facade type 1.1 composed of steel wires attached to opaque walls. 2. The Current Practice of Green Facades 2.2.1.2 Green Fagade Type 1.2 Green Fagades as moss walls Description. In this particular type of green wall, it is worth mentioning the work of the French botanist Patrick Blanc. Attempting to recreate the ability of some plants to grow without soil and under humid conditions, which he had observed in tropical and rain forests, Blanc has developed a particular soil-less 'vertical garden', which consists of: "A metallic frame, a PVC layer, and a layer of felt compose the construction system of the vertical garden. The metal frame is hung on a wall or can be self-standing. It provides an air layer acting as a very efficient thermic and phonic isolation system. A 1cm thick PVC sheet is riveted to the metal frame. This layer brings rigidity to the whole structure and makes it waterproof. A felt layer, made of polyamide, is stapled on the PVC. This felt is rootproof and its high capillarity allow an homogeneous water distribution. The roots grow on this felt. Plants are installed on this felt layer as seeds, cuttings or already grown plants. The density is about thirty plants per square meter. The watering is provided from the top. Tap water must be supplemented with nutrients. Watering and fertilisation are automated." 1 6 Examples. Patrick Blanc has collaborated with well-known architects, such as Jean Nouvel, Renzo Piano, and Herzog & de Meuron. The following figures show some examples of these collaborations, which include Quai Branly Museum in Paris with Jean Nouvel, and CaixaForum building in Madrid with Herzog and de Meuron, among others. 1 6 www.verticalRardenpatrickblanc.com I 2. The Current Practice of Green Fagades Figure 2.15 GF Type 1.2 Green fagades as moss walls 2 image waiting for ® permission Figure 2.16 Cartier Foundation, Jean Nouvel with Patrick Blanc. Paris, 1998. 3 images waiting for ® permission Figure 2.18 Quai Branly Museum J.Nouvel, Paris, 2006. Figure 2.1 7 Quai Branly Museum, J. Nouvel with P. Blanc. Paris, 2006. 2. The Current Practice of Green Facades IRRIGATION SYSTEM Drip irrigation system placed in the PVC sheet Section COMMENT This green fagade provides extreme exuberance contained within geometric boundaries, using high tech elements to make fantasy reality' 7. The system is static [like conventional opaque fagades] and accessibility for maintenance is complex. A r Table 2.3 Green fagade Type 1.2 as moss walls. 1 7 L'Atelier Vert www.frenchgardening.com | 2. The Current Practice of Green Fagades Comment. These green facades ach ieve spectacular exp los ion of different plant species, transmit the thickness and heaviness of ' l i v ing wa l l s ' , and "create diverse green tapestries r ich in texture and tonali t ies of green, and often punctuated by f l owers " 1 8 . The facade system is static, l ike convent iona l opaque facades, and accessib i l i ty for maintenance is diff icult. 3 images wa i t ing for ® permiss ion Figure 2.19 La Caixa Forum, Herzog & de Meuron with Blanc. Madrid, 2007; Les Halles, Blanc, Avignon France, 2006; and Reykjavik City Hall, 1992. These examples achieve spectacular diverse green tapestries, but are still very rigid structures. Manufacturers. A variety of this green facade type is proposed by the company Verdirsystem Inc. 1 9 in Vancouve r , reinterpret ing the env i ronment of plants attached to rocks. It presents two varieties of ' l i v i ng wa l l s ' associated w i th v o l c a n i c rock: in the first one , the 'Verd i r vo l can ic rocks ' are enc losed w i th in a metal l ic mesh , w h i l e in the second one the vo lcan ic rock is self-sustaining [Fig 2.20]. , 8 L'Atelier Vert www.frenchgardening.com 1 9 www.verdirsystems.com I 2 . The Current Pract ice of G r e e n Facades I 2 6 2 images wa i t i ng for ® permiss ion Figure 2.20 Green Fagade Systems of Verdir sytems Inc. Summary G reen Fagade type 1.2 Description: G reen fagades as moss wal l s that grow f rom the opaque w a l l . Examples: Q u a i Branly M u s e u m [Nouvel]; Ca i xaFo rum [Herzog & de Meuron] ; Les Hal les and Reykjav ic C i t y Ha l l [Blanc]. Comment: This green fagade provides passionate exuberance conta ined w i th in geometr ic boundaries. The system is static [like convent iona l opaque fagades], and access ib i l i ty for maintenance is diff icult. Table 2.4 Summary of the green fagade Type 1.2 green fagades as moss walls. 2. The Current Practice of Green Fagades 2.2.1.3 G r e e n Facades Type 1.3 Green Facades c o m p o s e d of green vert ical panels Description. This type of green facade consists of prefabr icated green vert ical panels c o m p o s e d wi th a layer of soi l for plants to grow, con f i ned by a k ind of a cage that enc loses the panel . It is usual ly bui l t as if it were a conven t iona l vent i la ted stone facade, whe re the vert ical green panels are fastened to a meta l l i c substructure attached to the opaque w a l l . G r e e n panels of a speci f ic s ize are fabricated creat ing a rhy thmica l green facade. Examples. G o r d i l l o Studio a n d Seedorf H o u s e are some examples of this type o f green facade in M a d r i d . Both examples are c o m p o s e d of prefabr icated green vert ical panels creat ing a regular square gr id in the facade of 60 by 6 0 c m . Figure 2 .22. Gordi l lo Studio extension, 2002 Madrid Figure 2 .23 Seedorf house, 2004 Madrid. Comment. Th is type of green facade seems to prov ide more con t ro l led l iv ing sk ins, s ince they are bui l t w i th in a gr id and fabricated as independen t modu les . Access ib i l i t y for ma in tenance is comp lex , as in the prev ious types, a l though the rep lacement is easier, w i th the opt ion of rep lac ing one modu le at a t ime. This c o m m e n t a lso app l ies to the f o l l ow ing examples . I 2 . The Current Pract ice of G reen Facades Figure 2.21 Type 1.3 green vertical panel Architect Duncan Lewis, in collaboration with Hugues Klein and Pierre Baumann, introduces similar green vertical panels for the West School Complex in Obernai, France. In this case, the dimension of the green module is 60 by 120cm, which interacts with the surrounding forest. However, the green fagade system is static. 3 images waiting for ® permission Figure 2.25 Obernai West School, France 2006 2 0. In the 2005 World Exhibition carried out in Aichi, Japan, green vertical panels - which were called bio-lung walls - were exposed. "The name Bio-lung was intended to communicate that this kind of structure can use the power of plants to function like a lung for cities" 2 1. 2 images waiting for ® permission Figure 2.26 Green vertical panels exhibited at Aichi Expo, Japan 2005. 2 0 Detail Magazine #1 2006 [Spanish edition] 2 1 World's Largest Green Wall - the 'Bio-Lung', www.japanfs.org I 2. The Current Practice of Green Fagades • • • • • I I H H l H H H i Green Facade Type 1.3 G reen Fagades c ompo sed of Green vert ical panels CONSTRUCTION SYSTEM Section The mode l is c ompo sed by w i th a layer of soi l for plants to grow, a thermal insulat ion layer, conf ined altogether in a cage that encloses it IRRIGATION SYSTEM Dr i p irrigation system placed w i th i n the panel interconnect ing al l of them Section COMMENT This type of green facade achieves more cont ro l led greenery, m o d e l l i n g it w i th in a regular grid. The system is static, and, a l though replacement of the modules is easy, access ib i l i ty for maintenance is diff icult. Table 2.5 Green facade Type 1.3 green facades composed of Green vertical Panels 2. The Current Practice of G reen Fagades Vancouver's aquarium includes another variety of green vertical panel facade. Designed by the landscape architect Randall Sharp, the panels are framed in plastic boxes attached to a metallic substructure which is attached to the opaque wall. The system provides local plant diversity and environmental benefits 2 2. Figure 2.27. Green vertical panels at Vancouver's Aquarium, 2006. In a different way, Herzog & de Meuron's green panels designed for the facade of the basement of Prada in Tokyo, also constitute another variety of green vertical panels. In this case, the modules are enclosed with a special anti-root cloth, which creates a mosaic that adapts to the different inclinations of the wall. Figure 2.28 Herzog & de Meuron's green vertical panels at Prada Store. Tokyo 2005. Steve Whysall. More than a Wal l . Vancouver Sun article November 10th, 2006. 2. The Current Practice of G reen Facades Manufacturers. The Spanish company Intemper S.A manufactures and installs the green vert ical panels descr ibed in the case of the G o r d i l l o studio and Seedorf House . The green vert ical panels are r iveted to the meta l l i c profi le, and consist of vert ical meta l l ic L prof i les attached to an opaque wa l l . The modu le of 60x60cm conta in ing the so i l , the insulat ion e lement, and plants is enc losed by a perforated meta l l i c plate and incorporates the irrigation system [Fig 2.29]. The C o m p a n y Elevated Landscape Techno logy Inc [ELT] from Vancouve r has deve loped a s imilar green vert ical panel system, ca l led the L iv ing W a l l System. In this case, the m o d u l e consists of plastic rectangles subd iv ided by mini -cel l s where the soil is p laced for the growth of plants. 1 image wa i t i ng for ® permiss ion Figure 2.29 Intemper's green panel Figure 2.30 ELT's Living Wal l Summary Green Facade type 1.3 fl i i fi> G» w b Description: G reen vert ical panels create a regular grid in the facade. Examples: G o r d i l l o Studio extension; Seedorf House; Obe rna i West Schoo l ; Learning Centre at Vancouve r Aqua r i um; Prada Store in Tokyo. Comment: Through green vertical panels, fagades are modulated in a regular square gr id. A l though access ibi l i ty for maintenance is diff icult, it is easier than in previous types due to the poss ibi l i ty of replacement of the modules . The system is static. Table 2.6 Summary of the green facade Type 1.3 composed of green vertical panels. 2. The Current Practice of G reen Fagades 32 2.2.2 Green Facades attached to a transparent wall The major attribute in green facades attached to transparent wal ls versus those attached to opaque ones is that the greenery is not on l y perce ived from the outdoor space, but also f rom the indoor space. In this sense, l ight passes through the green mass creating interesting scenes of lights and shadows as we l l as different co lours . A t the same t ime, the system permits solar energy to pass through the green facade into the indoor space, p rov id ing the opt ion to passively heat the bu i l d ing . G r e e n facades attached to a transparent wa l l are d i v ided into two main types: in the first one , the greenery is located between two transparent layers, whereas in the second one , the greenery represents the outdoor layer of the system. 2. The Current Pract ice of G reen Facades 2.2.2.1 G r e e n Facade T y p e 2.1 G r e e n e lement between two transparent layers Description. This green facade system is c o m p o s e d of three layers: two transparent layers in the extremes [ indoor and outdoor] with the green e lement in the midd le . Plants g row from a pot and are gu ided by metal l ic wires, meshes, or even by a sort of rope mesh similar to f ishing nets. T h e irrigation system consists of watering each plant pot and connects all plant pots. Examples. In the Univers i ty of Arts and H u m a n Sc iences bu i ld ing of G r e n o b l e , France, [Lacaton & Vassal, 2001], the inner layer is g laz ing and the external one is po lycarbonate. T h e facade acts as a thin greenhouse, and the venti lation needed by the plants between the two layers is p rov ided by open ings in the external po lycarbonate layer. "These greenhouses, like s lender transparent blades to north and south, create a filter of plants. T h e y prov ide an innovative image, at o n c e chang ing and poetic, match ing the bui ld ing ' s purpose and the artistic d imens i on of the classes he ld in i t " 2 3 <l] . a l ' l t Figure 2.31 Type 2.1 Green element between 2 images wait ing for ® permiss ion two transparent layers Figure 2.32 Arts and Human Sciences building, Grenoble, 1995 & 2001. Lacaton & Vassal. An example of green facade between two transparent layers: a polycarbonate screen is the external layer, a glazing facade is the internal layer, and plants with their pots grow between the two layers. 2 3 Frederic Migayrou and Marie-Ange Brayer. Archilab. Radical Experiments in Global Architecture. Thames and Hudson, New York, 2001 I 2. T h e Current Pract ice of G r e e n Facades I 34 Comment. The most remarkable aspect of this type of green facade is the poss ib i l i ty it prov ides to see through it. Consequen t l y , the greenery is perce ived both f rom the inside and f rom the outs ide, and the fagade permits l ight to pass through it, therefore faci l i tat ing a solar energy ga in . Another examp le of this type of green facade is one presented as part of the Casa Barce lona 05 project in the Cons t rumat Fair 2 0 0 5 . The des ign attempts to condense a greenhouse into a th in , doub le g laz ing f a c a d e 2 4 . The outdoor layer is c o m p o s e d of so l id po lycarbonate louvers on an a l u m i n i u m frame. The indoor layer consists of s l id ing g laz ing and a l u m i n i u m panels . The greenery is p laced in the intermediate layer, w h i c h is also moveab le by a s l id ing system [Fig 2.33] In this case, the different movemen t opt ions p roposed by this green facade of po lycarbonate louvers w i th s l id ing g laz ing and green panels, p rov ide the necessary f lex ib i l i ty for the facade to accommoda te different c l ima t i c cond i t i ons and user needs. 4 images wa i t i ng for • permiss ion Figure 2 .33 Casa Barcelona 05 - Green Facade. F. Pich-Aguilera, Intemper S.A. and Jon Laurenz [Rafael Escola Foundation], This green facade includes different movement options - polycarbonate louvers, sliding glazing and greenery- providing the necessary flexibility for the facade to adapt to different conditions. Figure 2 .34 Casa Barcelona 05 2 4 Laura Arenas. Casa Barcelona 05 - Green Facade. Construmat - Fira de Barcelona, Ingoprint S.A. Barcelona, 2006. | 2 . The Current Pract ice of G reen Facades Green Fagade Type 2.1 G r e e n e lement be tween two transparent layers H H H H H H H H H H B H i l i H H H r CONSTRUCTION SYSTEM Polycarbonate louvers in the external layer; s l i d ing g laz ing and a l u m i n i u m panels in the internal layer; and the moveab le greenery is p laced in the m idd le Section IRRIGATION SYSTEM D r i p irr igation system inc luded in plant pots, w i th a water cavi ty of 8 c m b e l o w the soi l COMMENT The system permits l ight and sun energy to pass through the fagade, and adapts to user needs by in t roduc ing the s l id ing movement . The greenery is not perce ived di rect ly , but insinuated through the first g laz ing layer. Table 2 .7 Green fagade Type 2.1 Green element between two transparent layers. 2 . The Current Pract ice of G r e e n Fagades Summary Green Facade type 2.1 4 A i i l Description: The greenery is placed between two transparent layers. Examples: Arts and Human Science building, Grenoble [Lacaton & Vassal]; Green Facade project in Casa Barcelona05, Construmat Fair. Comment: The fagade permits light and sun energy to pass through it. The greenery is perceived from both the inside and the outside. From the outside it is insinuated through the external transparent layer. Depending on the system, it provides flexibility for the facade to change in tandem with the outdoors. Table 2.7 Green facade Type 2.1 green element between two transparent layers. 2. The Current Practice of Green Facades 2.2.2.2 G r e e n Fagade Type 2.2 G r e e n external layer and g lazed internal layer Description. The general compos i t i on of this type of green fagade consists of a g lazed inner layer and a green external layer. The green e lement is usual ly gu ided by meta l l ic m e s h , w i res , or w o o d e n sticks. Examples. Aba los & Herreros in the Gymnas t i c pav i l ion in the Retiro Park, M a d r i d , [2002] propose metal l ic mesh to gu ide the growth of the plant in the external layer. The plant grows f rom the f loor sur round ing the bu i l d i ng , and the irr igation system is e m b e d d e d w i th in the so i l . The inner layer consists of a translucent po lycarbonate pane l , w h i c h prov ides the hermetec ism for the fagade. Figure 2.35 GF Type 2.2 green element as the external layer Figure 2.36 Gymnastic pavilion Abalos & Herreros, El Retiro Park. Madrid, 2002. Comment. Th is type of green fagade enables light and sun energy to pass through the fagade, s ince they are attached to a transparent layer. The greenery can be seen f rom both the inside and the outs ide. H o w e v e r , the system is static, w i th no f lex ib i l i ty for the user to choose his re lat ionship wi th the outdoor space, and the height of the green fagade is l imi ted by the growth of the plant. 2 . The Current Pract ice of G r e e n Fagades I 38 G r e e n Facade Type 2.2 G r e e n external layer and g lazed internal layer CONSTRUCTION SYSTEM M e t a l l i c mesh guides the plant growth in the external layer, a n d a translucent po lycarbonate panel in the inner layer enc loses the green facade. Section IRRIGATION SYSTEM The dr ip irr igation system is e m b e d d e d in the so i l . Section 'I L-I COMMENT This type of green facade enables light and sun energy to pass through the facade, and the greenery is seen f rom both the inside and the outs ide. It is a static so lut ion w i th no f lex ib i l i ty for the user and w i th the height l imit due to the plant g rowth . Table 2.9 Green facade Type 2.2 Green external layer and glazed internal layer 2. The Current Pract ice of G r e e n Facades The C o n s o r c i o Bu i l d i ng in Santiago de C h i l e , des igned by Enr ique Browne, is an office bu i ld ing wi th a green fagade c o m p o s e d of a g lazed inner layer, wi th metal l ic b l inds in the outdoor layer, and a green e lement in the intermediate layer. The greenery grows from plant pots located on each f loor and is gu ided by the meta l l ic b l inds of the outdoor layer! 5 images wa i t i ng for ® permiss ion Figure 2 .37 Consorcio Building Enrique Browne Santiago Chile 1993. House in Paul Harris Street, Chile Figure 2.38 Consorcio building 1982 fagade detail In add i t ion to same attributes as the prev ious examp le , in this case the green fagade height is not l imi ted by the growth of the plant because it is p lanted on each f loor, but it is still a r igid so lut ion. The Pergola Bu i l d i ng and the J&R Bu i ld ing , both des igned by Bruno Stagno and located in Costa Rica propose convent iona l g laz ing fagades wi th a "green screen" attached as an independent p lane. Therefore, there is no f lex ib i l i ty , and its height is still l imited by the growth of the plant. 3 images wa i t ing for ® permiss ion Figure 2 .39 Pergola Building Bruno Stagno, Costa Rica 2003. I 2 . The Current Pract ice of G reen Fagades J&R Building, Costa Rica 2000 40 Archi tects Edouard Francois and D u n c a n Lewis propose an innovat ive construct ion material w i th in this type of green facade: trees. They co l laborated in the projects of the Ho l i day Houses in Jupi l les and in the Thia is S c h o o l , both in France in 1996 . In both projects trees serve as a facade const ruct ion mater ia l . 5 images wa i t ing for ® permiss ion Figure 2.41 Houses in Jupilles Figure 2.40 Holiday Houses in Jupilles, 1996 Figure 2.42 Thiais School 3 images wa i t ing for ® permiss ion Figure 2.43 Thiais School. France, 1996" In both cases green elements are v is ib le f rom both sides and the dayl ight and sun energy pass through the facade. The system is static, and the height is l imited by the growth of the trees. 'Edouard Francois and Duncan Lewis. Construire avec la nature. Edisud, Aix-en-Provence 1999. 2 . The Current Pract ice of G reen Facades 41 Manufacturers. The c o m p a n y Jakob A G / S A manufactures different stainless steel w i res or metal l ic meshes to guide the greenery for this type of green facades. 3 images wa i t ing for c permiss ion Figure 2.44 Projects of green facades with Jakob AG/SA company system Summary Green Facade type 2 .2 Ii" 4 i I' 1 % i i> I Description: The greenery is p laced in the external layer and the transparent e lement in the internal layer. Examples: Gymnas t i c Pav i l i on in M a d r i d [Abalos & Herreros] ; C o n s o r c i o B ldg and H o u s e in Paul St. in Sant iago [Browne]; Pergo la B ldg and J&R B ldg in Cos ta Rica [Stagno]; H o l i d a y Houses and Thiais Schoo l in France [Francois and Lewis] Comment: The greenery is v is ib le f rom both the inside and the outs ide. It enab les light and solar energy to pass through it. Th is system does not p rov ide f lex ib i l i ty for the facade to change its re lat ionship w i th the outdoors . Table 2.10 Green fagade Type 2.2 Green external layer and glazed internal layer. 2. The Current Pract ice of Green Facades The following table compiles the different types of green facades identified in this chapter, with a preliminary and general analysis of the appropriateness of each type. Summary Types of Green Fagade Attached to an opaque wall GF 1. 1 with steel wires Eli Description: Green fagade composed of steel wires or! metallic meshes attached to opaque walls. Examples: Rues des Suisses Apartment complex [Herzog & de Meuron]; Parking buildings in Oviedo, Florida; Fullerton California; and Reston, Virginia. Comment: Unnoticeable steel wires or metallic mesh systems guide vines subtly. Plants limit the height of the green fagade and the system makes difficult the accessibility for maintenance. Attached to an opaque wall GF 1.2 as mc 1! JSS walls i \ Description: Green fagades as moss walls that grow from the opaque wall. Examples: Quai Branly Museum [Nouvel]; CaixaForum [Herzog & de Meuron]; Les Halles and Reykjavic City Hall [Blanc]. Comment: This green fagade provides passionate exuberance contained within geometric boundaries. The system is static (like conventional opaque fagades), and accessibility for maintenance is difficult. Attached to an opaque wall GF 1.3 as Green Panels Description: Green vertical panels create a regular grid in the fagade. Examples: Gordillo Studio extension; Seedorf House; Obernai West School; Learning Centre at Vancouver Aquarium; Prada Store in Tokyo. Comment: Through green vertical panels, fagades are modulated in a regular grid. Although accessibility for maintenance is difficult, it is easier than in previous types due to the possibility of replacement of the modules. The system is static. Attached to a transparent wall GF 2. 1 E i i Set. y B •wo layers Description: The greenery is placed between two transparent layers. Examples: Arts and Human Sciences building, Grenoble [Lacaton & Vassal]; Green Fagade project in Casa Barcelona05, Construmat Fair. Comment: The fagade permits light and solar energy to pass through it. The greenery is visible from both the inside and the outside. Depending on the system, it provides flexibility for the fagade to change its relationship with the outdoors. Attached to a transparent wall GF 2.2 ( >ee 4 I J A n in external i t Description: Greenery is placed in the external layer and the transparent element in the internal layer. Examples: Gymnastic Pavilion in Madrid; Consorcio Bldg and House in Paul St. in Santiago; Pergola Bldg and J&R Bldg in Costa Rica ; Holiday Houses and Thiais School in France Comment: The greenery is visible from both the inside and the outside. The fagade enables light and solar energy to pass through it. The solutions are often static and do not provide flexibility for the fagade to change its relationship with the outdoors. Table 2.11 The five major types of green fagades. 2. The Current Practice of Green Fagades This analysis of the current practices for bu i l d ing green facades shows part of their potential as w e l l as the classi f icat ion of the different systems of construct ion. A l l of the examples and readings analysed reveal green facades are be ing bui l t as a surface of expression pretending to participate in the current responsive architecture. H o w e v e r , they are not wor r ied about further impl icat ions that might be i nvo l ved , such as the habitat, hydro logy , c l imate, biodiversi ty, and user needs. Thus , in exam in ing this c lassi f icat ion of the types of exist ing green facades, there arises a need for eva luat ing green facades against a broader range of possibi l i t ies they c o u l d offer. In this sense the thesis deve lops a f ramework in order to incorporate these aspects and to prov ide a series of attributes to assist designers in def in ing green facades w i th a w ider knowledge of the subject. These, among other aspects, are studied in the f o l l ow ing chapter. 2. The Current Pract ice of G reen Facades 3 GREEN FACADES FRAMEWORK The prev ious analysis of ex is t ing green facades shows the possibi l i t ies that they offer, but also their cha l lenges. It detects the need to identify a larger range of opportuni t ies afforded by green facades. These can be approached f rom many different perspectives such as, economica l l y , b io log ica l ly , ag ronomica l ly, eco log ica l l y , mechan ica l l y , etc. These diverse v iewpo in ts w o u l d provide different opportuni t ies such as: Cost benefits. The reduct ion in c o o l i n g and heating that green facades can provide imp ly consequences of direct e c o n o m i c savings. Biological benefits. G reen facades cou ld offer the opportuni ty to enhance the activity of other l i v ing organisms. A deeper study cou ld analyse h o w different plant species enhance other k inds of urban w i ld l i fe , as we l l as h o w different plants interact wi th these wi ld l i fe . Plants behaviour. There is also the opportuni ty to f ind the most appropriate plant for a part icular case. To study the evapotranspirat ion, water needs, and metabo l ism, and to relate them to different types of green facades in order to assign them to a particular c l imate. It cou ld also inc lude the study of h o w different plants inf luence the fragrances of the surroundings, or the characterist ics of different types of soi ls, needs of nutrients, etc. Ecological processes. The inf luence of green facades in urban hydro logy cou ld be another oppor tun i ty to be stud ied. In add i t ion , h o w the sun exposure affects different plants cou ld also be i nc luded . Manufacturing opportunity. G r e e n facades c o u l d mix the convent iona l manner of fabricat ing the construct ion materials of facades, such as lattices and bl inds; wi th the w a y plants are " fabr icated" in the nursery. A manufacturer w o u l d look for the most efficient process to create green facades, i nc lud ing the t ime that plants need to ach ieve the ideal size required for a project. This w o u l d also inc lude the study of the transportation and management on site. I 3 . G r e e n Facades Framework H o w e v e r , this thesis focuses on an architectural perspect ive, inc lud ing the scale of landscape architecture and urban space. It identif ies a series of opportunit ies c o m b i n i n g the current architectural trend of the responsive architecture, wi th the trend of an architecture that is sensible to its env i ronment . Together w i th this, the ident i f icat ion of these opportuni t ies fo l lows an analysis of a series of research studies o n the benefits of greenery to the bui l t env i ronment ci ted in current l iterature. D u e to the l imi ted literature on green facades, the contr ibut ion of green facades to their sur round ing env i ronment is assumed to be simi lar to that of other green surfaces such as trees, grass, parks, or green roofs to the bui l t env i ronment . Cons ider ing these architectural trends and co l laborat ing w i th these research studies, this sect ion condenses and identif ies the major opportuni t ies afforded by green facades into the fo l l ow ing six areas: Human Comfort [HQ; Expressive capacity [EC]; Air and Water Quality [AWQ]; Indoor-Outdoor Relationship [IOR]; Urban Biodiversity [UB]; and Carbon Neutral Architecture [CNA]. Some of the six areas affect both sides of bu i l d i ng facades - indoor and outdoor spaces, and some perform differently depend ing on the or ientat ion of the facade. These w i l l therefore be analysed in considerat ion of these variables where appropr iate. Th is ident i f icat ion of the opportuni t ies in green facades, f rom an architectural perspect ive, together w i th the c lassi f icat ion of the types of green facades, establishes the basis needed to deve lop the green facades f ramework. In evaluat ing these attributes, the f ramework reflects c lear ly the crucial di f ference between the two main categories of green facades - attached to opaque wal ls , and attached to transparent wa l ls . The transparent green facades are v is ib le from both the outside and the inside, o p e n i n g the oppor tuni t ies in green facades to the indoor space. This means they perform m u c h better than the opaque green facades, in terms of indoor comfort temperature, reduct ion in energy d e m a n d , indoor v isual comfort , psycholog ica l benefits, etc. O n the contrary, opaque green facades can on l y part ial ly ach ieve many of these opportuni t ies. In add i t ion, some of the attributes are on l y evaluated for opaque green wal ls , such as the acoust ic inf luence, and others are on ly evaluated for transparent green facades, such as the inf luence on indoor visual comfort . I 3. G reen Facades Framework T h e f o l l o w i n g s e c t i o n e x p l a i n s e a c h o f t h e i d e n t i f i e d o p p o r t u n i t i e s , a s w e l l a s t h e e v a l u a t i o n p r o c e s s f o l l o w e d i n e a c h o f t h e m . 3.1 Human Comfort [HC] R e c e n t r e s e a r c h s u g g e s t s t h e o p p o r t u n i t y o f g r e e n f a g a d e s t o i m p r o v e h u m a n c o m f o r t c o n d i t i o n s . T h e s e i m p r o v e m e n t s f a l l i n t o f i v e m a i n c a t e g o r i e s : t h e i n f l u e n c e o f g r e e n f a g a d e s i n Comfort Temperature and Reduction in Energy Demand, Acoustic insulation, Visual C o m f o r t , Humidity, a n d Psychological Benefits. T h e s e a r e c o n s i d e r e d f r o m b o t h t h e i n s i d e a s w e l l a s t h e o u t s i d e o f t h e f a g a d e . 3.1.1 Comfort Temperature and Reduction in Energy Demand T h e a b i l i t y o f g r e e n f a g a d e s t o i n f l u e n c e t h e c o m f o r t t e m p e r a t u r e is t h e m o s t s t u d i e d a s p e c t . T h e s e r e s e a r c h s t u d i e s f o c u s o n t h e i n f l u e n c e o n i n d o o r c o m f o r t t e m p e r a t u r e , t h e d i r e c t c o n s e q u e n c e o f w h i c h is a c o n t r i b u t i o n t o r e d u c i n g t h e e n e r g y d e m a n d i n b u i l d i n g s i n t e r m s o f a i r c o n d i t i o n i n g a n d h e a t i n g . R e g a r d i n g t h e i n f l u e n c e o n o u t d o o r t e m p e r a t u r e , t h e a n a l y s i s o f t h e r o l e o f g r e e n s u r f a c e s , s u c h a s p a r k s a n d g r e e n c a n o p i e s , t o r e f r e s h t h e o u t d o o r t e m p e r a t u r e , a s s u m e s g r e e n f a g a d e s w o u l d c o n t r i b u t e i n a s i m i l a r m a n n e r . T h e i n f l u e n c e o n b o t h i n d o o r c o m f o r t t e m p e r a t u r e [ f r o m i n s i d e ] , a n d o u t d o o r c o m f o r t t e m p e r a t u r e [ f r o m o u t s i d e ] a r e s p e c i f i e d b e l o w . 3. G r e e n F a g a d e s F r a m e w o r k From inside. G r e e n facades contr ibute s igni f icant ly to the reduct ion of the indoor air temperature in summer , s ince they reduce the external air temperature of a west or ientat ion up to 4°C o n a clear August day in F u k u o k a , Japan; [A. H o y a n o , 1988 2 6 ] and by 5°C, in summer [D. H o l m , 1989] in South A f r i c a 2 7 . 1 Figure 3.1 Contribution of green facades to indoor Comfort Temperature. Therefore, green facades refresh and coo l the facade in summer cont r ibut ing to indoor comfor t temperature, and if they are attached to transparent wa l ls this means a reduct ion in air cond i t i on ing of up to 4 5 % ; and of up to 2 3 % in heat ing [Laurenz, 2 0 0 5 ] 2 8 . 2 6 Akira Hoyano. Climatological Uses of Plants for Solar Control and the Effects on the thermal Environment of a Building. Ed. Energy and buildings. Vol 11, no.1-3, pp 181-199. Tokyo 1988. 2 7 D. Holm. Thermal Improvement by means of Leaf Cover on External Walls - A simulation Model. Ed. Energy and buildings. Vo l 14, pp 19-30. South Africa. 1989. J. Laurenz. Natural Envelope. The Green element as a boundary limit. The 2005 World Sustainable Building Conference. Tokyo, 2005 3. G reen Facades F ramework I 4 8 From outside. G r e e n fagades amel iorate c i t ies ' urban heat islands by c o o l i n g the air temperature of their sur round ings . Regard ing the measures on temperatures taken in N e w York ' s Centra l Park [C. R o s e n z w e i g & W . S o e c k i , 2 0 0 6 2 9 ] , a as w e l l as in Tokyo ' s Sh in juku G y o e n Park [Hon jo , T 2 0 0 2 ] 3 0 , both suggest the temperature ins ide the park was a round 2°C lower than it was outs ide of the park. M o r e o v e r , C . Rosenzwe ig ' s study suggests Centra l Park a lso contr ibutes to reduc ing its nearby air temperature by between 2-5°C. This thesis extrapolates these f indings assuming that green fagades, w h e n app l ied to the bu i ld ings of a b lock or a c o u p l e of b locks , cou ld have s imi lar inf luences as parks, i nc l ud ing the sur round ing area. Th is opens up the possib i l i ty for cons ide r ing green fagade bu i ld ings as the n e w lungs of the ci ty in the future [Fig 3.2]. i l l fG B raSKf IBfSijet w4i&* i £ f vLl\ K»\ m m m m m m Figure 3.2 Green fagade A l though more accurate research on green fagades w o u l d be needed to verify this assumpt ion , this buildings as the new lungs sect ion conc ludes green fagades c o u l d contr ibute to reduce nearby temperatures by an average of o f c i t i e s -a round 2 °C . 2 9 C. R o s e n z w e i g , W . S o l e c k i , M i t i g a t i n g N e w Y o r k c i t y ' s heat i s land w i t h u rban forestry, l i v i n g roofs, a n d l ight surfaces. C o l u m b i a U n i v e r s i t y a n d Hun te r Co l l e ge , N Y . 2 0 0 6 . http://www.epa.gov/heatisland/resources/pdf/, and http://ams.confex.com/ams/pdfpapers/103341.pdf 3 0 H o n j o , T., Sugawara H., M i k a m i , T., Nar i ta , K., K i m u r a K. and Kuwata , N . Observation of thermal effect of Shinjuku Gyoen Park, A M S Fou r th S y m p o d i u m o n the U r b a n Env i ronment , 2 0 0 2 , p84 -85 . I 3. G r e e n Fagades Framework The a lbedo* di f ferences of surfaces are also remarkab le : "Pavement radiates as much as 50 percent more heat than does grass." 3 , A c c o r d i n g to the research on different surfaces for energy t ransmission and absorpt ion [Ciemat, 1994 3 2 ] , vegetat ion absorbs 8 0 % of the solar radiat ion - of w h i c h 7 0 % is used for plants ' transpirat ion - a n d transmits 0 % . The mean temperature of leaves is the same as the air temperature. G reen fagades can signif icant ly reduce the urban heat is land effect, by not transmitt ing heat to other surfaces s ince their temperature and the air temperature are the same. The f o l l ow ing graph [Fig 3.4] compares the temperature that different surfaces w o u l d reach, show ing the signif icant cont r ibut ion of green fagades to reduc ing urban heat islands. 1 image wa i t ing for ® permiss ion Figure 3.3 Various Environment Albedos" 1 image wai t ing for ® permiss ion A fagade comple te ly covered by vegetation Figure 3 . 4 3 3 Surface temperatures for different colours on fagades. Considering green fagade temperatures would be the same as the external temperature [6] it is evident that they significantly contribute both to indoor temperature insulation capacity and to reducing urban heat islands. * Albedo is the fraction of solar radiation reflected by a surface or object, often expressed as a percentage. [From IPCC Report. Croup I: The Scientific Basis] 3 ' Anne Whiston Spirn. The Granite Garden. Basic Books Inc, New York 1984. 3 2 Ciemat, Sevilla University, Andalucia Autonomic Government. Control climatico en espacios abiertos. EXPO'92. Madrid 1994. 3 3 Herzog, Krippner, Lang. Facade Construction Manual. Birkhauser publisher Munich 2004 I 3. G r e e n Fagades Framework I , 1 Figure 3.5 Contribution of green facades to outdoor temperature. Evaluation The f ramework deve lops a s imp le way of measur ing the potent ial of green facades to in f luence the comfor t temperature and the reduct ion in energy d e m a n d . It consists of eva luat ing the cont r ibut ion of each type of green facade based on a f ive point scale of va lues or percentages, w h i c h ranges from the lowest cont r ibu t ion to comfor t temperature and the reduct ion in energy d e m a n d [ L O V V - 0 ] , to 2 0 % cont r ibu t ion [0.2]; 4 0 % cont r ibu t ion [0.4]; and so o n , to the highest cont r ibut ion 1 0 0 % [ H I G H = 1], [Fig 3.6]. 3. G r e e n Facades F ramework L O W H I G H Comfor t Temperature and Reduc t ion in 0 0.2 0.4 0.6 0.8 1 Energy D e m a n d Figure 3.6 Range of values for the evaluation of the contribution to comfort temperature and reduction in energy demand It is important to remark h o w differently the two main categories of green facades [opaque and transparent] per form in their cont r ibut ion to comfor t temperature and reduc t ion in energy d e m a n d . This is ma in ly because transparent green facades a l l o w sun energy to pass through them, w h i l e opaque green facades d o not, a l though they insulate thermal ly more than the transparent ones. In this sense, w h e n eva luat ing green facades, the f ramework makes a clear d is t inct ion in the per formance of these two main categories of green facades. Together w i th this, the green facades f ramework makes a series of assumpt ions to evaluate the in f luence of the types of green facades to the comfort temperature and to the reduct ion in energy d e m a n d , as fo l l ows : - Orientation. The ma in assumpt ion is related to the or ientat ions of green facades. In this sense, f indings f rom research studies are most ly associated w i th west-or iented green facades. Based on the solar movemen t and the behav iour of facades for different or ientat ions, the f ramework assumes that a green facade performs s imi la r ly for east, west , and south or ientat ions, in terms of its in f luence on comfor t temperature and energy d e m a n d in bu i ld ings. Thus , it proposes two main groups of facade or ientat ions w h i c h are: nor th , and south, east-west. 3. G reen Facades F ramework • North. Cons ide r i ng the north orientated facades, the assumpt ion is that there are not signif icant solar gain opt ions through these facades, be ing more important to thermal ly insulate the bu i l d ing . Consequen t l y , in general , those green facades attached to opaque wa l l s [green facade category 1] ach ieve a higher contr ibut ion to comfort temperature and reduct ion of energy d e m a n d than those attached to transparent wal ls [green facade category 2]. Mo reove r , w i th in the category of green facades attached to opaque wal ls , those ca l led "moss wa l l s " [type 1.2] and "green panels" [type 1.3] perform better than those " composed of steels w i res " [type 1.1], s ince they prov ide higher thermal insulat ion required by north facades. • South, east-west. O n the contrary, the f ramework evaluates the types of green facades in a south-east-west or ientat ion just the oppos i te as in a north or ientat ion. This is due to the assumpt ion that those green facades attached to transparent wal ls and wi th dec iduous plants a l l o w solar energy gain through the g laz ing in colder months, he lp ing, consequent ly , to improve the indoor comfor t temperature and to reduce the heating demand by bui ld ings. O n the other hand, in summer , the densi ty of plants protects the facade from solar heat, he lp ing to improve the indoor comfort temperature and to reduce the air cond i t ion ing d e m a n d by bu i ld ings. G r e e n facades attached to opaque wal ls do not prov ide the opt ion of solar gain passing through them in winter , and thus, do not perform as we l l in these or ientat ions. 3. G reen Facades Framework - Scale. The second assumpt ion made by the green facades f ramework relates to the scale of green facades. The f ramework is based on research studies on green facades w h i c h analyse green surfaces in their ful l length and w id th . These inc lude, for instance, a study of a green facade attached to an opaque wa l l cover ing a west facing room of the Ts inghua Univers i ty Lybrary compared to an uncovered wa l l [Di and W a n g , 1999 3 4 ] . Another example is the comparat ive behav iour of a veranda wi th and wi thout a v ine sunscreen [A .Hoyano , 1988 3 5 ] . These research studies obta in data f rom different sensors located in different points from the exterior greenery to the indoor rooms. Therefore, accord ing to these research studies, the scale that the f ramework cons iders w h e n evaluat ing the contr ibut ion of green facades to the comfort temperature and the reduct ion in energy d e m a n d is the behaviour of a green facade that covers a storey comp le te l y f rom f loor to ce i l i ng - vert ical l imit - and the hor izontal l imit of the indoor r o o m , enc losed by the indoor wa l ls [Fig. 3.7]. 3 4 H.F. Di and D . N . Wang. Cooling effect of ivy on a wall . Experimental Heat Transfer, Volume 12, Issue 3 July 1999 , pages 235 - 245 3 5 Akira Hoyano. Climatological Uses of Plants for Solar Control and the Effects on the thermal Environment of a Building. Ed. Energy and buildings. Vol 1 1 , no.1-3, pp 181-199. Tokyo 1988. 3. G reen Facades F ramework I 54 elevation section P | a n v i e w h — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — -t : horizontal limit Fig 3.7 The scale considered by the framework to evaluate the contribution of green facades to comfort temperature and the reduction in energy demand is limited vertically from the floor to the ceiling of the room - from slab to slab - and horizontally by the horizontal limits of the room. Thus, the minimum requirements of green facades in order to consider their contribution to comfort temperature and reduction in energy demand are that the facade should cover the room completely from floor to floor vertically and within its wall limits horizontally. If not, green facades would contribute only partially to these aspects but today there is no way to evaluate that. According to this assumption, the contribution of green facades to these aspects could be extrapolated to a larger scale such as those rooms that are completely covered by greenery both horizontally and vertically, as well as the facade of a building completely covered by vegetation. In this sense, the framework evaluates the contribution of the types of green facades to the comfort temperature and the reduction in energy demand as follows: 3. Green Facades Framework Type of Green Facade I Orientation Contribution to Comfort Temperature GF Type 1.1 North South-east-west LOW HIGH 0 0 . 2 0 .4 0 .6 0 . 8 1 LOW HIGH 0 0 .2 0 .4 0 . 6 0 . 8 1 GF Type 1.2 North LOW HIGH 0 0 . 2 0 . 4 0 . 6 0 . 8 1 South-east-west LOW HIGH 0 0 .2 0 .4 0 . 6 0 . 8 1 GF Type 1.3 North LOW HIGH 0 0 . 2 0 . 4 0 . 6 0 . 8 1 South-east-west LOW HIGH 0 0 .2 0 .4 0 . 6 0 . 8 1 GF Type 2.1 North LOW HIGH 0 0 . 2 0 . 4 0 . 6 0 . 8 1 South-east-west LOW HIGH 0 0 . 2 0 . 4 0 . 6 0 . 8 1 GF Type 2.2 1 North South-east-west LOW HIGH 0 0 .2 0 .4 0 .6 0 . 8 1 LOW HIGH 0 0 . 2 0 . 4 0 . 6 0 . 8 1 Table 3.1. Contribution of green facades to comfort temperature and the reduction in energy demand depending on the orientation of the facade 3. Green Facades Framework 56 These results are represented us ing a sp ider-web graphic scale il lustrated in figure 3.8. This graph v isual ly descr ibes the suitabi l i ty of each type of green facade for different orientations, in terms of its cont r ibut ion to comfort temperature and reduct ion in energy demand . E S - 1 s Figure3.8 This spider-web graph shows the suitability of each type of green facade for different orientations, in terms of its contribution to comfort temperature and reduction in energy demand, reflecting the strengths and weaknesses of the different orientations. In this example the hypothetical green facade would perform very well for a north orientation, and not very well for the others. In this sense, the four fagade orientat ions are represented in each of the sides of the cross [N , S, E, and W ] . The contr ibut ion to comfort temperature and reduct ion in energy demand is shown in a grey hatch. It is ach ieved by interpret ing that the higher the contr ibut ion of the particular green fagade, the further away the d i rect ion stands f rom the axis. This scale graph reveals the strengths and weaknesses of each type of green fagade h ighl ight ing the areas for improvement . The f o l l ow ing chart incorporates this k ind of graph for each type of green fagade, w h i c h summar izes their cont r ibut ion to comfor t temperature and reduct ion in energy demand . It shows h o w transparent green fagades perform quite w e l l in south east and west orientations, reduc ing both heat ing and c o o l i n g d e m a n d ; w h i l e opaque green fagades perform quite we l l in north or ientat ions, insulat ing signi f icant ly f rom the c o l d . I 3. G reen Fagades Framework Type of Green Fagade Orientation Contribution to Comfort Temperature and Reduction in Energy Demand GF Type 1.1 North LOW HIGH 0 0.2 0.4 0.6 0.8 1 GF Type 1.2 GF Type 1.3 South-east-west North LOW HIGH 0 0.2 0.4 0.6 0.8 1 LOW HIGH 0 0.2 0.4 0.6 0.8 1 South-east-west LOW HIGH 0 0.2 0.4 0.6 0.8 1 North South-east-west LOW HIGH 0 0.2 0.4 0.6 0.8 1 LOW HIGH 0 0.2 0.4 0.6 0.8 1 N W • W-W-N A N 4 GF Type 2.1 North South-east-west LOW HIGH 0 0.2 0.4 0.6 0.8 1 LOW HIGH 0 0.2 0.4 0.6 0.8 1 GF Type 2.2 1 North South-east-west LOW HIGH 0 0.2 0.4 0.6 0.8 1 LOW HIGH 0 0.2 0.4 0.6 0.8 1 W w N Table 3.2. Contribution of green fagades to comfort temperature and the reduction in energy demand depending on the orientation of the fagade 3. Green Fagades Framework In order to visually represent the contribution of the types of green facades to the opportunity to improve comfort temperature and reduction in energy demand, the framework introduces them in the following chart [Fig 3.9], considering them as POOR contributors, if the total range of values is between 0 and 0.33; as MODERATE if it is between 0.33 and 0.66; and as G O O D if it is between 0.66 and 1. The following figure summarizes this [Figure 3.9]. CONTRIBUTION OF THE TYPES OF GREEN FACADES TO COMFORT TEMPERATURE AND REDUCTION IN ENERGY DEMAND Y. _ 1 Q o o o LU Q O 2 O o I I I! LL. north I I °*2 | i [ i [ north east-west-south east-west-south north east-west-south north east-west-south north east-west-south GF TYPE 1.1 Figure 3.9 Contribution of green facades GF TYPE 1.2 l GF TYPE 1.3 to comfort temperature and reduction in energy demand GF TYPE 2.1 GF TYPE 2.2. 3. Green Facades Framework 3.1.2 Acoustic insulation A series of research studies suggest that no ise reduct ions due to vegetat ion are smal l unless the vegetat ion belt is w i d e . For examp le , c o m p a r e d wi th grassland, a dense ly p lanted belt of trees -30m th ick - was requ i red to reduce noise by 6 dB(A) [Huddart , 1 9 9 0 3 6 ] . O the r research has l ooked at the re la t ionsh ip between the vegetat ion screen v is ib i l i ty and noise attenuation [Chih-Fang, De r -L in , 2 0 0 3 ] 3 7 and also the in f luence of fo l iage and leave sizes in no ise attenuat ion for different f requencies [V.Tyagy et. a l , 2 0 0 6 ] 3 8 . O v e r a l l , the literature consu l ted suggests w i d e vegetat ion bonds are needed to ach ieve signi f icant acoust ic effects. LI i i Figure 3 .10 Contribution of green facades to acoustic insulation is unappreciable. 3 6 Greg Watts et. al. The effects of vegetation on the perception of traffic noise. Applied Acoustics 56 (1999) 3 9 ± 5 6 . 3 7 Chih-Fang Fang, Der-Lin Ling. Investigation of the noise reduction provided by tree belts. Landscape and Urban Planning 63 (2003) 187-195 3 8 Vikrant Tyagi et. al. A study of the spectral characteristics of traffic noise attenuation by vegetation belts in Delhi. Applied Acoustics 67 (2006) 926-935 3. G reen Facades Framework 60 Evaluation This attribute is on l y evaluated for opaque green fagades, s ince based on the exp la ined research, transparent green fagades w o u l d not have any in f luence on acoust ic aspects. The f ramework evaluates it s imi lar ly acco rd ing to the inf luence on comfort temperature and reduct ion in energy d e m a n d . It is based on a low-h igh scale, mean ing the inf luence of the green fagade to acoust ic comfor t is high [good insulat ion, va lue : 1] or l o w [poor insulat ion, va lue: 0] [Fig 3.11]. Based on research, the f ramework acknow ledges that green fagades are not signif icant acoust ic insulators, but it argues that those green fagades as moss wal ls [type 1.2] and those composed of green vert ical panels [type 1.3] contr ibute m u c h more to acoust ic insulat ion - cons ider ing them as H I G H contr ibutors - than those c o m p o s e d of steel wi res [type 1.1]- L O W contr ibutors. This is ma in ly due to their construct ion system, s ince both type 1.2 and 1.3 are composed of an inner layer of soi l plus the greenery layer in the external layer. W i t h these considerat ions, Tab le 3.3 shows the evaluat ion of the contr ibut ion of opaque green fagades to acoust ic insulat ion. 3 . G r e e n Fagades Framework L O W H I G H Acous t i c insulat ion Type of Green Facade Contribution to Acoustic Insulation GF Type 1.1 LOW 0 HIGH 1 LOW 0 HIGH 1 LOW 0 HIGH 1 Table 3.3. Contribution of green facades to acoustic insulation 3. Green Facades Framework 3.1.3 Visual comfort From inside. In analys ing the indoor v isual comfort , the f ramework refers to the brightness created through a w i n d o w , w h i c h is d i v i ded into two k inds of brightness: Indirect brightness [ looking at a table natural ly i l luminated] and brightness by adaptation [ looking through a w i n d o w ] 3 9 . In the case of indirect brightness, p roduced by a surface's ref lect ion, the luminance contrast shou ld not be higher than 1 to 3 to be cons idered comfortable. Those green facades that a l l ow dayl ight to pass through them genera l ly create a luminance contrast higher than 3 [Laurenz, 2 0 0 5 ] 4 0 , w h i c h means it is not v isua l ly comfor tab le . The brightness by adaptation results w h e n the eye adapts to a luminance average f rom a visual of a very different l um inance average. Th is occurs w h e n the eye has to adapt f rom an indoor v iew to a v i e w through a w i n d o w . In this sense, the f ramework assumes green facades attached to g laz ing facades perform as lattices and bl inds d o [Serra 1998]4'. Therefore, they contr ibute to reduce l um inance dif ferences he lp ing the eye to adapt to these. Moreove r , those green facades that permit the user to manipu la te their re la t ionship wi th the outdoors contr ibute more to the visual comfort of the user than those w h i c h do not. Rafael Serra and Helena Coch. Arquitectura y energia natural. UPC , Barcelona, 1995 J. Laurenz. Natural Envelope. The Creen element as a boundary limit. The 2005 World Sustainable Building Conference. Tokyo, 2005. H. Coch, R. Serra. The Mediterranean Blind: Less light, better vision. Renewable Energy 15 (1998) 431436 3. G r e e n Facades Framework I 63 4JP!— — i- : ^  ~ — — — — — — ^- • Figure 3.12 Contribution of green facades to indoor visual comfort. From outside. In genera l , scenes of natural e lements cont r ibute to higher levels of personal sat isfact ion, re laxat ion, and even creativi ty. These aspects are further analysed in sect ion 3.1.5 on the opportuni t ies of green fagades to contr ibute to psycho log ica l benefits. Evaluation This attribute w i l l o n l y affect those green fagades attached to transparent wa l l s , s ince opaque green fagades are not v i s ib le f rom inside and therefore cannot in f luence indoor v isua l comfor t . The f ramework deve lops a low-h igh one-po in t scale of va lues s imi lar to the eva luat ion of the in f luence of green fagades to acous t i c insu lat ion. It assumes that transparent green fagades w o r k s imi lar ly to b l inds or lattices, and therefore they perform as H I G H contr ibutors [1] to indoor v isual comfor t [Fig 3.13]. I 3. G reen Fagades F ramework Visual Comfort L O W HIGH 0 1 Figure 3.13 Range of values for the evaluation of the contribution to Visual Comfort Table 3.4 shows the evaluation of the contribution of the types of green facades to visual comfort. It suggests transparent green facades perform well in contributing to indoor visual comfort, but deeper research considers how they might negatively affect indirect brightness, which would mean an overall moderate contribution to indoor visual comfort, instead of the high contribution initially estimated. Type of Green Facade Contribution to Visual Comfort GF Type 2.1 LOW 0 HIGH 1 GF Type 2.2 1 LOW 0 HIGH 1 Table 3.4. Contribution of green facades to visual comfort 3. Green Facades Framework 3.1.4 Humidity The literature rev iewed shows contradictory data regarding the inf luence of green facades to increased humid i ty . O n the one hand , research by Ak i r a H o y a n o conc ludes that al though a pred ic t ion w o u l d suggest higher humid i ty on a green facade compared to the same facade wi thout vegetat ion, due to the transpirat ion of leaves, no signif icant dif ference in humid i ty was found from the measurement [Hoyano , 1988 ] 4 2 . O n the other hand , research by Cantuar ia reveals that a west-fac ing vegetated w a l l , compared to an uncovered wa l l , raised humid i ty by 9% [ G . A . C . Cantuar ia 2 0 0 0 4 3 ] . Despi te this relat ively contradictory data, the f ramework assumes vegetation might somehow in f luence the humid i ty of the surroundings. M o r e o v e r , it makes another dist inct ion between opaque and transparent green facades, cons ider ing transparent green facades w i l l also affect the indoor humid i ty , w h i l e opaque green facades w i l l on ly affect the outdoor humidi ty . Thus, unti l further research obtains more accurate data, the f ramework assumes that transparent green facades perform as H I G H contr ibutors to increased humid i ty of indoor and outdoor spaces, wh i le opaque green facades perform as M O D E R A T E contr ibutors to increased humidi ty , since it can on ly affect the outdoor space. M o r e accurate research is needed in order to specify wh i ch type of green facade contr ibutes more to raised humid i ty than the others. The f o l l ow ing table 3.5 shows the assumpt ion made in evaluat ing the inf luence of green facades to humid i ty . 4 2 Akira Hoyano. Climatological Uses of Plants for Solar Control and the Effects on the thermal Environment of a Building. Ed. Energy and buildings. Vol 11, no.1-3, pp 181-199. Tokyo 1988. 4 3 G . A . C . Cantuaria. A comparative study of the thermal performance of vegetation on building surfaces. Proceeding of PLEA 2000 Ed. James & James [Science Publisher] ltd. pp 212-213. Cambridge, UK 2000. I 3. G r e e n Facades Framework | Type of Green Fagade Contribution to Humidity GF Type 1.1 Table 3.5. Contribution of green fagades to humidity 3. Green Fagades Framework 67 3.1.5 Psychological benefits " P e o p l e are often aware that nature is important to them. They appreciate hav ing da i l y contact w i th it, even if there is on l y a modest amount of nature nearby.. . they en joy t h e m " 3 8 The cont r ibu t ion of green facades to psycho log ica l benefits is based on a series of studies carr ied out by Rache l and Stephen Kap lan . The emerg ing b ioph i l i a hypothesis suggested by Edward O . W i l s o n in 1984 also argues for s imi lar benefi ts. A c c o r d i n g to Kap lan 's book T h e Experience of Nature: A psychological perspective'44, nature a lways appears as an important e lement w h e n s tudy ing peop le 's preferences for p laces. In s imi lar terms, peop le are genera l ly more satisfied w i th green places, and the in f luence of nature encourages faster recover ies f rom i l lnesses. Based on a series of surveys made f rom different groups of peop le in different p laces, Kap lan 's observes "the consistent f ind ings of a strong preference for natural sett ings" and that "hav ing green things nearby is unden iab ly p leasant" . Another interesting f ind ing f rom these studies suggests " m u c h of the pleasure that peop le der ive from nature comes f rom such occas ions to obse rve " and that "the v i e w of natural areas has been shown to make a di f ference w i th respect to health measures.. .as w e l l as sat isfact ion". Kaplan suggests nearby nature can also increase satisfaction in the w o r k setting, and that workers wi th a v i e w of natural e lements , such as trees and f lowers, cons ider their jobs less stressful and more sat isfying, and even en joyab le and re lax ing . Furthermore, he argues for the restorative capacit ies of natural settings, as it has been "demonstrated that the content of the v i e w is important in hospital pat ients ' recovery f rom surgery, w i th nature content cont r ibu t ing to faster recovery" . r m I 4 4 Rachel Kaplan & Stephen Kaplan. The Experience of Nature. A psychological perspective. Cambridge University Pi w&M i | 3. G reen Facades F ramework i i i ft The literature suggests that green fagades c o u l d p lay an important ro le in satisfying peop le ' s w o r k and l i v ing env i ronments , in e n h a n c i n g en joyment , re laxat ion, and l ower ing stress levels, and in cont r ibut ing to faster recover ies. In this context , green fagades at tached to g laz ing fagades c o u l d contr ibute to both indoor psycho log ica l benefits - by l ook ing at natural e lements f rom the ins ide -as we l l as ou tdoor psycho log ica l benefits - by v i e w i n g nature f rom the outs ide. H o w e v e r , more accurate research on green fagades in this d i rec t ion shou ld be d o n e to verify these intu i t ions, s ince other aspects of these studies suggest that "unfavored scenes dep ic ted unmanaged areas w i th heavy undergrowth . Tree densi ty, weeds , and a scrubby appearance contr ibuted to these l o w rat ings". Thus these aspects shou ld also be cons ider ed as a means of con t ro l l ing the greenery in order to ach ieve the highest level of satisfaction poss ib le . Figure 3.14 Contribution of green fagades to psychological benefits. From inside, [i.e. relaxation, contemplation.!. 3. G r e e n Fagades Framework Stephen Kellert co l lec ted a series of studies related to the intrinsic relat ionship of humans wi th the natural wo r l d in his book Biophilia Hypothesis45. B ioph i l i a hypothesis* 'proc la ims a "human dependence on nature that extends far beyond the s imple issues of material and physical sustenance to encompass as we l l the h u m a n crav ing for aesthetic, intel lectual , cogni t ive, and even spir i tual mean ing and sat isfact ion". Th is hypothesis, as the author himsel f admits, is in a very early stage, and attempts to show "the human inc l inat ion to affiliate wi th life and l i fel ike process". It presents the general aff i l iat ion of humans to the natural wo r l d ; and it also attempts to demonstrate the " innate ly emot iona l aff i l iat ion of human beings to other l iv ing organisms" by nine valuat ions of nature', i nc lud ing genet ic l inks. "The human search for a coherent and fu l f i l l ing existence is int imately dependent upon our re la t ionship to nature" But what is more relevant to this thesis is the speci f ic research in Kellert 's book, w h i c h analyzes the need that humans have for nature, s how i ng its inf luences on our emot iona l , cogni t ive, aesthetic, and even spir i tual deve lopment . In this sense, from the n ine valuat ions on nature proposed by Kellert, the natural ist ic and the aesthetic values are the most signif icant in cons ider ing the top ic of this thesis. H e descr ibes the naturalist ic va lue as a sense of fascinat ion, wonder , and awe der ived f rom an int imate exper ience of nature's diversity and complex i ty . H e argues that activit ies c lose ly l inked to nature "have been related to tension release, re laxat ion, peace of m i n d , and enhanced creat ivi ty der ived f rom the observat ion of diversity in nature". 4 5 Stephen Kellert, Edward O . Wilson. The Biophilia Hypothesis. Island Press Washington DC, 1993 * The term Biophilia was defined by Edward O . Wilson as the 'innate tendency to focus on life and life-like processes'. [1984] " The nine fundamental aspects of our basis for valuing and relating to the natural world are: the utilitarian, naturalistic, ecologistic-scientific, aesthetic, symbolic, humanistic, moralistic, dominionistic, and negativistic. | 3. G reen Facades Framework | 7 0 Regarding the aesthetic va lue he suggests that "the phys ica l beauty of nature is certa in ly a m o n g its most power fu l appeals to human a n i m a l " , argu ing that "the aesthetic exper ience of nature c o u l d further be associated w i th der ivat ive feel ings of t ranqui l i ty , peace of m i n d , and a related sense of psycho log ica l we l l - be ing and se l f -conf idence" . It is wor th men t i on ing the last of the va lues , the negative one , w h i c h refers to "the negativist ic exper ience of nature w h i c h is character ized by sentiments of fear, avers ion , and ant ipathy toward var ious aspects of the natural w o r l d " . Some of these examples are nature settings con ta in ing snakes or spiders, w h i c h can el ic i t p r o n o u n c e d au tonomic responses. G r e e n facades shou ld therefore a lso cons ider this property of negativ ist ic va lue of the natural w o r l d s ince they can contr ibute for instance to the appearance of spiders and bees, a m o n g other smal l insects. I FT Figure 3.15 Psychological benefits of green facades, from outside. 3. G reen Facades Framework Fina l ly , Kel lert exp la ins that there are three general types of b ioph i l i c responses to unthreatening natural landscapes: l i k ing/approach responses, restoration or stress recovery responses, and enhanced high-order cogni t ive funct ion ing. The l ik ing approach responses are very similar to the preferences suggested by Rachel and Stephen Kap lan . In this sense, Kellert suggests "preferences shou ld tend to be higher for settings hav ing green or somewhat verdant vegetat ion". H e conc ludes w i th simi lar data as Kaplan about the restorative capaci ty of nature as we l l as its capaci ty to facil i tate creativi ty. Several studies made in hospitals showed that recuperat ion from stress is much faster and thorough w h e n peop le are exposed to natural settings or images of natural settings. A c c o r d i n g to this research, the f ramework bel ieves green fagades present an opportuni ty to satisfy h u m a n psycho log ica l aspects such as aesthetic, intel lectual , cogni t ive, and even spiritual sensibi l i t ies. There is also a restorative capaci ty of green fagades to transmit tranquil i ty, re laxat ion, and encourage creativi ty. Evaluation A l though psycho log ica l benefits are dif f icult to evaluate, the green fagades f ramework considers green fagades in general pos i t ive ly affect human psycho logy. A c c o r d i n g to the b ioph i l ia hypothesis , humans need to be c lose ly related to nature, and green fagades offer an opportuni ty to enhance this. Thus , the f ramework evaluates those green fagades attached to opaque wal ls as L O W contr ibutors to psycho log ica l benefits [0.5], s ince they can on ly be perceived from the outs ide. O n the contrary, those green fagades attached to transparent wal ls are considered H I G H contr ibutors [1], as they are perce ived f rom both the outside and the inside. I 3 . G r e e n Fagades Framework Table 3.6 summar i zes these considerat ions. Type of G r e e n Fagade Cont r ibu t ion Psycho log ica l benefits G F Type 1.1 L O W 0 0 . 5 HIGH 1 L O W 0 0 . 5 HIGH 1 L O W 0 0 . 5 HIGH 1 G F Type 2.1 L O W 0 0 . 5 HIGH 1 L O W 0 0 . 5 HIGH 1 Table 3.6. Contribution of green fagades to psychological benefits C o m b i n i n g al l of the evaluat ions of the f ive aspects i nc luded w i th in human comfor t—comfor t temperature and reduct ion in energy d e m a n d , acoust ic insulat ion, v isual comfor t , humid i ty ; and psycho log ica l benefi ts—the fo l l ow ing chart reflects the overal l cont r ibut ion of the different types of green fagades to improve human comfor t [Table 3.7]. 3. G reen Fagades F ramework G F 1.1 C o m p o s e d of steel w i res G F 1.2 A s moss wa l ls G F 1.3 C o m p o s e d of ver t ica l pane ls Contribution of green facades to improve human comfort Comfort temperature & reduction in energy d. N W Comfort temperature & reduction in energy d. IN 4 Comfort temperature & reduction in energy d. w 4 Acoustic L O W Insulation 0 Visual Comfort Acoustic L O W Insulation 0 Visual Comfort Acoustic L O W Insulation 0 HIGH 1 Visual Comfort Humidity LOW 0 HIGH 1 Psychological benefits LOW 0 Humidity LOW 0 HIGH 1 Psychological benefits LOW 0 HIGH 1 Humidity LOW 0 HIGH 1 Psychological benefits LOW 0 G F 2.1 Be tween 2 transparent layers Comfort temperature & reduction in energy d. Acoustic Insulation Humidity LOW 0 HIGH 1 Visual Comfort HIGH 1 Psychological benefits LOW o S HIGH 1 G F 2.2 G r e e n ext. transparent int. 1 Comfort temperature & reduction in energy d. N Acoustic Insulation Humidity LOW 0 HIGH 1 i i Visual Comfort LOW 0 HIGH 1 Psychological benefits o a 0.5 IB HIGH 1 Table 3.7. Contribution of green facades to improve human comfort | 3. G r e e n Facades Framework 3.2 Expressive capacity The expressive capac i ty is the most exp lored e lement , if not the on ly one explored in green fagades. Today 's architects try to express the "unkempt a m b i e n c e " 4 6 of a green fagade bu i ld ing , as we l l as the "mater ia l w h i c h form seems to melt a w a y " 4 7 . Th is thesis explores green fagades as fascinat ing e lements that provide a range of possibi l i t ies for creat ing changeab le surfaces, p lay ing w i th different densit ies, colours and textures, and reth inking their integration w i th in their surroundings. H o w e v e r , a l though the concept of its expressive capac i ty is most c o m m o n l y cons idered in the design of a green fagade, this f ramework does not look at expressive capaci ty a lone , but rather, cons iders it as one vital attribute among others. This express ive capac i ty is understood in three different ways : by its changeable properties, in the w i d e range of densities, colours and textures it prov ides, and accord ing to the opt ions to integrate and engage in a dialogue w i th its surroundings. In this context , the changeable properties in green fagades refer to the opportuni ty they offer to in t roduce the d imens ion of T IME - or the ephemera l d imens ion , in Jean Nouve l ' s t e rms 4 8 - to the bu i l d i ng . G reen fagades change their appearance natural ly, responding and adapt ing to the nearby env i ronment 's s t imul i , such as the passing of t ime. In contrast to the tradit ional hermet ic and unchang ing character of bu i l d ing fagades, green fagades int roduce a l iv ing skin by bu i ld ing external layers in cont inuous change, w h i c h escape even the designer's contro l in a free deve lopmen t over t ime. Roger Sherwood, Rue des Suisses. www.housingprototypes.org Joann Gonchar, AIA. Musee du Quai Branly. Architectural Record February issue, New York 2007 A n interview to Jean Nouvel available in his office website: www.jeannouvel.com 3. G r e e n Fagades Framework Green facades also prov ide a w i d e range of densities, colours and textures. The select ion of plants f rom the broad variety of plant species avai lab le permits designers to def ine and play wi th green facades, tak ing advantage of these characterist ics. G reen facades also open the door to re th ink ing the integration oi bui ld ings w i th in their surroundings. They offer the oppor tun i ty to reinterpret the dialogue between a bu i ld ing and its immedia te context, as we l l as to p rov ide new resources for env is ion ing the current understanding of archi tecture as geography 4 9 . In this sense, green facades help us to understand architecture as another layer of eco logy or a game of surfaces. Evaluation In eva luat ing these aspects, the framework f inds that there are a lack of speci f ic references to determine w h i c h type of green facade satisfies the criteria for expressive capaci ty. A l though one c o u l d argue that those green facades attached to transparent wal ls contr ibute more to expressivity because they are v is ib le f rom the ins ide and f rom the outside, the f ramework considers al l f ive types as G O O D achievers of the expressive capac i ty of green facades [value: 1], s ince they are all cont r ibu t ing factors for w h y w e are exper ienc ing this k ind of b o o m in green facades today. H o w e v e r it acknowledges further research w o u l d be needed for a more accurate evaluat ion. Tab le 3.8 shows the assumpt ions made w h e n evaluat ing the contr ibut ion of the different types of green facades to the expressive capac i ty they offer. 4 9 Marie Ange Brayer, Beatrice Simonot - Manuel Causa. Architecture is [now] Geography - Archilab's Earth Buildings: Radical Experiments in Land Architecture. Thames & Hudson London, 2003. I 3 . G r e e n Facades Framework I 76 Type of G r e e n Fagade I Con t r ibu t ion to the expressive capac i ty G F Type 1.1 LOW 0 HIGH 1 LOW 0 HIGH 1 G F Type 1.3 LOW 0 HIGH 1 GF_Ty_De_2.1_ LOW 0 HIGH 1 G F Type 2.2 LOW 0 HIGH 1 Table 3.8. Contribution of green facades to the expressive capacity 3. G reen Fagades Framework I-3.3 Air & Water Quality [AWQ] The opportuni ty to improve air and water qual i ty l ies in the capaci ty of green facades to perform as pur i fy ing filters, e l im ina t ing pol lutants. 3.3.1 Air Quality A co l lec t ion of research on urban forests and green roofs suggests the potential for trees and plants to trap air pol lutants. The w o r k of M c P h e r s o n and N o w a k studies the role of urban forests in t rapping air pol lutants. In C h i c a g o ' s U rban Forest Ecosystem project, they show how urban trees " improve air qual i ty r emov ing approx imate ly 0.3-1 % to an average air qual i ty, reach ing 5 - 1 0 % " [McPherson and N o w a k , 1994 ] 5 0 . If w e apply these f indings to green facades, the thesis assumes they w o r k as vert ical green filters that trap air pol lutants and purify them. Based on the f indings from the book Urban Biodiversity5^, the f ramework d iv ides plant species into three main types: shrubs, c l imbers , and grasses. It suggests shrubs contr ibute the most in t rapping air pol lutants w h i l e grasses contr ibute the least. 5 0 E. Gregory McPherson, David J. Nowak, Rowan A. Rowntree. Chicago's Urban Forest Ecosystem. Gen. Tech. Rep. NE-186. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 1994 [check: http://www.fs.fed.us/ne/syracuse/Pubs/pubs.htm] 5 1 Schaefer, Rudd, Vala. Urban Biodiversity. Captus Press, Ontario, 2004. I 3. Green Facades F ramework I 78 Figure 3.16 Contribution of green facades to Air and Water Quality. 3.3.2 Water Quality. From inside. There is a remarkable opportunity to conserve water, which is a result of innovative models of irrigation for green facades. Existing irrigation systems for green fagades are generally based on conventional drip irrigation systems with few practices concentrating on water conservation. As water is a scarce resource in many parts of the world, an opportunity exists to rethink irrigation systems based on minimizing the water demands of plants. In this context, the research carried out by the Spanish green roof company, Intemper Espanola S.A, 5 2 suggests that by using their 'ecological roof, water savings up to 4 7 . 6 % can be achieved. Figure 3 .17 Intemper's ecological roof with an irrigation system composed of a water layer 8cm deep is connected to the soil through filter membranes that absorb water by capillaries when plants demand it. This system reduces water needs in green roofs by up to 47.6%. 2 Intemper, ETSAM and ETSIA. Estudio a esca/a natural que la azotea ecologica aljibe tiene sobre el ahorro energetico de los edificios. Madrid, 1999. 3. Green Fagades Framework 79 This irrigation system proposed in their 'ecological roof is based on a water storage cavity 8cm deep below the green roof, linked to the plants by filter membranes that guide water by capillaries to the plants when they demand it [Figure 3.17]. In the Casa Barcelona05 project 5 3, the green facade prototype transferred this irrigation system to a green facade. [Fig 3.18] soi Thus, the selected irrigation system also offers an important opportunity to reduce the water needs of green facades and ultimately to contribute to water conservation. water storage From outside. The green roofs study in Toronto suggests that greenery contributes to reduce runoff volume, stream erosion, and pollutants [City of Toronto 2005] 5 4.Green facades, as green roofs, filter contaminants from rainwater. "Most of the time heavy metals and nutrients that exist in stormwater are bound in the green roof growing substrate instead of being discharged in the Figure 3.18 Casa Barcelona 05 Green Facade transferred the Intemper ecological roof's irrigation system into the green facade. runoff" [City of Toronto 1999] 5 5. According to this study, "green roofs are normally able to retain 70 to 9 0% of the stormwater that falls on them during the summer months, depending on the frequency of rain and drying rates. In winter months, green roofs are predicted to retain 40 - 5 0% of the stormwater". This is something that depends on different climate conditions as well as on whether or not it is an extensive or an intensive green roof. The thesis assumes green facades would work in a similar manner as green roofs. 5 3 Laura Arenas. Casa Barcelona 05 - Green Facade. Construmat - Fira de Barcelona, Ingoprint S.A. Barcelona, 2006. The city of Toronto. Report on the Environmental Benefits and Costs of Green Roof Technology for the City of Toronto. http://www.toronto.ca/greenroofs/pdf/fullreport103105.pdf 3 5 City of Toronto. Report on the Environmental Benefits and Costs of Creen Roof Technology for the City of Toronto. www.toronto.ca/greenroofs/pdf/executivesummary.pdf. October, 2005. I 3. Green Facades Framework Evaluation The f ramework fo l lows the same 'one-po in t ' scale as in the other categor ies. H o w e v e r , it breaks the overa l l cont r ibu t ion of green facades d o w n to air and water qual i ty in a s imi lar w a y as in the cont r ibut ion to h u m a n comfort . In this sense, w i th in the one-po in t scale of values or percentages, it cons iders the in f luence on air and water qual i ty even ly , so that each of them have a highest value of 0 .5 , and added together p rov ide the overal l eva lua t ion , w h i c h has a highest va lue of 1. Those green fagades w i th a va lue c loser to 0.5 for air qual i ty have a higher in f luence on t rapp ing air pol lutants. This depends on the selected plants. Va lues range f rom a l o w in f luence in air qual i ty: grassy species [value: 0.15] ; to a higher in f luence: c l imber plants [0.3]; to the highest in f luence: sh rubby plants [0.5]. Regard ing the cont r ibut ion to water qual i ty there are t w o more values: those green fagades that a c c o m m o d a t e water storage w i th in the irr igation system [0.25], and those that a lso incorporate some k ind of grey-water treatment into the bu i l d i ng through green fagade [0.5]. The overal l eva luat ion is i l lustrated in Figure 3 .19. L O W H I G H 0 0 .15 0.3 0.5 0 .75 1 A i r and Water Qua l i t y f • • f • A i r qual i ty Water qual i ty Figure 3.19 Range of values for the evaluation of the contribution to Air and Water Quality The green fagades f ramework evaluates the in f luence of the types of green fagades to air and water qual i ty as fo l l ows : I 3. G r e e n Fagades Framework Air Quality. Depending on the plant species incorporated in the green facades the contribution to the improvement of air quality can be higher or lower. In this sense, according to Urban Biodiversity*6, the framework assumes that shrubs contribute the most in trapping pollutants [HIGH value = 0.5]; grasses, the least[LOW value = 0.15]; and vines or climbers moderately [0.3]. Moreover, if the green facade is attached to a transparent wall that can be opened, it is then also related to indoor space, contributing to the indoor air quality as a great deal of research at the University of Guelph suggests57. Water Quality. The framework evaluates as HIGH [0.5] those green facades that do allow some water storage within the irrigation system and some grey-water treatment for the building. It evaluates in the middle [0.25] those green facades that incorporate one of the two options; and as L O W [0] those green facades that do not include any of these. In this sense, the evaluation of green facades in terms of their contribution to air and water quality is summarized in Table 3.9. 5 6 Schaefer, Rudd, Vala. Urban Biodiversity. Captus Press, Ontario, 2004. 3 7 http://www.naturaire.com/library.html I 3. Green Facades Framework Type of Green Facade Contribution to Air and Water Quality Table 3.9. Contribution of green facades to air and water quality 3. Green Facades Framework 83 3.4 Indoor - Outdoor Relationship [IOR] The potential for green facades to contribute to the relationship between indoor and outdoor spaces is divided into three main aspects: relationship with the immediate context, indoor and outdoor flexible relationship, and maintenance. 3.4.1 The relationship with the immediate context The relationship of green fagades with their immediate context refers to the specificities of the site in terms of how green fagades engage with the immediate urban space, and how they are settled within an urban context, a park context, or a narrow street context, for instance. It considers whether or not the role of the green fagade is to oppose the nearby concrete hard surfaces, or to compliment a neighbouring park or the trees on the street. This aspect also refers to the appearance of green fagades, whether they appear as an impenetrable barrier, or as a permeable green screen, as well as the different views and grades of opacities created through the green layer. Figure 3.20 Simulation of natural changes of green facades from inside. Figure 3.21 Green Fagades and the immediate context. Photomontage of a green fagade building simulating its natural reaction and change to surroundings stimuli 3. Green Fagades Framework 3.4.2 Flexibility and Permeability The indoor and ou tdoor re la t ionship is also related to the f lex ib i l i ty and permeab i l i t y of the green facade system. This rel ies on the capaci ty of green facades to p rov ide enough f lex ib i l i ty for users to change their re la t ionship w i th the outdoor env i ronmen t and to be manipu la ted by it. By p rov id ing f lex ib i l i ty users have the op t ion to create, w h e n appropr ia te, dense green barriers w i th the outdoor space if they are l ook i ng for pr ivacy, or to create different grades of openness , t ransparencies, and permeabi l i ty by greenery and f lex ib le systems [such as s l id ing or rotating systems]. Figure 3.22 Green flexible facadesis the capacity of green facades to be manipulated by the user to change their relationship with the outdoor environment. 3. G reen Facades F ramework 3.4.3 Maintenance The maintenance is c lose ly related to the access ib i l i ty of a green facade. This includes both the accessibi l i ty of the construct ion system and the access ib i l i ty of the irrigation system. This is related to the capac i ty of the system to be rep laced or easily access ible for maintenance purposes. Evaluation Since it is d i f f icu l t to evaluate the indoor-outdoor relat ionship, especia l ly cons ider ing the w i d e variety of urban contexts, the green fagades f ramework focuses on the eva luat ion of the relat ionship between the indoor and outdoor of each type of green facade based main ly on the f lex ib i l i ty p rov ided to change this relat ionship, as we l l as on its access ibi l i ty. The overal l one-point scale of values or percentages is o rgan ized as fo l lows: L O W H I G H 0 0.5 0.75 1 Indoor - Ou tdoo r Relat ionship 1 Flex ib i l i ty Ma in tenance Figure 3.23 Range of values for the evaluation of the indoor-outdoor relationship If the green facade provides options for the users to change their re lat ionship w i th the outdoors [by movement systems such as s l id ing, rotating, etc] the f ramework evaluates it as a high contr ibutor [0.5]; whereas if it does not prov ide any opt ions [static systems] it evaluates it as l ow contr ibutor [0]. In terms of maintenance, in a s imilar manner, if the green facade system is easi ly accessible for prun ing or replacement, the f ramework evaluates it as a high contr ibutor to maintenance [0.25]. O n the contrary, if a green fagade system is not easi ly access ible, mak ing its maintenance diff icult, the f ramework evaluates it w i th a l ow va lue [0]. I 3. Green Fagades F ramework The framework follows the same reasoning for evaluating the maintenance of the irrigation system. In this sense, it evaluates as low those irrigation systems which have difficult accessibility [0], and evaluates as high those irrigation systems that are accessible, making maintenance easier. Table 3.10 summarizes the overall evaluation of the five types of green facades in terms of their contribution to the indoor-outdoor relationship. Type of Green Facade Indoor-Outdoor Relationship GF Type 1.1 M LOW 0 0.25 0.5 HIGH 0.75 1 LOW 0 0.25 0.5 HIGH 0.75 1 GF Type 1.3 LOW 0 0.25 0.5 HIGH 0.75 1 GF Type 2.1 LOW 0 0.25 0.5 HIGH 0.75 1 GF Type 2.2 LOW 0 0.25 0.5 HIGH 0.75 1 Table 3.10. Contribution of green facades to indoor-outdoor relationship 3. Green Facades Framework 3.5 Urban Biodiversity [UB] Biodiversity is defined as biological diversity, or the variety of life in an area [Schaefer 2004] 5 8. Today the World is facing the massive loss of biological diversity since the natural environment is disappearing [Kellert 1993] 5 9. More specifically, in the urban context, urban biodiversity is also faced with serious challenges of habitat loss and disturbances to air, water and soil [Schaefer 2004] 5 4. In this context, green facades represent an opportunity to contribute to urban biodiversity by creating microhabitats or patches, which enhance urban plant diversity and provide natural places for small animals to rest and live. Green facades can also contribute to linking isolated green spaces of cities, and participate in emerging projects for greenways and green corridors. In this sense, green fagades provides a habitat, which could mean safe nesting places for small animals, and even sources of food for humans. Further analysis and research is needed to acknowledge how green fagades can contribute to these features, since the current literature only suggests such intuitions. m * *# 1 t ft Figure 3.24 Contribution of Green Fagades to Urban Biodiversity 5 8 Valentin Schaefer, Hillary rud, and Jamie Vala. Urban Biodiversity. Captus Press, Ontario 2004 5 9 Stephen Kellert, Edward O. Wilson. The Biophilia Hypothesis. Island Press Washington DC, 1993 I 3. Green Fagades Framework I 88 As many authors such as Ian M a c H a r g [ 1 9 6 9 ] 6 0 and M i c h a e l H o u g h [1995] 6 1 have a l ready suggested, there is a need to embrace nature in our l ives in the city. In this sense, green facades present the oppor tun i ty not on l y to avo id d is turb ing urban b iodivers i ty but a lso e n h a n c i n g it, by incorporat ing green e lements that facil i tate life for other l i v ing organisms. By d o i n g so, green facades w o u l d be a step towards " G R E E N I N G G R A Y F I E L D S " [the city], in contrast w i th wha t ci t ies have a lways been d o i n g : " G R A Y I N G G R E E N F I E L D S " . Figure 3.25 Greening Grayfields vs Graying Greenfields Evaluation To evaluate the cont r ibu t ion of green facades to urban biodivers i ty , the f ramework d iv ides the one point scale of va lues or percentages into four quarters. It suggests that green facades a lways contr ibute in some w a y to urban b iodivers i ty , and therefore the evaluat ion a lways starts w i th a m i n i m u m value of 0 .25 . A b o v e this, the f ramework cons iders three aspects: plant biodiversity, location, and covered surface. Figure 3.26 il lustrates the eva lua t ion . 6 0 Ian MacHarg. Design with Nature. Natural History Press, NY 1969 6 1 Michael Hough. Cities and natural process. Routledge, London 1995 I 3. G reen Facades F ramework LOW HIGH 0 0.25 0.5 0.75 1 Urban Biodiversity • 1^ J£ l|l Species Location Coverage Figure 3.26 Range of values for the contribution to urban biodiversity 3.5.1 Plant diversity The direct possibility for green facades to contribute to urban biodiversity relies on the recognition of a city's different plant species, and therefore, to the environmental enrichment of the building surroundings. In this sense, for instance, the green facade at the Quai Branly Museum in Paris hosts more than 170 different species of plants in the installation 6 2, which includes perennials such campanulas, geraniums, ferns, ivies, and sages; shrubs such as shrubby veronicas, buddleias, hydrangeas, and honeysuckles; as well as grasses and sedges63. In the case of the Aquaquest Learning Building at the Vancouver Aquarium, 20 different species of plants were originally planted in the modules 6 4. It is difficult to evaluate this contribution because of the many variables it depends on, such as building scale, green facade dimension, etc. However, the framework evaluates as higher contributors those green facades which have more than 50 different species [0.25], and as lower contributors those green facades composed of less than 50 species [0]. Proefrock Philip. Living Walls, www.ecogeek.org L'Atelier Vert www.frenchgardening.com Randy Sharp. Green Design and Implementation: Vertical Gardens and Living Walls. Green Roofs for Healthy Cities meeting. Minneapolis May 2007 3. Green Fagades Framework 3.5.2 Location In c o n s i d e r i n g t h e p o t e n t i a l f o r g r e e n f a c a d e s a s a p l a c e f o r d i f f e r e n t l i v i n g s p e c i e s , s u c h a s b i r d s , b u t t e r f l i e s , a n d i n s e c t s , t h e f r a m e w o r k s u g g e s t s t h a t t h e c o n t r i b u t i o n is h i g h e r if t h e f a c a d e is l o c a t e d i n a c i t y ' s g r e e n n e t w o r k . In t h i s s e n s e , it e v a l u a t e s t h e c o n t r i b u t i o n a s l o w if t h e b u i l d i n g is n o t p l a c e d w i t h i n a c i t y ' s g r e e n n e t w o r k [0 ] , a n d a s h i g h if it is [ 0 . 2 5 ] . M o r e r e s e a r c h is n e e d e d t o d e t e r m i n e w h i c h g r e e n f a c a d e c o n t r i b u t e s m o r e t h a n a n o t h e r t o e n h a n c e l i v i n g a c t i v i t y . T h e t h e s i s s p e c u l a t e s g r e e n f a c a d e s a s s o c i a t e d w i t h a t r a n s p a r e n t w a l l m i g h t c o n t r i b u t e l e s s , s i n c e t h e e n v i r o n m e n t c r e a t e d b e t w e e n t h e g r e e n e r y a n d t h e t r a n s p a r e n t w a l l m i g h t n o t a f f o r d t h e m o s t a p p r o p r i a t e s p a c e s f o r l i v i n g s p e c i e s . H o w e v e r , m o r e s t u d i e s a r e n e e d e d t o d e t e r m i n e h o w g r e e n f a c a d e s ' d e n s i t y , t h i c k n e s s , v a r i a t i o n s i n t h e s c r e e n , e t c . c o u l d e n h a n c e t h e d i v e r s i t y o f l i v i n g o r g a n i s m s . 3.5.3 Coverage T h e f r a m e w o r k t a k e s i n t o a c c o u n t t h e p e r c e n t a g e o f t h e f a c a d e s u r f a c e t h a t is c o v e r e d b y t h e g r e e n e r y . D u e t o t h e s c a r c e l i t e r a t u r e o n t h i s i s s u e t h e g r e e n f a c a d e s f r a m e w o r k is b a s e d o n i n t u i t i o n , c o n s i d e r i n g a s l o w c o n t r i b u t o r s t o u r b a n b i o d i v e r s i t y t h o s e g r e e n f a c a d e s w h e r e t h e g r e e n e r y c o v e r s l e s s t h a n 5 0 % o f t h e f a c a d e s u r f a c e [0] , a n d a s h i g h c o n t r i b u t o r s t h o s e t h a t c o v e r m o r e t h a n 5 0 % [ 0 . 2 5 ] . T a b l e 3.11 s u m m a r i z e s t h e e s t i m a t i o n o f t h e c o n t r i b u t i o n o f t h e t y p e s o f g r e e n f a c a d e s t o u r b a n b i o d i v e r s i t y . 3 . G r e e n F a c a d e s F r a m e w o r k Type of Green Facade Contribution to urban biodiversity GF Type 1.1 Table 3 . 1 1 . Contribution of green facades to urban biodiversity 3. Green Facades Framework 92 3.6 Carbon Neutral Architecture [CNA] Carbon neutral architecture results in a net ze ro f l ow of carbon into the atmosphere in its design, const ruct ion, occupancy , and d e c o m m i s s i o n i n g phases, each independent ly [Ahman et. a l . 2 0 0 6 J 6 5 . It also "seeks to m i n i m i z e the negative env i ronmenta l impact of bui ld ings by enhanc ing ef f ic iency and moderat ion in the use of materials, energy, and deve lopment s p a c e " 6 6 . Today many simi lar concepts are used to refer to carbon neutral architecture such as zero carbon bui ld ings [Webb 2 0 0 1 ] 6 7 , ze ro energy homes [Iqbal, 2 0 0 4 ] 6 8 , l o w energy bui ld ings [Hestnes, 1996 ] 6 9 , etc. H o w e v e r , this thesis wants to emphas ize that the result of a net zero f l ow of carbon into the atmosphere w o u l d not mean it necessar i ly classif ies as carbon neutral architecture, since this shou ld be ach ieved by both passive and active des ign , as we l l as by m i n i m i z i n g its envi ronmental impact. In this context , the thesis looks at the cont r ibut ion of green fagades to carbon neutral architecture as rooted in three of their funct ions: first, green fagades are a low energy material, s ince they d e m a n d l o w energy in their fabr icat ion process; second , they reduce the energy demand of bu i ld ings, and therefore, their carbon emissions [Laurenz, 2 0 0 5 ] 7 0 ; and , last, they sequester CO2 a m o n g other air pol lutants [McPherson and N o w a k 1994 ] 7 1 . 6 5 Ahmann, Augustine, Grondzik, Haglund, Koziol , Kwok, Utzinger. Designing Carbon Neutral Buildings. SBSE Annual Retreat Pingree Park, C O July, 2006. 6 6 http://en.wikipedia.org/wiki/Sustainable architecture 6 7 Webb R. Towards Zero-Carbon Buildings. Refocus. Volume 2, Number 4, May 2001 , pp. 28-31 (4) 6 8 M.T. Iqbal. A feasibility study of a zero energy home in Newfoundland. Renewable Energy 29 (2004) 277-289. 6 9 Anne Grete Hestnes. Task 13: advanced solar low-energy buildings final task management repon. IEA October 1996. 7 0 J. Laurenz. Natural Envelope. The Creen element as a boundary limit. The 2005 World Sustainable Building Conference. Tokyo, 2005 7 1 E. Gregory McPherson, David J. Nowak, Rowan A . Rowntree. Chicago's Urban Forest Ecosystem. Gen. Tech. Rep. NE-186. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 1994 [check: http://www.fs.fed.us/ne/syracuse/Pubs/pubs.htm] I 3 . C r e e n Fagades Framework I 93 A low energy material, w h i c h refers to the life cyc le - carbon cyc le - of the components of a green facade, also inc ludes the study of the fabr icat ion process of green facades. A l though very little research has been done o n this issue, it w o u l d be interesting to manufacture vert ical green panels or green modu les that cou ld be created in plant nurseries, as a k ind of 'prefabricated green facade ' . In this context, green facades c o u l d be s tandard ized, faci l i tat ing the fabrication as we l l as the construct ion process, contr ibut ing ul t imately to l o w the energy requirements of green facade bu i ld ings. A c c o r d i n g to prev ious f indings [analysed in sect ion 3.1.1], the inf luence of green facades to reduce the energy d e m a n d of bu i ld ings means a reduct ion in air cond i t ion ing of up to 4 5 % , and up to 2 3 % in heat ing. Consequent l y , this also contr ibutes to reduce the CO2 emissions created to generate that energy; w h i c h shows the in f luence of green facades to d im in ish the negative consequences of h igh CO2 concentrat ions. Regard ing the capaci ty of greenery to sequester CO2, consul ted literature suggests this sequestrat ion represents a very little propor t ion of the total CO2 emitted by a city [ removing approx imate ly 0.3-1 % to an average air qual i ty ; reach ing 5-10% - M c P h e r s o n and N o w a k , 1994 7 2 ] . H o w e v e r , this thesis w o u l d l ike to emphas ize that green facades appear to be the on ly bu i l d i ng material that cou ld generate a posi t ive carbon load balance, cons ider ing their life cyc le . This c o u l d occur if the total CO2 emit ted to fabricate a green facade was lower than the total CO2 sequestered by that green facade in its life t ime. 7 2 E. Gregory McPherson, David J. Nowak, Rowan A. Rowntree. Chicago's Urban Forest Ecosystem. Gen. Tech. Rep. NE-186. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 1994 [check: http://www.fs.fed.us/ne/syracuse/Pubs/pubs.htm] 3. G r e e n Facades Framework I 94 Evaluation The framework on ly evaluates the first of the three aspects of ca rbon neutral archi tecture - l o w energy mater ia l . Th is is due to the fact that the other two - CO2 emiss ions and carbon sequestrat ion - have a l ready been ana lyzed in prev ious sect ions [3.1.1 reduct ion in energy d e m a n d and 3.3.1 air qual i ty ] . Therefore, to quant i fy the cont r ibut ion of green facades to carbon neutral archi tecture, the f ramework considers three values w i th in the one-point sca le: 0 - 0 . 5 - 1 . L O W H I G H C a r b o n neutral archi tecture ® Figure 3.27 Range of values of the contribution to carbon neutral architecture The framework expects that green facades contr ibute d i rect ly to l o w carbon mater ia ls, s ince the greenery is a natural material w i th a l ow carbon fabr icat ion process, cont r ibut ing, consequen t l y , to carbon neutral archi tecture. In this sense, the framework estimates that the cont r ibu t ion of a green facade to carbon neutral archi tecture w o u l d never be l o w [0], 0.5 be ing the m i n i m u m cont r ibu t ion . H o w e v e r , the framework also takes into account the carbon footpr int of the rest of the componen ts of the green facade. It considers the cont r ibu t ion as higher if the rest of the componen ts of the const ruct ion system, such as the green facade substructure, the plant gu id ing e lements, etc. are nature-fr iendly or l o w carbon materials, such as w o o d , recyc led materials, etc. 3. G reen Facades F ramework Table 3.12 illustrates the evaluat ion of the contr ibut ion of the types of green fagades to carbon neutral architecture. Type of G reen Fagade Cont r ibut ion to Carbon Neutra l Arch i tecture G F Type 1.1 LOW 0 0.5 HIGH 1 LOW 0 0.5 HIGH 1 G ^ T y p ^ 3 LOW 0 0.5 HIGH 1 G F Type 2.1 LOW 0 0.5 HIGH 1 G F Type 2.2 1 LOW 0 0.5 HIGH 1 Table 3.12. Contribution of green fagades to carbon neutral architecture. 3. G reen Fagades F ramework 96 3.7 Overview of the framework A c c o r d i n g to these considerations, the f ramework conc ludes that the influence of green facades in comfort temperature and reduct ion in energy demand [section 3.1.1] is based in technical ly deeper research studies than any of the others. It is the most studied aspect and consequently the most deep ly analysed in this thesis. Hence, it is based in research on the specif ic topic of green fagades, wh i l e the rest, such as air and water quality, are based in related research on green roofs and urban forests, and even in extrapolations and assumptions based on empir ica l data and intuitions, such as the inf luence of green fagades on urban biodiversity, their contr ibut ion to the indoor-outdoor relat ionship, and their contr ibut ion to carbon neutral architecture. This reveals the lack of literature and scarce research avai lable on the specif ic topic of green fagades, c la iming the need for deeper analysis on this topic. However , the f ramework reflects that, regarding the influence of green fagades on human comfort, those green facades attached to transparent fagades achieve a better fulf i lment of the opportunities, especia l ly for east, west and south orientations; whereas those green fagades attached to opaque wal l s ach ieve a better accomp l i shment of the opportunit ies for north orientations. This is true especia l ly for the opportun i ty to improve comfort temperature and reduction in energy demand, since those green facades attached to transparent wal l s a l l ow solar energy gain in the indoor space. O n the contrary, green fagades attached to opaque wal l s provide higher thermal insulation than those attached to transparent fagades, w h i c h is an important asset for north fagades. Thus, this analysis conc ludes that, in general and although a deeper analysis on local context wou l d be needed, for east, south and west orientations, those green fagades attached to transparent wal ls perform better in terms of the inf luence on human comfort than those attached to opaque wal ls. At the same t ime, for north orientations, green fagades attached to opaque wal l s perform better than those attached to transparent wal l s . I 3. G reen Fagades Framework The framework also shows some lost opportunities by all five types of green facades in considering those related to air & water quality and the indoor-outdoor relationship. This is mainly due to the lack of any effort to store rainwater for irrigation and grey water treatment in the building. Current green facade systems generally incorporate neither movement nor flexibility in facades, nor any option to be manipulated by its users. In general, most types of green fagades achieve quite good values for their contribution to urban biodiversity and carbon neutral architecture. The first is due to the assumption that green surfaces within the city always improve urban biodiversity, but further research is needed to clarify which would contribute more to urban biodiversity than others. Regarding the relatively high values achieved in terms of carbon neutral architecture, it seems logical since greenery is a natural element with low energy requirements during its fabrication, leaving the most significant determination of carbon neutral value to the rest of components of the green facade, such as wires or meshes to guide plants, plant pots, etc. Finally, it is striking that within the category of green facade, those facades incorporating opaque walls perform worse in the framework on the whole; yet, it is one of the most common practices, especially the green facade type 1.1. This confirms the suggestion that the current practices for building green facades are more concerned with exploring and developing their expressive capacity than with taking advantage of other opportunities that are available. Therefore, the framework considers the element of human comfort to be the most meaningful opportunity, especially with respect to the contribution to comfort temperature and reduction in energy demand. While the practice of green facades suggests the expressive capacity is the most commonly considered aspect of green facades, the research studies on the topic suggest human comfort conditions are the most relevant aspects. This thesis, while waiting for further research in the underdeveloped areas of study, acknowledges human comfort as the most determinant factor in green facades. I 3. Green Facades Framework 4 A P P L I C A T I O N O F G R E E N F A C A D E S F R A M E W O R K This chapter appl ies the green fagades f ramework to exist ing projects that fit the f ive types of green fagades w i th in the two major categories: attached to an opaque wa l l , and attached to a transparent w a l l . By d o i n g so, the thesis attempts to, on the one hand, present a better understanding of the f ramework by app l y i ng it to real green fagade pract ices and, on the other hand, enable a cr i t ique and evaluat ion of the suitabi l i ty of ex is t ing green fagades. This sect ion selects the most representative examples of those used in the deve lopment of the f ramework as a case study for each of the five types of green fagades. The example selected for a green fagade c o m p o s e d of steel wi res attached to an opaque wa l l [green fagade type 1.1] is the Rue des Suisses apartment c o m p l e x des igned by H e r z o g and the M e u r o n in Paris, in 2 0 0 0 . The example selected for a green fagade as a moss wa l l [green fagade type 1.2] is the Q u a i Branly M u s e u m by N o u v e l in Paris, in 2 0 0 6 . For a green fagade composed of green vertical panels [green fagade t ype l .3] the selected case study is Seedorf House , designed by M a n u e l Perez in M a d r i d , in 2004 . For a green fagade between two transparent layers [green fagade type 2.1] the selected example is the Arts and H u m a n Sciences bu i l d i ng by Lacaton & Vassal in Grenob le , France, 1995-2 0 0 1 . F ina l ly , the selected examp le for a green fagade where the external layer is the greenery and the internal layer is the transparent layer [green fagade type 2.2] is the Gymnast ic Pavi l ion des igned by A b a l o s and Herreros in M a d r i d in 2 0 0 2 . By app ly ing the f ramework to these exist ing examples of green fagades, a cr i t ique about the suitabi l i ty of each fagade is p rov ided. The app l ica t ion of the f ramework presents an overa l l evaluat ion of each of the selected exist ing examples summar i zed in the f o l l ow ing charts. These charts v isual ly show the evaluat ion of a part icular case study in the six ident i f ied areas [Human Comfort:; Expressive capacity; Air & Water Quality; Indoor-Outdoor Relationship; Urban Biodiversity; and Carbon Neutral Architecture], as a means of faci l i tat ing the understanding of the suitabi l i ty of each project to its particular case. I 4. App l i ca t i on of G reen Fagades Framework Evaluation of some opportunities is based on specific data, such as comfort temperature and reduction in energy demand, while in others it is based in empirical data or in intuitions and speculations, such as the opportunity for the expressive capacity of green facades and their contribution to carbon neutral architecture. In this sense, this thesis considers the opportunity for green facades to contribute to comfort temperature and reduction of energy demand as the most decisive aspect when determining a green facade. This is mainly due to the lack of scientific data for the rest of the identified factors specifically on the topic of green facades, the measures of which are extrapolated from research and empirical data on urban forests or green roofs, assumptions and intuitions. This chapter shows the evaluation of each of the selected case studies of green facades, as a means of critiquing them and determining their suitability for each particular case, bringing together the overall performance of the green facade based on each opportunity. 4.1 Case Study of Rue des Suisses apartment complex [Green Facade composed of steel wires] The selected green facade building composed of steel wires, as a representative example of this type of green facade, is the Rue des Suisses apartment complex designed by Herzog and the Meuron in Paris in 2000. The green facade building is constructed of an interior slab that is 3 floors in height and part of three interconnected apartment elements which infill a long perimeter block. The long narrow block is a free-standing building located in the interior garden of the perimeter block [Fig4.2]. 4. Application of Green Facades Framework 3 image wa i t i ng for ® permiss ion F ig . 4.2 Rue des Suisses apartment complex, the interior long block incorporates wooden blinds [south-east and south-west orientations] and the green facades [north-east and north west orientations], as a means of integrating and dialoguing with the interior garden, in contrast with the metallic meshes facades of the apartments facing the streets. In contrast to the meta l l ic mesh in the facades of the two bu i ld ing b locks that face the streets, the interior l ong narrow b lock presents w o o d e n b l ind facades and green facades as a means of softening their appearance, integrating and d ia logu ing wi th the interior garden: "V ines grow on a system of metal wi res fastened to the b lank wa l ls of the garden bui ld ings, help to create an ove rg rown , unkempt amb ience to the landscape a r e a s " n . The app l ica t ion of the green facades f ramework to the green facade in the Rue des Suisses apartment c o m p l e x is summar i zed in Tab le 4 . 1 , s h o w i n g the evaluat ion of its appropriateness in terms of the accomp l i shmen t of the six ident i f ied opportuni t ies. Roger Sherwood, Rue des Suisses. www.housingprototypes.org 4 . App l i ca t i on of G reen Facades Framework Rue des Susisses apartments, Paris Type 1.1 Green fagade composed of steel wires attached to an opaque wall 1. Human Comfort Comfort temperature &| reduction in energy d N W LOW Acoustic o insulation • H I G H 1 Visual Comfort Humidity LOW 0 H I G H 1 Psychological benefits H I G H 1 Project Apartment Building Location Rue des Suisses 19, Paris Year 2000 Architects Herzog & de Meuron Green Fagade orientatioi^ North-east & north-west 2. Expressive Capacity 3. Air and Water Quality 4. Indoor-Outdoor Relationship 5. Urban Biodiversity 6. Carbon Neutral Architecture LOW 0 HIGH 1 LOW HIGH 0 0.15 0.3 0.5 0.75 1 LOW 0 0.25 0.5 HIGH 0.75 1 LOW 0 0.25 0.5 HIGH 0.75 1 LOW HIGH 0 0.5 1 Table 4.1 Evaluation of the selected example - Rue des Suisses apartment - for a green fagade type 1.1 composed of steel wires attached to an opaque wall 4. Application of Green Fagades Framework Table 4.1 represents the accomplishment of each opportunity according to the selected case study for the green fagade composed of steel wires attached to an opaque wall. It shows how this particular case fulfils them, in general, quite poorly. The most relevant opportunity for the developed framework is the contribution to comfort temperature and reduction in energy demand, since it is based on scientific data. In this sense, the green fagade in the Rue des Suisses apartment complex is a north-east and north-west oriented fagade, which would have performed better in terms of contributing to comfort temperature and reduction in energy demand [red lines] had it proposed a solution with higher thermal insulation capacities. For the rest of the opportunities in the Human Comfort category, which are based on empirical data and intuitions, the performance is rather low. In the Expressive Capacity category of this case study, which seeks a soft integration with the surrounding interior garden by the subtle steel wires system, the framework is evaluated as a high contributor to the expressive capacity offered by this green fagade due to its attention to generating a dialogue with the immediate context. In the case of Air Quality, given that it consists of a climber plant [vine], its contribution to air quality is modest [0.3]; while regarding the Water Quality it would have performed better if it had incorporated some kind of rainwater retention system or treatment for the grey water used by the building. For the Indoor-Outdoor relationship, it does not perform well, since many parts of the green fagade are not easily accessible and since it offers no flexibility to allow users to change their relationship with the outdoor space. The performance of the fagade in terms of the contribution to Urban Biodiversity would have been better had it proposed more than just one plant species [vines]. In terms of the contribution to Carbon Neutral Architecture, the rest of the materials used other than greenery, such as stainless steel wires which are not particularly environmentally friendly, result in a moderate achievement of this opportunity. 4. Application of Green Fagades Framework 103 4.2 Case Study of Quai Branly Museum [Green Facade as moss wall] The f ramework is app l ied to the green facade of the Q u a i Branly M u s e u m designed by Jean Nouve l in Paris in 2006, as a representative case of a "green facade as a moss w a l l " . The M u s e u m is located in the left bank of the Seine a long the Q u a i Branly Street. The four storey green facade, from roof to s idewalk, has a north-west or ientation to the Left Bank Bou levard [Fig4.4]. Fig. 4.4 The green facade of the Quai Branly Museum faces the Left Bank Boulevard integrating with its vegetation. The green facade of the M u s e u m seems to look for a d isappearance w i th i n its surroundings, "where material form seems to melt away, g iv ing the impress ion [of] a sanctuary wi thout w a l l s . " 7 4 Tab le 4.2 summar izes the appl icat ion and evaluat ion of the f ramework for this green facade. Joann Gonchar, AIA. Musee du Quai Branly. Architectural Record February issue, New York 2007 4. App l i c a t i on of Green Facades F ramework Figure 4.3 Quai Branly Museum facing Left Bank Boulevard. 2 image wa i t i ng for permiss ion Quai Branly Museum, Paris Type 1.2 G reen fagade as moss w a l l s 1 . Human Comfort Comfort temperature &j reduction in energy d N W . Acoustic o insulation m HIGH 1 Visual Comfort Humidity LOW 0 HIGH 1 Psychological benefits LOW HIGH 0 0.5 1 s a Project Quai Branly Museum Location Quai Branly Street, Paris Year 2006 Architect Jean Nouvel Green Facade orientation North-west 2. Expressive Capacity 3. Air and Water Quality 4. Indoor-Outdoor Relationship 5. Urban Biodiversity 6. Carbon Neutral Architecture LOW 0 HIGH 1 LOW HIGH 0 0.15 0.3 0.5 0.75 1 LOW 0 0.25 0.5 HIGH 0.75 1 LOW 0 0.25 0.5 HIGH 0.75 1 LOW HIGH 0 0.5 1 Table 4 .2 Evaluation of the selected example - Quai Branly Museum - for a green fagade type 1.2 as moss walls attached to an opaque wall 4. Application of Green Fagades Framework A s Table 4.2 shows, the green facade of the Q u a i Branly M u s e u m performs relat ively we l l in terms of the cont r ibut ion to comfor t temperature and reduct ion in energy demand , s ince it is a green facade wi th high thermal capaci t ies located in a north-west or ientat ion. M o s t remarkable is perhaps its high per formance in the cont r ibu t ion to Urban Biodiversi ty, s ince it is p laced in one of the green networks of Paris - Left Bank Bou levard - enhanc ing life for other l i v ing organisms, and in t roduc ing more than 150 plant spec i es 7 5 . This case study of a green facade seeks integration wi th the sur round ing bou levard mel t ing into its greenery; hence, the evaluat ion of the Expressive Capac i ty as h igh. . O n the contrary, the rest of the opportuni t ies are not ful f i l led as highly. Mos t l y al l plant species are "grassy" species w h i c h per form at a l o w level w i th respect to their contr ibut ion to trap air pol lutants; and it does not cons ider any opt ion for incorporat ing rainwater retention systems or grey water re-use treatments to ach ieve a better performance in A i r and Water Qua l i t y . No r does it fulf i l the oppor tuni ty to improve the Indoor-Outdoor Relat ionship s ince it is not easi ly accessib le and it does not a l l o w any movemen t w i th in the green facade to prov ide f lexib i l i ty to users to establ ish the des i red re la t ionship w i th the outdoor space through the greenery. W i t h respect to C a r b o n Neutral Arch i tecture, the per formance w o u l d have been better had env i ronmenta l ly f r iendl ier componen ts of the facade been cons ide red , wh i ch w o u l d have meant using low energy materials instead of a P V C substructure. 7 5 Proefrock Philip. Living Walls, www.ecogeek.org I 4. App l i ca t i on of G reen Facades Framework | l 0 6 4.3 Case Study of Seedorf House [Green Fagade composed of vertical panels] The green fagade selected for green fagades c o m p o s e d of vert ical green panels is the Seedorf house in M a d r i d , a s ingle fami ly w e e k e n d h o m e des igned by M a n u e l Perez, Car los A r r o y o and Eleonora Guidot t i in 2 0 0 3 . The house is p laced in a smal l w o o d and reinterprets the trees of that sur round it p lay ing w i th green carpets - green fagades - and g laz ing fagades w i th d iverse opaci t ies. [Fig4.6] F igure 4 .5 Seedorf House. Green "boxes" facing east orientation 2 images wa i t i ng for ® permiss ion F ig . 4 .6 The green fagade of the Seedorf House is embedded by the trees of its surrounding environment. T h e green fagade interacts w i th the w o o d o f its sur round ing . These are suspended " l i ke p ieces of fruit, f rom the structural trunk fagade" p rov id ing " a b lanket of vegetat ion that changes co lou r w i th the seasons " 7 6 . The evaluat ion of this green fagade is s u m m a r i z e d in Tab le 4 .3 . 7 6 House of Love, www.carlosarroyo.net. 4 . App l i ca t i on of G r e e n Fagades F ramework Iirj7 Comfort temperature & reduction in energy d. A Acoustic insulation 0 • i M Humidity 0 • 0.5 • i w mm E Visual Comfort Psychological benefits 0 a 0.5 ia i s Seedorf House, Madrid 1. Human Comfort Type 1.3 Green facade composed of green vertical panels Project Seedorf House Location La Moraleja, Madrid Year 2003 Architects M . Perez & C. Arroyo & E. Cuidotti Green Facade orientatio North, south, east, west 2. Expressive Capacity 5. Urban Biodiversity 6. Carbon Neutral Architecture L O W 0 H I G H 1 L O W 3. Air and Water Quality 0 0 . 1 5 0 . 3 • • 0 . 5 0 . 7 5 1 L O W 4. Indoor-Outdoor Relationship 0 0 . 2 5 0 . 5 0 . 7 5 1 3 • s L O W 0 0 . 2 5 0 . 5 H I G H 0 . 7 5 1 L O W H I G H 0 0 . 5 1 Table 4.3 Evaluation of the selected green facade - Seedorf House - for a green facade type 1.3 composed of green vertical panels | 4 . A p p l i c a t i o n of G r e e n Facades Framework Tab le 4.3 suggests that the inf luence of the green facade in Seedorf House in comfort temperature and reduct ion in energy d e m a n d is higher w h e n fac ing north than w h e n facing other orientations. Th is is due to the high thermal capaci ty of this type of green facade. It is therefore striking to see the same proposal of for a green facade fac ing four different orientations, s ince the greenery reacts qui te dif ferently in each of these d i rect ions. St i l l , the facade performs quite we l l improv ing the bu i ld ing 's acoust ic insu lat ion. This green facade seeks integration w i th its surrounding wood lands through the comb ina t ion of greenery and g laz ing , w h i c h achieves a high evaluat ion in the category of Expressive Capac i ty . As for the rest of the categories, the per formance is basical ly modest and cou ld have been cons iderab ly better. S imi lar to the two previous case studies, it cou ld have performed better in terms of improv ing A i r and Water Qua l i t y if any opt ions for incorporat ing rainwater retention systems or grey water re-use treatment had been cons ide red . The Indoor-Outdoor Relat ionship c o u l d have been better had it p rov ided some k ind of f lexib i l i ty to the users to modi fy the re lat ionship w i th the ou tdoor space, and if the accessib i l i ty to different parts of the facade had been easier. The substructure of the green facade, made of stainless steel mesh, w h i c h is not a l ow energy mater ia l , results in a modest ach ievement of Ca rbon Neutral Archi tecture. 4. App l i ca t i on of G reen Facades Framework 4.4 Case Study of Arts and Human Science Bid [Green Fagade between two transparent layers] The representat ive examp le of green facades between two transparent layers to be eva luated by the f ramework is the Arts and H u m a n Sc iences Bu i l d i ng of the Pierre M e n d e s Univers i ty in G r e n o b l e , France, des igned by Lacaton and Vassa l , 1 9 9 5 - 2 0 0 0 . The c o m p l e x , bui l t in two stages, 1995 and 2 0 0 0 , is uni ted by the greenhouses p laced in the north and south fagades of the bu i ld ing . [Fig 4.8] Figure 4 .7 Arts and Human Science Building. Green fagades facing north and south 3 images wa i t ing for 0 permiss ion F ig . 4 .8 The Arts and Human Science building of the Pierre Mendes Universityin Grenoble unifies the two pieces of the building by the "thin greenhouses" proposed for the north and south orientations. The "thin g reenhouses" p roposed in this bu i l d i ng " o p e n the bu i l d ing to the campus and further sur round ings" seek ing a poet ic a tmosphere : "the v iews in and out are f i l tered by the plants in the conservator ies - bouga inv i l l ea on the south s ide and var ious types o f b a m b o o a long the north f a c e " 7 7 . The f ramework evaluates this green fagade as fo l l ows [Table 4.4]. 7 7 University Insititute in Grenoble. Detail Magazine, # 12, 2002. I 4 . A p p l i c a t i o n of G reen Fagades F ramework Arts and Human Science building in Grenoble Type 2.1 Green facade between two transparent layers 1. Human Comfort Comfort temperature &j reduction in energy d. N W Acoustic insulation Visual Comfort HIGH 1 Humidity L O W o Psychological L O W benefits ° HIGH 1 Project Arts and H. Science Bid Location U P M F , Grenoble Year 1995 & 2000 Architects Lacaton & Vassal Green Fagade orientation North and south 2. Expressive Capacity LOW 0 HIGH 1 3. Air and Water Quality LOW HIGH 0 0.15 0.3 0.5 0.75 1 4 . Indoor-Outdoor Relationship LOW 0 0.25 0.5 HIGH 0.75 1 5. Urban Biodiversity LOW 0 0.25 0.5 HIGH 0.75 1 6. Carbon Neutral Architecture LOW 0 0.5 HIGH 1 Table 4.4 Evaluation of the selected green fagade - Arts and Human Science Bid - for a green fagade type 2.1 between two transparent layers 4. A p p l i c a t i o n of G reen Fagades Framework 11 Focus ing on the graph that shows the in f luence to comfort temperature and reduct ion in energy d e m a n d of the green facade at the Arts and Sc iences Bu i ld ing in Grenob le , it is clear how differently the facade performs for the north and south orientat ions. Since it a l lows the solar energy to pass through the g laz ing facade, it performs qui te better in the south or ientat ion, wh i l e quite poor ly for the north or ientat ion, as it has little thermal inert ia. Thus, it is str iking to observe the same type of green facade for both or ientat ions. The facade, wi th greenery be ing v is ib le from both the inside and the outs ide of the bu i l d ing , performs qui te we l l for v isual comfort and psycholog ica l benefits. Th is , on the w h o l e , results in a successful ach ievement of the opportuni ty to improve H u m a n Comfor t . These thin greenhouses seek a poet ic atmosphere, f i l tering the v iews by the plants, w h i c h means a high per formance in the oppor tuni ty for the Expressive Capaci ty . Regard ing the cont r ibut ion to air qual i ty , it performs as the best of the f ive selected green facades, s ince the shrubby plants proposed perform we l l in this respect; whereas, as in the previous case studies, this green facade performs poor ly in its contr ibut ion to water qual i ty s ince it does not cons ider any opt ions for incorporat ing rainwater retention systems or treatment for the grey water used by the bu i ld ing , ach iev ing an overa l l moderate va lue in its contr ibut ion to A i r & Water Qua l i t y . Regard ing the indoor-outdoor re lat ionship, the facade system facilitates maintenance by a l l o w i n g access ib i l i ty on each f loor by w a y of the meta l l ic canti levers. Howeve r , it does not prov ide f lex ib i l i ty to the users to modi fy their re lat ionship wi th the outdoor space. The greatest f law of this green facade, w h e n compared wi th the other four case studies, is its poor contr ibut ion to U r b a n Biodivers i ty . This is due to the fact that the external transparent layer does not facil itate any interact ion wi th other l i v ing organisms. In cons ider ing the contr ibut ion to Carbon Neutral Arch i tec ture, the facade system does not ut i l ize env i ronmenta l ly fr iendly materials other than the greenery. 4. App l i ca t i on of G r e e n Fagades Framework 4.5 Case Study of the Gymnasium in the Retiro Park [Green Facade as the external layer] The G y m n a s i u m pav i l i on des igned by A b a l o s & Herreros in the Retiro Park in M a d r i d , 2 0 0 2 , is the selected examp le for the last type of green facade, in w h i c h the external layer is the greenery and the internal layer is transparent. The facade integrates the b u i l d i n g w i th the park by the dis integrat ion of archi tecture mel t ing into the sur round ing greenery. F ig . 4 . 10 The Gymnasium at the Retiro Park reinterpret the use of trellis and plants in old buildings of the park. The meta l l i c mesh gu id ing the vegetat ion enc loses the gymnas ium seeking a "s imi la r image to the vegetated structures w i th a long tradi t ion in gardening. . . Emula t ing these references the project strives to create a contemporary v is ion o f the pav i l ion theme in a garden by us ing an abstract compos i t i on wi th the vegetat ion ou t l ined wi th the f ramework . The construct ion w i l l thus be a n e w amalgam of natural and artif icial e lements " 7 8 . Tab le 4 .5 summar izes the eva luat ion of this green facade acco rd ing to the f ramework. Figure 4 .9 Gymnasium in the Retiro Park www.abalos-herreros.com 4 . A p p l i c a t i o n of G r e e n Facades F ramework 113 Gymnastic Pavilion in El Retiro, Madrid •HHBHHHHHHHHHHHHRH 1. Human Comfort Type 2.2 Creen external layer and glazed internal layer reduction in energy d. N Acoustic insulation Humidity 0 0.5 1 • • Visual 0 1 Psychological Comfort • benefits 0 a 0.5 • 1 Project Gymnastic Pavilion. Location El Retiro, Madrid Year 2002 Architects Abalos & Herreros Green Facade orientation; North, south, east, west 2. Expressive Capacity L O W H IGH 0 1 s 3. Air and Water Quality L O W H I G H 0 0.15 0.3 0.5 0.75 1 4. Indoor-Outdoor Relationship L O W 0 0.25 0.5 HIGH 0.75 1 5. Urban Biodiversity L O W H IGH 0 0.25 0.5 0.75 1 6. Carbon Neutral Architecture L O W H IGH 0 0.5 1 Table 4.5 Evaluation of the selected green facade - Gymnasium - for a green facade type 2.2 Green external layer and glazed internal layer 4. Application of Green Facades Framework 114 Regard ing the cont r ibut ion of this green fagade to comfort temperature and reduct ion in energy d e m a n d , the chart in Tab le 4.5 shows h o w differently it performs for, on the one hand, east, west, and south orientat ions, and , on the other, the north or ientat ion. In these terms, the fagade solut ion performs better for the first group, s ince it a l l ows the solar energy to pass through the g laz ing fagade, and performs poor ly for the latter. As a result, it is unfavourable to see the same solut ion app l ied to al l four or ientat ions. As for the other aspects of the fagade that contr ibute to H u m a n Comfor t , the green fagade does we l l to fulf i l its opportuni t ies for v isual comfort and psycholog ica l benefits, s ince the greenery is v is ib le f rom both the inside and the outside of the bu i ld ing . This green fagade looks for a w a y of integrating and camouf lag ing the bu i l d ing wi th in the landscape of the park by the mel t ing the archi tecture into the surrounding greenery, per forming h ighly in its cont r ibut ion to the Expressive Capac i ty . The contr ibut ion of the green fagade at the Gymnas t i c Pavi l ion to A i r and Water Qua l i t y , is rather l ow , as it consists of c l imber plants - parthenocissus qu inquefo l ia , per forming in a modest w a y in its cont r ibut ion to air qual i ty - and as it does not incorporate any rainwater retention systems or any treatment for the grey water used by the bu i l d ing . In the case of the opportuni ty to enr ich the indoor and outdoor re lat ionship, this green fagade system is still quite r igid and does not prov ide any movemen t to enable users to manipu la te and change their relat ionship w i th the outdoor space. In the case of Ca rbon Neutral Arch i tec ture, env i ronmenta l ly fr iendl ier components of the fagade shou ld have been cons ide red , such as recyc led materials to guide plants instead of the p roposed meta l l ic mesh . 4 . App l i ca t i on of G reen Fagades Framework 115 4.6 Overview of the Application The main conc lus ions of the app l ica t ion of the green fagades f ramework to the f ive exist ing case studies in terms of the six p roposed opportuni t ies are the fo l l ow ing : Human Comfort In terms of the cont r ibut ion of green fagades to the improvement of human comfort, the analysis reveals those green fagades attached to opaque wa l l s perform better for a north or ientat ion, wh i le those green fagades attached to transparent wa l ls perform better for east, west, and south or ientat ions. From this perspect ive, it is str ik ing to observe the same fagade solut ion proposed for al l four or ientat ions, w h i c h many of the case studies reveal . The green fagades that perform better as acoust ic insulators are, w i th in those attached to opaque wal ls , the Q u a i Branly M u s e u m and the Seedorf H o u s e [types 1.2 and 1.3 - as moss wa l ls and composed by green vertical panels, respect ively] . D u e to the scarce data on the in f luence of green fagades to humidi ty , the f ramework is not ab le to evaluate it. O n the other hand , those that perform better for v isual comfort and psycho log ica l benefits are those fagades where the greenery is v is ib le from both the inside and the outs ide; these are green fagades attached to transparent wal ls . Expressive Capacity The app l ica t ion of the f ramework reveals the di f f icul ty to object ively evaluate the expressive capac i ty of green fagades. The overal l per formance that the case studies reveal is rather h igh, partly due to the fact that they have been selected among the most representative examples wi th in the current international pract ices of bu i l d i ng green fagades. At the same t ime, the general ly high ach ievement of this oppor tun i ty , w h e n compared wi th those of the other six, illustrates h o w this aspect is someth ing current pract ice does fairly w e l l , wh i l e the others remain , so far, as relat ively missed opportuni t ies. 4 . App l i ca t i on of G reen Fagades Framework 116 Air & Water Quality Al though the use of different plant species as air filters t rapping air pollutants results in different per formances, the general cont r ibut ion to air and water qual i ty by the selected case studies is rather l ow . This is ma in l y due to a major f law: none of them considers the incorporat ion of rainwater retention or grey water treatment systems. The appl icat ion of the f ramework suggests there is a major neglect of this category and further considerat ion shou ld be taken. Indoor-Outdoor Relationship The general per formance of this oppor tun i ty is also rather low. Those facade solut ions w h i c h are access ib le for ma in tenance on each f loor perform somewhat better than those that do not. H o w e v e r , al l the case studies are re lat ively hermet ic and r ig id, indicat ing a need to advance the design of green facade solut ions to be more f lex ib le and moveab le , w h i c h w o u l d a l l ow the bu i l d i ng users to mod i f y and enhance their re lat ionship to the outside env i ronment . Urban Biodiversity. O v e r a l l , the cont r ibu t ion to urban biodivers i ty is fairly high in most cases. It is higher in those facade solut ions that incorporate a larger variety of species and that are located in urban greenways [i.e. Q u a i Branly Museum] and is lower in those solut ions where the greenery is kept f rom contact wi th the outs ide [Arts and H u m a n Sciences Bu id l ing , Grenob le ] . Carbon Neutral Architecture The appl icat ion of the f ramework suggests more effort is needed toward inc lud ing env i ronmenta l ly f r iendl ier materials for the rest of the components of green facades other than the greenery itself. H o w e v e r , the results for the evaluat ion of the fu l f i lment of this oppor tuni ty may be considered as part ial , s ince, on the o n e hand , the f ramework does not consider the CO2 sequestration capaci ty of different plant species [due to lack of speci f ic data], and on the other, the reduct ion of emissions by the bu i l d ing is cons idered in comfor t temperature and reduct ion in energy d e m a n d . 4. App l i ca t i on of G r e e n Facades Framework Since the most studied oppor tun i ty is the in f luence of green fagades to human comfort condi t ions, and more speci f ica l ly , to comfor t temperature and reduct ion in energy d e m a n d , the f ramework cons iders , unti l there is further research on the other core opportuni t ies, that this aspect is by far the most dec is ive in de f in ing a green fagade. Therefore, the f ramework considers that passive solar behav iour together w i th the energy behav iour of green fagades are the most crucia l aspects when des ign ing and de f in ing green fagades. In this sense, Table 4.6 compi les the evaluat ion of the cont r ibut ion of each of the case studies to comfort temperature and reduct ion in energy demand to show the appropr iateness of each of them. The spider graphs illustrate this contr ibut ion: red l ines illustrate spec i f ic or ientat ions [in the case of Rue des Suisses apartment the contr ibut ion of the north east and north west green fagades; in the case of Q u a i Branly M u s e u m the contr ibut ion of the north west or iented fagade; and in the case of Arts and H u m a n Sciences Bu i ld ing the cont r ibut ion of the north and south orientations]. The grey hatched graphs show this contr ibut ion of those green fagades to the four or ientat ions. F inal ly , the app l ica t ion of the f ramework to the selected case studies provides a first set of criteria to help determine the most appropr iate green fagade for a speci f ic project and , at the same t ime, acknow ledges the need for further research studies in all of the identi f ied areas. 4. App l i ca t i on of G reen Fagades Framework ; Comparison of the Appropriateness of the five selected examples of green fagades, regarding their contribution to comfort temperature ! and reduction in energy demand Green Facades attached to a transparent wall Green Fagades attached to an opaque wall N W Vv W VV w Table 4.6 Overview of the contribution of the five green fagade case studies to comfort temperature and reduction in energy demand, showing their appropriateness | 4. Application of Green Fagades Framework | 1 1 4. Application of Green Facades Framework 5 CONCLUSION 5.1 Overview of the thesis This thesis opens a larger range of quest ions than those that designers usual ly ask when des ign ing green facades. F rom these, this sect ion extracts two main conc lus ions : Types of green facades. Th is thesis prov ides a relevant classif icat ion of green facades be long ing to the two main categories: opaque and transparent green facades. This c lassi f icat ion is ach ieved by analys ing the current practices for bu i ld ing green facades, s tudy ing a series of exist ing examples , and ident i fy ing their systems of construct ion. Decisive attributes in green facades. O f all the analysed opportuni t ies the thesis identif ies, the most determinant attribute is human comfort , speci f ical ly comfort temperature and reduct ion in energy d e m a n d . This is main ly because it is the attribute that more spec i f ica l ly refers to passive architecture, in terms of different facade or ientat ions and opt ions for taking advantage of solar energy. Moreover , among all the analysed attributes, w h i c h are based on a series of research studies, the most deep ly studied relates to human comfort . The thesis proposes a f ramework w h i c h comb ines these two f indings, the one extracted from the current pract ices of green facades and the other extracted from related research. This br ings clar i ty to evaluate the appropr iateness of each type of green facade. This is indeed the most relevant cont r ibut ion of this thesis: to p rov ide an understanding of w h y a particular type of green facade, such as opaque , performs better in a north or ientat ion, wh i le other types of green facades, such as transparent facades, funct ion better for south, east and west or ientat ions. This framework also reveals clear di f ferences between the behaviour of the two main categor ies: opaque green facades and transparent green facades. It shows h o w opaque green facades can on ly part ial ly meet many of the ident i f ied attributes. This is main ly due to the fact that opaque green facades on l y affect one side of the facade, the outside, wh i l e transparent green facades affect both the inside and the outs ide. It also reflects the less ful f i l led opportuni t ies, w h i c h are the enr ichment of the indoor and outdoor relat ionship and the cont r ibut ion to air and water qual i ty. Th is is ma in ly because none of the exist ing green facades has incorporated any f lex ib le systems nor has the opt ion of retaining rain water or treating the grey water used by the bu i l d i ng been cons idered. The thesis attempts to c o m b i n e the current pract ice of green facades wi th the current research on green facades. Apparen t ly these two aspects w o r k independent ly wi thout interacting w i th one another. The current practices seem to be more concerned wi th exp lor ing the expressive capac i ty and research on exp lo r ing the in f luence on human comfort . This thesis, by c o m b i n i n g both and evaluat ing them, intends to prov ide a deeper study of green facades in order to improve the present status. G o i n g back to the two quest ions raised in the beg inn ing of the thesis: Does the current practice of green fagades accomplish the full range of opportunities they embody? A n d , What are the criteria that enable designers determine the most appropriate green facade for a given context? The analysis made throughout the thesis, first in a pre l iminary way in the classif icat ion of the current types of green facades, and later more thoroughly in the appl icat ion of the f ramework, reveals that the current practices for bu i l d i ng green facades do not accompl ish the full range of oppor tuni t ies they might e m b o d y . The results f rom the appl icat ion of the framework suggest that the current pract ices for bu i l d i ng green facades are ignor ing or underestimating many of possib i l i t ies, such as the improvement of human comfort , the contr ibut ion to air and water qual i ty , and the enhancement of the indoor-outdoor re lat ionship, among others. The f ramework suggests current architects, w h e n des ign ing green facades, are pr imar i ly concerned w i th the expressive capaci ty vegetat ion prov ides. A l though undoubtedly the natural changeabi l i ty green facades exhib i t is a relevant aspect that leading architects today are exp lo r ing , it is important to emphas ize that an expressive capaci ty is not the on ly opportuni ty green facades offer. In this sense, and as for the second quest ion , the f ramework proposes a set of cri teria to determine the appropr iateness of a green facade based on the ful f i l lment of a broader set of oppor tuni t ies beyond the expressive capaci ty . These criteria enable a cr i t ique of the current pract ice of green facades, p rov ide so l id arguments to dist inguish the conven ience of the ex is t ing types of green facades, facil itate a better understanding of the opportuni t ies, their accomp l i shmen t , and their ro le in a speci f ic context , and , ult imately, help def ine the most appropr iate green facade for a part icular project. 5.2 Framework Usefulness, Limitations, and Further Research 5.2.1 Framework Usefulness and Limitations The deve lopmen t and app l ica t ion of the green facades f ramework has proved useful in br inging clar i ty about a broader set of opportuni t ies in green facades beyond their expressive capaci ty. Through a cr i t ique in terms of the fu l f i l lment of the identi f ied opportuni t ies, it a l lows to determine the appropr iateness of a green facade for a spec i f ic project. Through the classi f icat ion of the current types of green fagades and the ident i f icat ion of the oppor tun i t ies, the f ramework permits designers to dist inguish the appropriateness of the different green fagades by understanding w h y and w h e n one particular type of green fagade performs better than others in a g iven context. It therefore intends to work as a comprehens ive tool related to the behav iour of the different types of green fagades for the six identi f ied areas. This f ramework is most useful to c o m b i n e the type of green fagade w i th the or ientat ion, and in understanding the appropr iateness of a part icular type for a part icular or ientat ion. Never theless, it is important to acknow ledge the l imitat ions of the f ramework. First, there are two important aspects w h e n def in ing a green fagade that have been in t roduced in the f ramework in a rather general manner . These are the loca l c l imate condi t ions and the loca l plant species. The f ramework c lear ly evaluates and differentiates the behavior of a green fagade for the different or ientat ions, but it a lso contr ibutes to further studies o n local c l imate cond i t ions as a means of de te rmin ing whether , for instance, it is more important to achieve a higher thermal insulat ion than to a l l o w solar energy to pass through the fagade, or v ice versa. In the case of local plant species, the f ramework d iv ides them qui te general ly into three main groups - shrubby, grassy, and c l imber plants. There is a need for further research on the suitabi l i ty of different plant species to enhance loca l species and on their behavior a n d main tenance to inform different construct ion systems. Ano ther major l imitat ion of the f ramework is that m u c h of the research o n w h i c h it is based o n is not research focused speci f ica l ly on green fagades. Rather, the f ramework extracts and extrapolates data from related research studies on U rban Forests and Green Roofs. This suggests a major need and opens the door for future research in al l of the identi f ied areas of the f ramework. 5.2.2 Further research The proposed f ramework and its l imitat ions demonstrate the need for further green facade-related research in al l areas ident i f ied in the f ramework: Human Comfort, Expressive capacity, Air and Water Quality, Indoor-Outdoor relationship, Urban Biodiversity, and Carbon Neutral Architecture. Th is w o u l d he lp improve the f ramework, adjust ing its usefulness, and prov id ing a better understanding of the behav iour of green facades. Further research themes and extrapolat ions are deta i led be low . - Human Comfort Figure 5.1 The contribution of green fagades to Human Comfort should be analyzed for the four orientations The different aspects w i th in H u m a n Comfor t are the most studied wi th speci f ic reference to green facades, espec ia l ly the in f luence of green facades on comfort temperature. Howeve r , these research studies are usual ly focused on analys ing the behaviour of west or iented green facades attached to an opaque wa l l [A. H o y a n o , 1 9 8 8 7 9 and D i and W a n g , 1999 8 0 ] . This suggests a need for more research on the in f luence in comfor t temperature and reduct ion in energy demand for nor th, south, and east or ientat ions, and for al l the different types of green facades. Mo reove r , the rest of the aspects affecting human comfort , such as acoust ic in f luence, v isual comfor t , and psycho log ica l benefits requi re more speci f ic research, s ince the data used have been extracted and emula ted to the behav iour of the in f luence of a dense tree belt [Huddart, 1990 8 1 ] , of b l inds in w i n d o w s [Serra and C o c h 1 9 9 5 ] 8 2 , and natural scenes [Kellert and W i l s o n ] 8 3 respect ively. 7 9 Akira Hoyano. Climatological Uses of Plants for Solar Control and the Effects on the thermal Environment of a Building. Ed. Energy and buildings. Vo l 11, no.1-3, pp 181-199. Tokyo 1988. 8 0 H.F. Di and D . N . Wang. Cool ing effect of ivy on a wal l . Experimental Heat Transfer, Volume 12, Issue 3 July 1999 , pages 235 - 245 8 1 Greg Watts et. al. The effects of vegetation on the perception of traffic noise. Applied Acoustics 56 (1999) 3 9 ± 5 6 . 8 2 Rafael Serra and Helena Coch. Arquftectura y energia natural. U P C , Barcelona, 1995 8 3 Stephen Kellert, Edward O. Wilson. The Biophilia Hypothesis. Island Press Washington DC, 1993 125 The in f luence of green fagades on increas ing humid i ty in the env i ronment is in need of more research to clar i fy the results observed in two contradictory studies [A. H o y a n o , 1 9 8 8 8 4 and G . A . C . Cantuar ia 2 0 0 0 8 5 ] . - Expressive capacity Al though this thesis argues that the express ive capaci ty that rel ies on green fagades is the ma in reason for the current use of green fagades, the f ramework needs to be able to evaluate more factors to exp la in whether one green fagade integrates better than others w i th in its surroundings; whether it answers more effect ively to a speci f ic urban context than others; and whether the textures and different grades of openness and c loseness they prov ide perform better in some situations than others. Therefore, the f ramework demands further analysis in this area a c k n o w l e d g i n g the lack of cr i ter ia for evaluat ing green fagades. - Air and Water Quality There is a need for further research o n the spec i f ic project of green fagades regarding the cont r ibut ion of green fagades to air qual i ty , s ince the current f ramework is based on related studies made on U rban Forests [McPherson and N o w a k , 1 9 9 4 ] 8 6 and U rban Biodivers i ty [Schaefer 2 0 0 4 ] 8 7 . In add i t i on , based on the latter study - urban b iodivers i ty - the f ramework considers the capac i ty of plants to trap air pol lutants d i v id ing them into three main groups 8 4 Akira Hoyano. Climatological Uses of Plants for Solar Control and the Effects on the thermal Environment of a Building. Ed. Energy and buildings. Vo l 11, no.1-3, pp 181-199. Tokyo 1988. 8 5 G . A . C . Cantuaria. A comparative study of the thermal performance of vegetation on building surfaces. Proceeding of PLEA 2000 Ed. James & James [Science Publisher] ltd. pp 212-213. Cambridge, UK 2000. 8 6 E. Gregory McPherson, David J. Nowak, Rowan A. Rowntree. Chicago's Urban Forest Ecosystem. Gen. Tech. Rep. NE-186. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 1994 [check: http://www.fs.fed.us/ne/syracuse/Pubs/pubs.htm] 8 7 Valentin Schaefer, Hillary rud, and Jamie Vala. Urban Biodiversity. Captus Press, Ontario 2004 | l 2 6 Figure 5.2 The expressive capacity of green fagades [shrubby plants as higher contr ibutors, c l imber plants as moderate contr ibutors, and grassy plants as lower contr ibutors] . In this sense, more deta i led studies are c l a imed to differentiate this con t r ibu t ion , for instance, w i th in the capaci ty of c l imbe r plants to trap pol lutants. In the case of water qual i ty , s imi lar conc lus ions c o u l d be extracted f rom the capac i ty of different plant species to trap and filter water pol lutants. But the major need for further research relates more to the fact that none of the ana lysed green facade systems incorporates any w a y of treating the grey water used by the bu i l d i ng , nor of reta in ing the rainwater for the water ing of the green facade, for examp le . Figure 5.3 The opportunity to treat greywater and retain rain water - Indoor - Outdoor relationship Together w i th the oppor tun i ty for green facades to contr ibute to air and water qual i ty , the indoor-ou tdoor re lat ionship is the less fu l f i l led of the oppor tuni t ies by the current practices for bu i l d i ng green facades. Th is is ma in l y due to the general r ig id i ty of current green facades. Th is fact opens the door to seek and investigate more f lex ib i l i ty w i th in green facade systems, in t roduc ing movemen t to the facade, such as s l i d ing or rotating green facades. Figure 5.4 The possibility of introducing flexibility in green facades Urban Biodiversity In terms of U rban Biodivers i ty , further research is needed regarding what types of green facades contr ibute more to enhance b iod ivers i ty , relat ing it to the se lect ion o f p lant species. Ano ther aspect to be i nc luded in urban b iod ivers i ty w o u l d be the re lat ionship between the scale of the green fagade and its cont r ibu t ion to urban biodiversi ty. By do ing so, it w o u l d be interesting to c o m p i l e data for the m i n i m u m green facade surface requ i red to ach ieve a m i n i m u m level of b iodivers i ty , and h o w this re la t ionsh ip w o u l d increase by increas ing the green coverage. Th is w o u l d strengthen the intuit ive eva luat ion current ly cons idered by the f ramework. 127 There is another emerg ing concep t related to urban b iodivers i ty , w h i c h is the cont r ibut ion of green facades to urban agr icul ture. S o m e recent research and architectural projects suggest the possib i l i ty of cu l t ivat ing green fagades, k n o w n as "ver t ica l f a r m s " 8 8 . In current t imes whe re peak 2 j m a g e s wa i t i ng for ® o i l consumpt ion is said to be a p p r o a c h i n g 8 9 and th ink ing of a w o r l d beyond o i l is emerg ing , the permiss ion not ion of re in forc ing loca l products and local food is b e c o m i n g stronger and stronger. In this context, the op t ion of vegetated and cul t ivated facades c o u l d turn into an important e lement , b e c o m i n g a sort of vert ical c o m m u n i t y garden ma in ta ined by the c o m m u n i t y , a l though this w o u l d raise other p rob lems such as the management of the fagade, etc. H o w e v e r , it is still a n e w Figure 5.5 Vertical Farm project fascinat ing w a y of l o o k i n g at green fagades. - Carbon Neutral Architecture In terms of C a r b o n Neutra l Arch i tec ture, more research is needed to determine the life cyc le of green fagades. No t o n l y the cons idera t ion of the fabr icat ion process of the greenery, w h i c h is l ikely to be in plant nurser ies, but also the life cyc l e and carbon cyc le of the rest of the componen ts of the green fagade, such as the materials used to gu ide the growth of plants -meta l l ic mesh , steel w i res , etc - or the materials for plant pots, etc. It w o u l d also be interesting to obtain data on the cont r ibu t ion of green fagades to sequester ca rbon . Ve ry little has been researched in this f i e ld , most l i ke ly because all the related research studies suggest that this cont r ibu t ion w o u l d be insigni f icant. Figure 5.6 Green Fagades' fabrication process: carbon footprint http://www.verticalfarm.com/designs.htm Colin J. Campbell, http://www.hubbertpeak.com/campbell/ |l28 BIBLIOGRAPHY 1. Introduction: L iv ing Skins. H E R Z O G ; K R I P P N E R ; L A N G . Facade Const ruc t ion M a n u a l . Birkhauser publ isher M u n i c h 2004 N O U V E L , J. 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