Yeang - What is Ecological Design

8/9/2019 Yeang - What is Ecological Design

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The GreenSkyscraper

The Basis forDesigning Susta inab leIntensive Bu i l d i ngsKen Yeang

' restelMunich. London. New York


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What isEcological Design?

What is Ecological or 'Green' Design?If we are to reg ard ecological design as a positive rather th an anegative endeavour and as designing to m eet ecological object-ives rather th an merely to cope with ecological constraints, thenOUT first task is to d efine ecological design, and th en t o identifycorresponding objectives.

Before doing so, we should first ask whether o ur architect s anddesigners are at present theoretically and technically e quipp ed atall to respond to t he new d emand s that arise from green design.The answer is likely no (MacKenzie,1997, Papanek,V., 1995, . 48), fo ralmo st all architects (except landscape architects) today have beentrained w ithout any serious background in ecology and environ-menta l biology. Hence it is contended t hat ecological design callsfor a rapid and fund amental reorientation of our thinking an ddesign approach with regard to the creation of our built environ-ment.

Connectedness: Architecture as Applied EcologyTo design in a n ecologically-responsive way will require a fu nda -mentally different view of our relation to and our place within t henatural world; it will require a depa rture from th e limitations ofcurren t science and the social, political and economic contex t whichimplicitly valorizes hu man enterprise as dominant over and essen-tially ind epen den t of natur e. Ecological design requires th e archi-tect to regard and to u nderstan d the environment as a functioningnatural system and t o recognise t he dependence of the built envir-onme nt on it. This sense of th e interdependence of the con structedan d the given (i.e.,'natural') environ ments could be called 'connect-edness.' Before we can proceed with o ur strategy of green d esignfor our intensive building type, we need not only to first define andundersta nd w hat constitutes green design, but also to unders tandits premises, for it w ould be counter-productive for the designer to


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leap into green design without Sustainabl e Developmentunderstanding an d agreeing to /]/carnvoressuch basic principles as connect-edness

Central to ecological design isof course the concept of "ecosys-tem" itself, which requires an a na-lytical understand ing of the envir-onment - and, specifically, h eparticular site in question -a scons~sting f biotic componentsand abiotic components acting asa whole (see Fig, 11 ) . This is crucial Sunll~htNutrientsto our ecological approach. Forinstance, a mechani stic use ofcomputer software for analysrngenergy conservation, airflow and temper ature acoustic factors Fig. 11 The cycling ofmaterials within an eco-which does not take i nto consideration the biological components system Source:(e.g. the flora and fauna) or th e edaphic factors o f the place could 1971)hardly be called ecological design at all. Similarly, if a designapproach does no t take into account the holistic aspects of theenvironme nt, it is certainly not ecological.

Slmply stated, in ecological design, we nee d to evaluate th e con-sequences of:

if we build (see chapter 4),where we build (see chapter 5),what we build (see chapters 4 and 6) andhow we build (see chapters 6 and 7).

The practice of ecological design is essentially 'applied ecology'orth e practical application of ecology to huma n intrusion in to thenatural environmen t (in which building is simply one of a multi-tude of man's activities that affect the environment).

A prerequisit e then for ecological design is an under standing ofth e basic systemic concepts of ecology and their applications. Thisis necessary to enable the designer to see how his endeavours, ashuman interventions in the environment (whether in agriculture,building development, he building of roads, and so forth) can becarried out in such a way as to integrate with the natu ral systems(e.g., with minim um disruption of the ecosystem, with pr uden t useof the earth's non-renewab le resources, and with the activities asso-ciated with t he designed system symbiotically compatible with theprocesses of the ecosystems). Meeting the se objectives is crucial inthe ecological approach.

The continued degradation of the biosphere through over-exploita-tion a nd abuse not only diminishes its ability to produce essentialresources but also its ability to recover from such abuses. A pre-requisite for sustainability is the maintenance of the functionalintegrity of the ecosphere so that it can remain resilient to hu man-induced stresses, as well as biologically productive. Non-renewableresources, as finit e assets, mus t be used or transforme d in such amanne r tha t they remain useful and accessible to future genera-tions. Seen in this light, the basis of the concept of 'ecologicaldesign'is not that it is a retreating (nor a losing) battle, constantlyseeking to minimise impacts on the natural environment andretar d degr adation. Rather, ecological design can be seen as envir-onmentally beneficial a nd productive, a positive contribution tothe natural environmen t. Further, ecological design should be apositive act of repair, restoration and renewal of the natural sys-tems of the environment (~erkebil e,., in Zeiher,1996,p. 31). 1 con-tend that green architecture as sustainable architecture is design-ing with na tur e in an environmentally responsible way as well as apositively-contributive way. Achieving these two objectives simul-taneously by design is probably the gre atest challenge confrontingthe ecological designer today.

All design endeavours in relation to t he earth's ecological sys-tems of course refer to the future ; they therefore can and should beprognostic an d anticipatory. For example, buildings should bedesigned with prior regard for th e recoverability, re-use a nd recycla-bility of their constitue nt mate rials and components. This is exem-plified in the concept of sustainability, which is described as 'meet-ing the needs of the pr esent without compromising the ability offutur e generations t o meet their own needs'(Brundtland, 1987).

This makes th e concept of sustainabi lity a complex one an dtherefore involves both subjective as well as objective (e.g. quant i-tati ve) decisions affecting human welfare both in the present a ndin the fu ture. More specifically, ecological design involves literallythous ands of ways in which a built system and its users connect t othe natural world.

Ecology is abou t linkages, interdepende nce and creative ad apt a-tion a s opposed t o compartmen talised causality, Ecological designtherefore can be seen as a holistic connection, entailing the pr ude ntmanagement of energy and materials in the built system (seechapter 4) alongside the ecosystems in the biosphere; it willinclude both those design endeavours that reduce the detrimentalimpacts of this management on the ecosystem and thos e that try


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to integrate positively with the natural environment. Furthermore,the meeting of these objectives is not a once-only occasion, but hasto be m anage d and monitored over the entire life cycle of the builtsystem, i.e, from its source t o sink (in Yeang, iggs).This complexityis dynamic, extending over time; this topic is discussed furth er inchapter 3.

The issue of susta inable development (of which ecologicaldesign is an element) at th e global level is now beginning to be ser-iously addressed by most governmen ts in the world, as well as byintergovernmental agencies and fora. A t the personal scale, con-cern for the environment has led some to seek 'green' alternativelife-styles (Slessor,1997).

At the level of the professional designer, what might be regard-ed as part of a slow but gradual greening of architec ture hasalready engendered some results, such as the es tablishment ofmore stringent thermal performance standards in buildings (e.g.BREEM in t he UK), the eco-labelling of building materi als and prod-ucts (particularly in Germany and Canada), he intention by s omedesigners to green the design and building process, and theincreasing monitoring of the energy performance of buildings inuse (by many of the architects and engineers in Europe and in USA)and a greater awareness of ecological factors on-site and t heimportance of biodiversity.

In ecological design, we need to acknowledge that many of theearth's ecological systems and processes are simply too complex tobe quantified and represented in their totality. Nevertheless, eco-logical design, as I shall show, remains a complex proposition andinvolves the resolution of a large numbe r of considerations of mul-tipl e sets of interacti ons (or corrections) (see chapter 3). Architects,designers, engineers and all those whose work affects the environ-ment mus t somehow make everyday design decisions. They need totake decisive action on issues daily on the basis of the environmen-tal information t hat is available at the time. It is thus vital tha t the

present inadequate s tat e of environmental knowledge not be usedas a justification for the evasion of the ecological approach (includ-ing preventive or corrective action ) and th e evasion of responsibilityfor the envi ronmental impact of building projects.

The significance of taking design action based on a proper andfull under standing of ecological criteria is obvious, because thedesign and planning decisions that ate made in the present will notonly have an im media te effect on human society and the environ-ment , but also could influence environmental quality for subse-quent generations, thereby contributing, to a greater or lesserextent, to a sus tainable f uture. In the process of ecological design,we should proceed on the basis of what is already known in ananticipato ry way, rather than with ignorance or, at worst, by exclud-ing environmental considerations in their entirety. Adopting adesign approach t hat is deemed t he best tha t can be ecologicallyachieved today (erring on the side of caution) may in many in-stances be better than waiting sometime tomorrow for the perfect,comprehensive solution -by which time extensive devastation ofth e ecosystems might already have taken place.

At the sam e time, if unavoidable design decisions need to bemade, we mus t also be aware of the hazards of a piecemeal approachto ecological design, which would not effectively address the globalissue of environmental degradation. Thus, any urgent s teps neededto stem t he continuation of the destruction of the environment byhigh energy-consuming and high waste-producing urban buildingsmust be mad e in full regard of the consequences on the environment(see chapter 3).Therefore, our efforts toward the green design of theintensive building type, although imperfect an d in some instancesfailing to fulfill the totali ty of the cri teria of a comprehensive eco-logical approach (due to current technologies'deficiency and otherfactors) mus t a t the sa me time be anticipatory in eliminating nega-tive impacts as much as possible. Our design must contribute t o thegreatest extent possible to reducing the overall environmentalimpact of such intensive buildings on the environment while allow-ing for futur e enhancements, improvements, and replacements.

In the long term, it must be acknowledged that at th e globaland national level, changes in the economic, social and political sys-tems based on holistic ecological principles a re crucial if t he objec-tives of a sustai nable futu re for mankind are to be met. Althoughthes e lie beyond the realm of this book as well as beyond the sphereof influence of the designer, the fundament al principles of greendesign as applied ecology remain relevant t o the development ofglobal systems of green politics, economics, physical planning andsocial systems.


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The Basis for Ecological DesignBesides underst anding th e principles of the ecosystem concept, it iscrucial for the designer t o understand some of th e fundament alpremises of the design approach. The objectives for ecologicaldesign ar e as follows:

Ecological design acknowledges the resilience of the natural envir-onment an d its limit.

abilitv t o withstand disturbances 1 'v-\'\,-',fl\ -1 ! + / 1 : i ,y&> XS~~:;~~::,~,-,and to recover from regular 'shocks'is essential to keeping th e bio-sphere's life-support systemoperating. Maintaining t he integrity of the web of species, func-tions, and processes within an ecosystem and the webs th at con-nect different systems is critical for ensuring stability an d resili-ence. As ecosystems become simplified an d their webs bec omedisconnected, they become more fragile and vulnerable to cata-strophic, irreversible decline. In m anm ade chang es such a s globalclimate change and t he breakdown of the ozone layer, th e biodi-versity deficit, th e collapse of fisheries, frequent outb reaks of redtides, and increasingly severe floods and droughts, here is nowampl e evidence tha t th e biosphere is becoming less resilient.

Some of the benefits (or outputs') provided by natural systemsinclude:

raw materials productionpollinationbiological control of pests and diseaseshabitat and refuge protectionwater supply and regulationwaste recycling and pollution controlnutrient cyclingsoil formation and protectionsoil building and maintenanceecosystem disturbance regulationclimate regulationatmospheric regulation (CO, bsorption and 0, release)

Many such natural benefits arise f ~ o mhe environment's ability toregulate a nd recycle water, nutrient s, and waste . One of the mostbasic aspects of t he cycling and recycling system is tha t wat er fallsas precipitation, running across the landscape to streams and riversand ultimately to t he sea. But human disruptions have impairedthis ability to filter a nd regulate water, to recharge ground-watersupplies, and t o move nutrients an d sediments - indeed, to sup -port life.

Human actions have even changed the fundamen tal forces ofnatu re by removing na tura l plant cover, ploughing fields, drainingwetlands, separati ng rivers from their flood plains, and paving overland. Continued and extensive urbanisation and land use have

Stage 1 Stage 2Ecolog~cal Art i f ic~alenvironment ~ ~ t i f i ~ i ~ l ~ ~ ~ l ~ ~ i ~nvironmentenvironment environment

The biosphereThe biosphere

Ecosystem


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changed the relationship of the manmade and natural environ-ments - ndeed, they have reversed them, so th at the huma n spherehas gone from being the'contained system'within na ture and th eear th to being the'containing one', Ecosystems, ncreasingly satur-ate d with manma de (synthetic) systems (see Fig. 12) (after Chermay-eff and Tzonis, 1971)~ave been losing their ability to self-regulateand to assimilate human outputs. A furth er effect has been th e lossof biodiversity. These trends have regional and global dimensions(see chapter 5).

Ecological design acknowledges the importance of biodiversity.Where urban development has reduced the number o f species an dthe size and integrity of ecosystems, the consequence has been areduction in nature's capacity to evolve and create new life. In justa few centur ies, we have gone from living off nature's "interests" tospending down the "capital" th at h as accum ulated over millions ofyears of evolution, as well as diminishing the capacity of natur e t ocreate new capital.

More specifically,building activity (e.g. site clearance, construc-tion works, etc.) usually result s in some degr ee of ecosystem simpli-fication - hat is,from a diversified state to a les s complex biologic-al stat e. The consequence of such simplified systems is a lack ofth at resilience which allows them to survive short-term adversitiesor long-term alterati ons such as climate change. Often this resultsin reducing th e flexibility of the relationship betwee n th e man-made e nvironment a nd the ecosystem, while simultaneouslyincreasing the ecosystem's constraints on the ma nma de environ-ment. The overall effect is tha t humanit y a nd its built systems havebecome not less dependen t upon the functioning of the ecosystemswithin th e biosphere, but on t he contrary, have now become moredepen dent. Diminished ecological capacity means t hat the scopef o ~uma n action is also narrowed and as humanity's op tionsreduce, so must we proceed with gre ater care in the use of thenatural environment (see chapter 5),particularly with regard tomaintaining biodiversity.

Ecological design has to take in to account the connectivity of eco-logical systems (see Fig. 13).As we have seen, a designe d system of any kind must necessarilyinteract with its environment. It thereby interacts with and affectsth e earth's ecology to a greater or lesser extent. But owing to theove~alloss of resilience in the ecosystem m entioned above, over

Water0 thers0Some environmentalists wrongly conceive the environment in terms ofd~screte nvironmental zones which do not interact with one another

Climate

Plants

time th e ecosystem grows more constrained, with the result th at iIthe ecological eleme nt of the designed system grows correspond- Iingly more impo rtant . Therefore, greater monitoring will be I/required. It is the c omponents (organisms, populations, species,habitats, etc.), processes (n utr ien t cycling, carbon cycles, ecologicalsuccession, etc.) and properties (resilience, health, integrity, etc.)that make up the ecosystems th at provide us with a life-supportingenvironment.

Ecological design mus t acknowledge tha t man made syntheticecological systems can never adequate ly duplicate t he complexityof natural ecological systems.

1In contradistinction to th e model being developed here, there a rethose, among them designers, who have held - erroneously- ha tthe abso rption capacity of global ecosystems is robust enough t owiths tand th e impac ts to which we have subjected it. They bolsterthis contention with th e claim that, even as human beings inter-vene in and interfer e with th e environme nt, it will be possible tosustain ecosystems by devising artificial 'subsystems', whose role isto replace the ones provided by nature. This view holds ou t thehope th at technology will allow human beings to stay ahea d of


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nature , in effect, until such point as technology renders u s com-pletely inde pen den t of natu re (e.g. Landers, ig66).This mechanisticand uto pian m odel, based on a blind faith th at technology will beable to su rmoun t all environmental problems in time, has alreadybeen applied in design practice. A prominent example is the devel-opme nt of a type of design incorporated into th e built environ-ment's life-support systems and known as 'artificial controls'or 'controlled environm ents'. In such a built syste m, all the exist-ing natural self-regulating mechanisms of the environment aresubstitu ted by man mad e mechanisms which control the struc-ture's m echanical and electrical systems, heat, air conditioning,lighting, waste man agem ent systems and othe r structures. Thisform of asystemic control has significant drawbacks, primary amo ngthem the fact that the interact ion between t he m anmad e sys tem(the built environm ent) and the existing self-regulating systemsof nature becomes concentrated in human hands (Goldsmith, 1971);and becau se manm ade systems are only gross approximations -or r ather, simplifications- of natu ral system s in all their com-plexity, these 'artificial controls' are prone t o failure . Ind eed, it isa fantasy th at such artificial systems can ever entirely take theplace of self-regulating natural systems.

Ecological design m ust seek to repair a nd restor e ecosystems.Our designed systems mus t aim to repair and restore devastatednatura l env ironments; properly restored or co nstructed ecosystemscan provide many of the services people require. For example,swam ps and wetlands were once viewed as wasted land, productiveonly if draine d or filled. Today, their roles in cleansing wate r, recyc-ling nutrients, recharging aquifers, controlling floods, and support-ing productive resources such as fish, wildlife, an d wild produce arebeing rec ognised. Their function as a line of defe nse in protectingcoast al and ocean ecosystems from land-bas ed pollution is clear, asis their ability to protect coasts from storms. Many countries arenow using th e assimilative capacity of natural or created wetlandsas a cost-effective way to control and filter storm w ater a nd indu s-trial an d agricultural runoff, to decompose hu ma n waste, and tocleanse w ater.Another example is with agricultural lands, where buffer stripsof trees, togeth er with restored or constructed wetland s, can reducerunoff of major pollutants such as sediments, phosphorus, andnitrogen by 80-100 percent. In both indu strial an d developingcountries, wetlands are a low-cost,low-technology alternative tosewage treatmen t plants.

Restored ecosystems can also bring back s ome of the flood con-trol capacity tha t natu re once provided - nd a t a lower cost andwith greater effectiveness than structural alternatives such asdams an d levees. Studies have foun d tha t with each 1 percentincrease in w etlands, flooding downstream is decreased by 2-4percent; watersheds tha t are 5-10 percent wetlands can reduce thepeak flood period by 5 0 percent compared with watersheds thathave no wetlands.

Even more effective than mitigating t he im pacts of activities orrejuvenating de graded ecosystems is maintaining healthy ecosys-tems. A few studies have measured the agg regate values of ecosys-tem s an d th e unanticipated losses of economic, social, and ecologi-cal benefits that can en sue when the systems are degraded.

As the resilience an d the a ssimilative ability of the ecosystemsin the biosphere continue t o be reduced, an eventual limit to theextent to which external man mad e controls may be permitted toreplace t he com plex, ecologically self-regulating o nes will bereached. The designer mus t appreciate tha t although an ecosystemi s able to ass imilate a cer tain amount of impairment to i ts pro-cesses, it ha s a definite limit to its assimilative ability, and that ifan ecosystem is not to be permanen tly impaired, the designer mu stensure th at all subsequ ent actions and activities tha t take place init must rem ain subjec t to the limitations inherent in the ecosystemand its components. In m ost instances, these limitations canbecome appa rent t o the designer only after a proper examinationof the ecosystem of th e project site and its properties has beenundertaken (see chapter 5). Therefore, before any buildin g can b eerected on a site, its ecology must be m apped and studied. Ecologic-al design mus t seek to minimise its dependency on the resiliencecapabilities of th e na tural environment both locally an d globally.Where this cannot be avoided, it must e nsure th at this resilience isnot pushed beyond its limits.

Ecological design seeks a symbiosis between manmade systemsand natural systems.Nature h as built-in ecological controls, such as the n urturin g ofinnum erable species, that are not ha rvested directly but which pro-vide imp orta nt 'free' services. Thus, species pollinate crops, keeppotentially harm ful org anisms in check, build a nd maintain soils,and decompose dead ma tter so i t can be used to build new l ife.Nature's 'service providers' - the birds an d bees, insects, worms,and microorganisms - show how small a nd seem ingly insignlfi-cant things can have disproportionate value. Unfortunately, their


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services are in increasingly short supply because hab itat fra gm en-tation and destruction have drastically reduced thei r numbers andtheir ability to functio n. In the present st ate of th e built environ-ment, people have created a situation where they must now returnto the natural ecological controls, develop new ones, or design som enew combination.

At present , it seems unlikely th at people can construct adeq uateartificial control systems ou t of engineering har dware only, whilecompletely ignoring th e natural climatic and ecological systems.Therefore, the 'green,'sustainable design option is to integra te thema nm ade systems with tho se of the env ironm ent symbiotically, soas to m ake use of existing natural controls (e.g., passive systems),andfo r combining both man mad e and ecosystem (or biological)control structures.

In th e case of the intensive building ty pe such as th e skyscraper,the discharges n eed to be recycled or reused with in the bu ilt systemitself or within t he larger overall urban context o f the city as muchas possible (e.g., hro ugh recycling or reuse of waste paper, officeand residential products, rainwater a nd w astewater, waste heat ,etc.). If we are un able to recycle these wastes with in th e built sys-tem, then they should be recycled within t he entire urban system inwhich th e designed system is located (i.e., within th e city's infra-structure). Essentially what this mean s is that a t the on set of ourdesign process, the larger-scale systems of ur ban recycling, reuseand repair mu st be taken into account. This applies not just to volu-metric waste bu t also to th e molecular waste (e.g.CO2 dischargesfrom th e building's stand-b y generators, heating systems, etc.), aswell as emissions of waste heat (e.g., hermal discharges, etc.)(see chapter 4).The curr ent sta te of site analysis by designers does not ad dressthes e issues. At present , a designer generally looks only at th e phys-ical featu res of th e site which the propo sed desig ned system willoccupy, This form of site analysis gives the design er a basis fordetermining the best location for the structure(s), creating t he lay-out, making provision for vehicular access, and oth er aspec ts of th edesign, including heigh t, shape, etc. Ecological design, however,goes beyond thes e physical features of th e site to include biologicalcriteria and a knowledge of the surrounding ecosystem a nd its pro-cesses. The designer will have to un derstand an d master t heseaspects of the proposed site to determi ne wha t type of buildingcould be allowed in that ecosystem by the criteria of sustainabledevelo pmen t and 'gree n' design principles. To creat e a symbiosisbetween the designed (manm ade)and natural systems is thedesigner's task; on a physical level, th e building's systemic feat-

Fig. 14 Disruption to th ecarbon cycle in the b io-sphere by human interven-tion through fossil-fuel

ures, processes and functioning have to be integrated with theecosystem's to avoid undesirable or destructive im pacts as a resultof hum an intervention in the natural environm ent (see chapter 4).

Ecological design t akes in to account entropy in n atural systems.The design er needs to be aware of entropy in natural systems in thebiosphere a nd n ot contribute by his designed system to furtheraccelerating t he entropic processes in th e natural environment.Entropy can be imagined as the degree t o which the universe'run s down'ov er time. Entropy increases in every natural process(Berry,1972), an d can be seen variously as representing disorder ordilution within a system. For our purpo ses as designers, one couldalso define entropy in terms of the am oun t of dissipation from aparticular system or as th e energy that allows the system to dowork; th e resulting dissipation could either be internal or could beexpelled from the system to its environment (Walmsley,1972).Entropy can also be conceived as the d egree of dilution or disorderin a system.

Atmosphere Human interven tion/I J,- .

Weathering Volcanicof rocks I I I Fossil-fuel /I combustion---....- - - - - -I LITHOSPHERE Dissolutionof carbonateiossil-fuel + r o d sformation

PrecipitationDecay of Decay of of carbonatesorganic matter

PLANTSPholosynthesl~ AND HYDROSPHERE- NIMALSAssimilation ofdissolved C02IRespiration


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Human activity throughou t history has exp ropriated naturalresources from the e arth ; as discussed above, the strain on ecosys-tem s due to h uman activity has eroded much of the biosphere'snatural self-regulating ability (its ability to'heal') - with the resultth at entropy has accelerated and increased. Perhaps the clearestexample of huma n interference in a natura l cycle or system relatest o th e carbon cycle. Fossil fuels are of course a key energy so urce,and are also non-renewable. Figure 14 llustrat es the cycle of thebiosphere responsible for their production. The high consumptionof fossil fuels by hum ans is in essence a sh ort-circuiting of the bio-geochem ical cycles. Huma n intervention in the form of resourceuse accelerates one aspect of the cycle (combustion or consum p-tion) to th e point w here it exceeds the system's ability to regener-ate naturally. A similar short-circuiting obtains in the case of otherelements a nd resources, such as iron an d other m etals, nitrogen,phosphorus, an d mercury (Bowen,1972;Holdren an d Ehrlich,1974).It goes without saying that these materials have been used inte n-sively in building and constsuction, and this consump tion has ou t-strippe d th e capacity of the nat ural cycles responsible for their for-mation in th e environment.

As thoug h to defend th e built environment from its implica-tion in t his process of entropy increase, som e designers have mis-takenly used th e orderly nature of architecture to claim thatdesign is anentropic. In this view, design an d building counteractthe effects of ent~ op yn th e biosphere, thus br inging 'order ou t ofchaos' . But this is an oversimplification of wh at a rchitecture do es(after Be ttalanffy, 1968).Entropy necessarily increases in an o pensystem. A living organism is itself an open system b ut it m aintain sitself in a stea dy stat e by importing energy-rich materials, con-sumin g the energy in complex organic molecules an d then expel-ling the simpler en d products of the process into its enviro nmen t.It app ears, hen , to avoid an increase in entropy. But i f we view theenviro nmen t an d the system holistically (and thus, incidentally, inline with th e green' perspective of our ecological design method) ,then the total energy exchange taking place in the sys tem organ-ism-plus-environment still conforms to th e second law of thermo-dynamics. Indeed, this will always be t he case, for only when th eliving system is seen in isolation does one have th e impressiontha t i t is tending towa rd a higher s ta te of order and complexity inan entropy -free way. Actually, he increasing order a nd differenti-ation of the open system (the organism) is at th e expense of en-ergy won by oxidation a nd oth er energy-yielding processes, andsom e of its internal rea ctions always produce a degree of entropy.Processes like growth, decomposition an d deat h a re facets of a

slow excha nge taking place within a steady state ; each is accom-panie d by the expen diture of energy. The second law of thermo-dynamics is not violated when t he comb ination of the open sys-tem an d the e nviron ment in which it exists is seen in its entirety,and e ntropy increase still takes place. This inescapability of theentropic process only underscores th e impo rtance of a holisticview and k nowledge of ecosystem properties in th e ecologicaldesign method.

Ecological design acknowledges that the e nvironment is th e finalcontext for all design.The designer must expand his or her previously restricted conceptof the environment (when considering a project. site) to incorporatethe ecologist's more holistic concept of the environment (see chap-te r 5). Ecologists contend that the environment of an y built systemmust be seen in the overall context of the ecosystem in which thebuilt system is located, and in tur n t ha t this ecosystem un it alsoexists within the context of other ecosystems on the earth. Whenthe te rm 'environment' is used in the presen t work, it refers to thistotality.In ecological design, the project site for our building mu st a t theouts et be conceived as pa rt of the locality's ecosystem by thedesigner and as an environmental unit consisting of both its bioticand abiotic (living and non-living) components functioning to-gether as a whole to form an ecosystem. Before any huma n actioncan be inflicted on the project site , he site's ecosystem featur es andinteractions must be identified and fully understood (see chapter 5).The living, natural world must be regarded as th e matrix for alldesign, an d therefore o ur design should follow, rather tha n oppose,the law s of life in th e ecosystems (e.g.Todd,N.J.,an d Todd, J., 1994).Therefore, the designer cann ot view all project sites a s uniform,or as economic commodities with uniform ecosystem features. Inthe s ame way th at n o two biological specimens are exactly thesame, each location for building is ecologically heterogeneous eventhough some superficial similarities may appear. A site's ecosystemhas physical attribut es, organisms, inorganic componen ts, andintera ction s (see Fig. 15) which ar e uniqu e. Site analysis has tobegin by capturing these uniqu e features; only on that basis canthe designer take decisions regarding their use, preservation, orconservation. Ecological design theref ore requires th at an analysisof the ecosystem of the project site, its compo nent s and its carryingcapacities be mad e before any construction activity can be permit-ted to st art (see chapter 5).


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Achillea lanulosa (California) \

Sierra Nevada Great Basin

The uniqueness of the ecosystem feature s of a s ite is mirroredby the specificity of designed systems. A built system th at works forone particula r site may not be translata ble to anoth er, even if ther eare superficial similarities between them (see chapter 5).The site ofa proposed building mus t be evaluated in terms of its ecologicalcomponents even if it appears devoid of any ecological features ;even ground-wat er conditions, topsoil, existing trees, an d othersuch ele ments may have ecological consequences.

Ecological design acknowledges that th e built enviro nment isdependent upon the earth as th e supplier of energy and materialresources.In addition to the built environment being de pende nt on the na t-ural environment for its ecosystem processes (see above), h edesigner has to be aware t hat the physical substance and form ofthe built environment are constructed from the renewable andnon-renewa ble energy and material resources which are derivedfrom the earth's m antle a nd its ambient en vironment (see Fig. 16).However, in addition t o the buil t system's dep enden ce upon th eearth's ecosystems, th e built system is also depe ndent upon theeart h for its continued existence in its operation s,for the ea rth is asupplier of energy and material resources (see chapt er 6).A5 a cons-equence, ecological design is aform of prude nt mana geme nt of theuse of the se resources in the ir life cycle (see chapter 4).

The earth is essentially a closed materials system with a fi nitemass, and all th e ecosystems within it, along with all of the earth'smaterial and fossil energy resources,form the final contextual limitto all our design activities.All design inevitably tak es place within

Fig. 15 Genetically idetical plants develop diffeently according to t heenvironment (Source;Yeang)

Fig.16 The built envir-onment as part of the flowof energy and materials(Source: Yeang , 1995)

th e confines of this l imit. For example, one of th e planet's first eco-system functions was the production of oxygen over billions ofyears of phot osynthetic activity, which allowed oxygen-breathingorganisms such as ourselves to exist. Our futu re existence will con-tinue to depen d on ecosystems that are responsible for maintain-ing the proper balance of atmosph eric gases such as oxygen andcarbon dioxide. There is no technological subst itut e for this vitalservice which natu re provides.

Humans have begun t o impair this system by generating toomuch carbon dioxide an d other greenhou se gases, and by reducingthe ability of ecosystems to absorb carbon dioxide. The benefits ofintact forests for global carbon se questratio n alone are self-evident.The consequence s of disruption of this natural function are begin -ning to be ev ident in the form of global climate change. Maintain-ing nature's ability to regula te local and global climates will beeven more valuable under t he predicted climate change scenario.At th e onset of ecological design, the designer ha s to acknowledgethis limitation.

Ecological design deman ds a rational use of th e ecosystem's pro-cesses and non-ren ewable resources. Such was not t he case in t h epast, when designers imagined that t he environment was essen-tially infinite -both in its capacity to supply resources and in itsability to act as a sink or dum p for the discharges of waste mater-ials. Such a view, as is obvious from the foregoing discussion, can

Organic and Builtinorganic Consumption BUILT systemsmaterials Fuel, food, goods. STRUCTURES becomeproduced by raw mater~al s building residuesmines, farms, malerlals ARTEFACTS (unlessforests recovered)

Rcs~duesrom Resldues from Residues fromextraction production consumptionprocesses processes processes

Residues: solids, particulates, gases, heal, liquids, etc


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no longer be ma intained, and the ecologically minded designermus t keep in mind t he very real limitations of the biosphere, andth e finite capacity of an ecosystem to recover from the loss ofresources (appr opriated for human development) on the one handand the influx of waste products on the other.

An ecological approach t o design, therefore, is a conservation-minded one. The question of non-renewable resources is critical.The production, operation, and eventual disposal of the designer'ssystem (the building itself) will consume a certain quantity ofresources, of which the designer mus t be aware. The designer ofthe built environment mu st also be informed about the degree towhich resources are utilised or reused - n essence, the efficiency ofresource consumption by the built system. One factor is the spatialarcommodati on th at h e or she has designed into th e system, whichmay be in excess in term s of the building's requirement s (see chap-te r 4). Should ther e be a difference in this provision of accommoda-tion, it will reflect th e efficiencyof energy and resource use by thebuilding in question . Such differences can also be quanti fied as ameasure of t he built environment's impact on th e biosphere and itsconsumption of earth resources.Ecological design in effect is design which:

utilises renewable resources ideally at rates less than the naturalrate a t which they regenerate;

optimise s the efficiency with which non-renewabl e resources areused.Ecosystems are the end point of waste, discharges, and all otheroutpu ts of human built systems; this is the idea of the biosphere as'sink'. But, because ecosystems are finite and their ability to absorbthes e ou tpu ts is likewise finite, limits have to be placed on the dis-charge of waste products from the building lest the surroundingecosystem's assimilative systems be overwhelmed. In a larger view,we see th at t he life' of the entire built system is finite as well, andhence th e designer has t o consider what will be the final fate of th ecomp onen ts of his building. When its usefulnes s is at an end, hebuilding itself becomes was te, and its material s have either to berecycled or disposed of. Thus we can distinguish two as pects of thewaste equ ation confronted by the designer, that relating to t heamoun t of waste th at will have to be processed during the build-ing's life, an d tha t which will have to be dealt with when, at theend of th at life, the structur e itself has to be disposed of. It is theethical and p~ofession alesponsibility of the ecological designert o consider both of thes e elements, for the responsibility for a

building does not end up on handover to the owners at t he comple-tion of construction; the designer's responsibility has to be fromsource to sink, covering the whole flow of the built system's compon-ents dur ing it s life cycle.

Ecological design acknowledges tha t all design has a globalimpact because of ecosystem connectivity.The designer must no t only see the impacts of his designed systemin the restricted confines of the ecosystem in which it happen s tobe located. Because ecosystems are interre lated, the effects of thebuilt system are passed through one ecosystem to another a nd mayultimately be global. As described above, the ecosystem in whichthe building exists is itself made up of systems, cycles, and f unc-tions which interact with each other; in a similar way, but on a larg-er scale, ecosystems interact with other ecosystems, generating fur-ther effects on the bios phere as a whole (in Todd,N.J., and Todd,J.,1994, t al.).

A further point is that environmental contamination does notrespect manma de borders. However, a building site - a t least in thecurrent understanding of the architectural and legal professions -isusually described by its lot boundaries in a legally recognized way,much as a country is defined by internationally agr eed borders. Anecosystem, by contrast, ha s evolved within natural boundar ies,which may be criss-crossed by human lines and divisions, which, ofcourse, the ecosystem does not respect. Just because th e environ-ment of the designer's site also has several or many other buildinglots contained within it does not mean th at the designer can thinkof his or her particul ar site as discrete, an isolated ent ity whichexists only within t he legally specified,manmade lot lines. A site isnot a square on a map, but in the world; actions taken on tha t sitehave effects on local ecology that will extend to the other hu man -made parcels (i.e,,building lots) in the same environment andbeyond. As we have seen, the scale of such impacts of a design canbe local, regional, continent al, and biospherical all at t he s ame time .

In the case of the urban building such as theskyscraper, mostsuch sites, being ur ban, would usually have been already extensive-ly degraded and render ed devoid of any biotic components. In suchinstances, the remaining environmental effects tha t th e built sys-tem would have to take in to account would be impact on t he localmicro-climate level (e.g. air pollution, ther mal emissions etc.),impacts on surrounding buildings, and emissions an d discharges ofwaste from th e built system into the city's infrastructural systeinwhich are t hen discharged elsewhere into th e environment, both


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locally and globally (because of the connectivity of all natural sys-tems in the biosphere).

Ecological design involves the managemen t of out puts from t hebuilt environment into the ecosystem,The designer must be aware tha t all designed systems, as open sys-tems, emit output s. These outputs, as waste, enter the surroundingecosystem, whether they are in solid, iquid, or gaseous form. In somecases, the o utpu ts are brought back into the bui lt system and recy-cled and reused, while other wastes may unavoidably be dischargedinto th e ecosystem and have t o be absorbed by t he environment. Ashas been men tioned before, the built system depends on its sur-rounding natu ral environment for the assimilation of the waste itproduces. Therefore, he designer cannot simply take the view that,once the wastes exit the built system, they no longer have to bethought about, as if they had somehow disappeared by passing theboundary of the built environment. Outputs from urban buildingssuch as skyscrapers, as from any built system, have to be absorbedinto the ambien t world; this may or may not require some degree oftrea tmen t to facilitate their assimilation by the ecosystem. Deter-mining whether and what level of pre treatmen t is necessary must, ofcourse, be t he responsibility of the designer, who will have to takeinto consideration various limiting factors. Meteorological featuresof t he local environment determine the rate of waste dispersion byair; rainfall and the r ate of groundwater run-off set limits on howmuch waste can be tolerated by riverine and othe r water systems;soil conditions affect not only land-based waste disposal, butbecause th e environment's systems are linked, they will deter minewaste-water reclamation and other factors. Similarly, opography,like soil conditions, affects the possibility of waste disposal throughlandfills, but also plays a pa rt in flooding and erosion - envr'ronmen-tal dangers tha t the designer must also take into account.

The designer m ust anticipat e and avoid such a scenario bykeeping outputs below a threshold deter mined by the ecosystem'sassimilative capacities. Hence, the designer has to have a completeknowledge not only of the prospective wast e out put s of the st ruc-ture he or she is designing, but also a detailed understanding of theambient ecosystem down t o th e level of each biological, chemicaland physical cycle. This background of knowledge am ount s to anecological profile of the locality in which the built environment is tobe placed; it goes without saying tha t this eco-profile has to becompiled in advance, before any hum an action is taken tha t im-pinges on the environment.

Design mus t include the estimation (before construction) andmonitoring (after construction ) of the ou tpu ts from the built sys-tem. As sta ted earlier, ecosystems can tolerate a certain am ount ofhuman intervention, but the re is a limit beyond which an ecosys-tem becomes irreparably damaged. The outputs from the de-signed system must f ind a place somewhere in the biosphere,whether within t he built environment ("in-use") or as waste t o bevoided elsewhere.

Ecological principles require all design to be regarded in t he con-text of its physical life cycle.Early in the design process - .e., the preliminary phase -th edesigner mus t have extrapolated to the degree possible all theeffects of th e building over its entire projected lifespan. These pro-jections obviously include estimated impact on the environmen t;by a process of feedback, the est imates then are factor ed into thedesign itself before any building ha s taken place (indeed, before thedesign has been finalized), so that the design of the built systemanticipa tes its own impact on the ecosystem. As has been men-tioned, the des igner has a source-to-sink responsibility encompas-sing the designed system's total requirements and o utput s of ma-terials and ener gy from construction through the period of its use-ful life and beyond, to its eventual disposal. It is also importan t tovisualize the flow of resources through th e building, from theirinitial extraction from the earth to their return t o the environmentas waste product s of the built system.

This is particularly important because the interactions betweenecosystems are dynamic processes and change over time. Ideally,the designer should anticipate t he impact an d the performance ofthe designed system in the local ecosystem throughout the entirespan of the designed system's life- during which the states'of theecosystems do not remain static but are themselves changing. In


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architectu ral practice, the current restricted range of responsibil-ities of t he designer would need to be expanded to include theresponsibility for the environmental impact of the designed systemover its whole useful life. Simultaneously, some form of environ-mental monitoring would be needed t o check the impact of thedesigned system on its environment during this period, includingthe changing s tate an d response of the environment.

Ecological design acknowledges that all building activity involvesecosystem spatial displacement, and some displacement of energyand materials.Even a well-designed building, merely by its existence, spatially dis-places the environment around it. Its physical presence on the sitechang es the ecosystem's composition. The siting, layout, structure,and component systems of a building a re all aspects of this physicalpresence, and therefo re have to be evaluated in terms of their effecton the corresponding systems embodied in the environmen t,including spatial pattern and functioning.

Ecological design must be environmentally holistic.A holistic approach takes into account th e entirety of the systemsand functions of the ambient envi ronment. The built system itselfhas ino rganic and organic components an d will have variousimpac ts on the systems of the environment; however, ecologicaldesign mus t not isolate any one environmental function or elem-ent, but rather see th e ecosystems as a functional whole. It is theresponsibility of th e designer to make certain tha t the existing eco-system survives the introduction of the foreign mass of the builtsystem intac t, and that no pa rt of the ecosystem is irrevocably dam-aged or destroyed, unless all contingencies have been taken in toaccount and corresponding preventive meas ures have been insti-tuted.

Ecological design must be a n anticipatory design approach.Ecological design endeavours must be responsive and anticipatorystra tegie s because environmental impact is inevitable. By its pres-ence, the built environment will cause changes, such as depletion,to th e ecosystem; its construction and function ing will necessitatethe consumption and redistribution of natural resources.

However, alteration of t he ecosystem through human activity isnot necessarily destructive or even undesirable. It would be a mis-

understanding to think tha t 'green' design means no design - ha tthe whole biosphere should be off limits to any kind of develop-men t. Ecosystems evolve Over time even in the absence of hum aninterventi on, so it would be impossible to set as a goal the preven-tion of any kind of envi ronmenta l change. Ecological design doesnot therefore aim to preserve the biosphere from human influence,but to relate human intervention in ecosystems to the environmentin a manner tha t does the least damage, which, as we have seen,means recognizing the limits of the ecosystems themselves. Only inthis way can we make our intervention by the designed s truct ure asbeneficial to t he ecosystems as possible, and with proper regard tothe anticipation of changes which will necessarily be wrough t onthe environment by the presence of the building.

Ecological design is multi-disciplinary.The designer's ecological solutions are usually multi-discipl inary.Environmental problems arising from human activities in the nat-ural environment arise from stresses caused by the intervention,and can take one or all of the following three forms: depletion,alteration , or addition to th e earth's ecosystems and resources (bothglobally and locally). Ecological design methods try t o minimise th eadverse impact of huma n interventions (built structures) and t oreduce as much as possible harm to th e ecosystem. It is up to th edesigner to, from the out set, anticipate adverse results tha t flowfrom the creation of the building and minimize them in th e designprocess, as well as making it a priority to ensure tha t t he elimina-tion of negative impacts on ecosystems and nat ural resources con-tinues - n essence, that t he ecological approach is institutional-ized.

An inter-disciplinary, ecological approach to building design iscrucial. It must encompass, obviously, ecology and architecture, butalso other relat ed disciplines, such as engineering, chemistry, andmaterials sciences, tha t are also concerned with the problems of theprotection, conservation and preservation of the envir onment.Unfortunately, most of today's designers lack the knowledge ofecology and biology ~eq uir edy 'green' design. A further problem isthat an agreed definition of what constit utes ecological architec-ture has yet to be produced, along with a'green'design theoryembodying a set of generally recognized principles. Because eco-logical design is as yet undertheorized , the presen t work seeks toprovide a sound an d comprehensive theoretical framework andunifying principles, in the absence of which ecological design willremain partial, misunderstood, and inconsistent (see chapter 3) .


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The need for ecological design has been given attent ion in re-cent years (e.g. Moorcroft,1972;Commoner, 1972;Marras,1999, t al.),but an awareness of the nexus of architecture-ecology, eflecting'the inti mate relationship of structur e and environment, mustbecome an integral par t of the practice of archit ecture -beginni ngwith its incorporation into architectural pedagogy.

More than a decorative art, architec ture is a social practicewhich involves various disciplines, each of which m akes a p articula rcontri butio n to it . Ecology, a science which deals with th e living sys-tem s of the biosphere and their many components - of whichhuman be ings a re one - needs to be included am ong th e disciplinesthat contribute to architecture. Human beings are constantly modi-fying the env ironm ent, and their activities are on e focus of ecology.The creation of a built environment within the natural o ne is aparamount way in which human beings affect ecology, often im-pairing th e natur al systems already in place by the imposition ofman mad e ones (the impact of urbanization is a chief example). Itwould go a long way toward minimising the ecological impact ofarchitecture and development if architects and designers were suf-ficiently train ed in ecology, so that conflicts betwe en arch itectureand nat ure, between th e built structure an d the ecology of its en-vironment, could be mimimised an d negative impacts reduced.Architecture today, however, takes an 'eitherlor' app roach ra therthan the holistic one that is being described here. The'spatial'(e.g. Martin, 1967)and th e c limatic ' approaches tend t o dom ina tearchitectural theory and practice at the presen t time (in Hillier,1977). The spatialist school stresses the deg ree to which any con-structed object (the building) takes up space in the env ironmentand ther eby modifies it. The climatic approach recognizes tha t th ebuilding, as a system which 'breathes'or interacts with the s ur-rounding environment, changes that environment an d particularlyits climate -being a key defining limit on t he ecosystem (as well as

on the internal climate of the built structure). Creen'design, how-ever, includes both aspects. The built env ironment as a'system' an dthe ea rth with its ecosystems as the 'environment'must be consider-ed simu ltaneou sly in the ecological approach to design (see chap-te r 3) .The climatic approach begins to take acou nt of the element of'feedback' , he man ner in which the outputs of the built structureinto th e environm ent cause ecological changes and therefore resultin new inpu ts to the built structure. But the range of ecosystemicinteractions between th e building a nd its environm ent is far broad-er than tha t taken in to account by current architectural practicean d pedagogy. Beyond the purely physical spatial displacementcaused by the insertion of th e building into an ecosystem, there aresystemic interactions between building and ecosystem which thedesigner must ta ke into account an d incorporate into his design.These interactions begin w ith the choice of material s to be used inthe structure, and the energy source to be used to make t he builtsystem run. The functioning of the building depend s on a set ofinterna l processes, th e building's 'metabolism', which interact withthe environment (into which, of course, their wastes and exhaustsare discharged). The architect has t o be aware of thes e processesand the ir effects, as well as the ecosystem's response to the m.

It is clear tha t th e continu ed unab ated conversion, simplifica-tion, and degradation of the earth's ecosystems need to be reversed.Degraded habitat s should be restored so tha t they can perform crit-ical functio ns. Examples of steps needed in this direction includeusing artificial wetlands for flood control and nitrogen abatement,and promoting reforestation for watershed protection and carbonsequestration.

We can no lo nger ass ume t hat nature 's beneficial 'services' willalways be there free for the taking. We mu st become more cautio usand forward-thinking before taking any actions that disrupt nat-ural systems andlimi t the options of futu re generations. We havealready seen that t he deg radatio n of the ecosystem can have severeeconomic, social, an d envir onme ntal costs, even thou gh w e can onlymeasu re a fraction of them a t present. We can rarely determ ine thefull impact of our actions; th e consequences for natu re are oftenunfor eseen an d unpredic table. The loss of individual species andhabitat and th e degradation and simplification of ecosystems canimpair nature's ability to provide th e functions on which our livesdepen d. Many of thes e losses are irreversible, and much of what islost is simply irreplaceable. Ecological design has t o be based onthe fact tha t nature 's processes, regenerative capability and 'resources are limited and th at conservation is essential.


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Maintaining nature's systemic viability- as the good health ofthe processes that are so important to us -requires looking beyondthe needs of this generation, with the goal of ensuring sustainabi l-ity for many genera tions to come. Thus, ecological design has to beanticipatory. We must act under th e assumption tha t futur e gener-ations will need a t least the sam e level of nature's services as wehave today - he safe minimum standard. Thus reason and equitydictate t hat we oper ate under th e precautionary principle. We canneither practically nor ethically decide tha t fut ure generations cansimply do without.

What can be done to stop the unraveling of nature's li fe-supportsystem and ensure tha t it can continue for generations? First,OU Tunderstandi ng of the true extent and value of nature's functions,and t he tools an d processes we use to make decisions, need to beredirected toward ensuring t he sustai nability of the planet's-life-support system. Understanding and valuing nature and ensuringthat it s resources are used equitably and within the finite limits ofits regenerative capacity is essential to sustainability.

To summarise, we need t o appreciate th e interconnected web oflife that we are part of and that supports us, both locally and glob-ally within t he natural systems of th e biosphere. We must realisethat t he cumulative impact of our activities on one location canhave an impact elsewhere on anot her location. Ecological designmust embody ways for man to use ecosystems tha t capitalise onnat ure while at th e same time maintaining its stability, resilienceand productivity. For example, by maintaining a nearby forest an destuary , a diversity of crops, and a variety within each crop, farmersare assured a sufficient harvest regardless of weather and pests.This may not yield the maxi mum und er ideal' conditions (whichrarely exist),but it is smart crop insurance'. Similarly,many humansocieties have evolved strategies for not only coping with natu re'sinevitable rhythms an d changes, but also for using those changesand disturbances' to their benefit, such as flood-dependent agricul-tur e and flood-plain fisheries. The bottom line is that for huma nsto be healthy an d resilient, the nat ural systems must be so, too.

This chapter has dealt with some of th e key aspects of the envir-onmental properties and processes that are crucial to und erstand-ing ecological design. We can summarise th e main ass umpt ionstha t underli e our ecological approach to design as follows:

The basis of a sustainable future is the knowledge that it is in th einte rest of humanit y to maintain local and global ecology in func-tioning and viable condition. This implies limiting a s far as possiblethe destructive effects of huma n systems and designs on ecosys-tems.

The current pace at which human beings are destroying globalecosystems is non-viable - which is why human actions (includingarchitectu ral design) have to become ecosystem-sensitive.

Natural resources are limited. Waste, once it is produced, is noteasily recycled. Design must be regar ded a s conservation ofresources.

People are part of a closed system in t he biosphere, and t he pro-cesses of the natural environment, being unitary, must be con-sidered holistically as part of the design a nd planning process inthe creation of the built environment.

There are interrelationships and interconnections between themanma de environment and the natu ral environment both locallyand globally. Hence, any changes to any part of any one of these sys-tems affect the entire system. Design must be regarded in terms ofconnectivity of global and local ecological processes and resources.

The design objectives discussed here are fundamen tal a nd vitalto our ecological approach; these basic premises need to beacknowledged in all design assignments and constructive under-takings. Furthermore, there is a need to establish for the designer amore general theoretical framework for ecological design whichwill unify all these elements int o a holistic design model (see chap-ter 3).

The key points to not e here are tha t ecological design is a com-plex endeavour, and t ha t design should in effect be a form ofapplied ecology, where a proper and thor ough understanding of theecosystem of the project site for our proposed building a nd its rela-tionships with t he biospheric functions and global resources areessential. To be environmentally holistic, the designer has t o regardhis built system as a set of connected interrelations hips and inter-actions with the natural systems in the environment.

We can define ecological design as the pr udent m ana gement ofthe holistic connections of energy and materials used in the builtsystem with the ecosystems and natural resources in the biosphere,in tandem with a concerted effort to reduce the detrimental impactof this managem ent, thus achieving a positive integr ation of builtand natural environments. In addition, we heed to e nsure tha t thisendeavour is not a once-only effort; the interactions of buildingand n ature have to be monitored and m anaged dynamically overtime (i.e. n the entire life cycle of th e built system from source-to-sink and encompassing th e totality of its use of energy and mat er-ials).

Documents

Yeang - What is Ecological Design