environmental management and health volume 13 number 4 2002

Access to Environmental Managementand Health online ___________________________________ 323

Editorial review board _____________________________ 324

Abstracts and keywords ___________________________ 325

Guest editorial ____________________________________ 328

Sustainable house design: Fernando de Noronha-BrazilRosangela Tenorio and Aldomar Pedrini ____________________________ 330

Sunny walls vs sunnier roofs: a study on theadvantages of roofs for solar collectionThanos N. Stasinopoulos _________________________________________ 339

IDEA: Interactive Database for Energy-efficientArchitectureFrank D. Heidt, Joachim Clemens, Stephan Benkert, Willi Weber,Peter Gallinelli, Johann Zirngibl, Claude Francois, Andre de Herde,Kristel de Myttenaere and Simos Yannas ____________________________ 348

Two low income social housings: a comparative studyof the environmental behaviorJuan Jose Mascaro ______________________________________________ 357

Urban planning instruments to improve winter solaraccess in open public spacesMaria Jose Leveratto ____________________________________________ 366

Environmental Managementand Health

Special issue on renewable energy for sustainable development andthe built environment

Guest EditorProfessor Fernando O. Pereira

Paper formatEnvironmental Managementand Health includes five issues intraditional paper format. Thecontents of this issue are detailedbelow.

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Volume 13Number 42002

CONTENTS

Energy saving by means of innovative buildingenvelope systemsItalo Meroni, Alba De Salvia, Roberto Lollini and M. Cristina Pollastro ____ 373

Green roofs in temperate climates and in thehot-humid tropics – far beyond the aestheticsManfred Kohler, Marco Schmidt, Friedrich Wilhelm Grimme, Michael Laar,Vera Lucia de Assuncao Paiva and Sergio Tavares____________________ 382

Optimal orientation and automatic control of externalshading devices in office buildingsAntonio Carbonari, Giancarlo Rossi and Piercarlo Romagnoni ___________ 392

A new language of architecture: in quest for asustainable futureArvind Krishan_________________________________________________ 405

News from the Net_________________________________ 420

News _____________________________________________ 424

Books and resources_______________________________ 426

Diary _____________________________________________ 429

CONTENTScontinued

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EDITORIAL REVIEW BOARD

Dr Joseph D. BeasleyInstitute of Health Policy & Practice, Amityville,New York, USA

Dr Alan BernsteinUniversity of Toronto, Canada

Professor Luca BonomoPolytechnic of Milan, Italy

Professor D. Bryce-SmithUniversity of Reading, UK

Ray ClarkeNabarro Nathanson, Doncaster, UK

Professor Bo R. DoosEnvironment Programme, Austria

Dr David ElliottOpen University, Walton Hall, Milton Keynes, UK

Professor Lars FribergThe Karolinska Institute, Stockholm, Sweden

Professor Robert J. Levine MDYale University, USA

Professor Dominique LisonUniversite Catholique de Louvain, Belgium

Professor Takao OhkuboNihon University, Japan

Ian PettmanThe Institute for Fresh Water Ecology, Ambleside,UK

Professor Wai-on PhoonUniversity of Sydney, Australia

Professor Robert E. PollackColumbia University, New York, USA

Professor F. Brian PyattNottingham Trent University, UK

Professor William J. Rea MDEnvironmental Health Centre, Dallas, USA

Mervyn RichardsonBASIC, Rickmansworth, UK

Professor M. Saric MDInstitute for Medical Research and OccupationalHealth, Zagreb, Croatia

Dr P.K. Suma’murIndustrial Relations and Labour StandardsInstitute, Jakarta, Indonesia

Professor Sun HonglieChinese Academy of Sciences, Beijing, China

Professor Gerald VintenHead of Business, European Business School,London, UK

Sir Frederick WarnerUniversity of Essex, UK

Dr J. WarfordEnvironment Department, The World BankWashington, USA

Professor Myron Winick MDPresident, University of Health Sciences,The Chicago Medical School, 3333 Green Bay Road,North Chicago, Illinois 60064-3095 USA

Sustainable house design: Fernando deNoronha-Brazil

Rosangela Tenorio and Aldomar Pedrini

Keywords Sustainable development,House building, Energy management

This paper describes the methodology and theenvironmental assessment results of theproposed sustainable house in Fernando deNoronha island (038 510 south and 328 250 west),at the Northeast Coast of Brazil. The projectwas developed at the same site of theEMBRATEL telecommunications station builtin 1997 and aimed to serve as a sustainabledemonstration project at the island withminimum impact on the surroundings.Characterized by a warm-humid tropicalclimate, overheating is the major problem allyear round. Conservation of resources, such aswater, energy and materials are the mainconcerns for architectural design projects to beimplemented at this island context. This projectconcentrated on a design that could minimizeenergy requirements, through improvement ofthermal comfort and low energy features, so thedaytime electrical needs could be accomplishedby the photovoltaic component (grid connectedsystem). The evaluation of performance andfeasibility of solutions were tested on a range ofdifferent simulation tools, such as VisualDOE-2.1 (LBL, USA), Esp-r (ESRU, UK),Ecotect(UWA, Australia) and PV Design PRO4.0. (Sandia Labs-USA). This project was afinalist at the WREA/UNESCO, WorldRenewable Energy 2000 environmental designcompetition.

Sunny walls vs sunnier roofs: a study onthe advantages of roofs for solarcollection

Thanos N. Stasinopoulos

Keywords Solar energy, Space utilization,Roofs

This study focuses on the widely acceptedprinciple that the equatorial sides of a buildingoffer the optimum solar potential for solarspace heating. A comparison between the solarirradiation on the south walls and horizontalroofs of buildings in London and Athenshighlights the energy benefits of facing thesky rather than the equator. Four buildingexamples exemplify practical ways to utilizethe rather neglected potential of roofs as solarcollectors for space heating.

IDEA: Interactive Database forEnergy-efficiency Architecture

Frank D. Heidt, Joachim Clemens,Stephan Benkert, Willi Weber, Peter Gallinelli,Johann Zirngibl, Claude Francois,Andre de Herde, Kristel de Myttenaere,Simos Yannas

Keywords Solar energy, Buildings,Databases, Architects, Energy management,Information exchange

The project IDEA: Interactive Database forEnergy-efficient Architecture – is amultinational collaborative project to build aEuropean knowledge base on advanced energyconscious building design. At the core of thisproject are two earlier multimedia developments,the Swiss program DIAS and the Germanadaptation NESA which present the principlesand applications of solar architecture in therespective national contexts. IDEA aims toimprove know-how of European professionalsand exchange of information between them. Thedatabase includes information on exemplarybuildings, their technical concepts and on otherspecific conditions. IDEA presents the existingstate of the art in the field of energy-efficientarchitecture by means of a multimedia databaseof built examples, an encyclopedia of designconcepts and a set of interactive design supporttools. The built examples have been selectedfrom around Europe. IDEA assembles technicalinformation on materials and energy-relatedstandards and regulations and providesclimatic data from all relevant European regions.

Two low income social housings: acomparative study of the environmentalbehavior

Juan Jose Mascaro

Keywords Housing, Environment, Spain,Brazil, Solar energy, Lighting

This paper studies the environmental behavior oftwo low-income social housings: one is located inBarcelona, Spain, and the other in Porto Alegre,Brazil. They were both built around the sametime. A comparative study of the climates of eachof the cities under consideration was made,pointing out the similarities and differences. Thegathering of data was done through in situmeasurement of the environmenta lcharacteristics of the open areas of the both lowincome multistorey housing and of the interior of

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two typical apartments. The technique ofobservation was also used to register the useand characteristics of the studied spaces. At thesame time, the solar insulation was studiedthroughout the year, using the solar simulator(‘‘heliodon’’). The computer simulations weredone to analyze the natural lateral lighting andthe natural ventilation. Based on theenvironmental measurements done throughoutthe year and the opinion poll about thesatisfaction of the user, the principles ofprojects and constructive characteristics, thecondition of the resulting habitability, as wellas the ways of using the exterior and interiorspaces and the user’s opinion about theirresidence were analyzed. It concludes with anevaluation of the results obtained.

Urban planning instruments to improvewinter solar access in open publicspaces

Maria Jose Leveratto

Keywords Land reform, Urban environment,Planning (town and country), Argentina

There is general consensus about the lack ofopen green spaces in Buenos Aires. Due to this,different actions are been proposed to improvethe quality of existing ones. This paperanalyses potential modifications of built formsto allow better winter solar access andameliorate microclimatic conditions of thosespaces, increasing their usability throughoutthe year. A typical urban configuration, withinthe dense residential grid, is simulated toevaluate the effects, advantages andlimitations of this proposal. In one case,volumes are shaped following existingplanning codes. In the other, modifications toavoid shadows on the open space during thecold period of the year are included. Resultingenvironments are evaluated and comparedtaking into account urban and economicimplications of the decisions involved.

Energy saving by means of innovativebuilding envelope systems

Italo Meroni, Alba De Salvia, Roberto Lolliniand M. Cristina Pollastro

Keywords Energy management,Solar energy, Air conditioning, Buildings

Nowadays, one of the main goals of thebuilding industry and architecture is to

exploit the solar source for the air-conditioning of buildings. Over the lastyears many activities have started todevelop new building and plant technologiesoriented to energy saving by improvingindoor comfort and reducing pollutionemission. The guidelines deriving fromvarious world conferences (Kyoto 1997,Buenos Aires 1998) are known. Industrialcountries have committed themselves to try tocarry out new strategies to reduce bothenergy consumption and air-pollution. Theseaims have increased research works orientedto find materials, components and systemsable to use energy gains from theenvironment, in particular from the sun.During the study carried out at ITC on thesubject, two envelope technologies have beenstudied and realised. The paper describessuch technologies and the methods used fortheir characterisation. It also reports on themost meaningful results obtained from theexperiments carried out.

Green roofs in temperate climates andin the hot-humid tropics – far beyondthe aesthetics

Manfred Kohler, Marco Schmidt,Friedrich Wilhelm Grimme, Michael Laar,Vera Lucia de Assuncao Paiva andSergio Tavares

Keywords Roofs, Recycling,Facilities management, Ecology,Green issues

Green roofs are still often seen as a pureaesthetical element in architecture, as a spleenof some ‘‘greenies’’. In fact green roofs alreadycontribute, to some extent, to a bettermicroclimate through evaporation, filteringof dust from the air and a decrease intemperatures at the rooftop. In cities likeBerlin and Munich many green roofs havealready been realised. Coupled with thismicroclimate improvement, is the thermalcomfort improvement under such roofs bymore mass, dry or wet substrate, and shadingthrough the plants. Besides improving themicroclimate and the indoor climate, theretention of rainwater is another importantadvantage. That means an importantreduction of the rainwater input in thesewage system during rainfalls, cutting thepeak load, avoiding an overload of the system,

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which might cause flooding and serioushealth problems. The risk of flooding incities, which is increasing in many cities dueto a ground sealed by buildings, asphalt andconcrete, can be diminished. One recentexample of the use of green roofs with thispurpose is the Potsdamer Platz in the centreof Berlin, where 100 percent of the rainwaterhas to be evaporated or used for toiletflushing on the building site. Scientificknowledge on green roofs is still limited totemperate climates, due to a developmentwhich took place in central Europe. Since 2000a scientific project in Rio de Janeiro ischecking local parameters, like possiblevegetation, which can be used and substratecomposition. Parallel to this four prototyperoofs, three greened and one blank, are usedto measure the retention rate of the rain waterand the temperature on the underside of theroofs in order to analyse the possibleimprovement of the thermal comfort inbuildings. This paper will describe thescientific results of Germany and discuss thepracticability on a larger scale under tropicalconditions.

Optimal orientation and automaticcontrol of external shading devices inoffice buildings

Antonio Carbonari, Giancarlo Rossi andPiercarlo Romagnoni

Keywords Solar energy, Ecology, Buildings,Facilities management

Movable shading devices are often used tocontrol solar radiation falling on large glazedsurfaces in contemporary non-residential

buildings. The paper presents some studieson optimal orientation of building in relation tothe type of adopted shading devices and theircontrol logic, in case of adjustable ones.Optimal orientation is the one minimisingtotal annual primary energy demand,including artificial lighting and climatisation,giving the same thermal and luminouscomfort. A case study, a room of an officebuilding, has been analysed by means ofcomputer simulations. The external wall ofthe room is entirely glazed. The effects of threedifferent shading elements configuration arecompared. The simulations have beenperformed in three Italian climates (Venice,Rome, Trapani).

A new language of architecture: inquest for a sustainable future

Arvind Krishan

Keywords Architecture, Ecology,Energy management

Sustainability and architecture are synonymousterms. While sustainability, physically andeconomically, is to a large extent manifest inthe habitat built form, it is the scientific temperthat will lend a design methodology andprocess, in order to render Architecturesustainable. To achieve this; a ‘‘Energy-resource Flow – Ecological Foot Print’’ modelis suggested which can help optimize input-output parameters and their relationship. Possibleformulation of these parameters leading to asustainability indicator is also suggested. Thisleads to a process of design and various actualprojects in response to critical issues. Thussuggesting a new language of architecture.

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Guest editorialAbout the Guest Editor Professor Fernando O. Pereira is a Professor at the Department ofArchitecture at Santa Catarina University in Florianopolis, Brazil and one of the co-organisers ofPLEA 2001.

It is worth noting that the late 1950s were, at the same time, the stage of the‘‘air conditioning era’’ and the ‘‘rediscovery’’ of bioclimatic design, acomprehensive design concept that includes all climatic impacts and placesuser well-being as the focus of building design. The energy shortage of the1970s is certainly responsible for including the area of energy conservation inbuildings in the global effort of developing renewable energy into a nationalenergy policy.

It is recognized worldwide that humankind has changed the naturalenvironment, and its impact on it is a matter of concern, not only throughindustry, agriculture and cattle raising, dams, or any other natural disaster, butalso through the cumulative effects of the simple process of urban livingactivities.

The making of a building or a set of buildings implies the creation of asystem that interacts with its surroundings, modifies the external environmentas well the internal one. A climate-sensitive approach should recognize andrespond to climatic changes for the sake of user’s well-being and comfort.

In this way, the notion of bioclimatic architecture means that the design ofbuildings and settlements should be inspired by nature, seek for minimizingenvironmental degradation and encourage a sense of well-being. In order toachieve these goals one must address the following issues: health andwell-being, energy and sustainability.

Renewable energy for a sustainable development of the built environment isslowly building momentum in the new millennium. If the last decade wasknown as the decade of quality, the incoming ones will certainly be dedicated toenvironmental aspects, worldwide denominated as sustainable development.Any energy planning activity intended to be truly compatible with theaccomplishment of a sustainable built environment must, in the long term, bebased mainly on the exploit of renewable energy resources. Nature is ourstrength.

For present and future societies to be able to prosper, sustainabledevelopment will have to be realised sooner or later. It is our task to make itcome sooner rather than later. Our role is to act as catalysts for change,accelerating the adoption of sustainable practices.

The papers selected for this special issue were presented in the 18thInternational Conference on Passive and Low Energy Architecture – PLEA2001, held in Florianopolis/SC, Brazil, 7-9 November 2001.

Although the reviewers and editors of the present issue have made everyeffort to ensure that the contributions are correct and absent of factual errors,

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the contents and opinions expressed are the sole responsibility of the authors.The role of the editors was one of selecting the appropriate contributions, andorganizing them into a meaningful and informative sequence.

I would like to thank Environmental Management and Health, Editors andthe staff, who offered us the scientific platform for publishing the results of ourstudies. In particular, Professor Walter Leal Filho who believed in thesignificance of the topic and has encouraged us to proceed.

Professor Fernando O. Pereira

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Sustainable house designFernando de Noronha-BrazilRosangela Tenorio and Aldomar PedriniSchool of Geography, Planning and Architecture,University of Queensland, Brisbane, Australia

Keywords Sustainable development, House building, Energy management

Abstract This paper describes the methodology and the environmental assessment results ofthe proposed sustainable house in Fernando de Noronha island (038 510 south and 328 250 west),at the Northeast Coast of Brazil. The project was developed at the same site of the EMBRATELtelecommunications station built in 1997 and aimed to serve as a sustainable demonstrationproject at the island with minimum impact on the surroundings. Characterized by a warm-humidtropical climate, overheating is the major problem all year round. Conservation of resources, suchas water, energy and materials are the main concerns for architectural design projects to beimplemented at this island context. This project concentrated on a design that could minimizeenergy requirements, through improvement of thermal comfort and low energy features, so thedaytime electrical needs could be accomplished by the photovoltaic component (grid connectedsystem). The evaluation of performance and feasibility of solutions were tested on a range ofdifferent simulation tools, such as VisualDOE-2.1 (LBL, USA), Esp-r (ESRU, UK), Ecotect(UWA, Australia) and PV Design PRO 4.0. (Sandia Labs-USA). This project was a finalist at theWREA/UNESCO, World Renewable Energy 2000 environmental design competition.

1. IntroductionThe archipelago of Fernando de Noronha is formed by 21 islands, with a totalarea of 26km2 (Plate 1). In 1988 approximately 70 percent of the archipelago wasdeclared a National Marine Park, with the goal of preserving the land and marineenvironment. Towards its goal various research projects are being developed inthe island related to marine, land and bird species. The energy of the island isprovided mainly by diesel generators, but since 1991, the first wind turbine wasinstalled by the Wind Energy Group-UFPE (Federal University of Pernambuco),as a grid connected system. The second wind turbine was installed in 1999 and itis providing 30 percent of the total energy needs of the island. Today Fernandode Noronha is a model of environmental preservation, existing side by side withsmall scale tourist activities, which are limited by the existing facilities.

2. Architecture and environmentResource consumption and economic status have a strong correlation. As theincome level of a society increases, so does its resource consumption. This is true forsocieties of virtually any size, be they families, cities or entire countries. A country’seconomic development will necessitate more factories, office buildings, andresidential buildings. For a household, the growth of incomes will lead to a desirefor a larger house with more expensive building materials, furnishings and homeappliances; more comfortable thermal conditions in interior spaces; and a largergarden or yard. However, as we should be aware of the impact or architecture onthe global ecosystem, a series of design processes should be taken into account. Asstated by Vale and Vale (1991), ‘‘buildings are constructed of materials taken from

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the earth, they are servicedwithwater and fire, and they interact with the air, water,fire and earth that their occupants depend upon for survival’’.

During a building’s existence, it affects the local and global environments via aseries of interconnected human activities and natural processes. At the earlystage, site development and construction influence indigenous ecologicalcharacteristics. Although temporary, the influx of construction equipment andpersonnel onto a building site and process of construction itself disrupt the localecology. The procurement and manufacturing of materials impact the globalenvironment. Once built, building operation inflicts a long-lasting impact on theenvironment. For instance, the energy and water used by its inhabitants producetoxic gases and sewage; the process of extracting, refining and transporting allthe resources used in building operation and maintenance also have numerouseffects on the environment (Kim and Rigdon, 1998). Therefore, the goal of asustainable design is to find architectural solutions that guarantee the well-beingof the global ecosystem, constituted of inorganic elements, living organisms andhumans.

3. Principles and strategiesConsidering the sustainable design goals defined before, this project attemptedto minimize the combined impact of architecture at the island’s ecosystemthrough the use of four sustainable design strategies:

(1) Low energy design and thermal comfort.

(2) Renewable energy use through grid-connected PV system; Solar waterheating system.

Plate 1.Archipelago Fernando

de Noronha-Brazil

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(3) Water conservation: rain water collection system and waste watertreatment.

(4) Materials conservation: recycledmaterials and low embodied energymaterials.

3.1. Low energy design and thermal comfortClimate analysis. In the analysis (www.labeee.ufsc.br), a pre-design simulation toolwas used for climatic examination. There was a well-defined warm-humid tropicalclimate, with two well-defined seasons: the rainy season from January to August,and the dry season for the rest of the year. Discomfort is found most of the time dueto high temperatures and humidity levels. The only possible passive coolingstrategy is promotion of air movement (by cross ventilation or induced by fans)(physiological cooling). This canminimize discomfort formost of the year.

The importance of relative humidity and ventilation is enormous in thisclimate. Thus, the setting of thermal comfort limits was essential for appropriatecomfort assessment. The adaptive model developed by De Dear et al. (1997)based on extensive research field with tropical inhabitants had demonstrated thedifferent acclimatization levels for people living in such conditions and was usedfor this project. A comfort zone based on De Dear et al.’s model was set, with theJanuary neutrality zone set for Fernando de Noronha as 23.6-28.6C and for July:23.1-28.1C (Figure 1).

Energy conscious site planning. A plan was implemented which maximizesthe use of natural resources on the site. For this case, an open plan, on theground floor open from the S-N axis (Figures 2 and 3). Protected from the east/west sun and directed to the prevailing breezes. Upper floor provided atransitional horizontal and vertical axis, which marked the central living space.

Passive cooling: natural ventilation. Maximize cross ventilation by presentationtoward prevailing breezes – NE to SE. Interaction with the outdoors andtreatment of potential barriers to the path of breeze through the house. Use ofadequate window openings to allow maximum air flow. Incorporatingsupplementary means of promoting air movement (fans). These were thestrategies for maximum comfort ventilation (Givoni, 1998). Discomfort is noticedduring the three hottest months of the year, even when fans or cross-ventilation is

Figure 1.Comfort zone based onDe Daar’s formula:Fernando de Noronha


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provided. A maximum of 1.5m/s was considered for physiological cooling. DOE-2.1 demonstrated the performance, when no control is used (either by shading orventilation). Temperatures reached up to 428C. The bedroom zone achieved thebest performance due to its orientation, minimal exposed surfaces, insulation andprovision of solar shading and ventilation (Figures 4-6).Shading design. Solar radiation incident on building surfaces is the mostsignificant energy input to buildings. For warm-humid climates, full shading isessential even during winter months. DOE 2.1 and SUNTOOL (Figures 1 and 2)simulated optimised shading devices for all exposed fenestrations (providingboth VSA – vertical shadow angles – and HAS – horizontal shadow angles). The

Figure 2.First floor sustainable

house

Figure 3.Ground floor

sustainable house

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roof and the SW wall had essentially contributed to minimizing the necessity forshading devices for this facade. Only doors were considered for west facades, asextended protection would be needed. DOE-2.1, simulated the overallperformance and demonstrated the high contribution on energy requirements ifwindows were left unshaded (Figures 7 and 8).Insulation and thermal mass. High performance windows and wall insulationprevented both heat gain and loss, and enhanced thermal performance.However, single glazed windows were used considering that full shading is

Figure 4.Comparisons on energyconsumption fordifferent designstrategies – DOE2.1

Figure 5.Bedroom temperaturesfor different designstrategies – DOE2.1


335

provided. Light colored roofs are related by many (Barkaszi and Parker, 1995;Parker and Sherwin, 1998), as being a powerful way of improving performance.White tiles were used for the central roof, with radiant barrier and R1.5 bulkinsulation lined internally with plasterboard. Western walls had also beenpainted a light colour (0.2 absorptance) and combined with bulk and reflectiveinsulation. Ventilated cavities were provided for both cases. Lightweightmaterials were used elsewhere for quick heat dissipation. Thermal mass hadbeen used only on living areas where daytime was the period of use for thehouse. This proved to be an efficient strategy for delaying heat gains throughthe envelope during the day.

Figure 6.Living temperatures for

different designstrategies – DOE2.1

Figure 7.Sustainable house as

modelled inVISUAL-DOE 2.5

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Energy efficient appliances and equipment. After construction costs, abuilding’s greatest expense is the cost of operation. Operation costs can evenexceed construction costs over a building’s lifetime. Careful selection of highefficient appliances and lighting further minimized the sustainable energyhome’s electrical load. Using smaller appliance lighting loads resulted in lessPV capacity required to meet the home’s total electrical load. These were

Figure 8.VSA/HSA calculations –Suntool-UWA

Figure 9.Annual energyconsumption by end-use


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based on the PROCEL (Brazilian Governmental Regulation Program forReduction of Energy Consumption through Appliances and Equipment). Highefficient compact fluorescent lighting and high-efficient appliances wereused. Figure 9 shows the annual energy consumption by end use, as modeledin DOE 2.1.

3.2 Renewable energy use: solarPV grid connected system and solar water heating system. A utility grid connectedPV roof systemwas used at this project and a solar hot water system. It was sizedto provide power that would offset as much of the household load as possible.

As no air conditioning system was considered for the sustainable energyhouse, the power generation was optimized to maximize annual yield, so PV hadthe same tilt angle as the latitude at the roof. (3.57N). The solar hot water heatingsystem had 15 + the latitude (18.57N). The array sizing was calculated based onthe total energy demand per day (watt-hours), the available solar insolation, thecell operating temperature and the electrical coupling efficiency. Radiasol (Figure10) evaluated the available insolation striking the array throughout the year, andPV design PRO-G determined the required array output per day (Figure 11). Anestimate of the maximum attainable value for the annual specific yield for thesustainable house gave an area of 25m2 of PV panels disposed. For theseestimates the electrical needs were accomplished by the PV component.

Figure 11.PV array as modelled

in PV-PRO-G(Sandia Labs)

Figure 10.Solar radiationas modelled in

Radiasol – (UFRGS)

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3.3 Water conservationA building requires a large quantity of water for the purposes of drinking, cooking,washing and cleaning, flushing toilets, irrigating plants, etc. All of this waterrequires treatment and delivery, which consumes energy. The water that exits thebuilding as sewage must also be treated. At this project the idea was to reduce bothinput and output of resources. A reduction in use also produces a reduction inwaste:

. Reuse of water onsite. Graywater was recycled within the building toirrigate plants and flush toilets.

. Rainwater tank collection. The roof became a rainwater-collecting device,in combination with the rainwater collection tank. This water could alsobe used for irrigation and toilet flushing.

. Biocomposting toilets. Used to treat sewage on site eliminating the needfor energy-intensive local treatment.

. Indigenous landscaping. Vegetation was used which was adapted to thelocal rainfall levels eliminating the need for additional watering.

3.4 Materials conservationUse of materials that can be recycled and has low embodied energy: plantationtimber for all floors, stairs and structural system were used. Brick was used forwalls and white tiles for the central part of the roof considering availability andtraditional construction techniques.

Nontoxic materials – as a people spend more than three quarters of their timeindoors, nontoxic materials are vital to the health of the building’s occupants.Adhesives which release volatile organic compounds into the air were avoided.

4. ConclusionsThe methodology and environmental design assessment for a sustainablehouse design in the northeast coast of Brazil has been presented. A block offour main sustainable design strategies were set and analysed. Extensivesimulation runs were defined for this purpose, using a number of simulationtools. The use of water and materials were treated on a sustainable basis. Lowenergy design features combined with the production of energy through a PVgrid connected system installed on top of the roof demonstrated that the energyloads were minimal and close to zero.

References

Barkaszi, S.F. Jr and Parker, D.S. (1995), Florida Exterior Wall Insulation Field Test: Final Report,FSEC-CR-868-95.

De Dear, R.J., Brager, G. and Cooper, D. (1997), Developing an Adaptive Model of ThermalComfort and Preference, Final Report, ASHRAE RP-884.

Givoni, B. (1998), Climate Considerations in Building and Urban Design, Van Nostrand Reinhold,New York, NY.

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Environmental Management andHealth, Vol. 13 No. 4, 2002,

pp. 339-347.# MCB UP Limited,0956-6163

DOI 10.1108/09566160210439242

Sunny walls vs sunnier roofsA study on the advantages of roofs for

solar collectionThanos N. Stasinopoulos

Papagou, Greece

Keywords Solar energy, Space utilization, Roofs

Abstract This study focuses on the widely accepted principle that the equatorial sides of abuilding offer the optimum solar potential for solar space heating. A comparison between thesolar irradiation on the south walls and horizontal roofs of buildings in London and Athenshighlights the energy benefits of facing the sky rather than the equator. Four building examplesexemplify practical ways to utilize the rather neglected potential of roofs as solar collectors forspace heating.

1. IntroductionA common rule of thumb in passive solar design is that the elevation of abuilding facing the equator offers the highest potential for solar collection;therefore the equatorial side of the building is the favorite area for applyingsolar heating techniques like direct gain, conservatories or Trombe walls. Thisapproach is based on the assumption that solar irradiance on surfaces directedto the equator is higher than to any other orientation.

But is it truly so? Always and everywhere? When solar data indicates higherincident energy on the equatorial elevation, is this what we really get in practice?And besides the energy per square meter, what about the total amount ofirradiation on the entire collector? If one wishes to harvest as much solar energyas possible through the building envelope, is the equatorial side the optimumoption? These are questions addressed by the present study, having as examplestwo locations with differing solar regimes, London andAthens.

2. Observations2.1. Radiation dataRadiation data from London and Athens (see Table I) support the presumedsuperiority of the equatorial side during some of the winter months (Figure 1)(in this study, ‘‘winter’’ denotes the period from November to April, when theaverage ambient temperature is less than 108C in London and 188C in Athens –see temperature data in Table I).

However, if we consider the entire winter period, the sum of incident energy ona vertical south surface is less than on horizontal, the highest values being for a408 slope (Figure 2). Naturally, the winter sum of irradiance on vertical wallsdirected away from south decreases – down to 1/3 of the horizontal (Figure 3).

These observations are more distinct in Athens due to higher solar paths,emphasizing the need of a different strategy for solar collection as we movecloser to the equator.



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Daily irradiance on south slopes, kWh/m2

Tilt Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec WS

London08 0.6 1.1 2.1 3.0 4.1 5.0 4.4 3.6 2.7 1.6 0.8 0.5 242108 0.6 1.2 2.3 3.2 4.2 5.1 4.5 3.7 2.9 1.7 0.9 0.6 265208 0.7 1.3 2.4 3.2 4.3 5.0 4.4 3.8 3.0 1.9 1.0 0.6 282308 0.7 1.4 2.5 3.2 4.2 4.9 4.3 3.7 3.1 1.9 1.1 0.7 292408 0.7 1.4 2.6 3.2 4.1 4.7 4.1 3.6 3.1 2.0 1.2 0.7 296508 0.7 1.4 2.6 3.0 3.8 4.3 3.9 3.4 3.0 2.0 1.2 0.8 294608 0.7 1.4 2.5 2.8 3.5 3.9 3.5 3.2 2.9 2.0 1.2 0.8 285708 0.7 1.4 2.4 2.6 3.2 3.5 3.1 2.8 2.7 1.9 1.2 0.8 271808 0.7 1.3 2.2 2.3 2.8 3.0 2.7 2.5 2.4 1.8 1.2 0.7 252908 0.6 1.2 2.0 2.0 2.3 2.4 2.2 2.1 2.1 1.6 1.1 0.7 229

Mean ambient temperature, 8C4.2 4.5 6.6 9.5 12.6 15.8 17.5 17.1 14.9 11.6 7.5 5.3

Athens08 1.8 2.6 3.8 5.1 6.4 6.8 6.9 6.2 4.9 3.4 2.3 1.7 524108 2.0 2.8 4.0 5.3 6.4 6.9 7.0 6.4 5.2 3.7 2.6 2.0 565208 2.1 3.0 4.2 5.2 6.3 6.7 7.0 6.5 5.3 4.0 2.9 2.2 593308 2.3 3.1 4.2 5.1 6.0 6.4 6.7 6.4 5.4 4.2 3.1 2.4 608408 2.3 3.1 4.2 4.9 5.6 5.9 6.4 6.1 5.3 4.2 3.2 2.5 608508 2.3 3.1 4.0 4.5 5.1 5.4 5.9 5.7 5.1 4.2 3.2 2.6 595608 2.3 2.9 3.8 4.1 4.5 4.7 5.2 5.2 4.7 4.0 3.2 2.6 568708 2.2 2.8 3.4 3.6 3.8 3.9 4.4 4.6 4.3 3.8 3.1 2.5 529808 2.1 2.5 3.0 3.0 3.1 3.1 3.6 3.8 3.7 3.5 2.9 2.4 480908 1.9 2.2 2.6 2.4 2.3 2.3 2.7 3.0 3.1 3.1 2.6 2.2 421

Mean ambient temperature, 8C9.4 10.3 11.7 15.8 20.6 25.2 27.9 27.8 23.9 18.7 15.0 11.4

Notes: Italic figures indicate maximum irradiance per month; columns WS give theirradiance sum for the winter period (data from Stasinopoulos (1999) with radiation data onslopes computed according to Page (1986)

Table I.Climatic data forLondon and Athens

Figure 1.Monthly irradiance on asouth vertical wall inLondon and Athens aspercent of horizontal


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2.2 Practical drawbacksIn practice, the brief supremacy of equatorial elevations in terms of irradiance,is often hampered by several obstacles:

. Size. The area of the collecting surface is confined by the total size of theequatorial wall, which sometimes is too small due to site or functionalrestrictions.

. Orientation. The equatorial side of a building might be unfit for solaruse, being for instance a blind party wall next to an adjoining buildingor to a steep hillside.

. Shading. The vertical sides of a building are frequently overshadowedby neighboring obstacles such as buildings, hills or trees, that reduceincident radiation -especially during winter when the sun is low.

. Safety. Solar collectors usually consist of glazing which -near groundlevel- poses a security risk and increases the possibility of vandalism,thus adding to the construction and running cost.

. Indoor effects. Applications like direct gain or conservatories can createoverheating, glare or privacy problems, sometimes forcing the occupantsto constrict or even block solar access, cancelling the passive process.

Figure 2.Winter sum of

irradiance on southslopes in London andAthens as percent of

horizontal (slope = 08)

Figure 3.Winter sum of

irradiance on verticalwalls direct from south(08) to north (1808) in

London and Athens aspercent of horizontal

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. Cloudy sky. Irradiance on the equatorial elevation drops considerablyunder overcast sky, which usually implies adverse weather conditionsthat increase energy requirements. In that case, maximum solar inputcomes from horizontal surfaces that face the entire sky.

Due to these frequent facts, another part of the building envelope can often bemore advantageous than the equatorial side: roofs as solar receivers present noneof the above drawbacks; furthermore, they may provide higher total solar inputdue to their large size which compensates for the lower irradiance during certainperiods. The potential of roofs for solar collection is examined below through asimple comparison between the irradiation on an equatorial wall and a flat roof.

3. Wall vs roof3.1. Annual comparisonLet us assume a flat roof sized W � D (width � depth) receiving RH solarradiation and a vertical wall facing the equator sized W � H (width � height)receiving RV. The ratio RH/RV is

RH=RV ¼ ðIH �W �DÞ=ðiv �W �HÞ or

RH=RV ¼ ðiH=ivÞ �ðD=HÞð1Þ

where iH and iV is the incident radiation on the horizontal and vertical surfaceper unit area (the effect of widthW is the same on both surfaces).

From (1) we conclude that a roof receives more energy than a verticalequatorial wall when

D=H > iV=iH : ð2Þ

Exploring relation (2) in practice, equation (1) has been applied on a number ofsimple rectangular volumes taking into account radiation data of London andAthens (Table I). The depth/height ratio (D/H) of the volumes is taken as 1/4, 1/2, 1, 2 and 4, as shown in Figure 4.

Figure 5 shows the seasonal variations of theRH/RV ratio for eachD/H value. Inboth locations the irradiation on the south elevation exceeds that on the roof onlyin the case of ‘‘shallow’’ buildings, that is those where the depth behind the southelevation is less than its height (D/H < 1). In ‘‘deep’’ buildings (whereD/H > 1), theroof generally receives more solar load than the south elevation.

3.2 Winter periodTo compare the potential for space heating applications, we take into accountonly the winter values of the RH/RV ratio, which are displayed by thecontinuous curve in Figure 6 as a function of the D/H proportion. At that

Figure 4.The volumes of the studyin section along N-S axis


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period, the roof receives more radiation in buildings where D/H > 1 (London) orD/H> 0.8 (Athens).

The solar potential of the equatorial elevation is further weakened if weconsider overshadowing – a fact occurring frequently on the sides of a buildingbut rarely on its roof. This is illustrated by the dotted curves in Figure 6, showingthe winter values of the RH/RV ratio assuming a 30 percent reduction of theirradiation on the south elevation due to overshadowing. Under such conditions(typical in urban contexts), the south elevation receives more solar energy inwinter only ifD/H< 0.7 (London) orD/H< 0.5 (Athens).

If the building is rotated off the N-S axis, solar irradiation on the equatorialelevation decreases accordingly (see Figure 3), but that on the roof remainsunaltered. This underlines the fact that the solar capacity of roofs isindependent of orientation, a convenient feature in cases where the alignmentof the building is dictated by factors other than solar access.

These observations highlight the solar potential offered by roofs due to theirlarge size, free from overshadowing and orientation restrictions. A fewexamples on how to utilize that potential follow next.

Figure 6.Winter values of theratio RH/RV (percent)

between irradiation on aflat roof and a southwall in London and

Athens, as a function ofthe D/H proportion;

dotted curves refer to 30percent overshadowing

on wall (logarithmicy-scale)

Figure 5.Monthly values of theRH/RV ratio (percent)

between irradiation on aflat roof and a southwall in London and

Athens, according to theD/H proportion of the

building assumingunobstructured solaraccess (logarithmic

y-scale)

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4. Solar roofs4.1 Current practiceRoofs are regularly used to install solar collectors for domestic hot water or PVarrays, but not so much for space heating applications. Passive solar deviceslike glazed openings (for direct gain) and conservatories, Trombe walls or aircollectors (for ventilation preheat) are typically attached to the equatorialelevation of the building rather than on its top.

In that manner the sun benefits just the equatorial side of the interior, whilethe rest can only be affected indirectly, especially in deep plans (an exception isthe Barra-Constantini system which transfers solar heat through air deeperthan the other techniques).

4.2 An alternative approachHowever, the top of a building can also accommodate most of the usual passivesolar means commonly installed on the equatorial side, adding certain advantages:

. Roofs do not present the shortcomings of the equatorial wallsdescribed earlier (insufficient size, improper orientation, over-shadowing, vandalism, etc.).

. Total energy input from the roof can be much higher than from theequatorial side, depending on size (D/H ratio) and season.

. In several building types like factories, sport halls or schools, roofs aretypically large surfaces used only to shield the volume underneath; theadditional function of solar collection can transform a usually idlestructure into a productive component.

4.3 Summer heatIn most solar applications for space heating, summer overheating is a crucialrisk. This is more so if the solar collectors are integrated with the interior as in,typically windows or conservatories, because they cannot be ‘‘shut down’’ sincethey are linked to other functions like view or space use.

The overheating risk is higher in roofs, given the intense radiation theyreceive from the sun above. But, just like the usual solar collectors for waterheating, solar devices on the roof can be:

. installed outside the insulation layer, thus preventing the conductiveheat flow towards the interior; and

. turned-off, ceasing the convective heat transfer (e.g. shutting-down thefans that draw warm air from a roof conservatory).

Furthermore, they can function as solar chimneys, promoting the extraction ofwarm air from indoors.

5. Examples5.1. Roof conservatoriesFigure 7 shows two typical apartment blocks on an E-W narrow street in densedowntown Athens, with conservatories added on the roof and upper balconies.


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Warm air from the top conservatory is driven by fans to the flats below viaexisting air shafts; in summer, indoor air is expelled outdoors through slidingsections of the glazing at opposite sides[1].

Besides the energy benefits, the roof sunspace can accommodate variousactivities by the occupants below, from drying clothes to growing plants,offering also a play area protected from bad weather, thus justifying its extracost in several ways.

Figure 8 refers to a two-storey school in Central Greece currently underconstruction. A sunspace over the middle corridor is used for ventilationpreheat and to enhance daylight in the classrooms through inner windows. Insummer, warm air from the classrooms raises to the sunspace, then it isexpelled outdoors. The concept is applied on both legs of the L-shaped plan ofthe school independently of their orientation.

5.2 Roofs as air collectorsAnother approach – perhaps more cost effective than a roof conservatory –would be to transform the entire roof into a large solar air collector bymodifying its design and materials. In the two examples presented below,ventilation preheat is achieved through the roof at a marginal extra cost.

Figure 9 shows a section of a two-storey detached house east of Athens. Theroof is facing south at a 138 slope and it consists of two layers of corrugated

Figure 8.Cross-section of a schoolin central Greece with a

sunspace over themiddle corridor

Figure 7.Cross-section of typical

apartment blocks inAthens with

conservatories fitted onthe upper floors and roof

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metal sheets with an air gap between them. Ambient air enters from the bottomend of the gap and is heated by the solar radiation absorped by the dark-coloured upper sheet. Warm air gradually raises to the top where a transparentcover enhances its temperature and flow, then it is collected in a well-insulated‘‘air tank’’ above the false ceiling. A centrifugal fan with dampers propels thewarm air into the interior through the hollow floor for mass storage or,alternatively, expels it outdoors, according to seasonal and diurnal conditions(for details see www.ntua.gr/arch/geometry/tns/ecompetition/).

Construction has not been completed, so the actual performance of thissimple scheme has not been tested yet. However, a similar air systemcommercially available in North America is claimed to yield up to 500W for anair flow of 25m3/h per m2 of opaque collector[2].

Figure 10 shows the same concept being applied on a detached house at thenorthern outskirts of Athens, with the roof directed 208 SW at a 158 slope. Inthis case translucent plastic sheets are used instead of the top ‘‘roof-tile looking’’corrugated metal, a choice that will boost performance. Construction of thisproject is on the way.

6. ConclusionsThe examples shown here illustrate techniques to utilize the high solarpotential of roofs – a standard but hardly used element in all buildings – using

Figure 9.Cross-section of a houseeast of Athens featuringan opaque solar roof

Figure 10.A similar solar roofdesign applied on adetached house at thenorthern outskirts ofAthens


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normal building components. Solar roofs – opaque or not – can supplypreheated air without the restrictions imposed by equatorial walls, whileoffering extra advantages:

. Collection area can be larger than the equatorial side, with minorconcern for orientation or overshading and at a low extra cost per kWh.

. All sides of the building are available for other functions, since solarenergy is collected by a normally idle element located ‘‘out of the way’’.

. Air as heat transfer fluid imposes fewer technical considerations thanthe water systems, like caution for leaks, corrosion or frost,consequently reducing building and running cost.

. Solar heat is kept outside the inner volume, minimizing the overheatingrisk.

Notes

1. A 1985 graduate student project by the author.

2. The Canadian Conserval Engineering Inc. has developed a vertical air collector systemwith opaque metal sheets – see www.solarwall.com

References

Page, J.K. (Ed.) (1986), Prediction of Solar Radiation on Inclined Surfaces, Vol. 3, ReidelPublishing Company, Dordrecht

Stasinopoulos, T.N. (1999), ‘‘Geometric form and insulation’’, PhD thesis, National TechnicalUniversity of Athens, Athens.

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IDEA: InteractiveDatabase for Energy-efficient

ArchitectureFrank D. Heidt, Joachim Clemens and Stephan BenkertDepartment of Physics, University of Siegen, Siegen, Germany

Willi Weber and Peter GallinelliCentre Universitaire d’Etude des Problemes de l’Energie,

University of Geneve, Geneve, Switzerland

Johann Zirngibl and Claude FrancoisCentre Scientifique et Technique du Batiment, Marne-la-Vallee, France

Andre de Herde and Kristel de MyttenaereCentre de Recherches en Architecture, Universite Catholique de Louvain,

Louvain-la-Neuve, Belgium

Simos YannasArchitectural Association Graduate School, London, UK

Keywords Solar energy, Buildings, Databases, Architects, Energy management,Information exchange

Abstract The project IDEA – Interactive Database for Energy-efficient Architecture – is amultinational collaborative project to build a European knowledge base on advanced energyconscious building design. At the core of this project are two earlier multimedia developments, theSwiss program DIAS and the German adaptation NESA which present the principles andapplications of solar architecture in the respective national contexts. IDEA aims to improve know-how of European professionals and exchange of information between them. The databaseincludes information on exemplary buildings, their technical concepts and on other specificconditions. IDEA presents the existing state of the art in the field of energy-efficient architectureby means of a multimedia database of built examples, an encyclopedia of design concepts and aset of interactive design support tools. The built examples have been selected from around Europe.IDEA assembles technical information on materials and energy-related standards andregulations and provides climatic data from all relevant European regions.

Aim and objective of IDEAThe effective use of solar energy and energy saving measures can drasticallyreduce the demand of heating, cooling and lighting energy required for conditioningbuildings. In almost every country there are many examples of diverse buildings –residential, commercial or institutional – where solar and energy saving conceptshave successfully been realized. But the architectural and environmental conceptsof these examples are not widespread, so as to reachmost architects.

Also, nowadays, too little attention is paid on solar and energy-savingbuilding methods. Instead of using a co-ordinated heating and ventilatingsystem, the heating of a building is mostly done by central heating, using non-renewable energies like gas or oil. The ventilation takes place by opening the



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windows, whereby the air change rate often increases far beyond thehygienically necessary rate.

Instead of using suitable shading devices or minimising internal loads toavoid summertime overheating, the installation of air conditioning increases.These systems use a tremendous amount of energy to transport surplus heatoutside of the buildings.

IDEA, the Interactive Database for Energy-efficient Architecture, has beenbuilt to show the possibilities for solar and energy-saving building andrenovating. The program presents the existing know-how with the help of amodern multimedia software and shall give inspiration and allow parametricsimulation for architectural projects from the beginning of early pre-design. Forthis purpose the program IDEA intends to:

. give an overall view of existing active and passive solar concepts andpossibilities by examples of buildings all around Europe;

. provide calculation and simulation tools to the user, e.g. for thedetermination of U-values, the heating demand of a building or thecalculation of the sun path;

. present an encyclopedia with a broad range of keywords and a moredetailed description of important topics in the field of using solar energy.

The program itself is easy to use; no special training or online-help is required.It is a well-suited application as source of information, as design-guide and asworking-tool for architects and engineers.

By its broad-ranged encyclopedia, its far-reaching database of buildingexamples which shows how low-energy and solar concepts can beincorporated to appealing architecture, and its large collection of useful tools,IDEA should be also interesting for students of architecture and civilengineering.

Altogether, the IDEA is, by its amount of presented information and its easyhandling, equally useful for consulting, education and general information.

Target groups of the program IDEA are architects, small and medium sizebuilding companies and building engineers, students of architecture and civilengineering as well as everybody who is interested in appealing architecture orin the field of solar and low-energetic building.

The dissemination of IDEA takes place at regional and internationalmeetings like conferences and workshops as well as at professionalinstitutions, universities and colleges.

The development and the consortiumThe project IDEA is a joint project of different universities and institutions ofEurope (Heidt and Benkert, 1998). Predecessors of the software IDEA are theSwiss program DIAS (Donnees Interactives d’Architecture Solaire) whichwas developed at the Centre Universitaire d’Etude des Problemes de l’Energie(CUEPE), University of Geneva (Weber et al., 1996), and its German

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adaptation NESA (Multimediale Datenbank zu Niedrigenergie- undSolararchitektur), developed at the University of Siegen (Heidt and Braeske,1996). Both databases contain national building examples as well ascalculation and simulation tools, referring to the national standards andclimatic values.

To create the all-European database IDEA, an international consortium fromdifferent European countries was brought into being: teams from Germany,Switzerland, France, the UK and Belgium are participating. These groups ofdevelopers consist of architects, engineers and physicists.

Because of the different languages of the involved countries, the consortiumof IDEA decided to make the program bilingual, in English and in French.

The development of IDEA has started at the beginning of October last year.Until now, a first version of IDEA has been brought into being. At the moment,the consortium is collecting the first comments for an evaluation of theprogram. The final version of IDEA will be available at the end of the year2002.

Main features of the programIDEAwill consist of different distinctive parts as follows.

1. DatabasesOne of the main components of IDEA is its collection of building descriptionswhich presents some 60 examples from around Europe, restricted to climaticconditions with a heating season of at least three months (see Figures 1 and 2).This includes:

. single family houses;

. pairs of semis;

. multi family houses;

. residential buildings;

. shops/commercial buildings;

. office buildings.

The examples were selected to provide a comprehensive survey of differentbuilding types. Attention was given to successful practice, i.e. there are nobuildings shown which are not ‘‘useful’’ for living or working.

To help the user to navigate through building examples, IDEA hasdifferent search functions, e.g. one can look for examples of a specialarchitect or for an interesting architectural or energetic concept. Plans,elevations and sectional drawings describe the buildings. Photos from thein-side and outside visualize essential textual information. Conceptualdrawings highlight special ideas for energetic concepts or use of solarenergy. Detailed drawings show constructional features, e.g. how to avoidthermal bridges. Information on building services and costs are included so

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Figure 1.Building example

from NESA, apredecessor of IDEA

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Figure 2.Building example fromDIAS, a predecessor ofIDEA

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that the user can assess the practical value of a building compared to owndesign needs.

IDEA also has a collection of climatic data for the different countries ofEurope. This accumulation contains maps of the outside temperatures (seeFigure 3) and of radiation.

2. The toolboxAnother important feature of IDEA is its toolbox. It integrates calculation andsimulation tools to evaluate the environmental performance of buildings. Heattransfer through building components or energy losses by ventilation can bedetermined in close interaction with material and component databases (seeFigures 4 and 5). Energy consumption can be calculated using the EuropeanNorm EN 832. According to that, the heat energy and the primary energydemand of a building can be determined. Of course there are also tools tocompare different buildings e.g. by primary energy demand, heat energydemand, transmission losses, ventilation losses, average U-value, solar gains, etc.

Another tool included in IDEA is an environmental assessment method todetermine the ecological behaviour of a given or planned building. The assessmentis based on amulti-criteria tool adapted for this purpose (Zirngibl, 1996).

Altogether, IDEA contains the following tools:

. energy balance – calculation of heat energy demand after EuropeanNorm EN 832;

Figure 3.Climatic data in IDEA

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Figure 4.Calculation of a U-value

Figure 5.Example from theencyclopedia of IDEA

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. comparison of building parameters;

. environmental analysis;

. calculation of shading;

. lighting of buildings;

. thermal comfort;

. CASAnova – an educational software for energy and hHeating eemand,solar heat gains and overheating risk in buildings;

. sun path diagrams.

3. EncyclopediaThe third distinctive part of IDEA is the encyclopedia which guides the user ina didactic manner all along the way from renewable energy fundamentals tothe design of low energy buildings compatible with the environment. Thisencyclopedia is divided into two parts. The first one is a glossary. Terms in thefield of architecture and solar and low energy building are listed in alphabeticalorder and described. The second part of the encyclopedia is a collection ofspecific topics. Technical details, concepts, definitions and equations areexplained in detail. This part of the encyclopedia is a fully illustrateddescription and discussion of the main aspects in the field of solar energy (seeFigure 6).

Figure 6.Sankey-diagram, created

by Balance

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SummaryIDEA was developed to improve dissemination in low-energy building andenergy saving architecture. The program presents the existing know-how withthe help of a modern multimedia software and shall give inspiration forarchitectural projects.

IDEA consists of a database with buildings which represent active andpassive solar components. The second part is a collection of simulation andcalculation tools, and the third part is a large encyclopedia.

IDEA helps to overcome a non-technical barrier, the barrier of ‘‘not-knowing’’to the introduction of new building technologies to the market.

References and further reading

de Herde, A., (1996), Guide de l’Architecture Solaire, LEARNET, Louvain-la-Neuve.

Heidt, F.D. and Benkert, S. (1998), ‘‘The European project IDEA for dissemination of knowledge onlow energy and solar architecture’’, Proceedings Environmentally Friendly Cities, PLEA ’98,15th International Conference on Passive and Low Energy Architecture, Lisbon, pp. 645-8.

Heidt, F.D. and Braeske, T. (1996), ‘‘Innovative software for education and visualization of passivesolar and low energy concepts’’, Proceedings PLEA 96, 13th International Conference onPassive and Low Energy Architecture, Louvain-la-Neuve, 16-18 July, pp. 51-6.

Weber, W., Drexler, H., Gallinelli, P., Haefeli, P. and Lachal, B. (1996), ‘‘DIAS Interactive Databaseon Solar Architecture – PEM Pascool Electronic Metahandbook’’, Conference Proceedings,4th European Conference on Solar Energy in Architecture and Urban Planning, Berlin H.S.Stephens &Associates, Bedford, 2 March, pp. 201-4.

Yannas, S. (1994a), Solar Energy and Housing Design, Vol. 1: Principles, Objectives, Guidelines,Architectural Association, London.

Yannas, S. (1994b), Solar Energy and Housing Design, Vol. 2 Built Examples, ArchitecturalAssociation, London.

Zirngibl, J. (1996), ‘‘De nouveaux criteres environnementaux pour l’evaluation des systemes dechauffage’’, Rencontres et Journees Techniques, 12-13 September, ADEME/Sophia-Antipolis, pp. 207-17.

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pp. 357-365. # MCB UP Limited,0956-6163

DOI 10.1108/09566160210439260


A comparative study of theenvironmental behaviour

Juan Jose MascaroDepartamento de Arquitetura e Urbanismo – UPF,

Universidade de Passo Fundo, Rio Grande do Sul, Brazil

Keywords Housing, Lighting, Environment, Spain, Brazil, Solar energy

Abstract This paper studies the environmental behavior of two low-income social housings: one islocated in Barcelona, Spain, and the other in Porto Alegre, Brazil. They were both built around thesame time. A comparative study of the climates of each of the cities under consideration was made,pointing out the similarities and differences. The gathering of data was done through in situmeasurement of the environmental characteristics of the open areas of the both low incomemultistorey housing and of the interior of two typical apartments. The technique of observation wasalso used to register the use and characteristics of the studied spaces. At the same time, the solarinsulation was studied throughout the year, using the solar simulator (‘‘heliodon’’). The computersimulations were done to analyze the natural lateral lighting and the natural ventilation. Based onthe environmental measurements done throughout the year and the opinion poll about thesatisfaction of the user, the principles of projects and constructive characteristics, the condition ofthe resulting habitability, as well as the ways of using the exterior and interior spaces and the user’sopinion about their residence were analyzed. It concludes with an evaluation of the results obtained.

1. IntroductionThe fundamental characteristic of the less extreme climates is the complexityof their architectural solicitations and solutions, Serra (1998) affirms. Contraryto what it may seem initially, when one focuses on the case of regions ofcomposite climate, the milder climate makes for more complicated solutionsthan the hot or cold climates because they present different problemssimultaneously or successively. The humidity of the air is more important inthese climates than in more rigorous climates. They are characterized forhaving intermediary periods in which the comfortable feeling can beinterrupted by an excess of heat or cold.

The generalized lack of knowledge of climatic solutions on the part of thedesigners and the small prestige of natural conditioning solutions are evidencedby the many, great project and construction errors found in practice. However,the climate presents itself as one of the fundamental elements of rational energyusage in buildings, including those of lower cost, where the consumption islimited (theoretically). Because the climate is complex and complicates theenergetic-environmental solutions, the situation becomes more critical, making itdifficult to adopt more correct design, technical and economic solutions.

The typology of the residential apartment complexes, especially thoseadopted since 1960, are not exactly characterized as having principles which



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are adequate for the climate as the base of their projects. Even though, in thedoctrinary plane, the vanguard architecture has not forgotten the need forhabitability, the constructive practice has shown the little importance that isgiven to the principles.

This phenomenon of negligence with the habitability is the most notable inthe erudite architecture, and especially in low-cost dwellings where it should bea basic necessity of the project, because these buildings are to be ‘‘lived in’’, arefor low-income users’ who cannot consume energy to solve the problemscreated by the lack of minimal conditions of habitability, even if they want to.

2. Comparison of the climates studiedThe climate of Barcelona, as well as that of Porto Alegre, presents situations ofthermal discomfort (cold in one case and humidity in the other), creatingdifficulties in solving the thermal comfort problem through the architecturalproject.

The average maximum andminimum temperatures in Porto Alegre in summeras well as in winter are higher than those of Barcelona; the average minimumtemperatures in both cities are similar in the summer and early autumn, those ofBarcelona being lower in the hottest months. The monthly average is a littlehigher in Porto Alegre, varying between 7.58C and 10.58C while in Barcelona thevariation is between 68C and 78C. In both cases the maximum monthly averagevariation rarely surpassed 108C. The average annual temperatures are agreeablein both cases: 178C in Barcelona and 20.58C in Porto Alegre.

The relative humidity of the air is the biggest climatic-architectural problembecause it is high all year round. The humidity average is lower in Barcelonathan in Porto Alegre almost all year round, becoming similar to Porto Alegre inthe hotter months. The averages of the minimum values of relative humidity ofthe air were more similar than the average of the maximums. In winter, theaverage relative humidity in Porto Alegre is 13 percent higher than inBarcelona; the average values of the maximums is close, being around 90percent or more in Porto Alegre .

These conditions are unfavorable for the interior environment of thebuildings where architectural decisions should solve the problem, with onlynatural resources efficient in this case, that create the possibilities of goodnatural ventilation, limiting the building types which are adequate for this typeof climate.

One way of visualizing the periods in which one is in thermal balance in each ofthe analyzed climates is to associate the comfort zones of winter and summer tothe monthly temperature oscillations (Figures 1(a) and (b)). Table I summarizesthe comparative climatic analysis done.

3. Description of the buildings3.1. The Polygon of Montbau, BarcelonaThe morphology of Montbau has the simplicity of the first urbanistic attemptsin Barcelona in the years following the 1940s. The urbanism of CIAM was still


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Figure 1.Monthly temperatureoscillation, Barcelona

and Port Alegre

MonthsThermal conditions Barcelona Porto Alegre Observation

Out of comfort zonebecause of cold

5.5 3 Porto Alegre partiallyout

Comfort zone 4.0 5

Out of comfort zonebecause of heat

2.5 4

Table I.Thermal comfort

periods in Barcelonaand Porto Alegre

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a myth that had not been put into crisis, and one had the confidence that byable management of the raw scheme of linear blocks between the green zones,one could even accommodate to the local economic limitations.

The part of the residential apartment complex Montbau under study wasconceived as various blocks in a more or less continuous line, with similar height,whose parallel juxtaposition does not take advantage of the uneven terrain,repeating a morphology of level lots. With five apartments per floor, the floor planpresents two kinds of apartments: two-bedroom (44m2) and three-bedroom (60m2)both facing the street (Figure 2). Due to the small amount of living space, acompact floor plan exists in which the hall, kitchen and dining and living areas areintegrated. The last two of these are joined by a small balcony, which advancesfrom the main construction. This type of plan allows for a greater building area,with economy as a consequence – at the same time increasing the thermal comfortin summer because of the cross ventilation of the apartments which face two sides.

Other non-justifiable aspects were observed on the facades: translucid sills onthe SE orientation (northern hemisphere), without offering security or solarprotection; curtains of unquestionable popular taste are used as improvisedprotection (solar and visual); and washed clothing is exposed on the main facadewithout second thought. This shows a lack of care in the project that causesvisual disorder and functional inefficiency (Plate 1). No ideology can intend tohave any validity when faced with the problem of housing that is not based onthe knowledge of a reality, even though it is badly formed (unequal socialconditions) and little informed (climatic, energetic and environmental aspects).

3.2. Santa Tereza Residential Apartment Complex, Porto AlegreFinanced by the BNH within the INOCOOP program, it is destined for familieswith an income between of 5.5 and 12 minimum salaries, the project were donein 1968. The residential blocks in an H shape and four stories have 20apartments per floor, with one, two, three, and four bedrooms (Figure 3 andPlate 2).

An abstract scheme of repetitive blocks of a monotonous design, whichcreates formal and environmentally badly solved spaces between the blocks, isthe urbanistic principle of this residential housing (Plate 2). Parameters andinstitutional norms set by BNH and the Codigo de Obras Municipal applied tothe land, and the construction can be considered as responsible for some of thegeometric characteristics of the physical components of the whole. However,acting in isolation or together, economic parameters, construction regulations,urbanistic norms and characteristics of the location cannot be invoked tojustify important decisions of configuration and distribution of the residentialblocks which compromise the formal and environmental whole.

Figure 2.Floor plan of MontbauResidential


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4. The measurementsThe goal of the measurements was to get in contact with the environmentalreality of each housing group studied, experience the environment and collectopinions from the users which, on one hand would give no simulation, and onthe other would allow the confirmation of the sensitivity of the computationaland mathematical models used in the simulations. The precision of the resultsto be obtained was always a secondary objective, considering that not only theavailable instruments, but also the difficult measurement situations made itimpossible for us to attend to this requirement correctly.

5. Comparative analysis5.1. Montbau, BarcelonaThe organization of the residential housing space does not modify the localmicro-climate. The temperature and relative air humidity values registeredaccompanied, without shifting, the information obtained by the localMeteorological Observatory. Some environmental aspects such as the distancebetween the buildings so as to avoid the projection of shadow between them

Plate 1.Montbau facade

Figure 3.Floor plan of SantaTereza Residential

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were taken into consideration. The vegetation, which partially covers the NWfacade, protects it from the afternoon sun, a positive aspect in summer, and can bethe cause of the humidity, which the users complain about in winter. The thermalsensation in summer, which is felt while walking along the street and which goes tothe building, is of intense heat because there is no type of protection from solarradiation. The awnings on the ground floor shops bring the only alternative tospaces in the shade, transforming it into a meeting place. The areas shaded by thevegetation are used intensely in the hot season.

The apartments clearly show the lack of preoccupation with habitability.The thermal inertia is minimal. The temperatures inside accompany theevolution of the exterior temperatures and by the adopted practice of maximumspatial integration, the conditions uniformed themselves, accenting(unfavorably) the winter thermal condition. Comparing the values obtained bythe calculations (Van Straaten, 1967) and measurements (very similar) with theregulations in force at the time, the apartment housing was built, we verify thatthe thermal conductance of the walls is greater than that permitted 4.5w/m2h(registered) and 2.1w/m2h (regulation) – 46.5 percent greater. This explains thelack of thermal comfort in the apartments. The roofing fulfils the regulations.The Ordenanzas Tecnicas established that the windows could not be more than40 percent of the walls they were contained in. In Montbau the windows are 64percent of the SE facade, except in the type C apartments, where they are nearthe value required: 42 percent. One finds the bedroom oriented to the NW in thesame situation. In apartments type A and B the situation is similar. Thisgreater permeability of the building decreases its thermal resistance to its

Plate 2.Santa Tereza entrance


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surroundings, making it more sensitive to climatic variations. The opinion ofthe users confirms the results obtained in the measuring.

5.2. Santa Tereza, Porto AlegreThe space organization of the residential housing changes (unfavorably) thelocal mesoclimate slightly, increasing the temperature and relative humidity ofthe air, and causing difficulties in the natural ventilation. No type ofenvironmental care was taken in the urbanistic project. The thermal sensationthat one has walking on the streets inside the apartment complex is a littleworse than that experienced on the treeless streets outside the apartmentcomplex, in which it is possible to experience a breeze when it exists. Thecommon spaces are hot in the summer and cold and humid in the winter,unfavorably conditioning the environmental performance of the apartmentblocks that make them up. This partially explains the lack of use of thesespaces. The lack of concern with the design made it lose not only thehabitability conditions, but also the richness and intensity of potential use.

The localization of the recreational areas is also arguable: it is not possible toaccept the convenience of putting them near the ground floor apartments withoutany protection, since they invade visual and acoustic privacy. The space is badlystructured physically and functionally. The use of the vegetation has acompletely ornamental character, forgetting its useful potentiality as an elementof shade or as a reinforcement element of the perceptive intelligibility of thephysical-functional organization of the group of buildings.

The apartments accompany the lack of care with the habitability and thephysical-functional organization of the exterior areas. The H typology adoptedcondemns them to lack of natural ventilation and lack of visual and causticprivacy and illumination in the bedrooms and kitchen of about 50 percent of theapartments. The best orientation from the point of view of the insulation (sun inthe morning) as well as ventilation (the cool winds blow from the E-SE insummer), is annulled in half of the blocks of the apartment complex which havethe worst possible orientation – west: cold and humid in winter, hot and nowinds in summer. The unfavorable environmental performance registered inthe measurements and simulations is more than justified by the typology andorientation chosen for the apartment blocks.

The thermal behavior of the facade and roofing is admissible, although thereis no regulation to be fulfilled. The Codigo de Obras, considering the size andfunction of the rooms without taking into consideration the orientationdetermines the size of the windows; the living room and bedrooms should haveshading elements on the windows. The project attends these requirements,which does not mean that the habitability is assured, as was verified in themeasurements and interviews done.

Although the thermal performance of the facades and roofing in Montbau isless than in Santa Tereza, the better solution of implantation of the housing andthe typology adopted with apartments opening to both sides, make the globalbehavior better in the summer conditions by permitting cross ventilation, the

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main project strategy in humid climates. By accompanying, with little thermaldelay, the daily evolution of the air temperature, they lose heat as easily as theygain it, being cool at night. This situation is favored by the night ventilation,which Barcelona has.

The orientation chosen for the buildings in Montbau is that which rationalistarchitects for temperate climates recommend – almost W-E – to permit thesunstroke of the main facades of the linear blocks. Even though the thermal loadin the facades is large in summer, this period is short and the orientations chosenpermit that in winter they receive 125W/m2 as the daily average and 595W/m2

maximum, which is most valuable for passive heating of the apartments. Thesame orientation was adopted for the Saint Tereza complex, following therecommendations for another type of climate, where, because of the elongatedform of the building and the subtropical localization, NE orientation was neededto minimize the thermal load in summer and optimize it in winter.

5.3. Comparison Montbau/Santa TerezaIn Table II we present a comparative summary of the environmental behaviorof the studied residential apartment complexes.

6. Simulation of insulationThe simulation of the insulation of the apartment complexes with the calotasolar confirmed the excellent sunstroke of Montbau in winter and theimpossibility of getting sun to the facades of the blocks that open to the interiorof the H, in Santa Tereza making these areas cold and humid. In a region wherethe sun is usually present, the users of this apartment complex, for the mostpart, do not have minimum insulation during the cold season.

7. Simulation of natural ventilationThis was done using the computational model ‘‘Daylight’’ for the equinoxconditions, representing 50 percent of the year, and the period between 10 a.m.and 2 p.m. The values of illumination obtained for the covered sky was

Montbau – (Barcelona) Santa Tereza – (Porto Alegre)

Sun and wind orientation Correct InadequateSpatial organization of theapartment complex

Correct Inadequate

Type of plan adopted Correct InadequateUse of vegetation Correct Not taken into considerationThermal behavior of the walls Inadequate CorrectThermal behavior of theopenings

Acceptable Acceptable

Window size Larger than recommended According to the Codigo deObras

Solar protection for thewindows

Acceptable CorrectTable II.Comparison Montbau/Santa Tereza


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corrected by calculated factors to make them correspond to partially cloudyskies (typical sky of Porto Alegre). The lighting performance of the apartmentsin the apartment complex of Montbau were better than those of Santa Tereza,due to the typology adopted, as expected.

8. Simulation of natural ventilationThis was done using the Breeze computational model, for the apartmentcomplex of Montbau, summer conditions. The results obtained confirmed theadequateness of the typology adopted to have cross ventilation. It was notpossible to do this simulation for the Santa Tereza apartment complex becausethe model does not allow us to simulate complex building structures, like an H.

9. ConclusionThe negligence with the habitability, the inadequateness of the adopted typology,the formal poverty, the impossibility of the users solving the project errors andtheir having no satisfaction with some of the environmental characteristics oftheir homes, this verified set of adverse situations not only a consequence of theadopted housing policies – including the corresponding technical legislation – butalso of the generalized lack of knowledge of climatic solicitations by thedesigners. The deficiencies of comfort and the waste pointed out can be seen asthe result of a series of combined factors, which go from lack of comprehension ofthe potentialities and limitations of the building capacity of the land to thecomplementarity and interdependence between the architectural project and itsenvironmental behavior. The deficiencies pointed out can not be explained norjustified by the project conditions required at that time (1950-1970), neithertechnical-economical nor legal and political, much less be considered as inevitableor negligible; that is why they worry us. The discussion falls inevitably and withabsolute contemporaneousness back on the definition and choice of the liveabletypologies and constructive techniques. The environmental parameter appearsvalued, since it receives the function of measuring the appropriate use of theavailable resources. But it would be naive to underestimate the formidableinstitutional mechanisms and ideologies that sustain (and sustained) therealization of the apartment complexes and which contribute to make unfeasiblecorrect strategies in the project dwellings of social interest. The tendency is togive excessive liberty to the project for public space and excessive strictness tothe private projects. It omits itself in relation to the rational use of energy in thebuilding and is miserly about habitability conditions. Without a doubt theproblem of lack of housing solutions would not be eliminated by the decrease incost. But it is possible to suppose that substantial advances would be achievedwhen the reality of development is recognized and accepted as the starting pointfor efficient and imaginative use of the limited resources.

References

Serra, J. (1988), Clima, Lugar y Arquitectura, 1st ed., CIEMAT, Madrid.

Van Straaten (1967), Thermal Performance of Buildings, 1st ed., Elsevier, Amsterdam.

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Urban planning instruments toimprove winter solar access in

open public spacesMaria Jose Leveratto

Programme for Municipal Technical Studies and Assistance,Faculty of Architecture, Design and Urbanism,

University of Buenos Aires, Buenos Aires, Argentina

Keywords Land reform, Urban environment, Planning (town and country), Argentina

Abstract There is general consensus about the lack of open green spaces in Buenos Aires. Dueto this, different actions are been proposed to improve the quality of existing ones. This paperanalyses potential modifications of built forms to allow better winter solar access and amelioratemicroclimatic conditions of those spaces, increasing their usability throughout the year. A typicalurban configuration, within the dense residential grid, is simulated to evaluate the effects,advantages and limitations of this proposal. In one case, volumes are shaped following existingplanning codes. In the other, modifications to avoid shadows on the open space during the coldperiod of the year are included. Resulting environments are evaluated and compared taking intoaccount urban and economic implications of the decisions involved.

IntroductionThis work focuses on the improvement of winter solar access in public openspaces in the city of Buenos Aires. It analyses the volumetric characteristics ofthe built environment around them and the urban impact of reshaping it toreduce sun shading.

The capital city of Argentina is located 34 degrees south of the Equator. It hasa mild climate where the outdoors can be enjoyed year round, providing someshading in summer and access to sun during the cool winter months. For smallparks, placed within the compact and dense city grid, the variable that mostlyaffects human thermal comfort conditions is the lack of sun access in winter.

With a surface of 200km2 and around 3 million inhabitants, green open spacesare few and unevenly distributed among the territory. This lack of publicvegetated areas for recreation, leisure and play is perceived by the population asone of the variables that affect the quality of their urban life the most. With aproportion of green space of 4.6m2/inhabitant, the city is well below the minimum10m2/inhabitant recommended by theWorld Health Organization (WHO). Emptyurban land is scarce; especially in the areas where green it is more needed.

Recognizing this problem, the new Urban and Environmental Plan forBuenos Aires (Secretaria de Planeamiento Urbano, GCBA, 2000) is proposing avariety of actions to improve the quality of existing green open spaces aimingto increase their usability, public access and beauty.

In this context, the study presented in this paper analyses the characteristicsof high-density residential areas in Buenos Aires, to evaluate potentialplanning instruments that could reshape the built environment and improve



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winter solar access in public open spaces. The work aims to point out thebenefits and losses involved, taking into account that dense areas in BuenosAires have good infrastructure, public transport and social amenities; withthese advantages reflected on the prices of land and buildings.

Another relevant factor to consider is that the new city plan is alsoproposing the densification of certain areas. Definitions about how to increasedensities without repeating already known mistakes is one of the challenges ofour urban future as planning decisions are long term and expensive.

MethodologyThe subject of studyThis paper concentrates on urban public squares of around 1 hectare of land.Typically, they are enclosed by high-density buildings and streets. These openpublic spaces (OPS), are actively used, mainly for every-day recreation, andusually grass and trees are abundant.

Variables and data collection methodsThe study evaluates OPS taking into account four different variables stronglyrelated to built form and urban economics. These variables are summarized inTable I.

To define the volumetric characteristics of buildings around the OPS, 3Dmodels are constructed using AutoCAD2000. One volume is built followingexisting planning codes. Another volume is constructed also following codesbut including limitations needed for a good winter sun access on the OPS. Tobuild this second configuration an adaptation of the method proposed byPereira and Nome Silva (1998) is used. Chosen winter solar angles are kept as‘‘blocks’’ for AutoCAD, that are pasted in the model to draw ‘‘regions’’. The solid3D volumes representing the built environment, constructed following existingcodes, are sliced using these regions as cutting planes.

Data about market prices are obtained performing field studies andinterviews. It is important to highlight that in some cases it could be difficult to

Built densityMaximum surfaces and heights around OPS Following planning codes

Including limitations for solar access

Price building unitsMarket value of units for sale in the area Facing an OPS

Away from an OPS

PopulationAmount of people with benefits from OPS Population living in apartment units facing

an OPSPopulation using the OPS for recreation, etc.

Sun accessArea shaded in winter due to surroundingconstructions

Area of permanent winter shadowArea shaded at 12 p.m. in winter

Table I.Urban planning

instruments to improvewinter solar access in

open public spaces

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isolate the influence of the OPS from all the many variables involved indefining the price of urban properties and the expertise of real state agents is avaluable resource.

Information about population is estimated assuming that all blocks are builtup to their maximum level, with an occupation rate of one person/50m2. Todefine the amount of people that would benefit from the use of the OPS on aregular basis, the potential population of an area of 400m around the space isconsidered.

Sun shading is simulated with AutoCAD renderings, a computer programmevery familiar to architects and urban designers.

AnalysisThe case studyA simplified urban configuration is chosen as a prototypical case study for thisanalysis. In this example the OPS is a square of 1 hectare limited by eightsquare blocks forming a regular grid with perpendicular streets. Theseconditions are very similar to what can be found in Buenos Aires, a city builtfollowing the traditional Spanish grid. The shape of each block is defined usingexisting legislation for high-density residential areas. It allows a maximumheight of around 29m, regardless the orientation of the plot.

Areas of interactionThe presence of a public common space within private profitable land defines arelationship with some particular characteristics:

. There is an urban area receiving direct benefits from the OPS, such asthe enjoyment of open views, proximity to vegetation, more privacy, etc.For the study, this area has been limited to the plots with at least onefacade facing the OPS. As it will be seen later, this privileged location isclearly reflected on land and apartment units’ prices.

. There is another area, limited by the angles of winter sunrays, wherebuilt volumes will shade the OPS, with a negative effect on its micro-climatic conditions. This area has been defined using 10 a.m. and 2 p.m.altitude and azimuth angles of sun for 15 July (Knowles, 1981). Its sizecould increase if higher constructions, such as freestanding towerbuildings, are found in the surroundings.

To measure the variables defined and summarized in Table I, the surface of thesurrounding areas influencing the climatic characteristics of the OPS needs tobe defined as well as the surrounding area benefit form the OPS.

The drawing in Figure 1 shows the surfaces included in these two areas.Shadows from buildings shaped following code regulations are also represented.It is important to notice that at noon on 15 July, 20 percent of the OPS’s surface isshaded by constructions. At 2.00 p.m. this percentage goes up to 28 percent. And,because of the north-south orientation of the grid, permanent shadows in wintercover up to 10 percent of the square.


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To avoid shading, some volumes around the OPS need to be reshapedand modified. Heights and buildable surfaces are reduced as shown inFigure 2).

As expected northern volumes, with facades facing south, are the mostcompromised. Their total surface needs to be reduced as much as 42 percent.On the east and west sides, total surface reductions are 9 percent for each

Figure 1.Plan view of the area

showing areas ofinfluence and winter

shadows

Figure 2.Section showingreduced surfaces

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facing volume. The resulting volumetric configuration of this operation ispresented in Figure 3.

To evaluate the feasibility of any proposal aiming to modify built densitiesin consolidated urban areas, the economic value of the land and propertiesinvolved has to be taken into account. In Table II mean prices of apartmentsand lots in these residential areas of Buenos Aires are presented

ResultsThe main results of the analysis are summarized in Table III. Values presented onthe left column show buildable areas, prices, population and shading conditionsobtained following existing codes and regulations, values on the right columnreflect the impact of reductions needed to improve winter solar access on the OPS.

It is interesting to highlight that an apartment with views to an OPS can beup to 15 percent more expensive than an equal unit without that benefit. Eventhose apartments not facing the OPS, but built on a plot in front of it, will costaround 5 percent more.

A reduction of 9100m2 of construction would benefit 46.160 people andimprove winter microclimatic conditions on 2.700m2 of public land. It isimportant to notice that to guarantee sun between 10 a.m. and 2 p.m. during thecold period of the year, total built densities need to be reduced only 10.4 percent, apercentage lower than the extra value of that land due to the presence of the OPS.

ConclusionsThis is a simplified urban configuration, and results only present tendencies,which should be further verified and discussed for each existing OPS. However,

Figure 3.Perspective usingAutoCAD, representingthe area around the OPSwith volumetriclimitation for wintersolar access

$/m2

Land 700-1,2000

Apartments 900-1,350

Apartment facing an open green space 1,000-15,000

Table II.Mean prices of landand apartments inhigh-density residentialareas of Beunos Aires,Argentina (in USdollars – January 2001)


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this work shows that technical proposals to control heights and volumes in highlydensified urban areas, should be addressed taking into account factors such as:

. The extra value of properties facing an OPS is a direct consequence ofthe existence of a space provided and maintained with public expenses,with no extra taxes to property owners. Despite of this, the cityGovernment spends around $10,000 a year only to cover basicmaintenance costs of a 1 hectare urban green area.

. If, in a city with the characteristics of Buenos Aires, it is expensive toincorporate new land for public outdoors recreation and leisure, it seemsto be economically unwise to reduce the possibility of use of more than20 percent of existing open public space during winter months due tourban forms that benefit only a few private owners.

. To be able to implement further density restrictions in these areas, theeconomic losses of the private sector should be evenly distributedamong all the actors that directly benefit from the OPS applying, forexample, differential taxes.

. Planning codes in Buenos Aires consider the four sides of the urbanblock equally, disregarding solar orientation as an important shapingvariable. Reductions on heights on south facing facades could becompensated with wider volumes at lower levels or other particularmodifications of the built environment.

. Improving microclimatic conditions in the OPS, will probably notincrease the value of the properties around it.

There are also some design considerations, affecting urban planning decisions,to be included in the discussion:

. Buildings shading winter solar access are the ones with worstorientations on their main facades. Reformulating shapes of these

With limitation for solar access

VariableFollowing planning codes

87.000m277.100m2

10.4 percent reduction

Built surface

Price of building In front of OPS Using OPS In front of OPS Using OPSunits 1,000-1,5000$/m2

approx 10 percenthigher

900-12,350$/m2 1,000-1,5000$/m2 900-1,350$/m2

Population In front of OPS Using OPS In front of OPS Using OPS1,740 46.350 1,518

12 percentreduction

46.1600.4 percentreduction

Solar shading onOPS

Permanent wintershadow

Shaded at 12 p.m. Permanent wintershadow

Shaded at 12 p.m.

10 percent 20 percent 0 percent 0 percent

Table III.Summary of theanalysis with thevariables involved

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constructions would not only reduce their impact on the public space,but also improve comfort conditions in those buildings, too.

. For good winter solar access in OPS, south-facing facades could grow upto three floors. This is enough to limit the urban space, preserving theenclosure characteristics of a compact city (Lynch, 1994).

. Public buildings and other facilities, such as schools, cultural centres,etc., generally require lower built densities and heights, and could be agood choice for south facing plots, if the design of the buildings can takeadvantage of the wide north facade inside the block.

. If avenues or wider streets are required, they should be plan on thenorthern side of the OPS, whenever possible, to increase distances andallow higher buildings.

Further studiesA second part of the study will consider the characteristics and consequences ofapplying these concepts on existing OPS in highly populated residential areas inBuenos Aires. Under real conditions diverse orientations and configurations willappear, and existing lots will define shapes and areas differently. Specialattention will be paid to those areas where legislation has been recently, or will besoon modified, to allow higher densities. Considering that urban scaleinterventions are expensive, long term and complex it is important to proposerecommendations before urban growth is completed and consolidated.

It should be mentioned that existing planning regulations in Buenos Airesindirectly tend to promote the construction of freestanding buildings (deSchiller, 1999). The presence of this typology can further complicate the analysis,highly influencing with its shadows isolation conditions of a much wider area(Leveratto, 1995).

Finally it is important to remark that existing OPS are designed withoutincluding any climatic considerations. Usually perennial trees shade playgroundareas in winter but not in summer; there is no protection against cold wind, etc.Although urban form plays an important role defining solar access to publicspaces, these other aspects need to be further studied and modified becauseinadequate landscaping could ruin any long-term bioclimatic planning approach tothe city.

References

de Schiller, S. (1999), ‘‘Impacto de la forma edilicia en el confort de espacios urbanos’’, II EncontroLatinoamericano de Conforto no Ambiente Construido Encac 99, p. 303.

Knowles, R. (1981), Sun Rhythm Form, MIT Press, Cambridge, MA.

Leveratto, M. J. (1995) ‘‘El impacto de edificios en torre de gran altura y confort en espacios urbanos’’,Anais I Encontro Latinoamericano de Conforto no Ambiente Construido, pp. 197-202.

Lynch, K. (1994), Good City Form, MIT Press, Cambridge, MA.

Pereira, F.O.R. and Nome Silva C.A. (1998), ‘‘A proposal for the implementation of the solarenvelope in urban planning as a concept for regulating the occupation of urban area’’,Proceedings of PLEA ‘98 Environmentally Friendly Cities, pp. 611-14.

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pp. 373-381. # MCB UP Limited,0956-6163

DOI 10.1108/09566160210439288

Energy saving by meansof innovative buildingenvelope systems

Italo Meroni, Alba De Salvia, Roberto Lollini andM. Cristina Pollastro

ITC – CNR, Construction Technologies Institute of the Italian NationalResearch Council, San Giuliano Milanese, Milano, Italy

Keywords Energy management, Solar energy, Air conditioning, Buildings

Abstract Nowadays, one of the main goals of the building industry and architecture is to exploitthe solar source for the air-conditioning of buildings. Over the last years many activities havestarted to develop new building and plant technologies oriented to energy saving by improvingindoor comfort and reducing pollution emission. The guidelines deriving from various worldconferences (Kyoto 1997, Buenos Aires 1998) are known. Industrial countries have committedthemselves to try and carry out new strategies to reduce both energy consumption and air-pollution. These aims have increased research works oriented to find materials, components andsystems able to use energy gains from the environment, in particular from the sun. During thestudy carried out at ITC on the subject, two envelope technologies have been studied and realised.The paper describes such technologies and the methods used for their characterisation. It alsoreports on the most meaningful results obtained from the experiments carried out.

IntroductionFinding and applying strategies to reduce polluting emissions through therestraint of building consumptions represents a challenge bigger than the oneof the 1970 energy crisis. The importance of such enterprise is underlined byworld conferences of the last years in which the industrial countries havecommitted themselves to try to carry out new strategies to reduce air-pollutionemissions. Implications will be relevant, especially in the energy field. TheItalian Government has committed itself to giving an immediate signal aboutthe problem, defining actions directed to a more efficient use of the energyresources and to the goals of the last world conferences about greenhouse effectgas emissions limits. Various actions have been promoted in the constructionfield, where wide margins of consumptions’ reduction exist. To this end, MIUR(Italian Ministry of University and Research) started a project oriented to thestudy and definition of techniques and materials able to improve the livingcomfort and life quality. Within this project, ITC-CNR, the ConstructionTechnologies Institute of the Italian National Research Council, defined a seriesof technological solutions, as meaningful answers to the above-mentionedproblems. Two of these solutions are hereafter presented.

The defined envelope technologiesThe studied systems belong to two technological units classes: opaque andtransparent vertical enclosures. They are two envelope technologies, for which



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materials and aesthetic-technological solutions have been chosen evaluatingthe following aspects: the ventilation; the energy control; the cost-benefit ratio;the integrability with the current building system; the maximisation of freegains; the improvement of indoor comfort (from the thermal and lighting pointof view); and the attention to the payback time (calculated mainly in terms ofenergy saving).

Both the systems are characterized by a dynamic behaviour, with an airspace in which air flows as energy vector between indoor and outdoorenvironments.

Thermal fluxes in the air space are suitably managed according to a logicbased on three temperatures: internal temperature, external temperature andtemperature in the air space. An electronic board, on the basis of the signalsfrom the thermal probes, sets electric and electro-mechanical devices. Thesedevices allow the air to flow in or out, in a natural or forced way, generatingheat gain or exhausting and controlling ventilation and fluxes conveyance,according to the demands.

Both the systems are equipped with a technical module, which contains theelectric, electronic and mechanical devices, for optimal management of thethermal fluxes. Such a module is placed on a multilayer element, in the opaquesystem, and a double window, in the transparent one. In fact this ischaracterized in the inner side by a sheet of variable transparency glass, thatcreates, with the double glass of the outer window, the air space (see Figure 1).

Photovoltaic modules, equipped with batteries, make the systems quiteautonomous from the electric point of view, even if inadequate externalconditions last.

The hardware and the managing softwareThe two systems’ hardware is made up by elements of a different kind:

. a ‘‘construction’’ component, that is the multilayer in the opaque systemand the window in the transparent one;

Figure 1.The systems inheat-gain and heat-exhaust behaviour

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. a ‘‘mechanical’’ component, that is the devices, mainly placed in thetechnical modules, which gather and manage air fluxes;

. an ‘‘electronic’’ component, the managing logic is implemented with.

The systems’ software is the main element accounting for their functionalityand ability to contribute, according to the ambiental conditions pointed out, tomaintaining the indoor comfort and to the reduction of primary energyconsumptions.

The managing software (Figure 2) is based on the setting of both the desiredinternal temperature and other parameters able to optimize the globalbehaviour of the systems. The comparison between the real and desired valueof internal temperature distinguishes the working modalities, that are mainlytwo: heat gain and heat-exhausting.

When the internal temperature is lower than the desired one, the systemswork in heat gain modality. The heating of the mass of air in the air space of themultilayer (in the opaque system) or between the window and the completelydarkened sheet (in the transparent) is exploited. The air, heated by green-houseeffect, is let in the internal environment or kept steady in the air space (staticinsulation) according to the difference between internal temperature and airtemperature in the air space. The air is let in, in a natural or forced way, by thesystems’ ventilation devices.

On the contrary, if the internal temperature is greater than the desired one,the systems work in heat-exhausting modality. In this way the system avoidsindoor air overheating, removing the excess of heat in a natural way (passivebehaviour) or through extractors (active behaviour), damping the enteringthermal wave and ventilating the air space.

Figure 2.The flow-chart of the

control logic

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In this case the electromechanical devices are opened and the ventilationdevices managed according to the difference between internal and externaltemperatures.

The experimentation on the systemsTwo main experimental rigs have been considered: the test-cells and anexperimental building.

The experimentation was developed in different phases, from a pre-test ofthe prototypes, through the experimentation on the test-cells, to the setting upof two prototypes of the opaque system and two of the transparent ones in afull-scale experimental building.

The test-cell analysisFor the functional and energy characterization of the prototypes the test-cellmethodology was used. It consists of the assessment of a system, through themodification of the dynamics of the physical parameters of an environment, forwhich the system itself works as vector of energy flux

Test-cells are optimised to compare the termoenergy behaviour of systemsstudied for the managing of solar contributions. In their characteristics, thetest-cells simulate the conditions of the effective thermal mass of recurrentbuilding typologies. Each cell is equipped with a thermostatic system for theinternal temperature, obtained by a simple electric heaters’ system.

The tested systems are put on the south facade of the cells (see Plate 1).Performances of the systems to assess are compared with the ones of referencestandard systems, evaluating the energy required to maintain the cells in assimilar as possible thermal conditions. This energy amount is called energycontribution.

This energy contribution, for each system, has the same dimensions of thevolumic coefficient of thermal losses. It is calculated for periods of one to fivedays and it is defined as follows:

Plate 1.The two innovativesystems during theexperimentation on thetest-cells

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C�g ¼ q

h� � ��TW=m3 �C

where:

Cg* = energy contribution (W/m38C).

q = energy consumed during measures (Wh).

h = length of measures (hours).

v = volume of the test-cell (m3).

�T = mean difference between int. and ext. temp (8C).

In the amount of energy considered for the calculation both energy used for theheating of the cell and energy for the electric and electronic devices of thesystem and of the cell are taken into account.

The analysis in the experimental buildingFor the evaluation of the systems’ contribution to the performance balance of afull scale building, ITC’s experimental building in Lecco was used. Suchbuilding consists of a structure beams-pillars of three levels equipped andcharacterized by interchangeable envelope and plants.

The area of each floor is about 130m2 and for the experimentation it wasdivided in two parts: the effective room for the tests and a technical room.

On the south facade of the first floor, two opaque prototypes were set up; twotransparent prototypes were set up on the second floor; the third floor was usedas reference floor (Plate 2).

Plate 2.The prototypes seton the experimental

building

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The internal parameters and the prototypes’ ones were monitored to assess theenergy and functional behaviour of the systems under real working conditionsand their influence on indoor comfort.

The obtained resultsThe results obtained during the experimentation for both winter and summerbehaviour are hereafter presented.

Heat gain behaviourThe analysis of the collected data showed how the systems can reduce theenergy consumptions, maximizing the solar free gains and improving theindoor comfort.

Figure 3 reports an example of the trend of some parameters characteristicfor the behaviour of the opaque prototype.

The average energy contribution, in winter conditions, of the opaque systemset on the test-cell is higher than 30 percent, compared to the reference component.

The energy contribution coefficient decreases with the solar radiation(Figure 4) which confirms the capacity of the system to exploit solar source.

Figure 5 reports the trend of the energy primary consumption in the twofloors of the experimental building with the innovative system and thereference one.

Figure 3.The trend of somecharacteristicparameters of theopaque system

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Regarding the analysis of indoor comfort in the real scale building, theemission of warm air, in the floor where innovative opaque prototypes are setup, increases the internal temperature and, as a consequence, reduces energyconsumption for the heating.

Moreover, the data related to internal parameters showed a morecomfortable situation for what concerns relative humidity, compared with thereference floor (Figure 6).

Also the transparent system has better performances than its reference, interms of energy contribution, even if more limited than the opaque one.

Heat-exhausting behaviourDuring the summer season, in heat-exhausting condition, the systems permitthe avoidance of overheating of the indoor environments.

Figure 4.The energy contribution

coefficient vs solarirradiation

Figure 5.Primary energy’s

consumptions in the twofloors of the

experimental building

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Comparing the behaviour of the opaque system with the traditional component,the innovative one can, during the night, exhaust the internal heat storedduring the central hours of the day (Figure 7).

In the transparent system the thermal wave damping and the nocturnalexhausting is more limited.

ConclusionsThe present energy situation binds us to consider the use of energy sources asan alternative to fossil fuels and oil by-products, that is by now a not verysustainable source, especially for countries poor in traditional primary sources.

Figure 6.Internal parameters inthe two floors of theexperimental building

Figure 7.Internal temperature ona summer’s day

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Thus, for an environmental sustainability, the use of renewable sources has aprimary role, and the energy consumption reduction, exploiting solar source,should be one of the main objects of nowadays architecture and constructionactivity.

Many improvements have been done over the last years and a continuationin this direction is to be hoped, for promoting the use of solar and insulatingtechnologies, reducing energy consumption and, as a consequence,environmental pollution.

The presented systems represent meaningful examples of this trend, beingable to contribute in a relevant way to the energy balance of the building theycould be set up on.

Further reading

Meroni, I., Lollini, R., Pollastro, C. and. De Salvia, A. (2001), ‘‘Innovative passive and hybriddynamic envelope systems: case studies’’, 3-4 October, Energie Solaire et BatimentCISBAT 2001, Lausanne.

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Green roofs in temperateclimates and in the hot-humid

tropics – far beyondthe aesthetics

Manfred KohlerFachbereich Agrarwirtschaft und Landespflege,

University of Applied Sciences, Neubrandenburg, GermanyMarco Schmidt

Department of Applied Hydrology, Resource Protection and Irrigation,Technical University of Berlin, Berlin, Germany

Friedrich Wilhelm Grimme and Michael LaarInstitut fur Tropentechnologie ITT, University of Applied Sciences,

Cologne, GermanyVera Lucia de Assuncao Paiva

Escola de Bellas Artes, Federal University of Rio de Janeiro,Rio de Janiro, BrazilSergio Tavares

CEFET-RJ, Rio de Janeiro, Brazil

Keywords Roofs, Recycling, Facilities management, Ecology, Green issues

Abstract Green roofs are still often seen as a pure aesthetical element in architecture, as a spleen ofsome ‘‘greenies’’. In fact green roofs already contribute, to some extent, to a better microclimatethrough evaporation, filtering of dust from the air and a decrease in temperatures at the rooftop. Incities like Berlin and Munich many green roofs have already been realised. Coupled with thismicroclimate improvement, is the thermal comfort improvement under such roofs by more mass, dryor wet substrate, and shading through the plants. Besides improving the microclimate and the indoorclimate, the retention of rainwater is another important advantage. That means an importantreduction of the rainwater input in the sewage system during rainfalls, cutting the peak load, avoidingan overload of the system, which might cause flooding and serious health problems. The risk of floodingin cities, which is increasing in many cities due to a ground sealed by buildings, asphalt and concrete,can be diminished. One recent example of the use of green roofs with this purpose is the PotsdamerPlatz in the centre of Berlin, where 100 percent of the rainwater has to be evaporated or used for toiletflushing on the building site. Scientific knowledge on green roofs is still limited to temperate climates,due to a development which took place in central Europe. Since 2000 a scientific project in Rio deJaneiro is checking local parameters, like possible vegetation, which can be used and substratecomposition. Parallel to this, four prototype roofs, three greened and one blank, are used to measurethe retention rate of the rain water and the temperature on the underside of the roofs in order toanalyse the possible improvement of the thermal comfort in buildings. This paper will describe thescientific results of Germany and discuss the practicability on a larger scale under tropical conditions.



The authors would like to thank their partners in the research group, which is also composed ofFernando Gusmao, Nisete Augusta de Amigo and Cristina Souza (all CEFET/RJ) as well as thesponsors of the projects, the DAAD (German Academic Exchange Service) and CAPES(Brazilian Academic Exchange Service).

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1. IntroductionGreen roofs do have a long tradition worldwide. The famous suspended(hanging) gardens of Semiramis, one the seven wonders of the antique world,may serve as an example. This type was a forerunner of what we call today an‘‘intensive’’ green roof. This kind of green roof is marked by a substrate heightof more than 50cm, artificial irrigation and a wide variety of plants. The staticof the roof has to be checked carefully, due to the substrate weight. Toguarantee a good performance, regular care is fundamental. Roof gardens are acommon element in representative buildings as well as luxury hotels. A wellknown example in Brazil is the roof garden designed by Burle Marx on thebuilding of the former Ministry of Education and Culture (MEC) in Rio deJaneiro (Plate 1).

In contrast to intensive green roofs or green gardens are the extensive greenroofs: they function in the first place as a ‘‘climatic skin’’ and have their originin, for example, Iceland (residential buildings) and Hungary (wine warehouses).Simple grass roofs were used to isolate the interior against heat in the summerand cold in the winter. Extensive green roofs are, like the name indicates, free oftending and do not need irrigation.

In 1900 the extensive green roof was further developed by a German rooferfor use on contemporary residential buildings. In many German cities theseroofs were built as a form of fire protection. This type of roof proved to be verydurable and until recently almost totally free of maintenance.

Special attention is being paid to the role of green roofs in the ecology ofurban centres. The city of Berlin was the vanguard in this discussion. Thegreen roof was discussed under several aspects:

. longer durability of the roof skin, due to lower surface temperatures anda better protection against UV-radiation;

. relieving the strain on the ecology of the city, principally concerningmicro-climate, rainwater retention and filtering of airborne pollutants;

. a biotope for animals and plants were a high impermeabilisation ratecreated ‘‘concrete deserts’’;

Plate 1.Green roof in Rio deJaneiro, designed by

Burle Marx

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. aesthetical improvements in denaturalised urban centres;

. creation of recreation areas in parts of the city, were real estate priceswould not allow the luxury of, for example, a restaurant with a garden.

Since 1980 the aspects of urban ecology are being investigated in Berlin.Parallel to this, at universities in other German cities technical aspects werebeing tested and improved, like substrate, sealing and drainage, leading toguidelines for the implementation.

The positive effects of green roofs are proved: reduction of the roof surfacetemperature, the retention of precipitation, the active evaporation in loci, areduction of the entry of air borne pollutants into lakes and rivers duringrainfalls. The cooling effect of evaporation, which is helpful in the Germansummer, works during the whole year in the tropics.

In Germany already 7 percent of all new constructed flat roofs are greenroofs. A growing amount of sloped roofs are also greened. What helpssignificantly in convincing clients to implement this technology is a warrantyof 30 years, which is basically the same warranty for sloped roofs withconventional materials.

The aim of this international and interdisciplinary project is an adaptation ofa technology well proved in Germany to an other climatic zone and, wherevernecessary, the development of new solutions to the very specific situation.

2. Thermal advantages of green roofs2.1 Roof surface temperaturesThe most obvious argument for green roofs is the reduction of the surfacetemperature. Own measurements in Berlin were started in 1984. The analysisof data obtained in three years proved, that, beside a reduction of the maximumtemperature, the years amplitude could reduced by half (Kohler, 1993); (Kohlerand Schmidt, 1997). That means a significant strain reduction for the sealingmaterial.

Beside measurements with PT-100, protected against sun, measurementsare being carried out with infrared sensors for some time, due to its higheraccuracy. This technology works ‘‘touchless’’ and ascertains the realtemperature of a small measurement spot. The following results for thelocations Berlin and Neubrandenburg are being published for the first time.

Two types of conventional roofs, one sealed with bitumen (Berlin), the othercovered with gravel (Neubrandenburg), were being compared with green roofsin the corresponding locations.

The green roof of the cultural centre ‘‘UFA-Fabrik" was realised in 1984 dueto a municipal program which focused a improvement of the urbanenvironment The average thickness of the substrate is around 8cm, thevegetation covers about 90-95 percent of the substrate (Figure 1).

The green roof in Neubrandenburg was being constructed in October 1998.Different types of Sedum and different types of moss grow on a 7cm layer ofsubstrate. The higher plants cover approximately 30 percent of the surface (Figure 2).


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Figure 2 shows temperature measurements from May 2000 exemplarily for thelocation of Neubrandenburg. The month was relatively warm for CentralEurope. The precipitation rate was very low.

Sensors used in this measurements are:

. Surface sensor, not shadowed – bt2.

. Surface, shadowed, gravel – tbod1.

. Surface, shadowed, green – tbod2.

. Temperature of substrate – bt1.

. Air temperature1m, shadowed – t1m.

Figure 2.Temperature of a

greened andnon-greened roof,

FH Neubrandenburg,Germany

Figure 1.Water retention and

drain delay of a greenedroof compared with a

flat bitumen roof (8cm ofsoil layer)

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The daily course of the temperatures vary at noon between 20-288C. The surfacetemperature of the gravel roof, which was measured while protected againstradiation, according to the German standard, takes a similar course like the greenroof, while the amplitude of the gravel roof is more pronounced. The gravel roofalready improves the surface temperature due to its shadowing effect. Itsdisadvantage is a relatively highweight without the benefits of vegetation.

The surface temperature (unprotected measurement) bt2 is around 10Khigher than the other readings. Temperatures of over 508C are being reached.The temperature of the substrate increases slowly, suppressing the highamplitudes which the other readings show.

Two positive effects can be observed here: first, the cooling effect of theevaporating water and second, as soon as the cavity water is evaporated (whateffects the plants negatively), the effect of the higher insulation.

Table I demonstrates the comparison of mean values for the month May,July, September and December (for the sensor description see above).

The attenuated temperature swing of the green roof represents the decisiveadditional buffer zone. Ideally it is composed of three layers:

(1) Top layer: plants, even dead leafs, shade the surface of the substratewithout blocking the air stream.

(2) Mid layer: 5-50cm of substrate. The effect depends on the kind ofsubstrate: material with high porosity and light colours are to bepreferred.

(3) Bottom layer: the drainage layer, can be composed of substrate or ofmaterial with big pores to drain the water, which can not be retained bythe cavity of the substrate.

Compared to this roof composition, a conventional (flat) roof is only composedof a thin layer of bitumen, sometimes protected by a layer of gravel, and istherefore very susceptible to damages.

The rather complex composition of the green roof improves the comfort of thetop floor apartments significantly: while top floor/under the roof apartments arenotorious for comfort problems in winter (too cold) and summer (too hot), thetenants of apartments, which were equipped with green roofs in the 1980s, arequite satisfied with their ‘‘under earth’’ apartments, as periodical interviews proved.

Sensor May July September December

Tbod1 15.9 16.0 13.7 3.2Tbod2 16.3 16.2 13.6 3.2Bt1 20.5 18.7 15.5 5.5Bt2 21.1 18.7 14.6 2.9T1m 14.3 15.3 13.3 3.3

Table I.Comparison of somemean values of May,July, September andDecember 2000


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3. Water retentionFigure 3 shows exemplarily the reduction of rain runoff on extensively greenedroofs.

The retention of water, caused by the evapotranspiration of the plants andthe soil layer, is the main aspect for the reduction of the temperature of thebuildings. The main idea to prevent the surface of a building from energy-impacts is to reduce the direct and diffuse radiation or to increase the reflectionof the surface. But these solutions may have an effect on the directneighbourhood due to thermal processes, because the radiation does not really‘‘disappear’’. A much better solution is to consume the incorporated radiationby greening facades and roofs.

Own measurements to the water retention of greened roofs yielded anevaporation between 60-79 percent (see Table II) of the annual precipitation.This value is applied to Berlin with a relationship of precipitation to potentialevaporation with 550-600mm. It found entrance into the building standards. Incomparison with green roofs, the run offs of the precipitation from a bitumen-roof are approximately 90 percent.

In green roofs the stored precipitations evaporate either directly from theroof-surface (interception, evaporation), or are transpirated by the plants(transpiration). For the evapotranspiration of these precipitations, energy isnecessary. This physical process generates the so-called evaporation coolingwith 2450J/g H2O. Table II shows the resultant cooling-rates with meanly

Figure 3.Reduction of rain runoffon extensively greenedroofs – comparison of

different substratethickness

Precipitation Runoff Runoff Pot. ETP Measured ETP CoolingYear (mm) (mm) (%) (mm) (mm) (kWh/(m2*a))

1987 702 179 25.5 641 523 3561988 595 157 26.4 696 437 2981989 468 98 20.9 750 370 252

Table II.Precipitation, runoff,

potential and measuredevapotranspiration andevaporation cooling of

greened roofs

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300kWh/(m2a) for Germany. For tropical countries, much higher cooling valuesare expected due to higher precipitation and evapotranspiration rates.

Under tropical conditions the evaporation rate on heated up buildings isimpressionably visualized after a rain shower: the roofs are steaming. During andafter a rain shower the temperature drops significantly. This positive effect does notlast long, due to a lack of rain water retention inmost urban areas. The rain water isdrained rapidly, many times causing inundations in the lower areas of the city. Asmore andmore urban soil is sealed, rain water overloads sewerage systems, leadingto untreated sewage finding its way directly into the surface water. Especially inthe case of tropical rain falls, which are very often characterized by extremely bigamounts of water in a short period, therefore causing an enormous peak load (TableIII), the retention capacity of green roofs might help to avoid inundations, which arevery frequent in, for example, Rio de Janeiro and Sao Paulo, Brazil.

In Germany a rate of 40-55mm/h is the probability for maximums in tenyears. 60-80mm/h are registered as a probability within 100 years.

A common problem in temperate climates is the leak of evaporation duringthe winter period due to temperatures well below zero degree centigrade. Thisdecrease of rain water retention will not show up in tropical and sub-tropicalclimates due to generally higher temperatures. For this reason green roofsappear to be even more indicated for tropical and sub-tropical climates than fortemperate climates.

What still has to be checked carefully is the retention rate on a hourly base: theretention rate depends on various factors, like thickness of the substrate layer,pore volume of the substrate, degree of saturation due to previous precipitation,etc. This part will be topic of future publications of this project group.

Figure 1 shows the water retention and drain delay of a greened roof (8cm ofsoil layer) compared with a flat bitumen roof in Berlin.

4. Retention of pollutants and nutrient removalRoof greening on a third aspect means more than just reducing the size ofsewerage systems. It also ensures better quality of surface waters as it reduces

Station mm/hour Date Hour

Campo Grande 116.2 19/03/2000 00:08Grajau 90.3 16/02/2000 23:01Sumare 81.3 02/04/1998 23:49Tanque 78.3 09/01/1997 18:42Tijuca 78.2 17/02/1998 15:15Vidigal 72.5 15/12/1998 17:43Cachambi 72.4 28/03/2001 22:17Tijuca 71.5 07/01/1998 19:00Anchieta 71.0 28/03/2001 21:23Madureira 71.0 31/01/1997 19:17

Source: Alerta Rio (2001)

Table III.The ten heaviestrainfalls in differentparts of Rio de Janeiro,Brazil from 1997 untilMarch 2001


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pollution caused by rain water runoff or combined sewer overflows. Thepositive effects like retention of pollutants and nutrient removal are essentialfor improving the water quality in our rivers and streams.

Figure 4 shows the balance of the nutrient- and heavy-metal retention inpercent of entry, measured on research plots of the TU Berlin in Berlin-Charlottenburg. The results are based on 36-monthly measurements each in athree years average.

Figure 5 demonstrates the increase of phosphate retention due to theestablishment of plants in the course of time. The magnitude of this effectdepends on the thickness of the substrate, the depot and the kind of vegetation.This effect is extremely important for urban water bodies, which generallysuffer from an algae problem (and therefore a lack of oxygen, etc.), due to anoverload of nutrients.

5. Example – Potsdamer Platz (Berlin)40,000m3 of extensive green roofs were implemented as a measure for anintegrated rainwater management at the DaimlerChrysler area at thePotsdamer Platz in the centre of Berlin.

A wide range of city-ecology measures is available today depending on thevarious local conditions. Combining different types of measures is seldompractised in large scale projects. The example of the construction-site of thePotsdamer Platz Project shows the importance of integrating all aspectsregarding ecology already in the planning process. As a part of an integrated

Figure 4.Retention of pollutantsin percentage of input

Figure 5.Phosphate retention dueto the establishment ofplants over the years

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ecological concept from energy-purposes to the use of environmental-friendlybuilding materials a large water-management concept was realized.

A condition dictated by the city council was the compliance of a maximumdraining of 3l/sec/ha for this specific area. The idea behind was a reduction ofpeak run offs during heavy precipitations and so an avoidance of rain water inthe mixed sewerage system. To comply with these regulations, differentmeasures were applied:

The management of 23,000m3 per year rainwater from 19 buildings arehandled by the following measures:

. extensively and intensively greened roofs;

. collecting of roof-runoff to be used for toilette flushing and irrigation ofgreen areas including intensively greened roofs;

. refilling an artificial lake.

Plate 2 shows an artificial lake with a size of 1.2ha, and a constructed wetlandfor rainwater treatment of 1,900m2.

6. ConclusionsThe following conclusions may be drawn from this case study:

. Green roofs are an important element of bio-climatic architecture. Thelowering of the temperature of the roof and the insulation effect due toplants and substrate are undeniably positive for the indoor climate.

. The durability of flat roofs is increased significantly.

. Green roofs are urban sponges, retaining rain water and generatingcooling effects, lowering the risks of inundations and improving theurban micro climate.

. Pollutants are retained, improving the rain water quality, which meansless pollution of rivers and (urban) lakes.

. Downsizing of sewerage systems.

Plate 2.Urban artificial lake,Potsdamer Platz, Berlin


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Green roofs have a long history: beginning with the ‘‘hanging gardens’’ ofSemiramis, to roofs gardens planed by Le Corbusier and Burle Marx to anintensive use at the Expo 2000 in Hannover, the concepts are similar but thedetails changed. Today green roofs are based on a stable fundament of researchand development. Materials were adapted, improved or newly developed. Theindustry in Germany gives a warranty of 30 years for green roofs . This alreadyincreases the implementation of green roofs in Germany, actually 7 percent ofall newly constructed flat roofs. Positive effects for indoor climate, microclimate and material durability are proven. The retention of rain water for theavoidance of inundations is not questioned any more and already found its wayinto municipal regulations in Central Europe.

There is still some research and development to be done for the applicationof this technology in the hot and humid tropics. Special attention will be paid tothe fauna and flora, due to possible hygienic problems (for example DengueFever transmitted by the Anopheles mosquito, which uses small water bodiesas a ‘‘cradle’’).

First results and theoretical calculations permit the conclusion that greenroofs might be as interesting for the tropics and sub-tropics as for temperateclimates.

References

Alerta Rio (2001, available at: www.rio.rj.gov.br/georio/

Kohler, M. (Ed.) (1993), Dach- und Fassadenbegrunung, Ulmer, Stuttgart, p. 329 S.

Kohler, M. and Schmidt, M. (1997), Hof-, Fassaden- und Dachbegrunung, Zentraler Baustein derStadtokologie’’, Landschaftsentwicklung und Umweltforschung, Vol. 105, pp. 1-177.

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Optimal orientationand automatic control of

external shading devices inoffice buildings

Antonio Carbonari, Giancarlo Rossi and Piercarlo RomagnoniDCA – Dipartimento di Costruzione dell’Architettura,

IUAV – Istituto Universitario di Architettura di Venezia, Venezia Italy

Keywords Solar energy, Ecology, Buildings, Facilities management

Abstract Movable shading devices are often used to control solar radiation falling on large glazedsurfaces in contemporary non-residential buildings. The paper presents some studies on optimalorientation of building in relation to the type of adopted shading devices and their control logic, in caseof adjustable ones. Optimal orientation is the one minimising total annual primary energy demand,including artificial lighting and climatisation, giving the same thermal and luminous comfort. A casestudy, a room of an office building, has been analysed by means of computer simulations. Theexternal wall of the room is entirely glazed. The effects of three different shading elementsconfiguration are compared. The simulations have been performed in three Italian climates (Venice,Rome, Trapani).

1. IntroductionNowadays wide glazed surfaces are used in offices buildings and an importanttask of the designer is to control solar radiation entering the rooms (Baker,1995). External solar shading devices, fixed or adjustable, shall be designedconsidering the latitude and the orientation of building facade.

The orientation of a building fitted by passive solar systems, in temperateclimates, has to maximise winter solar gain. To achieve this goal, mainbuilding axis is oriented east-west, in this way the main internal rooms facingsouth can receive a large solar contribution.

However, if the rooms overlook on the main two sides, and if the energy needsare analysed for the whole year, a more detailed study shall be performed.

Other important factors can affect the design as the thermal mass of thebuilding envelope, as the asymmetrical (referred to the solar noon) trend ofexternal air temperature and of the office occupancy time profile. So it is notobvious that the better orientation can be either E-W or N-S.

This work presents some studies on the optimal building orientation inrelation to the type of shading devices and their control logic, for adjustable ones.The analysis has been performed bymeans of computer simulations.

Optimal orientation is the one that minimises total annual primary energydemand, including artificial lighting and HVAC, giving the same internalluminous and thermal comfort.



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393

In the present study it is assumed that the office occupancy time profile iscontinuous from nine hours to 19 hours, and that the HVAC plant is activatedat eight hours.

2. The data2.1 The office moduleThe case study is a room of an office building with two working places. Theroom’s dimensions are 6m � 5m, 3.3m high. The external wall that is onlarger side is entirely glazed. All the other five surfaces delimiting the room

Figure 1.Plant of a typical floor

Figure 2.Cross-section of the

office module

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are assumed to be adiabatic. Figures 1 and 2 show the building plant for atypical floor and a cross section of an office module, a central corridorconnects the rooms whose windows are placed on the longer sides ofbuilding.The external wall is composed, from the exterior to the interior, as follows:adjustable louvers, double glazing of 0.004m thickness with 0.006m of air gap,and an internal diffusing blind.

The building structure is made up by reinforced concrete. Internal walls arein brick, 0.08m thick, with 0.02m thick plaster on both sides. Floors are built inbrick and reinforced concrete of 0.3m thickness. The assumed value of thermalcapacity per unit area is 136kJ�m-2�K-1 for internal walls, 377 for the floor.

The heating load, comprehensive of heat loss throughout the external walland ventilation rate of 40m3/(hour person), is 200�K-1.

The internal gains include artificial light and the time average value of thesensible thermal fluxes due to two occupants (2 � 60W) and two computers(2� 350W), during the utilisation time.

The HVAC plant is an air-and-water system, designed with primary air andfan coil units.

2.2 Shading elements control logicThree different configurations of solar control devices have been analysed:

(1) no external shading elements;

(2) external fixed louvers 458 tilted;

(3) automatically adjustable louvers with control logic (here called‘‘seasonal’’) that allows at each time the entrance of just the useable solarradiation, in order to minimise the energy needs for climatisation.

In the third configuration we suppose that at each time a computer codecalculates the necessary louvers’ angle and it adapts the louvers’ position bymeans of an electric engine. This code performs an approximated energybalance of the room using as input the measured external air temperature andan equivalent room’s thermal capacity, then it calculates the value of the solargain required to meet internal comfort. If measured solar radiation is higherthan that needed, the program calculates the louvers angle that is required tomake the first equal to the second.

In all the cases an internal diffusing blind can be lowered for spread light, ifnecessary, in order to avoid internal glare phenomena.

To compare energy balance of the same room when only the orientation ischanged, the louvers have been imposed for each orientation (for the northernone also). As consequence there is homogeneity in calculations of view factors(windows-sky) and shadows.


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3. The calculation’s procedure3.1 Energy analysisThe first step is to perform the energy analysis for a single module, then thesame job was performed on a couple of modules with opposite orientation. Theaverage energy demand of the coupled modules gives an indication about thepart of building energy demand that changes with orientation.

As first step, the better orientation of building main axis has been foundamong the following: north-south, east-west, NE-SW, NW-SE and heliothermicaxis (198 displaced from the N-S towards the NE-SW orientation). As a secondstep, slight variations have been explored to find the orientation that minimisestotal energy need.

The analysis has been performed for three Italian climatic zones: north(Venice 45.58N), Middle (Rome 41.88N) and south (Trapani 37.98N).

3.2 The computer codesThe computer codes utilised for the simulations are the following: Ener_lux, Midasand Comfort (Carbonari and Rossi, 2000a, b), see the bloc diagram in Figure 3.

They allow the simulation of the building behaviour concerning thermalbalance, lighting comfort and thermal comfort. Automatic feedbacks onmovable devices for comfort control are also simulated.

The input data are the hourly values of climatic data in monthly typicaldays, the geometric and thermal characteristics of the building.

The first code calculates hourly values of solar gains and daylight levelsinside the room. Simulation of ‘‘seasonal control logic’’ involves calculation ofthe position of the louvers. This is made in two steps. A first, hourly solar gainwith external louvers parallel to sun beams is calculated; as a second step thisactual value is compared with the pre-calculated value of useable solar gain.During the cooling period, this usable solar gain is zero. If the first value ishigher than the second one the program calculates the louvers’ angle requiredto reduce the entering radiation to the needed one.

A second control is performed on the glare level from daylight near the workingpositions. As a first condition the program verifies the absence of direct radiation onvisual task that can cause disability or veiling glare. As the second conditiondaylighting glare index (DGI), concerning discomfort glare, is calculated bymeans ofthe Cornell formula. If one of the two types of glare is out of the acceptable range theprogram simulates the blind’s lowering and repeats the hourly simulation-step.

As a final task the code calculates the level of luminous flux that the lightingplant shall do to reach lighting comfort; the related primary energy needs andthermal fluxes that the lamps give to the indoor air are calculated too.

The second code, Midas, simulates hour by hour the dynamic thermalbehaviour of the room, taking into account solar and internal gains, includingartificial lighting (from the results of Ener_lux). The code output is the primaryenergy need for climatisation and artificial light plant.

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The third code uses values of the indoor air and internal surfacestemperatures to calculate thermal comfort indexes, PMV and PPD, as definedby ISO 7730 and the equivalent EN standard.

If PMV is out of comfort range, the internal set-point temperature is modifiedand the simulation-step is repeated. The user shall manually put into practice

Figure 3.Bloc diagram of thecalculation’s procedure


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this feedback by modifying the input file. Data from the input file are availableto take into account yearly usual clothing variations and metabolic valuerelated to human activity.

4. The resultsResults of the simulations are resumed in the diagrams reported in this section,their analysis supports the following considerations.

With all the control logics here compared, and in all the climates the betterfacade orientation of the single module is the south one. Even if the south-orientedmodule is coupled with a north-oriented one their average energy demand is thelowest with respect to the other orientations. Thus the optimal orientation of thebuildingmain axis results the east-west.

Nevertheless climate and more control logic influence the differences inenergy demand related to different orientations.

4.1 Configuration without external louversThe analysis of this configuration is useful mainly to explain, in differentclimates, the amount of variation of different energy demands: heating, coolingand lighting.

Despite the large glazing areas, heating needs are, in general, not remarkablebecause of the high internal gains in the office rooms. Also in the climate ofVenice daily value of these contributions is double that of the heating plant; thelast being concentrated in the early hours of the morning. Both thesecontributions are very much higher than the solar gain (e.g. Figure 4).

In all the simulated climates the most relevant energy demand is related tocooling. Also in a cold climate such as Venice, variations of heating energy

Figure 4.Venice, office modulefacing south without

external shadingelements, energy

balance of internal airnode in the monthly

typical days of January,February and March.Internal gains due to

people and officeequipment are separatedfrom those due to lamps

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demand with orientation have a low influence on variation of total energy

demand; the last being influenced mainly by cooling and second by lighting.

In Venice energy demand for heating is the half part of cooling needs and it

is comparable with lighting energy needs. Moving toward lower latitudes,

energy demand for heating decreases and the energy request for cooling grows.

For a given orientation the energy needs due to the lighting is almost

constant in different climates.

Comparing different orientations of a single module the following

consideration can be made (e.g. Figures 5 and 6):

Figure 5.Venice, annual; primaryenergy demand of theoffice module fordifferent uses.Orientation is in X-axis

Figure 6.Trapani, annual primaryenergy demand of theoffice module fordifferent uses.Orientation is in X-axis


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. The minimum total energy demand corresponds to the module facingsouth: its advantage is higher in the colder climate (Venice) because ofenergy saving both for heating and for lighting, being their sum higherthan cooling disadvantage. In other climates, where the cooling energydemand is higher, advantage of south-exposure is smaller. At Trapani,total energy demand for north and south exposure becomes almostequal, here heating demand is really small and the lighting demand,bigger north exposure balances the lower cooling demand.

. In all climates the higher energy need corresponds nearly to eastorientation, and this is due to the cooling component that assumes thehighest value. The energy consumption decreases with orientationfollowing this order: west, then north and finally south.

. The heating component too shows two peaks for east and westorientations, but the second one is higher.

An analysis of energy fluxes over hourly profiles has been necessary tounderstand the reasons of this behaviour, that is different from the one of aresidential building (e.g. Figure 7). In the last case the overheating problems arehigher in corresponding west orientation, because of higher values of externalair temperature and solar radiation in the afternoon.

In this way we can observe that the higher cooling load of east orientation isdue to the effect of module thermal capacity and office occupancy time profile.

In warm periods, more or less from April to September, in correspondence ofeast orientation solar radiation heats the internal masses of floor and verticalwalls in the early morning; then these masses heat the internal air during theremaining part of the day. In correspondence of south and west orientation theinternal masses are heated later, then the duration of heat exchange withinternal air is shorter and it occurs also beyond the end of working time.

Figure 7.Venice, heat exchange

between internal air andmasses, comparison

between three modules,facing south, east andwest, in the monthly

typical days of January,April and July

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The effect of this behaviour on annual energy demand is a bigger coolingneed and a smaller heating need in correspondence of east orientation.

Another factor that contributes to a decrease in the energy demand for westorientation is the smaller internal gain due to electric light. In fact the numberof working hours in the afternoon is higher than in the morning and the officefacing west utilises the daylight in a better way, the difference in lightingenergy demand between east and west orientation is nearly to 30 percent.

Analysing average energy need of coupled modules with oppositeorientation differences between east and west orientation are mediated. Themore convenient orientation of building main axes results to be east-west (e.g.Figure 8).

4.2 Configuration with automatically movable louversPrevious simulations show that air conditioning is the more relevant componentof office module energy needs. The seasonal control logic is aimed to minimiseit: the louvers’ tilt angle is controlled to allow in each time the entrance of justthe useable solar radiation. Hourly value of useable solar energy is pre-calculated for each climate and for each building orientation.

In Venice the useable solar energy assumes the maximal value incorrespondence with the south orientation and it is concentrated in themorning. In the cold period the useable energy has the same value for east andwest orientation, but it is concentrated respectively in the morning and in theafternoon. In the less cold periods, because of higher external temperature ofthe afternoon, its value is smaller for west orientation. Later, during the periodfrom November to March, no solar energy is useable.

In Rome, with a warmer climate than Venice, useable energy is alwayshigher for the east than for west orientation; during springtime there is thegreatest difference. In Trapani the difference between east and west orientationis higher than in the other climates.

Figure 8.Venice, annual primaryenergy demand fordifferent uses of a coupleof office modules withopposite orientation.Building main axisorientation is in X-axis


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Analysing the single module, the lowest energy consuming orientationseems to be the south one. But this advantage is due exclusively to the lowerlighting consumption, while energy demand for climatisation is almostconstant with orientation. In fact, if overheating is avoided by means oflouvers, the bigger cooling loads in correspondence of east and west orientationdisappear.

Comparing the behaviour of a south-facing module with a north-facing one inwinter period, we can observe that in the first case, after the first hours of themorning, the louvers’ angle aimed to avoid overheating, is such to interceptcompletely direct radiation and a great part of the diffusion. On the other hand,on the north side the diffused radiation falling on the windows is alwaysmaximised. Thus the daily solar gain in the two cases is similar.

In the coupled modules’ case the variation of their average total energy needas a function of orientation is furthermore reduced, building energy needbecomes practically indifferent to orientation (e.g. Figure 9).

A little benefit of the east-west orientation of the buildingmain axis is present, butsensibly reduced with respect to this one when observed without solar control; onlyin the climate of Trapani is the advantage of this orientation a littlemore evident.

With seasonal control logic the only energy demand that is sensibly variablewith orientation is the lighting one. But when we analyse a couple of moduleswith opposite orientation the average value of it is practically indifferent to theorientation of the building axis.

4.3 Configuration with external louvers 458 tiltedWith this configuration not only the direct radiation, but also a good part of thediffusion are always intercepted, then the energy demand is practicallyconstant with changing of the axis orientation. The asymmetry of office

Figure 9.Venice, seasonal logic,annual primary energydemand for different

uses of a couple of officemodules with opposite

orientation

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working-time (with respect to the solar noon) and the higher external air

temperature during the afternoon can explain the small differences between

symmetrical orientations (i.e. south-east and south-west).

It is interesting to observe that in the warmer climate, Trapani, the north

oriented module, compared with the south-oriented, presents smaller

consumption for heating and a higher consumption for cooling; this is due to

the internal gain from electric light.

Figure 10.Venice, comparison ofdifferent control logics,total annual primaryenergy demand of theoffice module fordifferent orientations

Figure 11.Trapani, comparison ofdifferent control logics,total annual primaryenergy demand of theoffice module fordifferent orientations


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5. ConclusionsThe simulation’s results offer the orientation east-west of the building axis asthe better one in all the compared climates: variations of �118 are not relevantfor the energy needs.The automatic control of the louvers’ tilt angle, with seasonal logic, is, ingeneral, the optimal configuration. It is the more suitable choice in Venice,where heating demand is more relevant and solar energy input is hardlyinfluenced by the louvers’ tilt angle (e.g. Figure 10).

In Rome the benefits of this configuration with regard to the second (fixedlouvers at 458), are lower. In Trapani no relevant differences are foundespecially considering the whole building.

Analysing the single room in the climate of Trapani (e.g. Figure 11) the fixedlouvers are a bit more convenient than seasonal logic for orientation between

Figure 12.Venice, comparison ofdifferent control logics,total annual primaryenergy demand of a

couple of office-modulesfor different building

main axis orientations(on X-axis)

Figure 13.Trapani, comparison ofdifferent control logics,total annual primaryenergy demand of a

couple of office-modulesfor different building

main axis orientations(on X-axis)

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south and east; because both direct and diffuse solar radiation are shielded, andthe energy cooling needs are furthermore reduced.

Absence of external shading devices (no shad.) is in general the worstconfiguration. Looking at a single office module, the only case in which nocontrol by external shading should be preferable (with respect to the other twoconfigurations) is a single module facing north in Venice. Considering thewhole building only in the same climate, and with the building axis east-westorientated, this configuration is more convenient for fixed louvers but lessconvenient for seasonal logic (e.g. Figures 12 and 13).

Both seasonal control and fixed louvers make unappreciable the effect oforientation on the energy needs. This is more evident in the climates of Romeand Trapani, while in Venice there are a small convenience for each buildingaxis orientations situated between the SSW-NNE and NNW-SSE directions.In this work no shadows from surrounding buildings are considered, the urbancontext and the morphology of the geographical site are ignored. An analysis ofthese aspects would require simulation not only of the behaviour of a couple ofoffice modules, but also all the modules present in the building, because theurban shading profile is different for each one.

References

Baker, N. (1995), ‘‘Light and shade: optimizing daylighting design’’, European Directory ofSustainable and Efficient Building, pp. 78-83.

Carbonari, A. and Rossi, G. (2000a), ‘‘A computer method for evaluation of total energy demandin buildings shaded by horizontal blades with automatic control’’, Proceedings of PLEA2000, the 17th International Conference on Passive and Low Energy Architecture,Architecture City Environment, Cambridge, pp. 845-6.

Carbonari, A. and Rossi, G. (2000b), ‘‘Logiche di controllo a comfort costante per laminimizzazione dei consumi energetici globali in tipologie per uffici dotate di elementifrangisole mobili’’, Proc. of 55th ATI Associazione Termotecnica Italiana NationalCongress, Bari Matera.

A new languageof architecture

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pp. 405-419. # MCB UP Limited,0956-6163

DOI 10.1108/09566160210439314

A new language ofarchitecture: in quest for a

sustainable futureArvind Krishan

Center for Architectural Systems Alternatives, New Delhi, India

Keywords Architecture, Ecology, Energy management

Abstract Sustainability and architecture are synonymous terms. While sustainability, physicallyand economically, is to a large extent manifest in the habitat built form, it is the scientific temperthat will lend a design methodology and process, in order to render architecture sustainable. Toachieve this; a ‘‘Energy-resource Flow – Ecological Footprint’’ model is suggested which can helpoptimize input-output parameters and their relationship. Possible formulation of these parametersleading to a sustainability indicator is also suggested. This leads to a process of design and variousactual projects in response to critical issues. Thus suggesting a new language of architecture.

1. PreambleSustainability the ‘‘keyword’’ and ‘‘catchword’’, used by professionals and politiciansalike – an issue that will determine decision making for the next millennium – hasbeen an integral part of lifecycle sincemankind took charge of his destiny. Althoughthen, it did not have the high profile definition – ‘‘sustainability’’ – that it has now.

Human habitat and nature were synonymous – habitat of cold deserts ofLadakh (India), the hot deserts of Jaiselmer (India) and the plains of Hyderabad(Sind) stand as testimony. Yet, today with a technology that can put man on themoon and clone sheep we find ourselves on the verge of a global environmentalcatastrophe.

When the entire planet seems to be hurtling perhaps towards aunsustainable future: architecture – the human habitat, which is the largestconsumer of natural and manmade resources, in my considered opinion, offersa potent tool for moving towards a sustainable future. It more than ever callsfor: a new language for architecture.

2. Present scenario – urban dilemmaCentral to the issue of sustainability at the global scale is the human-habitatcondition that now prevails in large and most populated countries – India andChina, which together make a third of the total world population.

Rising urbanization in India –12 percent in 1940 to 27.52 percent in 1991,increase in urban centers with a total of 218 million urban population mark a shiftin rural population to urban centers. Growth of metropolises from three in 1901 to23 in 1991 is a phenomenon that is changing the urban context at a very fast rate.

Indigenous cities of Indian civilization which bear witness to human historyof many a millennium – Mohenjodaro, Harrapa, Jaiselmer, are home toarchitecture of excellence . . . Yet, the indigenous city in the context of today, isvirtually overwhelmed by a population explosion. Any of the ‘‘modern’’



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developmental/infrastructural solutions prove counterproductive.

3. Emerging scenarioA literal crisis situation in urban areas and an alarming depletion in naturalresources in India prevails: only 44 percent of urban poor have access to potablewater. All metropolises suffer from air pollution due to automobile and industrialemissions. Whereas nearly 54 percent of the land is used for agriculture, which isvery high compared to world average, land use under habitation, on the otherhand, shows a sudden increase from 4.09 percent in 1961 to 6.2 percent in 1981.From a forest cover of over 33 percent only 50 years ago, forest cover as of 1991is 19.44 percent out of which 11.71 percent is dense forest.

The environmental conditions thus prevailing demand a radical shift inplanning and design paradigm.

4. Energy, Resource Flow – Ecological Footprint ModelHuman habitat, a physical manifestation of socio-economic ecological context, is themajor consumer and generator of energy and resource. The Energy-Resource Flowmodel developed and shown in Figure 1, illustrates the input-output relationships.

While air, water, land are the environmental major resource inputs, materials(embodied energy) andfossil fuels (primary energy) are the major naturalresource inputs. Outputs-emissions, are the major source that modify theenvironmental context. This input-output intrinsic relationship determines theecological footprint: the community, city or the region/country – the ultimatedeterminant of sustainability.

Whereas direct intervention in the reduction of environmental and naturalresource inputs can be made by coupling with ‘‘renewable energy’’ systems, wasteprocessing – energy extraction offers re-cycling of energy and resource. Yet, centralto this entire flow model is the habitat/building. It is both in the construction andoperation of this habitat/building that energy-resource flow can be optimised.Outlining the criticality of planning and design of the habitat/building, wherein,climate-responsive architectural design and ecological planning become thedeterminants of energy-resource flow and offer a powerful tool for optimisation.

5. Parameters for energy ‘‘E’’ optimisationIn order to achieve an optimum ecological footprint, various parameters may beoptimized as follows.

5.1 Reduction in energy input

. Through climate responsive design.

. Appropriate technology.

. Optimization of embodied energy through value engineering andlifecycle costing.

This may thus be formulated as:


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Figure 1.Energy-ResourceFlow EcologicalFootprint: model

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. Climate ‘‘C’’ " (systemic strategy of climate responsive design is criticaland is the first level of priority).

. App. tech. and embodied E. ‘‘D’’ " (optimize embodied energy throughvalue engineering and life cycle costing).

. User ‘‘E’’ # (intelligent and participatory use through daylight optimization,active environmental control):; LowE (1) (Climate ‘‘C’’ " + app. tech. and embodiedE. ‘‘D’’ + user ‘‘E’’.

5.2 Lower environmental impact

. Env. imp.$ ‘‘F’’ (optimize land use, maximize landscape integration, re-cycle rain water).

. Tox. ‘‘M’’ # (avoid toxic materials).

. Emi. ‘‘EM’’ # (minimize CFC, CO 2 and other environmentally degradingemissions):; Low E (2) � env. imp.$+ tox. ‘‘M’’ #+ emi. ‘‘EM’’ #.

5.3 Lower waste production

. Low ‘‘W’’ # (use of re-cycled materials, increase ability of elements andmaterials in building to be re-cycled).

. High ‘‘R’’ " (re-cycle waste as alternative material/source for energy,water, etc.):; (Low E (3) � Low ‘‘W’’ #+High ‘‘R’’ ".

5.4 Maximise use of renewable energy

. Sol. ‘‘SE’’ " (maximize use of solar energy through passive (buildingdesign) and active PV integration, and solar thermal means, etc.).

. Ren. energy ‘‘RE’’ (maximize alternative energy sources of energy, i.e. co-generation, wind, mini -hydro, bio-mass, etc.):High E (4) � Sol. ‘‘SE’’ "+ ren. energy ‘‘RE’’ ".

6. Sustainability indicator: Sus ‘‘I’’Above parameters of planning and design can thus be optimized leading to asustainability indicator:

; Sus ‘‘I’’ � low E (1) + low E (2) + low e (3) + high E (4) (renewableenergy systems)

7. Climate responsive architecture – the tool and the processThis leads to defining a process of architectural design that is scientific anddeveloped on an ecological basis.

Process of architectural design is a complex exercise, involving interactiverelationships between parameters of diverse nature and varying magnitude


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(see Figure 2). Yet, it is the prime generator of architecture as we see and

experience.

Various ideas have dominated architectural thought from time to time. Yet, the

fundamental issue of energy as an embodiment of sun, wind and light – the

ecological context – have not been a basic paradigm of design. Therefore

relationship between built-form and ecology should become the driving force

behind the process, based on a scientific methodology – leading to climate

responsive architecture.

The idea of climatically responsive design is to modulate the conditions

such that they are always within or as close as possible to the band

of appropriate design as illustrated in the ecological process of design

(Figure 3).

Figure 2.Graphical representation

of process of design

Figure 3.Ecological process of

design

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Ecological process of designBased on this premise, a design decision making knowledge based expertsystem has been developed by the author (Kirshan, 2001).

8. Some contemporary solutionsOne single parameter that embodies the state and use of natural resources intheir various forms is energy. The author presents some contemporarysolutions that optimize energy use/consumption through architectural design.

Design principles elicited from analysis of indigenous architecture and thescientific process of design have been translated into design of followingmodern buildings at various locations in the country with diverse ecologicalcontext – outline critical architectural responses to key issues.

8.1 How do we build in a high altitude extreme cold-dry ecological context?Sustainable solutions for these projects incorporate the following elements andfeatures achieved through architectural design:

. Architectural design optimizes solar exposure throughout the daily andannual solar cycle.

. Daylight distribution is optimized by three dimensional configuration ofthe building and reflecting it off design elements: light shelves andceiling, providing a uniform and glare-free distribution.

. Embodied energy consumption in building construction is optimized bythe use of local materials and relevant technology of construction.

8.1.1 Hill Council Complex, Leh, India. A major civic structure designed andbuilt as architectural design solutions for this context (see Plates 1 and 2 andFigure 4). Located at 3,514 M above MSL in cold-dry climate with a severe longwinter: October to March end (Min. DBT – 308C).

Plate 1.Bird’s eye view of thecomplex


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Main objectives and features of the design besides elements as sustainable

solutions are:

. The complex has been designed for the severe winter period. Earth

sheltering and earth-berming on the northside and a sunken lobby

reduces northern exposure and stabilizes internal temperatures even in

critical period (see Plates 3 and 4).

. Optimize solar heat gain to office and assembly hall during critical

periods of the year, with adequate penetration of sun. While heat gain is

Plate 2.Section through council

hall

Figure 4.Section

Plate 3.Main approach to

the complex

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optimized, its absorption in the judiciously designed thermal; mass,provides heat in the spaces over the diurnal cycle.

. Glare-free daylight to minimize lighting load thereby consumption ofenergy in the building.

. A new expression of ‘‘Ladakhi’’ architecture by harmonizingindigenous with modern incorporating local materials has beencreated. This helps sustain the artisan and the local art ofconstruction as well.

8.2 What possible architectural responses can be evolved for a composite climateand the context of urbanity of Chandigarh?8.2.1 PEDA Office complex, Chandigarh, India. Located at Chandigarh, on aflat practically square site with no major topographical variations. Chandigarhas a city lies on the planes at the foot of the ‘‘lower Himalayas’’, in a ‘‘compositeclimate context’’ (see Figures 5-7 and Plates 5 and 6).

. With climate swings over the year i.e. very hot and a dry period ofalmost two and a half months (Max. DBT 448C) and a quite cold periodof shorter duration (Min. DBT 38C). The hot dry period is followed by ahot humid monsoon period (Max DBT 388C and Max R.H. 90 percent) ofabout two months with intervening periods of milder climate.

. Equally important for Chandigarh is the context in space and time.Chandigarh, a bold experiment in city planning and architecture, was

Plate 4.Front facade of thecomplex

Figure 5.Sectional perspective


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based on the professed ethos of design: build with climate. Le Corbusierput into practice his theory on ‘‘Brise Soleil’’. While the major buildingsof the Capitol Complex extensively employed ‘‘Brise Soleil’’ in its variousform and applications, many residences designed by Pierre Jeanneret,

Figure 6.Plan

Figure 7.The building integrates

daylight and naturalventilation strategies

through light andventilation wells with

renewal energy systems,i.e. photovoltaic andsolar water heating

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Maxwell Fry and Jane Drew made solar shading devices as a major

element of design and expression. Yet, in its application both the method

and ‘‘device’’ lack a scientific basis. Many times its repetitive use on

buildings irrespective of orientation and the use of similar devices on

different facade belie the claim.

. Can the design of a building be designed based on a scientific process of

design, which responds to the ecological context and yet does not violate

the urbanity of Chandigarh and its urban palette, i.e. the material,

texture and colour? That is the professional challenge unparalleled, to

which we have addressed ourselves.

Plate 5.Southern facadeshowing the Domicalight vaults

Plate 6.PV integrated Roosystem


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. While the three dimensional form of the building has been developed inresponse to solar geometry i.e. minimizing solar heat gain in hot-dryperiod and maximizing it in winters.

. To achieve a climate responsive building an innovative concept inarchitectural design has been developed. In place of the ‘‘central loadedcorridor’’ plan stacked on top of each other to make various floors –which has virtually become the generic form for an office, the PEDAbuilding is a series of overlapping floors at different levels in spacefloating in a large volume of air, with inter penetrating large vertical cut-outs. These cut-outs are integrated with light wells and solar activatednaturally ventilating domical structures.

. Consequently the design is thermally responsive to its climatic contextand very good daylight distribution is achieved, thereby minimizingconsumption of electrical energy.

8.3 What can we do with the existing?There is the equally important issue of existing stock of buildings thatconsume disproportionate amount of natural resources in the form of energy invarious forms. If by ‘‘retrofitting’’ we can render these buildings energyefficient, that will indeed be a great step towards sustainability.

8.3.1 Himurja Building, Shimla, India. This perhaps is a befitting example ofa solution in retrofitting and re-designation of use. A two-storeyed existingbuilding being used for shops and warehouse use was handed over to us to beredesigned as a climate responsive building and converted into offices (seeFigure 8 and Plate 7).

. The building was redesigned as a four-and-a-half storeyed building with ahybrid RCC frame (existing) and steel structure for the additional floors.

Figure 8.Section

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. Optimize solar heat gain to all office during critical periods of the year,with adequate penetration of the sun and protection from mutualshading achieved through architectural design.

. Glare-free daylight to minimize lighting load thereby consumption ofenergy in the building.

. Distribution of heat within the building is achieved through a doubleconvective loop.

8.4 Can we evolve a new language of ecological architecture for an innovative institute?8.4.1 Sardar Swaran Singh – National Institute of Renewable Energy, Ministryof Non-Conventional Energy sources, Government of India. The author wasinvited to participate in limited competition for the project shown in Plate 8. Aninnovative architectural design evolving a language of ecological architecture

Plate 7.The solarium

Plate 8.View of the entirecomplex


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presented by the author was selected by the jury for implementation of the

project. The site plan is shown in Figure 9.

8.4.2 Strategies for planning and design

. Control of micro-climate of the site by generating a water-body drawn of

the canal and by forestation of the site.

. Entire complex and each building designed as a climate responsive –

solar passive building.

. Architectural design: the primary generator/tool for developing a low

energy building design.

. Maximize environmental control through naturally conditioned

laboratories and spaces.

. Maximize use of daylight to minimize electricity consumption in day time.

. Couple evaporative cooling from water-body with building design.

8.4.3 Ecological architectural design of R&D wings. Since sophisticated R&D

work is to be carried out in these wings, it is envisaged that three types of

laboratories will be required:

(1) Naturally conditioned laboratory.

(2) Hybrid.

(3) Environmentally controlled through HVAC systems:

. R&D wing has therefore been designed to couple the naturally

conditioned laboratories and spaces to the water-body through wind

towers coupled with earth-tunnels to the laboratory and building spaces

(see Plate 9).

. Domical light vault designed for adequate daylight distribution

integrated with solar chimney on domical vault coupled to wind towers.

Figure 9.Site plan

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8.4.4 Roof system

(1) Roof forms the critical element of the building design since it attracts themaximum solar heat gain and can be used as an element to generateefficient daylight distribution.

(2) Hyperbolic paraboloid used as the structural element for the roof:

. To optimize on structural design since this is the only doubly-curvedsurface generated by a straight line making it simple to constructand since it generates only direct stresses.

. Double curved surface responds naturally to solar geometry cuttingof solar heat gain due to summer sum and allowing penetration solarheat gain for winters (Figures 10 and 11).

8.4.5 Housing dedign

. Unique courtyard housing design developed as overlapped duplex design.

. All living spaces face the courtyard.

. Courtyard coupled with wind tower for natural conditioning of spaces.

Figure 10.Sectional perspective

Plate 9.View from the waterbody


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8.4.6 Integration of renewable energy systems

. Solar chimneys integrated with building design for natural ventilation.

. Photovoltaic panels sandwiched in translucent panels on the southfacing central spaces for generating electricity and allowing penetration

of diffused daylight.

. Water management system to be coupled with entire building complex

for recycling of water and waste management.

9. Conclusions: a dream for a sustainable future

. As a citizen. I want open and transparent systems of governance, which

allows me to participate in the decisions that affect my life and make use

of my knowledge of the resource base.

. As a consumer. I can demand products and services in the market thatare less polluting and more resource conserving, with fewer chemicals

and more natural materials.

. As a business person. I would like to see policies that allow level playing

fields that give me access to technologies, finance and markets that

enable me to serve the needs of widest possible clientele – but needs as

defined by them.

Figure 11.Typical section through

curved vault

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Environmental Management andHealth, Vol. 13 No. 4, 2002,pp. 420-423. # MCB UP Limited,0956-6163

News from the Net

Handy little utilitiesDesktop tickersIf you spend a large part of the day at your computer, this utility might interestyou. A small piece of software delivers the latest news (including sport, financeand travel) to your desktop, courtesy of the BBC, one of the largest newsorganisations in the world. The software is free and is for several flavours ofMac andWindows. Get it here: http://www.bbc.co.uk/newsline/

Similarly a US company provides an identical service (Windows only) at:http://www.desktopnews.com/

Atomic clockDo not lose track of the time, download a small utility that updates your ownpc’s clock with a central super accurate Atomic clock.

For a pc get it here: www.worldtimeserver.com/atomic-clock/For a Mac: http://download.com.com/3000-2234-896416.html

World populationAn excellent site from the US Census Bureau. There is lots of information here,world population clock, computer software, world population database, etc. Youcan even download a free copy of the international population database on to yourown pc (10mb). The site concentrates on data, always the best place to start a study.

Find the site at: www.census.gov/ipc/www/

United Nations Population FundThis site is more centred on the control of population growth, areas of the site dealwith planned parenthood, HIV control, etc. There aremany reports to be downloadedthat reveal the work and the large volumes of cash being spent in verymany cornersof the world. As youwould expect this is amajor site at www.unfpa.org/

CalsartThis site bills itself as the site for up-to-date information on alternativetransport. The site content is very comprehensive and very US based. If you arelooking for one view of the advanced transportation scene then this site is foryou. Find it at www.calstart.org/calindex3backup.html

Environmental Transport Association (ETA)A British-based organisation that campaigns for a sound and sustainabletransport system. Interestingly this organisation offers a carbon neutralmotoring service, for £2.50 per 1,000 miles of motoring they will plant theequivalent number of trees to make your motoring carbon neutral. Likewise for£40 pa, your house can be carbon neutral, as eight trees will be planted. Theyalso offer a traditional roadside vehicle breakdown service.

Find them at: www.eta.co.uk/

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Freewheelers

This is an idea that could easily be adapted for your own corner of the world. Asite dedicated to car sharing, purely and simply at: www.freewheelers. co.uk/index.php

High efficiency boat hullsI came across this very interesting article published in Scientific American.Written by David Giles it chronicles the developments in hull design needed toincrease the efficiency and speed of boats. Interestingly the modern ‘‘rules’’ ofhull design, which people like David Giles are in the process of breaking, werelaid down by William Froude a British naval architect in the 1800s. Now thatmust be a very special way of being remembered as a scientist 200 years later.Read this article at: www.sciam.com/1097issue/1097giles.html

Sea searchContinuing on a marine theme this site, which is European Union supported, isa gateway to marine and oceanographic data and information. There are detailsfor marine research centres throughout the EU, international links and loads ofinformation on research projects.

A good starting point site at: www.sea-search.net/

IOCThe Intergovernmental Oceanographic Commission (IOC) of UNESCO wasfounded in 1960 to expand our knowledge of the oceans. The IOC is committed tointernational cooperation and exchange in order to improve our capabilities inoceanographic research, systematic ocean observations, technology developmentand transfer, and related education and training. The IOC has a number ofsubsidiary bodies the International Oceanographic Data and InformationExchange being just one. The home page of the IOC is http://ioc.unesco.org/iode/

This organisation also maintains the ocean portal Web site at www.oceanportal.org/ This has a very extensive array of links to resources in thisfield.

Blue AngelA German site, also available in English, this organisation has beenauthenticating eco-friendly products for the last 25 years. There is a newsletter,information on campaigns and events. There is full information on how to getyour own product certified, and last, but not least, an extensive list of links toother GermanWeb sites that carry information in the same field.

If you are German or your German is up to speed this is a very useful site:www.blauer-engel.de/englisch/navigation/body_blauer_engel.htm in English andwww.blauer-engel.de/deutsch/navigation/body_blauer_engel.htm in German.

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Emas eco management and audit schemePart of the European Union this site invites business to take part in anenvironmental management scheme. This is part of Europe’s efforts to becomesustainable.

You can download a toolkit to enable your organisation take part here:www.inem.org/emas-toolkit/

Korean sustainable development networkAvailable in English and Korean, of course, this site gives the browser news,events, as well as the usual fare of bulletin boards. There is advice for localcitizens as well.

A feature of the site is a large library of information for download. Thiscontains many international texts as well as those with a local scope.

The library area alone makes this site well worth a visit, drop off at:www.ksdn.or.kr/index_e.htm

New Zealand Ministry of the EnvironmentA site aimed fairly and squarely at local needs and requirements, which isas good a reason as any to have a site on the Web. Lots of local informationthat allows the casual browser to have a snapshot look at New Zealandissues.

The site is at: www.mfe.govt.nz/

Environment of Planet EarthThere is a tremendous range and depth of educational resources on this site, orlinked to it. There are many graphics including some unusual animated imagesthat could be used as resources, with the authors permission. An outstandingfeature is the many specialist areas covering different environmental issues.Each area offers numerous bullet points that would make good teaching aids aswell as colourful graphics. There are very many links in some of these areas toother student resources.

Aimed probably at fairly young children. If you find yourself needing thissort of resource then this is the site for you.

The site is at: www.eco-pros.com/

EctopiaThis is, primarily, a news site carrying environment news from around theworld. A notable feature is that the news and a respectable set of links are fromthe more unusual corners of the world, Africa and South America featurestrongly. There are links to sister sites in Bolivia, Venezuela and Honduras. Avery good site with lots of links to unusual corners of the world.

It can be found at: www.ecotopia.com/index.asp

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Two phase thermo-syphon water heater technologydevelopmentThis is not something I usually review, a high efficiency domestic hot waterheater, but this site offers a product to make immediate savings for a family.This has got to be a worthy cause.

The site is at: www.ecotopia.com/tpts/

Environmental PeriodicalsThis site consists of lists of environmental periodicals, quite simple and quiteuseful. Each periodical has a hyperlink. I would not like to say how manyperiodicals are linked here, certainly many hundreds. These pages form part ofa larger site that has some very extensive links it is one site I have returned to anumber of times looking for sources of information. An excellent site atwww.deb.uminho.pt/fontes/enviroinfo/publications/atoz-a.htm

Coral Reefs.netGood information and news on coral reefs here, although the site does wanderoff seriously into political campaigning.

The site is at: www.coralreefs.net/

All the links in this article were correct and working at the time of writing.However the Internet is a fast moving place and URLs change, my apologies iflinks are out of date. If any reader has any site they wish to have reviewed, tobe included in future articles, or any comments please feel free to contact me at:[email protected]

Chris Jones

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News

United Nations warn of looming worldwide water crisisThe United Nations issued a report stating that two in three people will facewater shortages by 2025. It reports that more than 2.7 billion people will facesevere water shortages by the year 2025 if the world continues consumingwater at the same rate. The new report says that another 2.5 billion people willlive in areas where it will be difficult to find sufficient fresh water to meet theirneeds. It warns that fierce national competition over water resources hasprompted fears that water issues contain the seeds of violent conflict. Thelooming crisis is being blamed on mismanagement of existing water resources,population growth and changing weather patterns. The areas most at risk fromthe growing water scarcity are in semi-arid regions of sub-Saharan Africa andAsia. But, according to new figures from the UN Economic Commission forEurope, at least 120 million people living in Europe – one in seven of thepopulation – still do not have access to clean water and sanitation. Thecommission is calling for greater effort to be made in the developed world toconserve and protect water resources. The people in sub-Saharan Africa andAsia are most at risk.

The UN body says wasted water is costing Europe around US$10 billion ayear. According to the report, by the International Atomic Energy Agency(IAEA), an estimated 1.1 billion people have no access to safe drinking water,2.5 billion lack proper sanitation and more than five million people die fromwaterborne diseases each year – ten times the number of casualties killed inwars around the globe. Less than 3 percent of the Earth’s water is fresh andmost of it is in the form of polar ice or too deep underground to reach. Theamount of fresh water that is accessible in lakes, rivers and reservoirs is lessthan a quarter of 1 percent of the total. ‘‘Even where supplies are sufficient orplentiful, they are increasingly at risk from pollution and rising demand’’, UNSecretary General Kofi Annan said. There are fears that future competition forwater could spark conflicts. People will be forced from their homes to seekwater. ‘‘Fierce national competition over water resources has prompted fearsthat water issues contain the seeds of violent conflict’’, Mr Annan said.

Water shortage in developing countriesA looming water crisis could threaten one in three people by 2025, sparking asmuch conflict this century as oil did in the last, the UN-sponsored Third WorldWater Forum said in a statement. Governments must urgently find new waysto conserve shrinking water supplies amid rising demand, forum participants –including leading scientists and environmentalists – were told on the openingday of the week-long conference. The statement said about 450 million peoplein 29 countries already suffered from water shortages and that Asia and sub-Saharan Africa – both heavily populated – would face the most severeproblems. The Middle East, India, Pakistan and China would also struggle with

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serious water shortages in coming years unless opposing groups ofenvironmental and agricultural scientists can agree on how to tackle water use,the forum said. ‘‘Water could become the new oil as a major source of conflict’’,Dutch Crown Prince Willem-Alexander, patron of the 1999 World WaterForum, told Reuters in an interview after delivering the opening speech inStockholm. ‘‘Increasing scarcity, competition and arguments over water in thefirst quarter of the twenty-first century will dramatically change the way wevalue and use water and the way we mobilize and manage water resources’’,Willem-Alexander said. Environmentalists are lobbying for a 10 percent cut inwater use to protect rivers, lakes and wetlands on which millions of peopledepend for their livelihoods. Agricultural scientists say farm water use,especially irrigation, should be boosted by 15-20 percent over 25 years to securefood supplies and battle famine. For example, China’s loss of agriculturalproduction due to pollution amounts to about $160 million annually, the forumsaid, adding that it was unlikely traditional agriculture could feed the world’spopulation in 2025. The forum is made up of ten international organizationssuch as the World Health Organisation, the World Wide Fund for Nature(WWF) and the United Nations Environment Program.

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Books and resourcesThe Love of Nature and the End of the World –The UnspokenDimensions of Environmental ConcernShierry Weber NicholsenMIT PressCambridge, MA2001ISBN 0-262-14076-46 � 9, 226 pp.$27.95/£19.95

Virtually everyone values some aspect of the natural world. Yet many peopleare surprisingly unconcerned about environmental issues, treating them as theprovince of special interest groups. Seeking to understand how ourappreciation for the beauty of nature and our indifference to its destruction cancoexist in us, Shierry Weber Nicholsen explores dimensions of our emotionalexperience with the natural world that are so deep and painful that they oftenremain unspoken.

The Love of Nature and the End of the World is a gathering of meditationsand collages. Its evocations of our emotional attachment to the natural worldand the emotional impact of environmental deterioration are meant toencourage individual and collective reflection on a difficult dilemma. Nicholsendraws on work in environmental philosophy and ecopsychology; the writingsof psychoanalytic thinkers such as Wilfred Bion, Donald Meltzer and D.W.Winnicott; and ideas from Buddhist and Sufi traditions. She shows how ouremotional responses to the vulnerabilities of the natural world range fromintense caring and compassion, through grief and outrage, to diffusedepression. Individual chapters focus on silence and the process whereby wemove from the unspoken to the spoken, the love of nature, the ‘‘perceptualreciprocity’’ with the natural world to which we might mature, beauty in thehuman and natural realms, the psychological impact of the destruction of thenatural world, and reflections on the future.

Environmentalism UnboundRobert GottliebMIT PressCambridge, MA2001ISBN 0-262-07210-6408 pp.$32.95/£22.95

In Environmentalism Unbound, Robert Gottlieb proposes a new strategy forsocial and environmental change that involves reframing and linking the

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Conference on Environmental Engineering and Management, 26-28September 2002, Iasi, RomaniaOrganized by the Department of Environmental Engineering, to celebrate adecade of existence of the Environmental Engineering academic profile at theTechnical University of Iasi, Romania. Further information is available athttp://www.fwn.rug.nl/chemshop/iceem2002.html

Conference on Ecolabels and the Greening of the Food Market,Boston, Massachusetts, USA, 7-9 November 2002Papers are invited for a conference on all aspects of ecolabels or foods and otheragricultural products. The term ‘‘ecolabel’’ will be interpreted broadly, meaninglabels such as "certified organic" or any others intended to convey that aproduct is preferable regarding either environmental protection, biodiversityand wildlife, farm animal welfare, social justice, local origin, or any other aspectof ecological and social sustainability.

This conference is a response to the rapidly growing use of ecolabels, which hasraised several questions: How credible are they? How can labels motivated by bonafide environmental concern be distinguished from those that are just a marketingploy? How well do consumers understand what they mean, and how muchconfidence do they have in them? How much of a marketing advantage do theygive, both domestically and in world trade? What are the appropriate roles ofgovernment and private organizations in setting standards and enforcingcompliance?

The conference will provide an opportunity for a broad range of participantsto review this important development in the food market, including standard-setting, certifying, and accreditation bodies; environmental and consumerinterest groups; farmer organizations; the food processing and marketingindustry; agricultural commodity groups; and agencies concerned with foodlabeling and world trade. Further information is available from WillieLockeretz, Friedman School of Nutrition Science and Policy, Tufts University,Medford, MA 02155, USA. E-mail: [email protected]

SAGEEP 2003 Call for PapersThe Symposium on the Application of Geophysics to Environmental andEngineering Problems (SAGEEP) will be held in San Antonio, Texas, 6-10April 2003 at the Omni Hotel. For a full list of session topics and information onhow to submit abstracts for review, access the EEGS Web site (www.eegs.org)and click on the SAGEEP 2003 logo or click on the following link: http://www.eegs.org/PDFfiles/Call%20for%20papers.pdf

environmental management and health volume 13 number 4 2002

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