a number is worth a thousand pictures - core

A Number is Worth a Thousand PicturesThis paper attempts to focus attention on modelling the functional behaviour of buildings - arelatively neglected topic in the current CAAD literature. It provides a review of the seminal workwhich has been done and argues that further development would provide student architects withthe means of designing buildings which are more fit-for-purpose, energy-efficient,environmentally-friendly and cost-effective.

Key words: function, performance, integrated appraisal, design decision support

Professor T W MaverDepartment of Architecture and Building ScienceUniversity of Strathclyde131 RottenrowGLASGOWG4 ONGUKTel: **44 141 552 4400Fax: **44 141 552 3996Email: [email protected]

1. Introduction

The CAAD community is lucky indeed to be involved in a field ofteaching and learning which is evolving so fast, which contributes somuch to the theory and practice of that most complex and interestinghuman activity - design, and which clearly excites such a high level ofinterest and commitment from our students.

There is much upon which the CAAD community can congratulateitself; each year the proceedings of ECAADE, ACADIA, CAAD Futuresand now CAADRIA expose an increasingly rich diversity ofapplications of the information technologies to architectural education.The purpose of this paper, however, is to highlight the relative paucityof applications which lie at the very centre of design education - i.e. the"cause and effect" of how design decisions impact upon the quality ofthe building.

The proposition, enunciated many times over the last two decades isquite simple:

i) if (student) designers were better able to make explicitand, therefore, understand and communicate theconsequences of their decisions on the cost andperformance of the building, the chances would beenhanced of an outcome which is fit-for-purpose,cost-effective, environmentally-friendly and pleasing toclients and users.

ii) computers can help achieve this.

The main part of this paper is devoted to a summary of a number ofseminal developments which, over two decades, have targeted thisextremely important but relatively neglected area of CAAD. Theintention is to celebrate the achievements, however modest, in thehope of stimulating further development and greater uptake in designstudios throughout the European Schools of Architecture.

A Number is Worth a Thousand Pictures

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2. Seminal Developments

2.1 The Origins

It is interesting to go back some 25 years to two of theearliest contributions, one in Europe and one in the USA.

In the UK, Whitehead and El'Dars [1] programmed analgorithm which sought to generate a single-floor planlayout which minimised the pedestrian travel distancewithin the building. In the USA, Souder et al [2], in one ofthe first uses of computer graphics ~ a cathode ray tubeand "light-pen" ~ developed a system which appraisedhuman-generated hospital plan-layouts in terms of thepedestrian travel efficiency.

Interestingly, these two independent developments bothfocus on the notion of numerical measures ofplanning-efficiency; they differ fundamentally, of course,in approach: one generative, one evaluative.

Not unnaturally, these developments excited someopposition, not least because they sought to optimise alayout on the basis of a single variable, viz travelefficiency: what is optimism from the point-of-view oftravel efficiency might be pessimism from all otherpoints of view.

Nonetheless, both demonstrated the huge potential ofcomputers to assess numerically (and thereforeobjectively), in part at least, the inherent functionality ofcompeting design solutions.

2.2. The Energy Imperative

The so-called "oil-crisis" around 1970 provided a stimulusto software developments which sought to appraisedesign schemes in relation to their energy-efficiency.

Shaviv at the Technion has sustained a highly productiveprogramme of research and development since then,producing applications software for use both in thedesign studio and in practice. Building progressively onearlier work she had by the late 1980s developed anintegrated knowledge-based CAAD system for the designof solar and low energy buildings [3] in which theknowledge base, which contains heuristic rules, inconjunction with a simulation model, guides the (student)designer through the decision-making process.

Milne [4] at UCLA, has also sustained a major effort inthe development of computer-based "design tools" forenergy efficient buildings. He defined a design tool as "apiece of computer software that has an easy--to-useinterface that allows the manipulation of the buildingsthree-dimensional representation and that shows the(student) architect something useful about theperformance of the building". His signal contribution wastwo-fold:



i) integration of both heating and lighting(both natural and artificial) into the energyappraisal.

ii) turning the numerical output from thesimulations into highly informative graphicalrepresentations.

The simulation of the energy behaviour of buildingsthrows up the issue which lies at the heart of allmodelling activities: what is the appropriate trade-offbetween the accuracy of the model and the ease ofaccess to it.

As part of its long term commitment to the developmentand validation of energy models, ABACUS, at theUniversity of Strathclyde, compared the performance ofits own advanced model, ESP, with a simple model beingpromoted at that time by the RIBA. The RIBA modelgenerated results diametrically opposite to thosegenerated by ESP [4]! The CAAD teaching communityfaces the problem that:

i) reasonably accurate models are tooinaccessible to students,

and

ii) reasonably accessible models are tooinaccurate to be useful.

This gap will be closed by improved deployment of IT.

Hopefully, the interest in energy efficient building design,initially stimulated by the oil crisis, will be maintainedunder the imperative of sustainability.

2.3 Integrated Appraisal

As early as 1972 ABACUS attempted to build on thework of Whitehead and El'Dars and Souder by authoringone of the first integrated appraisal systems. The initialprototype (PACE) [5] evolved into the software known asGOAL, the use of which in teaching was reported at the1993 ECAADE conference [6]. The (student) designerproposes a geometry and a choice of constructionmaterials, GOAL accesses a number of databases whichhold information on climate, unit costs of materials, userrequirements, building regulations etc and numericallyappraises each proposed design in terms of constructioncost, annual energy costs, combined costs-in-use,thermal energy consumption, lighting energyconsumption and planning efficiency; additionally thesoftware generates any number of perspective views ofthe geometry. Related software (GLOSS), allows the"fingerprint" - i.e. the main design and performancecharacteristics - of every design hypothesis to berecorded and compared. These fingerprint archivesprovide the benchmark against which each new designcan be compared; the more designs which are



appraised, the more knowledgeable and useful thedatabase becomes.

Although developed and extensively used before theterms were invented, GOAL embodies all thecharacteristics of a "knowledge-based, integrated,case-based design decision support system".Regrettably, it is still embalmed in a medieval hardwareand software platform.

Danahy [7], at the University of Toronto, brought thesame integrated approach to landscape design andcleverly integrated the formal representation of anyscheme with a range of measure of its functionality. Hissoftware is put into the hands of the studio tutor and critstake place "on-line".

2.4 Design Decision Support Systems

Two developments outside the field of architecture havebeen significant in their impact upon CAAD research anddevelopment:

i) the emergence from the computerscience community of advance hardwareand software technologies in the field ofartificial intelligence andtelecommunications.

ii) a significant increase in design-relatedresearch and development across therange of engineering disciplines.

This sub-section of the paper identifies a number ofCAAD projects which draw from these other fields.

At Carnegie Mellon University, Mahdavi [8] hasdeveloped in SEMPER, the notion of an "open"simulation environment in what he calls a"multidirectional" approach to simulation-basedperformance evaluation. A preference-basedformalisation of design intentions/criteria is used to copewith ambiguities through dynamic control of the degreesof freedom of design-related parameters during theinteractive design process. The system, then, has somedegree of generative capability.

Mahdavi's work is contemporary with two otherdevelopments in the USA. Pohl [9] at CaliforniaPolytechnic State University has been developing theICADS system in which it is intended that multipledomain agents interact with each other and with (student)designers to cooperatively solve design problems.Researchers at the Lawrence Berkely Laboratory havebeen developing the Building Design Advisor [10], asoftware environment that seeks to support theintegrated use of multiple analysis and visualisation tools;currently the system supports a daylight analysis tool, anenergy analysis tool and a multimedia case-studiesdatabase.



The European Community gave recognition to this areaof research and development by funding, over the lastfive years, the pan-European COMBINE project [11]which has concentrated on the development of anintegrated data model which facilitates data exchangebetween tools and offers tool-tool interaction supervisionvia a blackboard mechanism.

Current research and development by Chen and Maver[12] at the University of Strathclyde and Georgia Instituteof Technology has yielded a prototype implementation ofwhat they call a Virtual Studio Environment (VSE). Theuniqueness of this work lies in its attempt to combine thestrengths of several other related approaches, namelythe product modelling from traditional integrated designsystems, the distributed architecture based onmessage-passing communications from cooperativedesign systems and the explicit support forhuman-human interaction from computer-supportedco-operative work (CSCW).

The VSE recognises the importance of maintaining acollaborative context as the basis for design toolintegration; this context consists of information not onlyon the design data and design tools but also on thehuman designers. The VSE framework links the technicalresources with the human resources.Collaboration-aware properties have been added intodesign data and tool models. The current implementationsupports three levels of integration; tool-toolinteroperability, automated coordination of toolinteroperation and dedicated human-human interactionfacilities for semi-automated and informal coordination ofthe design project. The VSE is currently populated withtools for energy analysis, lighting analysis and costanalysis.

The intention is to re-implement the VSE on the WWW tofacilitate its evaluation by interested parties.

3. Numbers and Pictures

This paper was provocatively entitled A Number is Worth aThousand Pictures to try to focus attention on a topic which isrelatively neglected in the current CAAD literature: the modelling of thefunctional behaviour as opposed to the formal character. Theintention of the paper has been to highlight the importance ofmodelling and predicting as many aspects of the cost and performanceof buildings as possible particularly at the early formative stage of thedesign decision-making. The experience of using the GOAL softwarein the Department of Architecture and Building Science providesevidence that when students have the facility to predict thecost/performance profile of their building, they produce buildings whichare substantively better in terms of fitness-for-purpose, energyefficiency and cost-effectiveness; additionally, the more a student usesthe model, the greater is her/his generic understanding of how her/hisdesign decisions (the "cause") impact upon cost and performance (the



"effect").

Section 2 of the paper summarises some only of the attempts whichhave been made to build software systems to facilitate the functionalappraisal of design schemes. Not all of the attempts have resulted insystems useful for teaching and learning; of those which are, there islamentably little evidence of the experiences of using them in thestudio. The little evidence there is however [6] is compelling in itspedagogical merit and a stimulus, it is suggested, for moredevelopment work in the aspect of CAAD.

In truth we need more numbers and more pictures if our students areto develop their design skills in the service of a built environment inwhich form and function are in harmonious balance.

4. References

1 The Planning of Single Storey LayoutsWhitehead, B and El'Dars, MZBuilding Science, 1, 127, 1965

2. Planning for Hospitals: a Systems Approach Using Computer AidedTechniquesSouder, J J et alAmerican Hospitals Association, Chicago

3. An Integrated KB-CAAD System for the Design of Solar and LowEnergy BuildingsShaviv, E and Peleg, UCAAD Futures 91 (Ed. Schmitt, G), Vieweg, 1991

4. Deemed to Satisfy?Valtos and ABACUSArchitects Journal, 24 October 1979

5. PACE: An Interactive Package for Building Design AppraisalMaver, TWProceedings of On-Line '72, Brunel, 1972

6. CAD in the Design StudioPetric, J and Maver, TWProceedings of ECAADE 93Technical University of Eindhoven, 1993

7. Irises in the Landscape: An Experiment in Dynamic Interaction andTeaching Design StudioDanahy, JThe Electronic Design Studio (Ed McCullough et al)MIT Press, 1990

8. Computational Support for Performance Based Reasoning inBuilding DesignMahdavi, ADesign Computation: Collaboration, Reasoning, Pedagogy (EdMcIntosh, P and Ozel, F)ACADIA, 1996



9. A Distributed Cooperative Model for Architectural DesignPohl, J and Myers, LAutomation in Construction, 3, 2/3, 1994

10. The Building Design AdvisorPapamichael, K et alDesign Computation: Collaboration,Reasoning, Pedagogy (EdMcIntosh, P and Ozel, F)ACADIA, 1996

11. The Combine Project: A Global AssessmentAugenbroe, G' Modelling of Buildings Through Their Life Cycle (Ed Fisher, MA et al)CIB Publication No 180, 1995

12. The Design and Implementation of a Virtual Studio EnvironmentChen, YZ and Maver TWProceedings of 2nd East-West Conference on IT in Design, Moscow,1996

Figure 1. Variability in the prediction of energy consumption from a number of energy models. [4].



Figure 2. Output from the SEMPER system. [8].



Figure 3. Part of the output from the BDA system. [10].



Figure 4. A frame from the multimedia section of the BDA system. [10].



Figure 5. Representative output from the Virtual Studio environment. [12].



a number is worth a thousand pictures - core

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