The architectural design business is marked by a progressive increase in operators all cooperating towards the realization of building structures and complex infrastructures (Jenckes, 1997). This type of design implies the simulta-neous activity of specialists in different fields, often working a considerable dis-tance apart, on increasingly distributed design studies. Collaborative Architectural Design comprises a vast field of studies that em-braces also these sectors and problems. To mention but a few: communication among operators in the building and design sector; design process system logic architecture; conceptual structure of the building organism; building component representation; conflict identification and management; sharing of knowledge; and also, user interface; global evaluation of solutions adopted; IT definition of objects; inter-object communication (in the IT sense). The point of view of the research is that of the designers of the architectural arte-fact (Simon, 1996); its focus consists of the relations among the various design operators and among the latter and the information exchanged: the Building Objects. Its primary research goal is thus the conceptual structure of the building organ-ism for the purpose of managing conflicts and developing possible methods of resolving them

Carrara, Gianfranco

Fioravanti, Antonio

Novembri, Gabriele

English

CARRARA, Gianfranco

FIORAVANTI, Antonio

NOVEMBRI, Gabriele

Archivio della ricerca- Università di Roma La Sapienza

Architectural Information Management – 04 Collaborative Design80Knowledge-based System to Support ArchitecturalDesignIntelligent objects, project net-constraints, collaborativeworkCARRARA, Gianfranco; FIORAVANTI, Antonio; NOVEMBRI, GabrieleDpt. Architettura e Urbanistica Università degli Studi di Roma “La Sapienza”http://www.dau.uniroma1.it antonio.fioravanti@uniroma1.itThe architectural design business is marked by a progressive increase in operators allcooperating towards the realization of building structures and complex infrastructures(Jenckes, 1997). This type of design implies the simultaneous activity of specialists indifferent fields, often working a considerable distance apart, on increasingly distributeddesign studies.Collaborative Architectural Design comprises a vast field of studies that embraces alsothese sectors and problems. To mention but a few: communication among operators in thebuilding and design sector; design process system logic architecture; conceptual structureof the building organism; building component representation; conflict identification andmanagement; sharing of knowledge; and also, user interface; global evaluation of solutionsadopted; IT definition of objects; inter-object communication (in the IT sense).The point of view of the research is that of the designers of the architectural artefact(Simon, 1996); its focus consists of the relations among the various design operators andamong the latter and the information exchanged: the Building Objects.Its primary research goal is thus the conceptual structure of the building organism for thepurpose of managing conflicts and developing possible methods of resolving them.Keywords. Collaborative Design; Architectural and Building Knowledge; DistributedKnowledge Bases; Information Management; Multidisciplinarity.Scientific basesAt the beginning of the new millennium, designcompanies, especially architectural designcompanies, are characterised by a new advancedworking method, Collaborative Design (Howard, 1997;Kvan, 2001), by which is meant a design processcharacterised by a continuous exchange of designinformation among all the operators involved, evenacross the customary interdisciplinary borders, andby asynchronous and/or concurrent working methods.Two paradigmsIn this field of investigation, two different schools ofthought have emerged over time: the first , definedas the Conventional Method, is to provide a low-levelshared data exchange platform enhanced by specificapplications for each discipline (Gero, ;Björk, 1992);the second, calledas Collaborative Design, is basedon a semantically rich Common Knowledge Baseupon which the various professional profiles may draw,Fig. 1.Architectural Information Management – 04 Collaborative Design 81The following research may be included in thefirst paradigm:STEP - The main aim is stated in the name -STandard for Exchange Product data model. Its firstand second implementation in the building sector,although attaining draft status, have never becomean ISO standards.COMBINE - COmputer Models for the BuildingIndustry in Europe. Although based on the STEP-EXPRESS to transfer the conceptual schema (object,type, definition) and the “neutral files” STEP to transferobject instances, it is a prototype specialized inevaluating energy and HVAC performance (Amor etal., 1995; and 1998) (fig 1 & 2).OXSYS - Software commissioned by the Oxfordregional health authorities, it was conceived as anaid in the integrated design of hospitals using apredefined “kit of parts”, namely the Oxford system.ICADS - A system based on a very small numberof architectural objects (seven) which develops a setof controls according to the blackboard paradigm anda set of rule-based expert systems in the design of abuilding (Pohl and Myers, 1994).The following systems may be considered asbelonging to the second paradigm:KAAD - Strongly design aid oriented (Galle, 1995).Its strengths: semantic richness, the large number ofbuilding components used, multiple inheritance, beingopen and scalable. Composed entirely of objects, alsoits graphic representation is additive. Allowsconstraints to be activated and de-activated, and newones created. It does not determine a single top-downor bottom-up design flow (Carrara, Kalay, andNovembri, 1994).EDM - Developed to represent a building havingdifferent levels of abstraction, building technologiesand projected uses. These aspects are representedby the objects BOUNDED_SPACE,CONSTRUCTED_FORM and ACTIVITY, respectively.It too is open and scalable. One of its drawbacks isthe separation of the representation of the buildingfrom its geometry.BDA - Building Design Advisor. Comprisesdifferent integrated performance evaluationapplications (such as DOE-2, Superlite, etc.). It has aunified and known interface, supplies a representationof shared data and envisages format exchange tools.It acts as a repository for the values produced by thedifferent applications (Papamichael et al., 1996).The first paradigm encounters the serious problemof the impossibility of modifying or increasing theapplications, which are fixed like the shared dataplatforms at a low semantic level. They are often toogeneric. On the other hand, they are more practicalto use and easier to implement.The second runs up against the complexity implicitin the large number of complex object relations, andis characterized by a rough and ready implementationof objects and semantically rich relations.Figure 1 (left). Twoparadigms of CollaborativeDesign.Figure 2 (right). The structureof representation.Architectural Information Management – 04 Collaborative Design82These two paradigms are closely linked with thealgorithmic and IT problems involved in CollaborativeDesign. These include building constraintmanagement, the automated or semi-automatedsolution of inconsistencies, as well as the complexorganization of the system to allow the exchange andmerging of contributions from all Collaborative Designparticipants.All these aspects are only partially resolved bycommercial packages and applications deriving fromindustrial initiatives, such as that of the Bentley Systemfor the IFC.Ongoing researchWith regard to that previously explained, the researchis placed in the second paradigm of CollaborativeDesign.The Aim of the research is to develop instrumentsfor a Collaborative Design through the managementof knowledge. The knowledge which has been takeninto consideration is that pertaining to the preliminaryphase of building and architectural design, when thesimultaneous collaboration of various professionalsis most obvious and crucial.We think that developing the component basedon the designer’s knowledge so as it is able to takeinto account the constraints and the consequencesof each design decision, show up the inconsistenciesand possibly suggest alternative solutions.The structure of the software system model, whichcomplies with the customary effective designprocesses, will consist of a set of systems themselvesconsisting of: Knowledge Bases, Data Bases, bothgraphics and network programs, an inferential engine,and Structures of Relations.The latter consist of semantic and/or operatingrelations among the elements comprising a BuildingObject, with regard to a given physical phenomenonand/or a design object. The Structures of Relationsare not necessarily systems external to the KBs. Forexample, the goal of achieving a correct coupling ofobjects is contained in the objects themselves whichknow which surroundings are desirable or denied oracceptable (fig 3 & 4).Figure 3 (left). KnowledgeBases and the BuildingObject.Figure 4 (right). Relationsamong prototypes andinstances for a typical wall.Architectural Information Management – 04 Collaborative Design 83The case of energy saving is different. This goaltakes into account the entire Building Object andconfigures the Structures of Relations as a softwareSystem in its own right.The Knowledge Base is constituted by:• Common Knowledge Base of all participants(CKB);• Specialist Knowledge Base, peculiar to eachparticipant (SKB);• Project Knowledge Base of the single project(PKB).The three levels of the Knowledge Base are additive,Fig. 3.Perspectives allow each operator to see only therelevant information in a building being designed ((the instance created from the Knowledge Bases).The PKB was set up in addition to the conventionalrepresentation of objects in a Building Body as it wasnecessary for design purposes,. In fact, the need tocreate a new building component may arise. Forexample, in certain climactic conditions, there maybe the need to define a new type of external wall,which cannot be derived from those of the CKB orfrom the SKB. It is useful to create this new wallbecause it will be in much demand during thatparticular project, although it does not necessarily goso far as to increase the other Knowledge Bases.Even though it has been created from zero, it willbe part of the KB’s in order to take advantage ofinheritance, geometric representation, constraintchecks, the spatial congruence relations, interrelationswith the other building components in the project aswell as verifying their performances.The same may occur when introducing newconstraints. For example in health institutions for theaged, it is better if the bedroom is at least twentymetres from the lift; or in an art gallery it is better if thelighting is over a certain lux level.The structure of representation ofthe Building ObjectEach project has its own ADB (Assembly Data Base)that goes alongside the KB (given by CKB + SKB +PKB), since the two components are different: the PKBallows for a dynamic verification of the performanceand constraints activated at the moment data isinserted or the creation of a new instance (Fig. 4) (bothas a building component and as a constraint check);whereas the ADB allows for a rapid gathering of stateddata, as the net surface of a floor to instant data aboutthe project process (without utilizing the inheritanceas its control) including the geometric data of theBuilding Object, allowing the spatial congruence ofthe objects comprising the B. O. to be verified.The CKB that both the SKB and the PKB conformto, has the following structure: two independentsystems, the Space System and the TechnologicalSystem bound by “ Structures of Relations” (Carrara,Fioravanti and Novembri, 2000).The Space System is the structured set ofequivalent classes to the space needed to carry out aspecific activity. It is made up of two Domains:Environmental and Elementary Space. The firstconsists of spaces mainly contained by physicalelements like its BUs and SUs (Building Units andSpace Units) components; the second is made up ofspaces that are not surrounded by physical elementslike its ESs and PEs (Elementary Spaces and PartitionElements).In the same way the Technological System orphysical elements system is sub-divided into twoDomains: Constructive and Row Materials. The formeris made up of constructive building componentscapable of carrying out one or more functionswhichgive a certain performance through its FSS andFE (Functional Sub-Systems and FunctionalElements); the second is made up of materials thathave only properties: the BE and RM (Base ElementsRaw and Materials).The division of the two Systems into two Domainsis arbitrary for certain versos but functional for thesciences involved. The Domains of the ElementarySpace and Row Materials have a lattice structure. TheEnvironmental and Technology Domains have a semi-lattice structure since in the KB and in their constituentelements only “whole” (also known as IMS, ImmediateSuccessor) unidirectional relations are present.Architectural Information Management – 04 Collaborative Design84This is how each element of the KB is able tohave more than one “father element” and thus permitsthe multiple inheritance to be obtained. Thus with onlya few simple elements many complex componentscan be obtained.The challenge of the research is thus focused onthe capacity to transfer knowledge to the objects, sothat they acquire “intelligent” behaviour and become“active” design elements.The “intelligence” of the objects comprising theSpatial System, the Technological System and theStructure of Relations lie in the possibility of:• having a semantics, knowing what they arethrough a definition thereof, through thehierarchical structures to which they belong;• providing explanations, not only on their state butalso on their behaviour;• possess rules of behaviour towards other objects,constraints, goals;• having a coherent and accurate representationof the context, meaning by this the design phaseand the applicational environment in which it isinstanced;• knowing its own positioning versus a referencesystem and also other objects (at any moment itis possible to verify the dimension constraints);• being multi-hierarchical so that it can be orderedaccording to different criteria using ConceptualClustering techniques (not only through propertiesexplicitly defined in the object);• varying its own IT structure to relate to objectshaving a different structure in other applications(polymorphism).Above all, however, all these characteristics must bedynamic.Conflicts and design objectives.The capacity to provide explanations concerningseveral project or physical constraints is essential inorder to resolve conflicts rapidly.The resolution of conflicts as quickly as possibleis a considerable advantage in improving the designprocess both temporally and costwise. Whenever aconflict is not identified in time and the design activitiesare continued in the meantime, the construction ofthe building object may be impaired by unsatisfactorysolutions.Not only, but also the capacity to provideexplanations about a constraint not respected byanother professional (or disciplinary sector) is apowerful aid in asynchronous design.The Structure of Relations Filter has the task ofcorrelating the representation of an element used inthe ADB with another representation of the sameelement used in a different application. This occursby transforming the structure of the IT representationof the component. Another application of theperspective is when we wish to regroup severalcomponents on the basis of “conceptual clustering”methods (Carrara et al.., 1995).Implementation of the system modelfor Collaborative Design andconclusionsIn the past our Research group has developed asupport system for architectural design within only oneworking group, and thus with a single KB (Carrara,Kalay, Novembri, 1994), by using a frame languagein LISP.It has been used even recently by Kalay (1998),thanks to its effective four-tier hierarchical structure:frame, slot, facet and value,.Everything described in the preceding chapters(our choice of the multi-Perspective Vs the multi-Modalrepresentation, the fact that the operators of the designprocess vary in time and that all the skills are notknown a priori) we must use computerizedrepresentation structures that are as flexible aspossible.From another viewpoint, with the experienceacquired during the development of ad hoc softwareproduced in-house at great cost in terms of resources,also therefore for basic software (e.g. for multipleinheritance, the creation of instances, to change thedirect superclasses), it is preferable to adopt thestandard ANSI structures of information technologyrepresentation.Architectural Information Management – 04 Collaborative Design 85The choice thus fell on CLOS as, in agreementwith the findings of authoritative researchers (Zangand Norman, 1994; and several researchers atPARC), its use in the case of distributed KBs wasconsidered more appropriate.However, CLOS with its fixed three-level structure- frame, slot, facet -, seems to be more constrainingthat the pure four-level frame structure.To get round this it was decided to transform alsothe slots and facets into objects, Intelligent Links(ILNK) which, depending on the validation providedin a given disciplinary area, project phase, SWapplication context, project manager and objectcreator, allow the object structure to be varied.In this way we free ourselves from the “ frameproblem” due to a purely encodigism approach(Bickhard and Terween, 1995). The frame problemarises when too many objects are needed to fullydescribe a complex set or “word”.The development of this approach seems topromise well despite the large number of relationsamong objects (a reflection of the complexity of thedesign process): although it has to be performedmanually, it is an exciting task.ReferencesAmor, R., Augenbroe G., Hosking F., RomboutsW.and Grundy J.: 1995, Directions in modellingEnvironments, Automation in Construction, 4(3),pp. 173-187.Amor, R.: 1998, A Survey and Analysis of IntegratedProject Databases, CIB-W78, Sweden.Bickhard, M.H., Terween, L.: 1995, FoundationalIssues in Artificial Intelligence and CognitiveScience, Elsevier Science Publishers B.V.,Amsterdam, NL.Björk, B.C.: 1992, A unified approach for modellingconstruction information, Building andEnvironments, 27, pp. 173-194.Carrara, G., Confessore, G., Fioravanti, A.,Novembri, G.: 1995, Multimedia andknowledge-based Computer-aided ArchitecturalDesign, B. Colajanni and G. Pellitteri (Eds.),Multimedia and Architectural Disciplines,Proceedings of eCAADe 1995, pp. 323-330,ISBN/ISSN: 0-9623687-1-4.Carrara, G., Fioravanti, A., and Novembri, G.: 2000,A framework for an Architectural CollaborativeDesign, Promise and Reality, Proceedings ofeCAADe 2000 18th Conference, Dessau.Carrara G., Kalay, Y.E., and Novembri, G.: 1994,Knowledge-Based Computational Support forArchitectural Design, G. Carrara and Y.E. Kalay(eds.), Knowledge-Based Computer-AidedArchitectural Design, Elsevier SciencePublishers B.V., Amsterdam, NL.Eastman C.M., and Siabiris, A.: 1995, A GenericBuilding Product Model incorporating BuildingType Information, Automation in Construction,3(4), pp. 283-304Galle P.: 1995, Towards Integrated, ‘Intelligent’, andCompliant Computer Modeling of Buildings,Automation in Construction 4(3), 189-211.Jenckes, C.: 1997, Nonlinear Architecture. New-science= new architecture?, ArchitecturalDesign 67(9/10), pp. 6-9; 14-31.Howard, R. (guest ed.): 1997, Automation inConstruction, Special Issue Building IT 2005,6(1) pp. 1-68.Kalay, Y.E, Séquim, C.F.: 1998, A suite of prototypeCAD tools to support early phases ofarchitectural design, Automation inConstruction, 7, pp. 449-464.Kvan T. (guest ed.): 2001, Automation inConstruction, Special Issue CAADRIA, 10(3)pp. 293-382.Papamichael K., La Porta, J., Chauvet, H., Collins,D., Trzcinski, T., Thorpe, J., and Selkowitz, S.:1996, The Building Design Advisor, ACADIA ’96Conference proceedings, Tucson, Arizona.Pohl, J., Myers, L.: 1994, A Distributed CooperativeModel for Architectural Design, in G. Carrara &Y.E. Kalay, (eds.), Knowledge-Based ComputerAided Architectural Design,  Elsivier SciencePublishers, Amsterdam, The Netherlands.Simon, H.A.: 1996, The Sciences of the Artificial,MIT Press, Cambridge, MA, USA.Zhang, F., Norman D.A.: 1994, Representations inDistributed Cognitive Tasks, Cognitive Science,18, pp. 87-122.

Knowledge-based System to Support Architectural Design. Intelligent objects, project net-constraints, collaborative work

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Knowledge-based System to Support Architectural Design. Intelligent objects, project net-constraints, collaborative work

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