The purpose of the evaluative model is to explore ordescribe something such as properties or experiencesthat are not manifest in the model itself but are relatedto it. The evaluative model differs from predictive andexplorative types since with these last-mentioned it isthe model itself that attempts to assist the understandingof reality or a particular phenomenon. By contrast, theevaluative model seeks to assist such understanding byits use, and to do this it relies upon information andactions external to it. Not to be confused with predictivemodels, which produce quantitative data, evaluativemodels are intended to provide data of a qualitativenature, i.e. those properties whose variable effects can beperceived rather than measured. As a result, an evaluativemodel is typically – but not exclusively – used duringthe later stages of the overall design process, when manyof the design variables have been determined. Using anarchitectural model for evaluative purposes is certainlynot a new idea. The use of full-scale evaluative modelsfor experiencing architectural components in situ is welldocumented throughout architectural history. It wasparticularly prominent in the Age of Enlightenment,when maquette makers held some superiority overpractitioners of the more traditional technique ofperspective drawing. The degree to which such modelsare detailed obviously depends upon the information tobe evaluated, but the potential of representing all spatial,visual and tactile qualities at a level almost equal to that of reality is naturally highly valuable. This applicationof models clearly has beneﬁcial opportunities for thearchitect who wishes to articulate space and develop adesign following the reaction of its intended users.
There is, of course, some overlap between thesevarious model applications, depending on who is usingthem and why. This allows a transformation in the modeltype as a result of an exchange of intention, i.e. theevaluative model may also become a predictive modelbecause it not only provides qualitative information butalso data of a quantitative nature. This is particularlyevident in the case of detailed and full-size mock-ups ofbuilding components and construction samples, sincethe form, materials and assembly have been determinedand the model can now be used to predict structuralbehaviour – information that has to be measured ratherthan simply perceived – as well as evaluate it. Therefore,rather than explore or describe, for evaluative purposes,something that isn’t manifest in the model itself but isrelated to it the model is now used to communicate theway reality is or could become, using the behaviour ofthe model itself.
Evaluative models can play an important role in thedesign development process. The complexity of a projectsuch as the Walt Disney Concert Hall, Los Angeles, byGehry Partners, LLP, demonstrates a fascinating journeyof a design process paralleled by modelmaking. Fromthe initial design in 1987, via the beginning of theconstruction phase in 1999, to the building’s completionin 2003, various types of models were made to examinedifferent design options (see page 96). A number ofdesign ideas evolved during the project’s developmentincluding the foyer size, consideration and subsequentelimination of a chamber hall and hotel, and perhapsmost notably the Hall’s shape. Achieving the acousticperformance of such a prestigious venue and integratingthis with innovative formal ideas required detail modelsto be made as shown here in this 1:10 model.