A Practical Approach for Cost/Benefit Analysis of Early Design Decisions: Application to Architectural Daylighting

Abstract

Although several methods exist for performing cost/benefit analysis in architecture, mechanical and civil engineering, etc., the use of these methods in early design phases remains limited. Realizing the importance of the decisions made early in the design process and their effect on cost performance, several research efforts have developed tools and aids to help design professionals perform early cost/benefit analyses. Examples include rules of thumb, simplified formulae, algorithms, spreadsheets and nomographs. Nomographs have been developed to help in cost/benefit analyses for various applications such as generic time-value of money analysis, mechanical equipment sizing, engineering, architectural design, etc. This paper compares and discusses the use of nomographs in relation to specialized spreadsheets as tools for practical cost/benefit analysis. The paper suggests that spreadsheets in general offer a more effective and robust analysis tool when it comes to cost/benefit analysis in the built environment fields, especially for decisions in the early stages of design. The superiority of spreadsheets to nomographs is demonstrated through a practical cost/benefit analysis application to architectural daylighting design decisions. The spreadsheet method has several advantages over the nomograph method, which are explored through an actual case study of daylight cost/benefit analysis for the Kuwait Autism Center. The comparisons can be generalized for several disciplines and domains in other parts of the world.