A function-based cost model for early cost advice on new-build schools projects

Abstract

Establishing a reliable budget estimate based on limited information at the briefing stage of a construction project is a challenge for any client and design team. Unreliable estimates based on ill defined client needs and wants are all too frequent in practice (Newton 1991; Akintoye & Fitzgerald, 2000; Longmaid, 2003; Sonmez, 2004; Elahg et al., 2005 and Aibinu & Pasco, 2008). A review of the literature revealed a lack of accuracy of current cost estimation methods as a consequence of limited design information available at the conceptual stage. The focus of the investigation was newbuild school projects and, though much published design guidance on schools is available, there is little or no specific construction cost estimation guidance. Previous studies have not considered how the richness of information that is available at the briefing stage might inform cost estimates. The main purpose of the study, therefore, was to develop a function-based cost model for application at the briefing stage of school projects to estimate cost prior to the technical design phase. Exploring the current briefing practices and available design guidance breadth of school projects and consulting the various UK council representatives revealed eighty eight design and engineering requirements as the initial basis of the cost model. The model developed uses the identified functional requirements to prepare a cost estimate that does not rely on technical design information. The research approach adopted was a mixed methodology combining qualitative and quantitative data collection. Initially, a qualitative survey of the various UK councils involved in the delivery of new-build school projects was conducted to investigate the current practices of briefing and costing new school projects. A quantitative study was then undertaken to determine the various general design and engineering requirements asked by the school clients. Finally, another quantitative survey was employed to establish the various levels of performances which the existing UK school buildings achieve for the distilled requirements. Regression analysis was used to develop the proposed cost model using all the information which would be available at the briefing stage. The study showed that clearly identifying all client requirements, determined at the briefing stage in predicting the project cost, would enhance the accuracy level of the model. Conversely, neglecting any part of briefing information would reduce the reliability and accuracy of estimates. The function-based cost model was developed and iii validated within the school projects sector. The cost model would estimate the cost of new-build projects accurately relying only on clients’ design and engineering requirements sought at the briefing stage. The cost model provides a decision aid for the client which, if developed and applied, could be used at the briefing and technical design stage of school projects in evaluating the affordability of alternative options.