The Singapore buildable design appraisal system: A preliminary review of the relationship between buildability, site productivity and cost

This paper presents preliminary findings of a study to examine the relationship between site productivity, construction costs and the 'buildable score' of a buildable design appraisal system recently developed by the Singapore Construction Industry Development Board. The buildable score for a building is a numerical figure computed by taking into account the level of standardization, simplicity and extent of integrated elements used in the design of a building. The stated objective of the appraisal system is 'to promote more buildable designs in the industry through assessing the contribution of design to site efficiency and productivity'. Empirical results from 37 completed building projects provide support for the appraisal system's proposition that 'a design with a higher buildable score will result in more efficient labour usage in construction and therefore higher site labour productivity'. However, the relationship between construction costs and buildable score is less distinct.