Modelling levels of accuracy in design cost estimation

The use of fee competition by construction industry clients has increased the need for design consultants to predict more accurately the cost of their professional services. There is evidence of concern among clients that fee reductions resulting from fee competition have been accompanied in many cases by a reduction in the level of services provided by consultants. However, there is little published work on design cost estimation methods and their accuracy. This paper describes a recently completed programme of research in design cost estimation practice in the United Kingdom. An overview of design cost estimation practice is presented and the development and operation of a model which simulates the design cost estimation process is described. The paper explains and presents the results of a data collection strategy that was adopted to provide input for the model and conclusions are drawn on the validity of the model when compared to the indicative levels of accuracy in design cost estimation suggested in the literature. Finally, recommendations are given for future research work that should lead to a usable cost estimation tool for design consultants.