On Measuring Project Performance: Some Problems of Aggregation

Abstract

Performance evaluation of buildings--by means of postconstruction evaluation--has traditionally focused on the performance measurement of building subsystems. This approach, based on the horizontal view of the building process, suffers from two important shortcomings. First, its underlying assumption that a completed building's performance can be arrived at simply by aggregating the individual performances of its parts is not valid. Like most complex systems, a completed building is much more than the sum of its parts. Second, the focus of traditional appraisal on subsystems, with its feedback information on individual products and services, actively encourages suboptimization of tasks. It is a condition that is contrary to the requirements imposed by the multiorganizational nature of the building team, and the resulting interdependence of tasks, where useful feedback information is that which relates to the project as a whole. To overcome these shortcomings of the traditional building appraisal model, an alternative model based on the vertical view of the building process is propose