Title: A concept for developing construction element cost models for German residential building projects

Authors: Christian Stoy; Spiro Pollalis; Onur Dursun

Addresses: Institute for Construction Economics, University of Stuttgart, Keplerstrasse 11, 70174 Stuttgart, Germany. ' Graduate School of Design (GSD), Harvard University, 48 Quincy Street, Cambridge, MA 02138, USA. ' Institute for Construction Economics, University of Stuttgart, Keplerstrasse 11, 70174 Stuttgart, Germany

Abstract: Early cost estimate of construction projects plays a vital role hence it forms a foundation for budgeting, planning, monitoring and even for litigation aims. In German practice, the first stage cost estimation is performed at the pre-design stage where no design details exist. Thus, the practical relevance of any model to be developed that requires further design information, would be questionable. The German norms describe construction cost elements as the subcategories for cost of construction works. Therefore, the accuracy of the first stage estimate can be improved by modelling construction cost elements where more detailed information incorporates. In this context, it is aimed to demonstrate the development of a predictive model for the most relevant cost element: external walls. Historical data was randomly sampled from Building Cost Information Centre (Baukosteninformationszentrum) database. The most significant predictors for cost of external walls were determined by backwards regression method. Multiple linear regression methodology is employed for the final parameter estimation. The results reveal that substantial variation in the cost of external walls can be explained by the proposed model which leads to high prediction accuracy. The development of the model is anticipated to influence further studies that address cost modelling in Germany.

Keywords: cost estimation; residential buildings; multiple linear regression; MLR; Germany; construction projects; cost modelling; construction cost elements; external walls.

DOI: 10.1504/IJPOM.2012.045363

International Journal of Project Organisation and Management, 2012 Vol.4 No.1, pp.38 - 53

Accepted: 05 Oct 2010
Published online: 16 Aug 2014 *

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