Developing a fuzzy new -generation whole-life cost model for medium-sized office buildings.

Purpose of this paper The purpose of this paper is to explore the investment appraisal aspects of the new-generation whole-life cost (NWLC) model and develops a fuzzy new-generation whole-life cost model for 25 simulated configurations of a steel-type medium sized office building Design/methodology/approach This work builds on the new-generation whole-life cost model attributed to Ellingham and Fawcett (2006) and replaces the binomially derived probability values by a fuzzy relation matrix using the cosine amplitude formulae. Simulated cost data of a medium-sized office building were computed using the existing whole-life cost techniques. The cost data were then analysed using the Spearman’s rank order correlation coefficient to assess the correlation in the preferences of clients based on each model Findings and value This work reveals a perfect correlation between the standard whole-life cost model and the fuzzy lower new-generation whole-life cost model. Equally, there is a strong correlation between the new-generation whole-life cost model and the fuzzy upper new-generation whole-life cost model. Research limitations/implications This research examined only 25 building configuration permutations and the statistical tests were conducted at a 90% confidence interval level. Equally, the results are consistent for typical steel curtain baseline office buildings in the Philadelphia region of the United States. Practical implications Employing fuzzy set theory in modelling uncertainty in whole-life costing provides a sufficient and robust template for evaluating the cost implications over the estimated life of a building. Originality/value of paper This paper provides a robust technique that can assist decision-makers and facility managers in selecting the effective choice amongst a number of competing building configuration alternatives. This paper develops a new approach using fuzzy set theory for modelling uncertainty in the new-generation whole-life cost mechanism. Conclusions: It is instructive that a single-point whole-life cost estimate might be misleading for construction clients requiring conclusive guidance on the most economical option over the life of their built. Hence the range of whole-life cost values provided by fuzzy set theory is beneficial for construction clients in making more rational decision choices towards selecting an optimal configuration over the estimated life of the building.