Preserving continuity in whole-life cost models for net-zero carbon buildings

Investment in net-zero carbon buildings requires comprehensive evaluation especially with regards to economic viability. Mathematical modelling of whole-life costing provides a relevant framework to assess the investment potential of net-zero carbon buildings. Previous studies in investment analysis have suggested insufficiency in the discounting mechanism of cash flows leading to unrealistic estimation, and in some instances, incorrect decisions. There is a growing body of evidence that conceptual adjustments to cost models could facilitate improvements in the costing of zero carbon buildings. This study, - which is part of a PhD investigation on cost studies in zero carbon buildings, presents an approach to preserving continuity in whole-life cost models using the binomial theorem. The work builds on the New Generation whole-life costing developed in Ellingham and Fawcett (2006) by extending the period under consideration and concurrently providing for other elements of time, uncertainty and irrevocability. The study also highlights the conceptual importance of continuity in decision-models. An illustrative costing exercise is carried out, over a 25-year period, on a conventional and net-zero carbon building using three different whole-life cost procedures. Results from the study suggest that continuous whole-life cost models provide a realistic template for representing cost variables especially in comparative studies. Future research will examine the implications of continuous whole-life costing for a generic net-zero carbon building. This will provide construction professionals with clear aspirational objectives on the economic performance of net-zero carbon buildings.