Developing energy conservation measure assembly costs for rapid integrated retrofit feasibility

Cost estimating for energy retrofit projects typically carries high margins and large contingency due to high degrees of risk, particularly unforeseen conditions and variability in return on energy investments. Abundant literature is available on the risks a contractor faces to stay within a fixed price for new construction, however, retrofit projects offer a unique side of the industry due to the level of definition of the existing conditions. While typical early design estimates for a new capital facility focus on high level project and system based decisions, retrofit projects have sufficient detail to focus on more detailed considerations for defining the "problem" from the outset. This paper addresses the issue of risk in applying an assemblies based estimating approach for energy retrofits, with special attention direction towards identifying heuristic means for linking costs for individual energy conservation measures to observable data in existing buildings to identify and reduce risk. The paper presents the method used for example energy conservation measures embedded in an ongoing energy audit and retrofit feasibility tool, with comparison of costing with actual project costs from case study energy retrofit projects to demonstrate the value of the process. The paper will conclude with outcomes for the case studies along with future directions for refining the costing methodology.