Measuring the Success Rate of ECMs in New Construction

Lara Greden, Prasad Vaidya, James Douglas, Tom McDougall, and David Eijadi, The Weidt Group
Richard Walker and Fredrick Leuthauser, MidAmerican Energy

Keywords

Abstract

The effectiveness of a third-party review and feedback process during the construction phase in achieving implementation of energy conservation measures (ECMs) is addressed in this study. The process consists of construction document review and field verification. A data set of 105 new buildings that participated in MidAmerican Energy’s Commercial New Construction program is analyzed. The final incentive from the utility is based on modeled energy savings of the ECMs observed during the final field verification.

Implementation rate, defined as the ratio of modeled energy savings (on a kWh basis) for a particular review phase compared to modeled energy savings initially predicted at the end of the design phase, is analyzed with respect to various factors. Overall, the projects achieved a yearly average final implementation rate of 94%-101% in 2003-2005, which equate to final modeled energy cost savings of 7%-66% (compared to the local energy code, a variant of ASHRAE 90.1-1989). A subset of 24 projects showed an average implementation rate of 80% on a kWh basis for the initial review of construction documents that improved to 91% after feedback. At the initial site visit, the implementation rate dropped to 88% and improved to 92% after feedback. The results from this preliminary study demonstrate the value of ongoing construction-phase assistance, particularly at the stage of initial review of construction documents. Other results include higher implementation rates for repeat program participants and for schools compared to other building types. Of the technology groups, daylighting controls are implemented the least, suggesting a need for further assistance.