Multifamily New Construction: Utility Program Leads the Way Toward Changing Building Practice and Energy Codes

Debra Tachibana, Seattle City Light
Bing Tso and Jeffrey Romberger, SBW Consulting, Inc.

Keywords

Abstract

New construction of multifamily buildings in the Seattle area is becoming much more energy efficient. Two studies a decade apart reveal a 35% decline in energy use indexes (EUIs) among Built Smart program participants and a 45% decline among local-area baseline buildings. The findings point to ongoing transformation of the market place, led by a utility efficiency program that has touched most new projects in the past 15 years. Changes in standard practice have likely also been influenced by increased public awareness of energy efficiency, improved building designs and construction practices, and tighter building codes.

This paper describes the methods employed and empirical findings from two studies evaluating an evolving program that provides financial incentives to building developers to upgrade efficiency through building envelope specifications, efficient lighting fixtures, other equipment, and rigorous in-progress inspections. Evaluation methods included a review of billing and characteristics data for samples of participants and nonparticipants to form the basis for developing separate energy simulation models calibrated to utility billing records. Parameters from the nonparticipant model were substituted into the participant model to generate a baseline model.

Key findings show that, between 1994 and 2004, annual baseline EUIs declined from 13.26 to 7.36 kWh per square foot, while participant EUIs dropped from 10.26 to 6.66. This decline was demonstrated in all end uses: space heat, domestic hot water, lighting, and miscellaneous loads. While a welcome development, it also presents future challenges for the program to continue "pushing the envelope" of energy efficiency in multifamily new construction.