Utility Benefits of Homes Approaching “Zero Energy”

Robb A. Aldrich, Steven Winter Associates, Inc.
John T. Walsh, Western Massachusetts Electric Company
Joseph Swift, Northeast Utilities

Keywords

Abstract

A tremendous number of energy efficiency measures in homes are cost-effective but don’t seem to appeal to builders or homeowners. Solar energy systems, on the other hand, are quite appealing to many but their high costs tend to discourage buyers. Combining both efficiency and renewable energy – moving towards “zero energy” – offers market appeal greater than either separately; and when combined into a single package it can be cost effective. In 2003, Western Massachusetts Electric Company (“WMECO,” a Northeast Utilities System company) and Steven Winter Associates, Inc. (SWA, with funding from U.S. Department of Energy’s Building America program) began this research effort consisting of three parts:

Supporting construction of a home in western Massachusetts by upgrading energy efficiency measures and incorporating active solar thermal and electric systems.
Detailed monitoring of the home’s energy performance.
Evaluation of the project using the Total Resource benefit-cost test.

The home was completed in Spring of 2004. During 2005 (the first complete calendar year monitored), the solar thermal system provided 62% of energy to heat domestic hot water. The home’s electricity consumption was 9.7 kWh/day – approximately 50% of the New England average consumption for all housing (per RECS EIA 2001). The 2.6-kW PV system produced an average of 7.3 kWh/day providing a solar fraction of 76%. More important to the utility: the home was almost always a peak net generator during critical summer peak periods. Total Resource benefit-cost analysis was performed using very recent avoided cost values (ICF 2005). The analysis showed that life-cycle benefits associated with efficiency and renewable energy were significantly greater than the costs (shown in Table 1).