Comparative Analysis of Utility Consumption and Costs of Near-ZEHs and Comparison Homes in California

Timothy C. Coburn, Abilene Christian University
Barbara C. Farhar, National Renewable Energy Laboratory
Lew Pratsch, U.S. Department of Energy

Keywords

Abstract

A SheaHomes development at Scripps Highlands in San Diego, California, began in June 2001 to offer near-zero-energy homes (ZEHs)—highly efficient homes with solar water heating, and in some, solar electricity as standard features—the first such offering in the United States. By November 2003, all 306 homes were sold. The National Renewable Energy Laboratory (NREL) has followed this development, including the builder experience; home resale values; homeowner characteristics, decisions, and experiences; and the consumption and cost of electricity and gas in the near-ZEHs and in adjacent comparison homes. Three papers on these topics (except the utility analysis) have been presented at the American Council for an Energy-Efficient Economy 2002 and 2004 Summer Studies (Coburn, Farhar & Murphy 2004; Farhar, Coburn & Collins 2002; and Farhar, Coburn & Murphy 2004).

We analyzed the utility data obtained for the SheaHomes and comparison homes to determine whether statistically significant differences in energy consumption and energy costs can be attributed to the energy efficiency and solar features of the high-performance homes by comparing them with similar conventional homes in the identical climate during the same 12-month period (July 1, 2003 through June 30, 2004). This paper presents the results of an analysis of differences in electricity and gas consumption and costs in the high-performance homes in the context of recently published analyses on near-ZEHs in other parts of California. The results suggest an emergent pattern of data that support claims of substantial savings in electricity costs in near-ZEHs.