A Comparison of Domestic Water Heating Options in the Austin Electric Service Area

Abstract

This report examines the energy, demand, and economic effects of three alternative electric water heating systems from the perspective of both the City of Austin Electric Utility and its ratepayers. An hourly computer simulation was used to model the operation of (1) a conventional electric resistance water heater (ERWH), (2) a heat pump water heater (HPWH), and (3) a heat recovery water heater (HRWH). Data from a previously conducted field test of solar water heaters (SWH) in the Austin area was used to compare this fourth water heating option. In the base case, the SWH was found to save the most energy relative to a conventional ERWH followed by the HPWH and the HRWH, respectively. However, under most economic assumptions thought to be reasonable for the Austin area, the heat recovery water heater appeared to be the best choice for the Austin all-electric ratepayer. From the Utility's perspective, it was determined that: (1) widespread ratepayer use of heat recovery water heater systems would be beneficial to the Utility; (2) ratepayer use of solar water heater systems would be marginally beneficial to the Utility; and (3) ratepayer use of heat pump water heater systems would not be beneficial to the Utility.