Payback Analysis of Design Options for Residential Water Heaters
This paper describes the results of an analysis to determine the costs of increased energy efficiency for residential water heaters. In this study, cost and efficiency data were developed for a total of 23 design options for typical tank sizes applied to one or more of three water heater product classes, i.e., electric, gas-fired, and oil-fired. This analysis used computer simulation models and other analytical methods to investigate the efficiency improvements due to design options and combinations of designs. The calculations were based on the U.S. Department of Energy (DOE) test procedure for residential water heaters. The analysis included two insulation blowing agents based on non-ozone-depleting substances - HFC-245fa and water-blown. The analysis used average manufacturer, distributor, and installer costs to calculate the costs of different water heater designs. Consumer operating expenses were calculated based on modeled energy consumption and U.S. average energy prices. With this information, a cost-efficiency relationship was developed to show the average manufacturer and consumer cost to achieve increased efficiency. The results provided the engineering basis for DOE's proposed efficiency standard for residential water heaters. These data were subsequently used in the Life-Cycle Cost and National Energy Savings components of the appliance standards rulemaking process.