Energy equivalency analysis of trade-offs between thermal efficiency and standby loss requirements for commercial gas service water heaters

摘要

The American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) Standing Standard Project Committee 90.1 has approved an addendum (90.lb) to ASHRAE /IES Standard 90.1-1989. The addendum specifies an increase in the minimum thermal efficiency requirement (from 77% to 78%), accompanied by an easing of the standby loss requirements, for commercial gas-fired service water heaters. The Pacific Northwest Laboratory performed an energy equivalency analysis to assess the impact of trade-offs between the improved thermal efficiency and the less stringent standby loss requirements. The analysis objective was to estimate whether the energy savings during firing would offset the increased energy losses during standby periods. The primary focus of this report is to summarize the major results of the analysis and provide a recommendation for minimum energy-efficiency commercial gas-fired service water heaters. Limitations to the availability of detailed performance and energy-use data for these commercial water heaters are also pointed out.