CH-99-16-1 -- WHAM: Simplified Tool for Calculating Water Heater Energy Use

Water heating comprises a significant portion of residential energy consumption--17% in the U.S., according to the residential energy consumption survey (RECS) (EIA 1995). For such a significant energy end use, energy analysts need a method to quickly and reliably assess current and future energy requirements for a variety of conservation policies and programs. To fill this need, the water heater analysis model (WHAM) was developed as a simple energy equation that accounts for different operating conditions and water heater characteristics when calculating energy consumption. The results of WHAM are compared to the results of detailed water heater simulation programs and show a high level of accuracy in estimating energy consumption. WHAM energy calculations are based on assumptions that account for a variety of field conditions and water heater types. By including seven parameters-- recovery efficiency (RE), standby heat loss coefficient (UA), rated input power (Pon), average daily hot water draw volume, inlet water temperature, thermostat setting, and air temperature around the water heater--WHAM provides an accurate estimate of energy consumption in the majority of cases.

Units: Dual