Modeling Commercial Water Heating System

The Northwest Energy Efficiency Alliance (NEEA) contracted with GTI Energy to conduct parametric modeling simulations for different configurations of natural gas and electric water heaters used in commercial water heating systems. Parameters simulated as part of the study included three typical commercial building types (hotel, restaurant, multifamily) over four Northwest climates (Boise, Missoula, Portland, Seattle). Overall system efficiency, operating costs and site carbon emissions were determined for each simulation based on local energy pricing.

In total, 384 different combinations were simulated by varying values within each of the following inputs: Building Type (for demand profiles), Climate Zone, Water Heating Technologies, Baseline Systems, Water Heater Capacity (% peak load), Storage Tank Size and Swing Tank Setpoint Temp.

Although the results vary due to electricity-to-gas price ratios, this study indicates modulating gas heat pumps as providing the lowest annual cost of operation and all-electric heat pump water heaters as being the most efficient technology.