Both cold-climate air-source heat pumps (ccASHPs) and heat pump water heaters (EHPWHs) have gained significant popularity due to increasing interest towards electrification of residential HVAC and water heating appliances. Seasonal Energy Efficiency Ratio (SEER), Heating Seasonal Performance Factor (HSPF) and Uniform Energy Factor (UEF) ratings used by manufacturers to compare appliance efficiencies cannot determine the efficiency of a HVAC and water heating system in multiple climate zones or integrate impact associated to the appliances interaction. This paper describes the resulting performance characterizations of a ccASHP and an EHPWH from an alternative evaluation method developed by GTI to compare residential appliances as installed, the Virtual Test Home (VTH).

SEER, HSPF and UEF ratings are not useful for HVAC engineers when selecting equipment for the most efficient HVAC and water heating system based on climate zone or understanding the interaction amongst appliances. The VTH identifies the parameters that affect individual space heating/cooling and water heating appliances performance throughout a series of laboratory evaluations. Performance curves and modeling algorithms are developed for each appliance and implemented in building energy models to estimate a HVAC and water heating system annual energy consumption, operating costs and GHG emissions. This paper presents the estimated combined ccASHP and EHPWH annual efficiencies, operating costs and GHG emissions in a low-load home in multiple International Energy Conservation Code (IECC) climate zones.