• Christopher Marleau

Heat pump performance ratings are based on test procedures that generally test equipment in a laboratory under steady-state
conditions. These operating conditions rarely occur in the real world and because there is limited research on how this
equipment functions in service, it is difficult to understand their true efficiency at partial loads and throughout the year. This
study provides a better indication of the real-world efficiency of air-source heat pump retrofits in existing homes in coastal
temperate to cold interior regions of British Columbia. Twenty ductless and central heat pump systems were monitored at
eighteen distinct single-family residential sites from Vancouver Island to the interior of British Columbia. In-situ
measurements of key heat pump system parameters and corresponding outdoor environment conditions were collected for
each site over a one-year monitoring period. Some factors affecting heat pump performance were also explored, including
indoor unit volumetric flow rates, equipment sizing, short-cycling, defrost control, supplemental heating, and installation
considerations. Results from this study show that ductless heat pumps generally performed lower than manufacturer rated
efficiencies and central ducted systems performed as rated, where variations in performance are discussed throughout.

RDH Building Science