The Northwest Energy Efficiency Alliance (NEEA) contracted with Larson Energy Research and Cascade Engineering Services, Inc. to conduct a laboratory assessment of space requirements and venting strategies for standard unitary heat pump water heaters (HPWH). The laboratory testing provides detailed information about known but previously unquantified challenges for HPWH efficiency in enclosed rooms. Interpretation and application of the findings can help increase the number of cases in which a HPWH retrofit installation can be recommended and successfully implemented. This study intends to provide actionable guidance and inform manufacturers, building designers, engineers, installers, and owners on various installation strategies and their impacts.
