For a 6-month period, the Building America team Consortium for Advanced Residential Buildings monitored the performance of a heat pump water heater (HPWH) in Windermere, Florida. The study found that the HPWH performed 144% more efficiently than a traditional electric resistance water heater, saving approximately 64% on water heating annually. The monitoring showed that the domestic hot water draw was a primary factor affecting the system's operating efficiency.