To address the problems of inconsistent energy efficiency evaluation indicators between air-source heat pumps and storage-type electric water heaters in China, this study proposes a unified energy efficiency evaluation method based on 24-h dynamic water usage tests. Based on an analysis of the hot-water usage habits of Chinese residents, a typical water usage pattern was established that included water usage time distribution, temperature demand, and flow characteristics. A unified evaluation index based on primary energy utilization efficiency was also designed. Experimental verification shows that the primary energy efficiency of heat pump water heaters (67.7%-99.2%) is significantly higher than that of storage electric water heaters (31.5%-36.4%).