Thermal characterization of domestic electric water heating systems as distributed storage

Domestic electric water heating (DEWH) is one of the most energy-consuming applications in modern households worldwide. Two of the most common technologies are hot water storage tanks with resistive heaters and heat pumps. This study evaluates the thermal behavior of hot water tanks under different heating control strategies, hot water draw profiles and technologies. A novel approach is presented using an integrated Python/TRANSYS framework to perform annual thermal simulations for two types of heaters: resistive and heat pumps. The results show that the DEWH tank storage efficiency is affected more by the control strategy than the household behavior, with average annual efficiencies between 65 and 70 %. The best performance control strategies are the “nighttime” controlled load, and a solar soak (SS) timer. The results were extended across different Australian cities to capture the impact of different climate variables. Regarding the technologies, moving from resistive heaters to heat pumps can reduce emissions up to 67 %, while using a solar soak timer can decrease emissions between 3 %–19 % in different Australian capital cities with different renewable energy penetrations in the electricity mix. • Heater efficiency averages 65–70 % driven by control strategy. • Heat pumps cut emissions up to 67 % over resistive heaters. • Solar soak strategy yields 46 % energy from household solar. • Control strategies outperform user behavior in DEWH performance.