WATER HEATING

Water heating typically accounts for approximately 19 percent of total home energy use in the U.S. This guide outlines immediate low-cost efficiency improvements, such as lowering thermostat settings to 115–120°F and insulating tanks, alongside long-term equipment upgrades. It compares the economics of various water heaters, noting that demand (tankless) heaters and heat pumps offer significant efficiency gains over standard electric tanks. The document also details solar thermal options and drain-water heat recovery systems, which can capture heat from water that would otherwise be wasted.

• Water heating is generally the second largest energy user in the home, representing about 19 percent of total energy use and costing an average household more than $300 annually.
• Installing water-efficient fixtures and appliances can reduce a four-person household's water use by one-third. Replacing fixtures older than ten years with modern low-flow versions can achieve water savings of 25–60 percent.
• Simple maintenance and behavioral changes can lower costs: reducing the water temperature to 115–120°F can save up to 5 percent for every 10-degree reduction, and adding an insulating jacket to a tank can reduce heat loss by 25–45 percent, saving 4–9 percent of costs.
• Demand or tankless water heaters are more efficient than storage tanks, with efficiency gains of 8–14 percent for high-water-use homes and 24–34 percent for low-water-use homes.
• Heat-pump water heaters are 33–50 percent more efficient than electric water heaters. In hot climates, integrating space cooling and water heating with a heat pump can reduce energy use by 25–70 percent compared to a typical electric heater.
• Gravity film exchange drain-water heat recovery systems can save 25–30 percent of total water-heating energy by capturing heat from water that typically goes down the drain.
• Switching from an electric to a gas water heater is highly cost-effective because natural gas is generally cheaper; a standard gas tank can save approximately $142 per year over a standard electric tank.

APA

Goorskey, S., Smith, A., & Wang, K. (2004). WATER HEATING. RMI. https://rmi.org/app/uploads/2017/05/RMI_Document_Repository_Public-Reprts_HEB5WaterHeat.pdf

Chicago

Goorskey, Sarah, Andy Smith, and Katherine Wang. WATER HEATING. RMI, 2004. https://rmi.org/app/uploads/2017/05/RMI_Document_Repository_Public-Reprts_HEB5WaterHeat.pdf.

Wikipedia

{{cite report |last1=Goorskey |first1=Sarah |last2=Smith |first2=Andy |last3=Wang |first3=Katherine |title=WATER HEATING |publisher=RMI |date=2004 |url=https://rmi.org/app/uploads/2017/05/RMI_Document_Repository_Public-Reprts_HEB5WaterHeat.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{goorskey2004water, author = {Goorskey, Sarah and Smith, Andy and Wang, Katherine}, title = {{WATER HEATING}}, institution = {RMI}, year = {2004}, url = {https://rmi.org/app/uploads/2017/05/RMI_Document_Repository_Public-Reprts_HEB5WaterHeat.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }