ECM: Domestic Water-Heating Systems

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W7. Convert Water-Heating System to Solar

Description

Solar domestic hot water (DHW) systems save energy by utilizing the sun’s energy instead of electricity, gas, oil, or other fuels. Solar panels located on the roof or on the ground collect energy from the sun. In “active” solar water-heating systems, the energy is then transferred to the hot water storage tank using heat transfer fluid and a device called a heat exchanger. The system includes an auxiliary fuel source, such as gas or electricity, to heat the water when the sun’s rays are not sufficient to meet water heating needs.

Applicability

• Single-family and multifamily buildings, particularly in sunny climates

Types

• Systems:
  • passive circulation
  • active circulation
• Collectors: flat plate
  • integral collector and storage systems
  • evacuated tube collectors

Considerations

• Because maintenance costs of solar DHW systems can be significant, they should be taken into account before making a decision.
• The installation of solar DHW systems in high-rise buildings requires extensive new hot-water-distribution plumbing and therefore is less cost-effective than systems installed in low-rise buildings or single-family homes.
• Pipes connecting solar panels to the storage tank should be insulated.

Performance/Economics

• Installing a separate water heater to provide hot water during the summer months can provide efficiency gains of 25 percent or more.
• Performing this ECM in several PHAs has shown savings results ranging from zero to more than 25 percent.

Resources/Links

Energy Conservation for Housing – A Workbook, HUD, September 1998. Pages 7-163 and 7-164 address converting DHW systems to solar. 

Energy Performance Contracting for Public and Indian Housing: A Guide for Participants, HUD, February 1992. Pages 161 through 163 address solar water heaters. 

Consumer Guide to Home Energy Savings, American Council for an Energy Efficient Economy, 1999, ISBN 0-918249-38-4. Pages 119 and 120 address solar water heating.

Solar Water Heaters. Part of the U.S. Department of Energy's Consumer's Guide. Discusses how solar water heaters work, sizing, costs, codes, maintenance, and incentives.

Solar Water Heating. Provides links to additional materials on solar water heating.