Washington - The U.S. Department of Energy has announced the final criteria for its water heater Energy Star program that will begin next January.
Water heating represents between 13% and 17% of national residential energy consumption, making it the third largest energy end use in homes, behind heating and cooling and kitchen appliances, DOE said in its Final Criteria Analysis, released in April. As homes become more energy efficient, DOE noted, the percentage of energy used for water heating steadily increases. Water heating is the only major residential energy end use that Energy Star has not addressed.
“We're very pleased to have an Energy Star for water heaters program,” said Bill Hoover, director-at-large, A.O. Smith Corp., Milwaukee. “It will sensitize the buying public to the fact that there are more efficient water heaters out there and it will encourage them to invest in them.”
Hoover noted that the water heater industry as a whole was pleased to work with DOE and the Environmental Protection Agency in crafting the Energy Star program.
Almost all water heaters sold in the U.S. are traditional storage units with nearly an even split between gas and electric. Of the 9.8 million water heater shipments in the U.S. in 2006, 4.8 million were conventional electric-resistance and 4.7 million were conventional gas storage. Gas tankless water heaters accounted for 254,600 shipments, representing 2.6% of the market. Currently, small manufacturers with limited production capacity are the predominant producers of solar and heat pump water heaters. Solar water heater shipments amount to an estimated 8,500 units per year, while heat pump water heater shipments amount to less than 2,000 units per year. While condensing boilers are used in some water heating applications, residential gas-condensing water heaters are currently not in the market.
DOE included residential high-efficiency gas storage water heaters in the program at a minimum Energy Factor of 0.62. DOE will sunset this minimum level, however, on Aug. 31, 2010, requiring a minimum Energy Factor of 0.67 thereafter for gas storage models. DOE said that it is the department's intent to accelerate the provision of high-performance gas storage water heaters in the market by establishing a goal for manufacturers to meet, said Richard H. Karney, P.E., Energy Star products manager at DOE.
DOE is including residential whole-house gas tankless water heaters at a minimum Energy Factor of 0.82. DOE reduced the minimum gallons-per-minute requirement from 3.0 in the previous draft criteria to 2.5-GPM at a 77°F rise. DOE said that the change in criteria will allow qualified units to be compatible with the hot water demand of apartments and condominium occupants, while not penalizing whole-house applications.
Although they are not significant market factors, the agency is including residential gas condensing water heaters with a minimum Energy Factor of 0.80, residential drop-in or integrated heat pump water heaters with the minimum Energy Factor set at 2.0, and residential solar water heaters in the program, requiring a minimum Solar Fraction of 0.50.
DOE believes that Energy Star should act as a driver of the market and is willing to give manufacturers additional time to develop high-performance gas storage water heaters that are non-condensing and that don't require a power vent. Manufacturers are optimistic high-performance gas water heaters can act as a bridge to advanced non-condensing or near-condensing gas storage water heating technologies.
DOE said it is intent on establishing an ambitious deadline for the qualifying criteria to ascend to the high-performance gas storage level. DOE acceded to manufacturers' requests to implement a minimum Energy Factor requirement for the inclusion of high-efficiency gas storage water heaters at the program's onset. By setting a hard deadline of September 2010, DOE is obligating manufacturers to fulfill the market niche for high-performance gas storage water heaters in the near term.
“We will see some models of improved efficiency on the market, but most of the higher efficiency models will be either power vented or condensing,” Hoover said. “It will make getting people to step up to be more of a challenge because there will be more installation costs.”
Hoover said that it's a good bet that atmospheric water heaters will be banned by the government in the next round of energy regulations in 2015.
Natural gas and propane water heaters would also need a minimum first-hour rating requirement of 67-GPH, to ensure models earning the label provide sufficient hot water delivery. They must have a minimum six-year limited warranty on the sealed system, to ensure models earning the label are reliable and perform properly. The units must also comply with ANSI Z21.10.1/CSA 4.1 standards. Using the DOE test procedure for calculations, a 50-gal. gas storage water heater with a 0.67 Energy Factor would consume an estimated 224 therms per year, a savings of 14%, or 37 therms, in comparison to the typical conventional gas water heater. The annual energy savings equal $51 using the national average gas rate. The monetary savings will pay for the price premium in eight years, given the estimated price premium in the market.
Residential whole-house gas tankless water heaters must have a minimum Energy Factor of 0.82; a minimum GPM requirement of 2.5-GPM at a 77°F rise; a minimum 10-year limited warranty on the heat exchanger and five-year warranty on parts; and compliance with ANSI Z21.10.1/CSA 4.1 or ANSI Z21.10.3/CSA 4.3, depending on burner size.
Using the DOE test procedure for calculations, a whole-house gas tankless water heater with a 0.82 Energy Factor would consume 183 therms per year, a savings of 30%, or 78 therms, compared to a typical gas storage water heater. The annual energy savings equal $108 using the national average gas rate. The monetary savings will pay for the price premium in five and a half to 15 years, depending on installed cost. DOE noted that tankless heaters may be better suited to new construction because they require a larger gas line. Finally, DOE has evaluated the inclusion of electric resistance technologies into the program and determined, while there may be slight initial savings to be attained, there are few, if any, technology improvements possible with this form of water heating to warrant the long-term qualification of electric resistance water heaters in the program.
Both electric-resistance storage and tankless water heaters present limited individual energy savings potential. The perfect electric-resistance water heater could not exceed an Energy Factor of 1.0 due to this technology's physical limitations, DOE noted. The best electric-resistance storage water heaters achieve an Energy Factor of 0.95 and the best electric-resistance tankless water heaters achieve an Energy Factor of 0.99. This technology has little to no room for improving its current energy savings.
A savings of 4.8% and 8.7% is not significant and does not offer meaningful differentiation in accordance with the Energy Star guiding principles. In addition, electric resistance technology has nearly maximized its energy savings potential. Given current and potential energy savings, electric resistance water heating technology is not under consideration for Energy Star.