U.S. Policies May Drive Poor Heat Pump Water Heater Choices
Published: December 15, 2010
Essie Snell
New U.S. policies are driving increased interest in heat pump water heaters (HPWHs), but they may also indirectly encourage customers to make poor choices regarding this technology. HPWHs are high-efficiency electric water heaters that draw heat out of the surrounding air, and they have the potential to cut hot-water energy use in half. Following the establishment of Energy Star product criteria and federal efficiency standards focused on these units, major manufacturers (including GE, A.O. Smith, Rheem, State, and Whirlpool) are beginning to ramp up production of HPWHs. Increased market penetration of this technology is likely to be a boon for utility customers because it enables them to reduce the amount of energy they use for water heating; however, these criteria and standards may also encourage (or in some cases, force) utility customers to install HPWHs in situations in which they are not beneficial.
Two major recent developments have spurred a renewed interest in HPWHs. The first of these, in 2009, was the creation of Energy Star’s HPWH product criteria. Because Energy Star is one of the major certifications that customers look to when they’re interested in saving energy, the program has generally been effective at encouraging market penetration of new efficient technologies. The second development was a new federal water-heater standard requiring all electric water heaters with a capacity greater than 55 gallons to have an energy factor larger than 1 if purchased after April 16, 2015—effectively requiring the use of heat pump technology or a solar collector.
The biggest problem posed by the new Energy Star criteria and federal standard is that they don’t provide guidance to consumers on the conditions under which HPWHs produce useful savings. HPWHs use a refrigeration cycle to transfer heat from air to water and are supplemented by an electric heating element. Because HPWHs draw energy out of the surrounding air, they have a net cooling effect wherever they are installed. In hot climates, this provides an extra benefit for the customer, but in cold climates the customer’s space-heating system must work even harder to maintain comfortable conditions, thereby eliminating any energy savings. Although there are ways to get around this problem, more field research is needed to quantify the overall effectiveness and economical viability of these approaches. Unless utilities in cold climates identify and promote effective methods for addressing the heating load imposed by HPWHs within the next few years, the installation of new HPWHs could leave customers’ overall energy use effectively unchanged—or worse, it could lead to customer dissatisfaction.
In addition to cold-climate problems, there are other potential obstacles for utilities to be aware of. For instance, HPWHs are currently larger than standard tank water heaters and cost two to three times as much, so if customers decide (or are forced) to purchase new HPWHs, they may have to spend significant funds to do so. In addition, there still isn’t any research available to demonstrate that these new units have overcome the kinds of reliability problems that presented a barrier to successful market penetration in the past. Last, many utilities currently have demand-response programs in place that control water heaters to reduce peak load, but—at least at present—HPWHs are impractical for these programs because they can’t easily be cycled on and off due to their sophisticated control packages.
E Source has a number of resources focused on HPWH technology, including an upcoming report that will cover the impact of the Energy Star criteria and federal standard in greater detail. Contact us for more information. |
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About the Author
Essie Snell
RESEARCH ANALYST, E SOURCE
Essie Snell, a research analyst and member of the technology assessment team at E Source, researches and writes about various topics, including building envelope components, drivepower, transportation, plug loads, and “black-box” technologies. He previously worked with Point380, a consulting firm specializing in energy management, where he gained experience with carbon footprinting and neutrality strategies. Essie holds a BS from the University of Colorado at Boulder in engineering physics. |
