U.S. Department of Energy - Energy Efficiency and Renewable EnergyFederal Energy Management Program – Energy-Efficient ProductsHow to Buy an Energy-Efficient Air-Source Heat Pump
Information about energy-efficient air-source heat pumps in this section includes the following:
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a This efficiency recommendation meets ENERGY STAR® specification effective October 1, 2002. SEER (seasonal energy efficiency ratio) is the total cooling output (in Btu) provided by the unit during its normal annual usage period for cooling divided by the total energy input (in Wh) during the same period.
a The HSPF and SEER efficiency of the base model is just sufficient to meet current U.S. DOE national standard. The EER of the base model shown represents the most common model on the market. HSPF, SEER, and EER may apply to different models. Cost-Effectiveness Assumptions: Annual energy use calculation is based on average operating conditions in Charleston, South Carolina—an appropriate area for a stand-alone heat pump. Heat pump model: heating and cooling capacity of 36,000Btu/hour. Usage assumption: 1,400 heating load hours and 1,400 cooling load hours per year. Since the heating mode is substantially less efficient than the cooling mode, about 60% of the heat pump's operating expense is due to heating energy (despite roughly equal heating and cooling load hours). Assumed electricity price: $0.06/kWh, the Federal average electricity price (including demand charges) in the U.S. How to Select an Energy-Efficient Heat PumpFor heat pumps purchased through commercial sources (retailer or distributor), look for the EPA/DOE ENERGY STAR® label; all ENERGY STAR® models meet this Efficiency Recommendation. Visit the ENERGY STAR® Web site for a list of complying models. Alternatively, look at the yellow "Energy Guide" label to identify models with an HSPF and SEER that meet this recommendation. For a contractor-supplied heat pump, specify an ENERGY STAR® qualified model, or one with an HSPF and SEER that meet the recommended levels. Buyer TipsHeat pumps operate very inefficiently at sub-freezing temperatures, so should be avoided as stand-alone heating systems in cold climates. However, they will always offer energy savings over straight electric resistance heating coupled with central air conditioning. In climates with mild winters, heat pumps may provide cost-effective heating when compared with gas or oil furnaces, depending on relative utility costs. SizingOversizing of heat pumps, besides raising purchase cost, will result in weaker energy efficiency, poorer humidity control, and shorter product life, all due to excessive on-off cycling. The required heat pump capacity should be determined based on the referenced ACCA calculation procedures (see "For More Information," below). Special attention should be paid to identifying the heating and cooling requirements separately, since these may be very different. InstallationLeaky ductwork is a particular problem with heat pumps since heat losses will cause the electric resistance, or "back-up" heat to operate much more frequently; consider duct sealing in conjunction with heat pump installation. Choosing and setting controls properly is also important in preventing energy losses with heat pumps; careful attention should be paid to minimizing operation of the back-up heating. User TipsConsider leaving your heat pump off during unoccupied hours, or using a set-back thermostat to minimize unnecessary operation of the unit. However, precaution should be taken in heating seasons to make sure this strategy does not trigger excessive use of back-up heating. Environmental TipsRefrigerants with ozone-destroying chlorofluorocarbons (CFCs) were used many years ago in heat pumps, but almost all equipment on the market today uses HCFC refrigerants, which have a much lower ozone-depleting effect. There are a few heat pump models now on the market that use refrigerants with no ozone-depleting effect; ask your supplier for information. In the future, heat pumps with ozone-safe refrigerants are expected to be more widely available. When retiring a heat pump that contains CFCs or HCFCs, the Clean Air Act requires that the refrigerant be recovered on-site by a certified technician. For compliance information, contact the EPA Stratospheric Ozone Information Hotline at (800) 296-1996. For More Information
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