Information about energy-efficient commercial heat pumps in this section includes the following:
Also provided is a portable document format version of How to Buy an Energy-Efficient Commercial Heat Pump (PDF 183 KB, 2 pp). Download Acrobat Reader.
| Efficiency Recommendation |
| Product Type and Size |
Recommended Levela |
Best Availableb |
Air-sourcec
< 65 MBtu/h |
12.0 SEER or more
7.7 HSPF or more |
13.2 SEER
8.5 HSPF |
Air-source
65 - 135 MBtu/h |
10.1 EER or more
10.4 IPLV or more
3.2 COP or more |
11.5 EER
13.4 IPLV
4.0 COP |
Air-source
136 - 240 MBtu/h |
9.3 EER or more
9.5 IPLV or more
3.1 COP or more |
10.5 EER
12.4 IPLV
3.3 COP |
Water-sourced
65 - 135 MBtu/h |
12.8 EER or more
4.5 COP or more |
14.5 EER
5.0 COP |
a Efficiency levels for air-source units sized between 65 and 240 MBtu/h meet ASHRAE 90.1 minimum efficiency requirements.
b The best available EER and best available COP apply to different models.
c Only units with 3-phase power supply are covered in this category.
d Water source heat pumps covered here use cooling towers and boilers as the heat transfer sink or source in a closed loop piping system. This may increase boiler energy use by lowering the return water temperature. Auxiliary pumping energy is not included in the WSHP efficiency rating.
EER (energy efficiency ratio) is the cooling capacity (in Btu/hour) of the unit divided by its electrical input (in watts) at standard peak rating conditions. SEER (seasonal energy efficiency ratio) and IPLV (integrated part-load value) are similar to EER, but weigh performance during the cooling season.
COP (Coefficient of Performance) is the heating capacity (in Btu/h) at standard heating conditions divided by its electrical input (also in Btu/h). HSPF (Heating Seasonal Performance Factor), like SEER, weighs heating performance at various conditions.
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| Cost-Effectiveness Example (120 MBtu/h - 10 tons) |
| Performance |
Base Modela |
Recommended Levelb |
Best Available |
| EER/IPLV/COP |
8.9/9.2/3.0 |
11.0/11.4/3.2 |
11.8/13.0/4.0 |
| Annual Energy Use |
37,100 kWh |
33,800 kWh |
26,600 kWh |
| Annual Energy Cost |
$2,200 |
$2,050 |
$1,600 |
| Lifetime Energy Costc |
$22,200 |
$20,200 |
$15,900 |
| Lifetime Energy Cost Savings |
— |
$2,000 |
$6,300 |
a The integrated part-load value (IPLV) corresponds to an average model meeting the minimum national standard EER of 8.9.
b For illustration only, there may not be an actual model available that just meets both EER and IPLV efficiency criteria.
c Lifetime energy cost is the sum of the discounted (present) value of annual energy costs based on average usage and an assumed heat pump life of 15 years. Future electricity price trends and a discount rate of 3.3% are based on Federal guidelines (effective from April 2001 to March 2002).
Metric Conversions:
1 Ton = 12,000 Btu/h
1,000 Btu/h = 293 watts
°F = (1.8 * °C) + 32
1 Foot = 30.5 cm
Cost-Effectiveness Assumptions: The cost-effectiveness example assumes annual energy use is based on the standard DOE test procedure for a model with 1,500 equivalent full-load hours per year. The assumed electricity price is 6¢/kWh (including demand charges).
Using the Cost-Effectiveness Table: In the example shown above, an air-source heat pump with an EER of 10.1, an IPLV of 10.4, and a COP of 3.2 is cost-effective if its purchase price is no more than $2,000 above the price of the base model. The best available model, with an EER of 11.5, an IPLV of 13.4, and a COP of 4.0, is cost-effective if its price is no more than $6,300 above the price of the base model.
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FEMP provides a Web-based energy cost calculator screening tool that simplifies energy cost comparisons between different commercial heat pumps. This cost calculator allows you to adjust the capacity, hours of operation, and electricity cost for your installation.
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When selecting a commercial heat pump, specify or select an ENERGY STAR® labeled model or one that meets or exceeds these recommended levels. All ENERGY STAR commercial heat pumps meet the levels listed in this recommendation. The ENERGY STAR Web page lists complying models.
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Oversizing of heat pumps, besides raising purchase cost, will increase energy use, reduce humidity removal, and shorten product life, all due to excessive on-off cycling ("short-cycling"). The required heat pump capacity should be determined based on the referenced ASHRAE calculation procedure (see For More Information).
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Air source heat pumps operate inefficiently at sub-freezing temperatures, so avoid them as stand-alone heating systems in cold climates. However, in mild climates, they generally offer savings comparable to those units with electric resistance heating coupled with a unitary air conditioner. Depending on both climate and utility costs, heat pumps may be cost-effective when compared to gas or oil furnaces.
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In large applications with multiple units, water-source models may be cost-effective, but cooling tower energy (pumps and fans) must be considered in the economic analysis. Economizers use controllable dampers to provide "free" cooling by letting outside air cool the space when the outdoor temperature or enthalpy are below the building's return air values. When properly controlled and maintained, economizers can decrease cooling energy usage substantially. If there is adequate land space, ground source heat pumps can be more cost effective than air or water source heat pumps because of the lower energy and maintenance costs (see How to Buy an Energy-Efficient Ground-Source Heat Pump).
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Proper installation and maintenance of commercial heat pumps are essential for effective and efficient operation. ACEEE's Guide to Energy-Efficient Commercial Equipment, along with other publications from CEE, provides tips on installation and maintenance concerns. Duct losses are a major source of energy waste and comfort problems with heat pumps; make sure ducts are well sealed. Choosing and setting controls properly is also important to preventing energy losses; careful attention should be paid to minimizing operation of electric resistance heating.
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Many of today's commercial heat pumps use HCFC refrigerants and other refrigerants with a low Ozone Depletion Factor (ODF). 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 information, contact EPA's hotline at (800) 296-1996.
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