How to Buy an Energy-Efficient Central Air Conditioner
Information about energy-efficient central air conditioners in this section includes the following:
| Efficiency Recommendation Cost-Effectiveness Example How to Select Sizing |
Installation Tips User Tips Environmental Tips For More Information |
Also provided is a portable document format version of How to Buy an Energy-Efficient Central Air Conditioner (PDF 49 KB, 2 pp). Download Adobe Reader.
| Efficiency Recommendation | ||
|---|---|---|
| Product Typea | Recommended Levelb | Best Available |
| Split Systems | 11.0 or more EER 13.0 or more SEERc |
14.6 EER 16.5 SEERc |
| Single Package | 10.5 or more EER 12.0 or more SEERc |
12.2 EER 16.0 SEERc |
a Split system and single package units with capacity under 65,000 Btuh are covered here. This analysis excludes window units and packaged terminal units.
b This efficiency recommendation meets ENERGY STAR® specification effective October 1, 2002.
c 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. Based on DOE test procedure, see 10 CFR 430, Sub-Part B, Appendix M.
| Cost-Effectiveness Example | ||||
|---|---|---|---|---|
| Performance | Base Modela | Recommended Level | Best Available | |
| EER | 9.2 | 11.0 | 14.5 | |
| SEER | 10.0 | 13.0 | 16.5 | |
| Annual Energy Use | 3,600 kWh | 2,770 kWh | 2,000 kWh | |
| Annual Energy Cost | $216 | $166 | $131 | |
| Lifetime Energy Costb | $2,350 | $1,800 | $1,420 | |
| Lifetime Energy Cost Savings | — | $550 | $930 | |
a The efficiency (SEER) of the base model is just sufficient to meet current U.S. DOE national appliance standards. The SEER efficiency of the base model is just sufficient to meet current U.S. DOE national standard. The EER of 9.2 of the base model shown represents the most common model on the market. SEER and EER may apply to different models.
b Lifetime energy cost is the sum of the discounted value of annual energy costs based on average usage and an assumed air conditioner life of 15 years. Future electricity price trends and a discount rate of 3.2% are based on Federal guidelines (effective from April 2002 to March 2003).
Cost-Effectiveness Assumptions: Annual energy use calculation is based on the standard DOE test procedure. Central air conditioner model: cooling capacity of 36,000 Btu/hr. Usage assumption: 1,000 cooling load hours per year. Assumed electricity price: $0.06/kWh, the Federal average electricity price (including demand charges) in the U.S.
How to Select an Energy-Efficient Central Air Conditioner
For air conditioners 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 "EnergyGuide" label to identify models with an SEER that meets this recommendation.
For a contractor-supplied central air conditioner, specify an ENERGY STAR® qualified model, or one with an SEER that meets the recommended level.
Sizing
Oversizing of air conditioners, besides raising purchase cost, will result in reduced energy efficiency, poorer humidity control, and shorter product life, all due to excessive on-off cycling. The required air conditioner capacity should be determined based on the referenced ACCA calculation procedure (see For More Information).
Installation Tips
Leaky ductwork is responsible for substantial energy losses and comfort problems in most residences; consider sealing ducts in conjunction with central air conditioner installation. Placing the outdoor ("condensing") unit in a well-shaded area will also reduce energy consumption.
User Tips
Consider leaving air conditioning off during unoccupied hours, or using a set-back thermostat to minimize unnecessary operation of the unit.
Environmental Tips
Refrigerants with ozone-destroying chlorofluorocarbons (CFCs) were used many years ago in central air conditioners but most existing equipment today uses HCFC refrigerants, which have a much lower ozone-depleting effect. There are some central air conditioner models now on the market that use refrigerants with no ozone-depleting effect; ask your supplier for information. In the future, central air conditioners with ozone-safe refrigerants are expected to be more widely available.
When retiring a central air conditioner 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
- Environmental Protection Agency has ENERGY STAR® central air conditioner model listings.
Phone: (888) 782-7937 - American Council for an Energy-Efficient Economy (ACEEE) publishes the Consumer Guide to Home Energy Savings.
Phone: (202) 429-0063 - Air Conditioning Contractors of America (ACCA) publishes Manual J, a load calculation guide for residential heating and air conditioning, and Manual S, a sizing guide for heating and cooling equipment.
Phone: (202) 483-9370. - Consortium for Energy Efficiency (CEE) has utility programs promoting energy-efficient central air conditioners and publishes the Specification of Energy-Efficient Installation and Maintenance Practices for Residential HVAC Systems.
Phone: (617) 589-3949 - Home Energy magazine provides energy conservation tips.
Phone: (510) 524-5405 - Lawrence Berkeley National Laboratory provided supporting analysis for this recommendation.
Phone: (202) 646-7950