Editor's note:The Energy Services Bulletin features real answers to real questions posed to our staff at the Energy Services Power Line. We hope you find it useful.

Do you have information about the efficiency of residential heat pumps? We plan to replace our existing system with an air-to-air heat pump for heating and air conditioning. The house is about 1,200 square feet and 14 years old.

One of the best sources of information on energy-efficient appliances is the American Council for an Energy Efficiency Economy. Their publication Consumer Guide to Home Energy Savings is quite useful. It provides some selection guidelines and shows the make and model number as well as the heating and cooling efficiency of the most energy-efficient heat pumps available at the time of publication.

For heating and cooling equipment, the most popular source of product information is the Air Conditioning and Refrigeration Institute's Directory. The information comes from independent testing labs, so it should be useful in comparing one brand to another. The air-source heat pump section alone is almost 600 pages. The directory is available in many libraries, including ours. You will find the information you are looking for in the Unitary Directory.

If you provide the specific capacity and configuration of equipment you are looking for and the brands you are considering, the Power Line could search this for you and send you the most relevant pages. The directory also includes instructions on using the energy ratings in making energy-savings comparisons.

Another source of information is the EPA's Energy Star Residential Heating and Cooling Program. Although much more limited in scope than the ARI directory, it contains useful information.

The following publications will provide further information for your own research:

• ASHRAE's Green Tips (276K .pdf)
  A list of 29 sustainable design elements for building designers that includes a description, pros and cons, applicability, key elements of cost and additional resources. A resource excerpted from the ASHRAE GreenGuide.

• Ductless, Mini Split-System Air-Conditioners and Heat Pumps
  DOE's Consumer Guide on non-ducted heating and cooling systems, which are small and flexible units for room conditioning.

• Earth Comfort Updates: Current and archived issues of the Geothermal Heat Pump Consortium's newsletter

• Energy Efficient Home Cooling, a factsheet by Western Area Power Administration (152k pdf) 
  Choosing an air conditioning system is an important decision. The best system depends on your climate, cooling needs and the design of your house.