COOLING
Air conditioners vary considerably in efficiency and in the amount of energy used. Therefore, select equipment
based on its federal energy efficiency rating. Central air-conditioner units are rated on their Seasonal Energy Efficiency Ratio, or SEER.
A rating of 14 SEER is excellent, and the minimum cooling efficiency for air conditioners and heat pumps is 13 SEER. An ENERGY STAR® unit will have a SEER level of 14. For window units, this rating is the Energy Efficiency Ratio, or EER. For many types of room air conditioners, the minimum EER is 9.0 or 9.7. As a general rule, an EER of 11 or more is excellent. An ENERGY STAR® unit will have an EER of 11.5.
HEATING
If you are buying a new heating system, consider a high-efficiency electric air source or ground source heat pump. The energy efficiency is rated according to a federal standard called the Heating Seasonal Performance Factor, or HSPF. Heat pumps with an HSPF of 10 are almost three times more efficient than the most efficient gas furnaces. In January 2006, the new minimum efficiency for air source heat pumps rose to 7.7 HSPF, while efficiency levels for furnaces and boilers have not increased since 1992.
Ground source heat pumps, or GeoExchange units, use the Earth as a heat source in the winter and as a heat sink in the summer. Ground source heat pumps are rated in terms of Coefficient of Performance (COP) for the winter. The higher the COP, the higher the efficiency. Where gas furnaces have COP values in the 0.78 to 0.94 range, ground source heat pumps have COP values in the 3.0 to 5.0 range.
Installing a ground source heating and cooling system, such as a Geo-Exchange system, reduces heating and cooling bills by 30 to 50 percent.
