According to the U.S. Department of Energy, a heat pump's cooling efficiency is rated by its seasonal energy efficiency ratio (SEER). While older heat pumps from the 1970s typically had a SEER rating of 6, by 2011, the highest efficiency heat pumps have a SEER of between 14 and 18.
The heating seasonal performance factor (HSPF) rates a heat pump's compressor efficiency and its electric-resistance elements. According to the Department of Energy, the highest-rated heat pumps have an HSPF between 8 and 10.
As of 2011, the federal government will provide a tax credit of up to 30 percent of the installation cost for new heat pumps that have the Energy Star rating. These heat pumps are about 9 percent more efficient than standard models, and as much as 20 percent more efficient than the heat pumps many homeowners have in their homes, according to the U.S. Environmental Protection Agency.