Boilers - More common in relatively older homes, a boiler-based heating system uses gas, oil or electricity to heat water and produce steam that moves through pipes to heat radiators in individual rooms. All-electric boilers can achieve up to 95% to 100% AFUE, according to the DOE. Newer gas boilers must achieve 80% AFUE and newer fossil-fueled boilers must achieve a 75% AFUE.
Air-source heat pumps - If your home relies on cheap electricity rates, a high-efficiency heat pump may be a better choice. Used for both heating and cooling, an air-source heat pump condenses warm air and moves it either indoors or outdoors. In warm weather, it condenses and extracts heat from inside, cooling a home, and in cool weather, it condenses and extracts heat from outdoor air, heating a home.
According to the DOE, the heating efficiency of an air-source heat pump is determined by its heating season performance factor, or HSPF. It's a measure of the total space heating required during the heating season, expressed in BTUs, divided by the total electrical energy consumed during the same season, expressed in watt-hours.
Geothermal heat pumps - A geothermal heat pump is one of the most energy efficient methods of heating or cooling a home. Relying on a series of liquid-filled pipes, a home can be heated in cooler months by transferring and condensing energy from the 50 to 60 temperatures just a few feet below ground. In the summer months, the process is reversed, thereby cooling a home by removing heat.
Geothermal offers maximum efficiency while costing less to operate and lasting longer. Upfront installation costs are high, ranging from $10,000 to $30,000 depending on the site conditions, but some of these costs may be recouped through local, state or federal tax incentives.