According to the U.S. Department of Energy’s Energy Efficiency and Renewable Energy Information Center (EERE), even though the installation price of a geothermal system can be several times that of an air-source system of the same heating and cooling capacity, the additional costs are made up in energy savings in five to ten years. Inside components should last at least 25 years and the ground loop, more than 50 years.
Wood and pellet-burning heaters. Wood heating can make economic sense in rural areas if you enjoy stacking wood and stoking the stove or furnace. But for fuel efficiency and cost effectiveness, it is important to properly size the heater to the space, otherwise your heating plans will just go up in smoke—literally. All wood heaters sold today should bear a U.S. Environmental Protection Agency certification sticker, which specifies that they meet emissions standards. Higher-efficiency heaters (typically 63% to 78% efficiency) produce fewer emissions and are often safer, since complete combustion helps to prevent a buildup of flammable chimney deposits.
Pellet stoves, which use small pellets made of sawdust and wood chips for fuel, have lower point-of-use emissions than wood heaters and offer users greater convenience, temperature control, and indoor air quality, along with combustion efficiencies between 78% and 85%. One drawback is that they require electricity to run fans, controls, and pellet feeders. Under normal usage, they consume about 100 KWH of electricity per month.
Although gas (and most wood) fireplaces provide a warm glow, they are not an efficient heat source. Fireplace-heated homes generally lose more heat than they provide, because heated air is drawn through the unit and must be replaced by cold outside air. However, if the fireplace has a tight-sealing glass door, its own source of outside air for combustion, and a good chimney damper, it can provide some useful heat.
According to the EERE, masonry heaters produce more heat and less pollution than any other wood- or pellet-burning heater, reaching combustion efficiencies of 90%. Masonry heaters include a firebox, a large masonry mass (such as bricks), and long twisting flue channels that run through the mass. A small, hot fire built once or twice a day releases heated gases into the flue tunnels that, in turn, heat the masonry. This heat slowly radiates outward into the home.
Burning natural gas, oil, propane, cordwood, or pellets in your home with a high-efficiency furnace or boiler can be a very efficient way to deliver heat to your home. Of these, natural gas has the fewest direct emissions. Some fuel-oil furnaces or boilers can also burn biodiesel—a more sustainable and low-pollution solution. Be sure to check with your system’s manufacturer first.
Electric resistance converts electricity directly into heat, which means on-site efficiency for electric heaters is very high and there is no point-of-use pollution emitted. But when the inefficiency of electricity generation by the power company and transmission losses are taken into account, it is actually pretty inefficient to heat with electric resistance. Roughly one-third of the heating value of the fuel burned in a power plant is delivered as useful heat in your house—the remaining two-thirds are lost to generation and transmission inefficiencies. On the other hand, electricity is used to run heat pumps, which have the benefit of producing more energy than the electricity they consume and can balance out the efficiency losses at the power plant.
In many cases, surplus electricity from an off-grid solar-, wind-, or hydro-electric system can be routed to a heating load, such as an air or water heating element. This can be one effective application of heating with renewably produced electricity. If your home has a large enough grid-tied RE-electric system, the electricity produced may be enough to offset a significant portion of the energy consumed by an electric heating system. If avoiding utility-powered electric heating is not an option, consider purchasing enough “green tags” or green energy credits from your utility to offset your electrical heating energy use.