A heat pump is a single electric appliance that can replace both your traditional air conditioner and home heating system (like a furnace or boiler).
At the simplest level, heat pumps use electricity to move heat from one place to another. In cooling mode, a heat pump acts like an air conditioner, moving the heat from inside your home to the outside. In heating mode, heat pumps go into reverse and pump heat from the air outside your home to the inside. That might seem a bit counterintuitive. After all, how can something move heat from the outside air when it's 20°F? But heat is just energy, and there's energy in the air all the way down to absolute zero, which is -465°F. Heat pumps designed for cold climates can keep your home warm — without a backup heating source — even when outside temperatures are below -10°F.
Heat pumps come in two main forms: ducted and ductless. Ducted heat pumps use your home's existing ductwork (or new ducts if needed) to disperse heated or cooled air throughout your home. Ductless (or “mini-split”) heat pumps are easier to install where there is no existing ductwork. Ductless heat pump heads are usually mounted high on the wall, and each one serves one room or area of your home. There are also window-unit heat pumps, which are an especially good option for renters.
Heat pumps are 3-5 times more efficient than most gas or oil-powered heating systems. This is because it takes less energy to move heat around than to produce it. In a natural gas furnace, the heat must first be produced by burning gas and then additional energy must be used to distribute it around your house. With a heat pump, the heat energy itself is taken directly from the air outside, so energy is only needed to transport that heat indoors and then distribute it around your house.
As a result, heat pumps are often far less expensive to run than other heating systems, which translates to hundreds of dollars per year in savings for an average household.
Heat pumps don't burn fossil fuels — they're electric! When paired with clean electricity sources like rooftop or community solar, heat pumps warm your home without warming the planet. Even if your electricity supply isn't 100 percent clean today, heat pumps are still more climate-friendly than other heating systems because they use so much less total energy. And as the grid gets cleaner, their emissions will continue to fall.
Because they are not connected to the gas grid, heat pumps also do not contribute damaging methane leaks into the atmosphere. Your gas furnace (and the gas lines connected to your house) are the source of ongoing emissions of unburned methane gas, which has many times the global warming effect of carbon dioxide.
Heat pumps do use small amounts of refrigerants that can sometimes leak into the atmosphere and contribute to climate change. However, the United States is moving with other countries to adopt strong standards that require the use of new, climate-friendly refrigerants.
Heat pumps can dehumidify the air on hot summer days and filter the air all year long. They're also more comfortable and customizable than traditional HVAC systems: modern heat pumps are internet-connected (controllable from your smartphone) and variable-speed (keeping your home at a steady temperature, and some allow the temperature to be customized room-by-room).