Many Homes Are Converting Their Fossil Fuel-powered Heating and Cooling Systems to Electric-powered Heat Pumps

The Independent's journalism is supported by our readers. People who rent their homes, or don’t have enough money to make major upgrades to their homes, have for many years been left out of a major shift in heating and cooling technology that can improve efficiency, save money and be better for the global climate: heat pumps. Heating and cooling buildings consumes 35% of all the energy used in the United States each year.

Until recently, that process has required a significant amount of sizable and expensive equipment to be permanently installed in a building, which needs a professional contractor and can cost as much as US$10,000 just for the installation – in addition to the actual equipment. Often called mini-splits, these systems usually have a condenser outside the building that exchanges heat with the outdoor air and an evaporator inside that exchanges heat with the indoor air. But now window heat pumps are becoming available in the U.S. Much like a window air conditioner, these self-contained devices can be installed without professional help and plugged into a wall outlet.

Unlike window air conditioners, though, they can provide heat as well as cooling. They cost much less than a permanent system – between $3,000 and $4,000 – and can be moved to a new property if the owner relocates. There aren’t many options commercially available yet, and those on the market can’t heat or cool very large spaces on their own.

And they work less efficiently when heating homes in places with extremely cold outdoor temperatures. A few models are available on the market that are even cheaper, but they don’t have efficiency ratings, don’t work when outdoor temperatures are very cold, and are louder when running. I have designed and evaluated a wide range of building energy efficiency technologies; here’s how these window heat pumps work, and why they may allow apartment dwellers and residents of older houses to easily and relatively inexpensively make significant improvements to their homes’ heating and cooling systems.

Federal subsidies for this type of equipment expired in 2025, but some utility companies, states and local governments may still offer money to help pay the costs. Heat pumps use a reversible refrigeration cycle and can provide similar heating and cooling as electric-powered space heaters, furnaces and baseboard heaters, while using less than half the electricity. The most common heat pumps transfer heat between air indoors and outdoors, but other systems can exchange heat with the ground or with bodies of water, such as lakes. Heat pumps’ capacities are defined by the amount of heat they can transfer in a particular period of time.