American homes need heat pumps, not space heaters

To heat homes more cleanly, people often consider two electric options. One is an electric resistance heater, also known as a space heater. It works like a giant toaster, using electricity to create warmth. The other option is a heat pump. This device pulls warmth from outside air, even when it's cold, and moves it indoors. It's similar to how a refrigerator moves heat from inside the fridge to your kitchen.

Experts say that replacing gas furnaces and boilers with heat pumps is crucial for reducing greenhouse gas emissions and improving health. It's also important to replace space heaters with heat pumps. This would make homes more comfortable and efficient, leading to lower heating costs.

The Benefits of Heat Pumps

A new report from RMI, an energy nonprofit, shows that one in five U.S. homes uses electric resistance heating as its main heat source. Switching these homes to heat pumps could save families about $1,530 each year. This adds up to $20 billion annually across the country for single-family homes.

This change would also significantly lower demand on the electrical grid. Total carbon emissions from homes that switch to heat pumps for heating, cooling, and water heating would drop by about 40%. Ryan Shea, a manager at RMI, noted that these changes benefit the grid, leading to lower energy rates and less energy use overall.

Heat pumps use a physics trick to work. They change the pressure of refrigerants to draw warmth from outdoor air or underground liquids, then bring it inside. In summer, the process reverses to cool the home like an air conditioner. They are very efficient because they transfer heat instead of generating it by burning fuel or using electricity directly.

Heat pumps have a "coefficient of performance" (COP) of about three. This means they produce three units of heat for every unit of electricity used, making them 300% efficient. This is three times more efficient than electric resistance heating, which has a COP of one. Even the best gas furnaces are less efficient.

Heat Pumps for Every Home

Heat pumps are replacing electric resistance heating and gas furnaces in many types of homes. For homes without ducts, wall-mounted units can exchange air between indoors and outdoors. If a home has ducts, an indoor unit replaces the furnace and connects to an outdoor unit for heat exchange.

If an old air conditioning unit needs replacing, installing a heat pump provides both cooling and highly efficient heating. Shea mentioned that replacing an old AC unit is often a good time for people to consider a heat pump.

New heat pump designs are also being made for apartment dwellers. A company called Gradient is working with building owners and public housing authorities to install units that fit over window sills and plug into standard outlets. These can replace old window AC units, offering both clean heating and cooling.

The goal is to install these appliances quickly and affordably in large buildings. This avoids the need for landlords to retrofit each unit, especially if they are replacing a central fossil-fuel boiler. Gradient installed 277 units in a Providence, Rhode Island public housing development in less than two weeks. This development previously used electric resistance heating.

Vince Romanin, Gradient's founder, said this is a straightforward process that leads to huge energy savings. He added that it provides a much better service by adding cooling.

Challenges and Solutions

The RMI report points out that the U.S. builds nearly 1.5 million homes each year. About 200,000 of these use electric resistance heating. Also, a million AC units are installed annually in homes with electric resistance heating. These could instead be heat pumps, saving occupants money.

To encourage the use of these efficient appliances, policymakers and utility companies need to offer incentives like rebates. Maine, for example, reached its goal of installing 100,000 heat pumps two years early with such programs. It aims to install 175,000 more by next year.

However, simply replacing all furnaces and space heaters with heat pumps isn't enough. Homes also need to become more efficient through better insulation and double-pane windows. This helps homes retain heat in winter and cool air in summer, so heat pumps don't have to run as much. Gernot Wagner, a climate economist, emphasized that not burning fossil fuels and insulating homes go hand-in-hand.

The electrical grid also needs upgrades for heat pumps to reach their full potential. Ideally, heat pumps should be powered by renewable energy like wind and solar. Even if not, they are still more efficient than gas furnaces. Heat pumps, along with electric vehicles and induction stoves, increase demand on the grid.

Utilities are already upgrading the grid to handle this increased electrification. They are installing large battery banks to store renewable energy for times when the sun isn't shining or the wind isn't blowing. They are also exploring vehicle-to-grid (V2G) technology, which allows electric vehicles to send power back to the grid during peak demand.

To truly move away from fossil fuels, all these systems must work together: more renewable energy, more batteries, and fewer space heaters.