Heat Pumps Provide Both Warmth and Cooling, and They're Essential to California's Climate Future

California has set itself some of the most ambitious climate goals of any state. In fact, only 25 states have set any serious goals at all when it comes to reducing greenhouse gas emissions to help avert a climate catastrophe. In addition to the general goal of producing 100 percent of its electricity with renewable sources by 2040, reducing greenhouse gas emissions by 85 percent and air pollution by 71 percent by 2045, the state has some specific goals to achieve those ends. 

What is this miracle machine? It’s called a heat pump, and in addition to being a climate-saver, it has the added benefit of acting as both heater and air conditioner for homes and buildings.

California will ban sales of all new gasoline-powered vehicles starting in 2035, and will—if the goal is met—generate 25 gigawatts of offshore wind energy (enough to power almost 19 million homes) by 2045. The state also aims to build 7 million climate-friendly homes—that is, homes with very low or zero carbon footprints—by 2035. 

But one goal is even more specific, zeroing in on a specific type of devise that could cut carbon emissions by 3 gigatons worldwide each year, according to a report by the global consulting firm McKinsey. That’s 3 billion metric tons of carbon. For sake of comparison, it would take 200,000 gasoline-powered cars 12,000 miles of driving each to emit one million tons of emissions. 

A Brief History of Heat Pumps

What is this miracle machine? It’s called a heat pump, and in addition to being a climate-saver, it has the added benefit of acting as both heater and air conditioner for homes and buildings. The technology for heat pumps has been around for almost 170 years. In 1855 an Austrian government mining and agriculture administrator—who doubled as an inventor—named Peter von Rittinger published a paper describing for the first time how a steam-powered heat pump would work. 

Nine decades later, in the United States, inventor Robert C. Webber was tinkering with an electric freezer when he unexpectedly burned his hands on the back of the unit. He realized that the same electrified process used to create cold temperatures deep enough to freeze whatever was put inside could also be used to generate high levels of heat. In 1948, Webber created the first electric heat pump, simply by reusing the otherwise wasted heat from a freezer unit. He set up his invention to heat and cool his entire home. 

The use of heat pumps has exploded in recent years, but there still aren’t enough. In California, there are currently about 1.5 million heat pumps installed in homes and buildings. The state’s goal as part of its net zero carbon plan is to get that number up to 6 million by 2030.

What Does a Heat Pump Do?

The “heat pump” may be a bit of a misnomer for the device that bears the name. Yes, heat pumps provide heat for homes and larger buildings—but they also act as central air conditioning systems. In fact, heat pumps do not generate any heat at all. They work by transferring heat from one thing to another.

Not all heat pumps are created equal. Less advanced, less expensive, models will generally require some type of backup heating system—one that will probably run on fossil fuels—to provide heat when the air temperature outside is extremely cold.

For example, a standard heat pump works by pulling heat from the outdoors air and pumping it through the existing HVAC ducts in a house. When the weather is warmer, the heat pump pulls the heat from indoors and pumps it outs, cooling the building.

Standard heat pumps, then, replace both a standard heating system, which usually burns some type of fossil fuel, and an air conditioning system, saving money by allowing one system to do both jobs. They operate with far greater energy efficiency because they’re mostly just moving heat around rather than generating it.

So when there’s no heat to be transferred, standard heat pumps don’t work. Right? 

A little physics fact: there is always heat available. At any temperature above absolute zero, which is -459.67 degrees Fahrenheit, all objects produce at least some heat. In practical terms, heat pumps designed to work in the cold can generate enough heat to keep a home relatively comfortable at outdoor temperatures as low as 5 degrees Fahrenheit. 

Not all heat pumps are created equal, however. Less advanced, and therefore less expensive, models will generally require some type of backup heating system—one that will probably run on fossil fuels—to provide heat when the air temperature outside is extremely cold. Home insurers may also want to see a backup system in place, to prevent frozen pipes and other cold-related damage.

A standard heat pump consists of only one actual pumping unit, positioned outdoors. A ductless system does not require existing HVAC ducts, instead employing one heat pump unit, or more,  outside and at least one indoors. The indoor and outdoor pumps are connected through a variety of tubing and cables. 

Exchanging Heat Between the Air and Earth

The indoor units contain a set of coils that both extract the heat from warm air, and heat up cold air, again serving as both air conditioner and heater. Because they require multiple units and use a somewhat more complex mechanism of heating and cooling, ductless (also called mini-split) systems tend to cost more than standard heat pumps. 

The cost of installing a geo-thermal heat pump can be considerably more than that of a solely air-sourced one. But according to the United States Department of Energy, “the additional costs may be returned in energy savings in 5 to 10 years.”

More expensive still are geo-thermal heat pumps, also known as GeoExchange, earth-coupled, or ground-source heat pumps, which work by taking heat from a few feet underground and pumping it into the structures in need of heating. Or cooling. Like other heat pumps, geo-thermal units perform both functions. 

These units take advantage of the fact that even in extremely hot or cold climates, underground temperatures remain more or less constant. Because that temperature is warmer than the atmospheric air in cold weather, and cooler warm weather, geo-thermal heat pumps can operate with a high degree of efficiency.

The cost of installing a geo-thermal heat pump can be considerably more than that of a solely air-sourced one. But according to the United States Department of Energy, “the additional costs may be returned in energy savings in 5 to 10 years, depending on the cost of energy and available incentives in your area.” 

Is There Any Reason Not to Use a Heat Pump?

The advantages of heat pumps are clear: They’re more energy efficient than other systems, lowering utility bills; they serve two functions, heating and cooling; they provide steadier service and therefore more even, comfortable temperatures; they’re safer (because they don’t burn anything) and easier to maintain than conventional systems. As an extra added bonus, they produce far less greenhouse gas.

The price of converting to a heat pump system can also be brought down using tax credits. At the federal level, the Inflation Reduction Act signed by Pres. Joe Biden in 2022 includes a wide variety of tax incentives for clean energy conversions—including heat pumps. 

That all sounds great. So is there any reason not to install a heat pump? 

There are, indeed, several reasons why heat pumps may not be for everyone. The one that may be the most daunting is the higher up-front installation cost. Air-sourced heat pumps (duct and ductless) can cost anywhere from $3,000 to $7,500 up front, according to the American Society of Home Inspectors (ASHI). Geo-thermal models can run upwards of $10,000. Bigger homes will require bigger heat pumps, and that raises up-front costs even further.

The ASHI also notes, however, that the energy efficiency of heat pumps can lead to enough savings in utility costs that the systems eventually pay for themselves. Typically, a heat pump system produces three times as much heat as the energy it uses to produce it. With some heat pumps, that can lead to savings that cover the costs of installation in as little as two years—but most standard heat pumps, as with geo-thermal heat pumps, , take five to 10 years to even the balance sheet.

The price of converting to a heat pump system can also be brought down using tax credits. At the federal level, the Inflation Reduction Act signed by Pres. Joe Biden in 2022 includes a wide variety of tax incentives for clean energy conversions—including heat pumps. 

According to the Internal Revenue Service, homeowners can claim a $2,000 credit in any year they install a heat pump, or make improvements to their heat pump system, until the end of 2032. The credit applies only to a homeowner’s primary residence. It can’t be claimed by landlords or other absentee property owners.

Not Always 100 Percent Environmentally Friendly

Due to their energy efficiency, there’s no real debate over the fact that heat pumps are for the environment and essential to creating a carbon-neutral future. But heat pumps have their own environmental issues. First, they rely on electricity to operate which not only means that they rely at least to some degree on fossil fuels, it also means that in a power outage, they stop working. 

Puron is a powerful greenhouse gas, at least 750 times stronger than carbon dioxide when it comes to trapping heat in the atmosphere, creating the global warming effect. The good news is that updated refrigerants exist that are in the works that run significantly cleaner.

Heat pumps use refrigerants to perform their cooling functions—another environmental risk. The most common cooling agent is Freon, which is a blanket term that could refer to any one of several chemicals. 

The most hazardous of those was known as R12, a type of chlorofluorocarbon, or CFC. But some forms of CFCs have been banned since the late 1970s due to their ozone-depleting effects. R12 was one target of a 1994 ban, meaning that any recently manufactured heat pump should not rely on that form of Freon. 

Another type, known as R22, was phased out only in 2020 in accordance with the 2010 Clean Air Act, due to its greenhouse gas-producing effects. Because heat pumps can last 20 years or more, there are likely thousands of units that still use that type of environmentally damaging coolant.

The newest version is R410A, or Puron. Is Puron safer and more environmentally friendly than Freon? The Environmental Protection Agency has approved Puron for use in cooling systems, including heat pumps. The newer refrigerant does not deplete the atmosphere’s ozone layer, in non-toxic to humans and because it is still in greater supply than Freon, is cheaper to buy and use.

Nonetheless, Puron is a powerful greenhouse gas, at least 750 times stronger than carbon dioxide when it comes to trapping heat in the atmosphere, creating the global warming effect. The good news is that updated refrigerants exist that are in the works that run significantly cleaner than R410A. The most popular is a substance that goes by the code R-1234YF, and is widely used in car air conditioning in the U.S. and European Union.

California: Heat Pump Opportunities Wasted (So Far)

California, as it turns out, could be a paradise for heat pump use. “Heat pumps don’t just work well in California—the environment is perfect for them,” according to the clean energy nonprofit Efficiency First California. The problem is, few Californians actually use them.

Only about 5 percent of California homes currently have installed heat pumps. The leader in the country: South Carolina, where almost half—46 percent—of all homes use heat pumps.

“The more moderate the temperature outside, the easier it is for a heat pump to collect and transfer heat. Although heat pump technology has made significant advancements, heat pumps aren’t as efficient when it gets too cold outside,” the group says on its website. “Since most of California experiences mild winters, heat pumps work extraordinarily well here.” 

And yet, only about 5 percent of California homes currently have installed heat pumps. The leader in the country: South Carolina, where almost half—46 percent—of all homes use heat pumps. Even Florida, the state with which Gov. Gavin Newsom has struck up an acrimonious rivalry, far outstrips California for heat pump deployment. About one of every three Floridian homes—32 percent—heats and cools itself with a heat pump system.

Southern states generally make more extensive use of heat pumps. That’s because homes in those states are more likely to already run completely on electricity. There are various reasons for that, but one of the most important is the age of houses. California homes tend to be on the older end, with the average owner-occupied home constructed between 41 and 50 years ago (as of 2021 statistics).

Homes in Florida, as well as in North Carolina and Alabama where heat pump use is also above 40 percent, average between 31 and 35 years old. Older homes are likely to have been built in an era when gas networks were widely set up, and came set up for natural gas connections. Newer homes, as in the South, often have no capacity to use gas for heat.

According to data from 2020, 26 percent of homes nationwide were all-electric, but in California that number was only 8 percent. If that percentage increases, the percentage of homes with heat pumps installed can be expected to rise as well.