Heat pumps now required for new homes in Washington state

New-build residences will have to install energy-efficient heat pumps starting in July as part of Washington’s ambitious efforts to curb carbon emissions.

A multistory white home with trees in the yard and a large heat pump
A heat pump installed at a home in the Montlake neighborhood of Seattle, Washington by TC Legend Homes (Dept. of Energy)
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Heat pumps will soon warm (and cool) every new house and apartment built in Washington state. 

Late last week, Washington’s State Building Code Council voted in favor of mandating new-home construction to install heat pumps for space and water heating starting in July 2023. The 95 vote comes months after the little-known state body ruled to restrict the use of gas-fired systems in new office complexes and other large commercial buildings beginning next year.

With the latest ruling, Washington’s building codes are now among the nation’s strongest when it comes to requiring heat pumps in all new construction, supporters say.

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It’s an exciting step forward toward meeting our goal to reduce greenhouse gases in our state,” Katy Sheehan, a council member who voted to approve the new residential building codes, told Spokane’s Spokesman-Review.

City and state officials nationwide are using building codes as tools to accelerate the shift away from gas-fueled heaters, boilers and stoves. To date, 90 cities and counties across 12 states and Washington, D.C. have adopted policies that encourage or require building electrification, including most recently a $4 billion initiative to switch New York City’s existing school buildings to all-electric heating.

The push to electrify buildings is particularly pertinent to Washington state, where steady population growth is boosting demand for new housing units. Greenhouse gas emissions from buildings increased by more than 50 percent between 1990 and 2015, making it the fastest-growing source of climate pollution in the state.

The state council, whose members are appointed by the governor, is tasked with updating building codes to help meet Washington’s energy and climate targets. The state passed a law in 2021 requiring emissions reductions of 45 percent by 2030 and 95 percent by 2050, compared with 1990 levels. As part of that effort, Washington must also increase energy efficiency in buildings by 70 percent by 2031

Heat pumps can be useful tools for shrinking buildings’ energy demand and curbing emissions. Electricity-powered heat pumps can be two to four times more energy-efficient than typical gas heating equipment, and they don’t directly emit methane — a potent greenhouse gas and a major source of health-harming air pollutants.

The devices work a lot like air conditioners. To cool rooms, heat pumps use a condensing liquid to absorb the excess heat indoors and transfer it outdoors. To warm rooms, the units work in reverse, pulling the outside air inside and transferring heat in the process — even in extremely cold winter temperatures. Heat-pump systems for water supplies work similarly, except that the heat is transferred from the air into large water storage tanks.

The State Building Code Council made the right choice for Washingtonians,” Rachel Koller, managing director of the green-building alliance Shift Zero, said in a statement. From an economic, equity and sustainability perspective, it makes sense to build efficient, electric homes right from the start.”

Some elected officials and council members pushed back against the heat pump rule, arguing that requiring the devices would increase the cost of building new homes. State Sen. Lynda Wilson (R-Vancouver) also questioned whether the council had the authority to require residents to use electric heating instead of gas, according to the Spokesman-Review.

However, the revised building codes will allow new homes to install backup gas systems, which would fire up when temperatures reach chilly lows in winter. And the federal government is poised to provide a raft of incentives to help families nationwide improve energy efficiency and reduce heating bills.

The Inflation Reduction Act is offering tens of billions of dollars in tax credits, federal rebates, grants and lending capacity for heat pumps, electric appliances, efficiency retrofits, rooftop solar and other building improvements. Last week, the White House announced an additional $4.5 billion to help low- and moderate-income families to lower their energy costs, especially as communities grapple with extreme temperatures and weather events fueled by climate change.

The federal incentives, along with statewide programs in Washington, are also expected to accelerate electrification in existing buildings, helping homeowners and renters to begin replacing gas-fueled stoves, heaters and boilers with cleaner yet potentially more expensive electric versions.

Transitioning existing homes to be more efficient and fossil-fuel-free is critical for our climate and our health,” Koller said.

She told Canary Media that Shift Zero doesn’t expect to see substantial numbers of backup gas-powered heating systems installed in new homes — even in colder weather areas. She pointed to a report by the Northwest Energy Efficiency Alliance that found around 88 percent of new homes in Washington already used electricity for primary space heating in 2018, while 87 percent used electricity for water heating.

While the new code retains a choice for builders, it heavily incentivizes electric heat pumps, which can fully perform in even the coldest Washington climate,” she said, adding that the ruling reflects the overall trend towards efficient electric heating in new-home construction.”

Maria Gallucci is a clean energy reporter at Canary Media, where she covers hard-to-decarbonize sectors and efforts to make the energy transition more affordable and equitable.