In a Cold State, Maine’s Whole-Home Heat Pumps Holding Their Own

August 19, 2022

Energy News:

Recent research by Efficiency Maine makes the case that replacing homes’ entire heating systems with heat pumps can be cost-effective and comfortable, even in Maine’s notoriously cold winters. 

“Here, it got 21 below last winter,” said George Hardy, who participated in a pilot program as part of the research. “I was a little worried about the heat pumps, but they held out. They kept us warm.”

As Maine attempts to reach its ambitious goal of going carbon neutral by 2045, home heating is going to be a major problem to solve. More than 60% of the state’s home heating systems burn oil — one of the most carbon-intensive heating fuels — more than any other state.

Maine has made air-source heat pumps a centerpiece of its strategy. Heat pumps pull heat out of the surrounding air, even at cold temperatures, and transfer it into the home. The only fuel they use is the electricity needed to run the pump. Maine has set a goal of installing 100,000 heat pumps by 2025, a target it is well on its way to reaching: In 2021 alone, more than 27,000 new heat pumps came online in the state. 

Often, however, homeowners install just one heat pump, but continue to use fossil fuel sources as a backup, an arrangement that can undercut the ability of heat pumps to save money and reduce emissions. Efficiency Maine, therefore, has been undertaking research to bolster the argument for jettisoning the oil and propane altogether and moving toward whole-home heat pump systems. 

“We’re reaffirming our expectation that they work in cold climates and will keep you comfortable through the entire winter,” said Michael Stoddard, executive director of Efficiency Maine. “We want to see the heat pumps being used to their full capacity.”

Recent results have been promising. An ongoing pilot program replaced fossil fuel furnaces in 19 homes — 10 mobile homes and nine conventional wood-framed homes — with heat pumps to investigate how well standalone systems would perform. Feedback from participants after one winter has been overwhelmingly positive, Efficiency Maine reports. Homeowners praised the evenness of the heat and say it kept them toasty even as temperatures dropped well below zero.

Efficiency Maine also conducted case studies, assessing the performance of 10 homes that were already using a heat pump as their primary heat source. The homes ranged in size and age, and used a variety of heat pump technologies. They also had a range of backup system types, including oil, wood, electric, propane, and kerosene. The participating homes were metered from February to June of 2021, so researchers could understand how much energy was used, how well the systems performed, and how indoor temperatures fared when temperatures dropped outdoors.  

Over the study period, seven of the 10 homes did not need to use their backup heating. As outdoor air temperatures rose and fell throughout each day, the indoor air temperatures stayed within a narrow range, avoiding the temperature spikes and plunges so often associated with fossil fuel furnaces. All participants reported they were satisfied or very satisfied with the performance of their heat pump systems during the study period. 

Hardy and his wife Catherine, of Dexter, Maine, already had one heat pump in their 1890s home when they joined the pilot. They received a second heat pump, replacing their previous oil-burning forced hot air system. 

They have not one negative thing to say about the experience, they said. From November through April — the most heating-intensive months of the year — they paid a total of $1,000 for electricity. By way of comparison, heating a home with an oil furnace for a full year would have cost more than $3,000 even at last winter’s much lower heating oil prices. Their heat is even and reliable, and they now get to enjoy air conditioning during warmer months as well. 

“I don’t hesitate to leave it on in the summer because I know it’s going to cost us hardly anything,” Catherine Hardy said. 

Department of Energy:

WASHINGTON, D.C. — The U.S. Department of Energy (DOE) today announced that American heat pump manufacturer Lennox International became the first partner in the U.S. Department of Energy’s (DOE’s) Residential Cold Climate Heat Pump Technology Challenge to develop a next-generation electric heat pump that can more effectively heat homes in northern climates relative to today’s models. Cold climate heat pumps (CCHPs) can provide high-efficiency heating in freezing temperatures without producing greenhouse gas emissions and can save families as much as $500 a year on their utility bills. This achievement is a massive step toward providing reliable clean heating and cooling for millions of American families through domestically produced CCHPS, which is crucial to reducing energy costs and achieving President Biden’s goal of a net-zero carbon economy by 2050. 

“DOE’s Cold Climate Heat Pump Challenge calls on American businesses to make heat pumps more effective at heating and cooling, more efficient in their energy use, and more attractive options for consumers—so more households can unlock $500 in savings each year on utility bills. With this newest prototype, Lennox has answered that call,” said U.S. Secretary of Energy Jennifer M. Granholm. “Tapping into the emerging clean energy market is a huge economic opportunity that will bring a bolstered manufacturing sector, good paying jobs, and a brighter, cleaner future to Texas and communities across America.”  

Space conditioning and water heating account for 46% of building emissions and over 40% of primary energy used in American residential and commercial. They also account for 42% of all building energy bills and 56% of household energy bills each year. 


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