Heat pumps conjure warmth from sub-zero airBy Becca TuckerMichael Helme carries a tray upstairs with two cups of tea and assorted nuts, to the coziest room in the house. This spare bedroom used to be known as “The Chaos.” Its door tended to stay shut in the winter, and Helme and his wife, Xiaotong Gong, started using it to store overflow stuff. Now it’s so toasty that Helme has made it his office. What changed? We sit down and Helme begins his PowerPoint presentation. Yes, Helme, a member of Sustainable Warwick and a support staffer at a big law firm (and full disclosure: the copy editor for this magazine), is the kind of guy who makes a PowerPoint presentation about his house. And Excel spreadsheets about the production of his solar panels. Helme and Gong, an acupuncturist, moved into this 1953 Cape Cod six years ago, and with the zeal of first-time homeowners, started making improvements. The first year, they got a free energy audit that the state offers, and following those recommendations, they weatherized the basement and upstairs with insulation. Their propane usage dropped from 932 to 712 gallons. Year two, they installed a wood burning stove in the basement. Their propane usage dropped from 712 to 432 gallons and two cords of firewood. “Oh that made me feel good,” said Helme.Year three, they had green builder Thom Woglom put up a pavilion in their yard, and SunCommon (formerly Hudson Solar) installed 10 solar panels on its roof. Propane usage fell to 230 gallons and two-plus cords of wood. But it crept back up in 2018 when they got tired of lugging firewood that spring that wouldn’t stop snowing. Firewood, too, had begun to give Helme pause. It was better than propane, but while sustainably harvested wood is a renewable resource, and burning it is homey and picturesque, what’s coming out of the stovepipe is air pollution. The couple still burns some wood, but much less, because year six was their big year. This was the year they installed air-source heat pumps, a $20,000 investment. Heat pumps have been around for decades in places like Israel and Texas, but innovations have improved them so that this generation of cold climate air-source heat pumps can suck warmth out of air as cold as -15 degrees. Record cold in Warwick? It just jumped from -10 to -13 this winter. Heat pumps are super-efficient, because instead of creating heat by burning something like propane or wood, they concentrate heat from the air and move it around. “Some people like to say there are little gremlins in there that separate the heat from the cold,” said Helme, probably seeing the incomprehension in my face. They work like refrigerators, but in the opposite direction. (They can also be used for cooling and dehumidifying when it’s hot out.) They’re a big buy, but the heat pumps should pay for themselves and then some. Helme, the number cruncher, estimates that they’ll break even if propane prices stay steady, and save thousands if those prices skyrocket, as he expects. “But even if we lose that bet,” he said, the point is to cut “a huge chunk out of our carbon footprint.”Their electricity usage looks like it will triple with the heat pumps online. Next up on on the laundry list of upgrades is expanding their solar array to power them. Helme and Gong still don’t crank the heat — that’s not their style. Gong, a Buddhist, will microwave a beanbag to hold on her lap while meditating in the cooler sun room. But their home’s cozy factor has gone way up this year, especially upstairs. They’ve even taken to bringing their breakfast up and eating it in the room formerly known as The Chaos.