Juneau gets most of its electricity from lakes that offer a clean hydropower resource. This means that it is particularly ecofriendly to install electrified heating systems in the city.
But, to be fair, Juneau lies at the warmer end of the state and doesn’t tend to experience the same blisteringly cold winter weather that can afflict places farther north like Anchorage or Fairbanks, where using heat pumps could be less cost-effective.
In the village of Eklutna, not far from Anchorage, electrician Derek Lampert has found a heat pump that copes with extreme temperatures. He lives in a house that he built with his father during the pandemic. The walls are 22 inches thick, he boasts. Lampert planned for the house to be as energy efficient as possible, and so he invested in a SANCO2 heat pump, which uses CO2 for a refrigerant. The machine provides space heating and hot water supply.
“We’ve had it as cold as –20 degrees Fahrenheit and it still worked,” says Lampert. “I was getting 135-degree water.”
High efficiency was certainly Lampert’s goal, and overall he’s happy with the results. Financially, at least, the well-insulated house and heat pump setup has proved beneficial. “People in my neighborhood spend more [than my entire electricity bill] on propane and heating oil,” says Lampert.
However, because a heat pump sucks heat indoors from outside, sometimes for long periods, the outer part of the machine can get especially cold and make the device less energy efficient. Heat pumps are generally designed to defrost themselves periodically, but Lampert argues that his model could be better at this. He says he has noticed a fair amount of frosting and ice build-up around the exterior of his heat pump when it’s very cold. “Certainly, the colder it gets, the worse it gets. It just struggles with all the moisture,” he explains.
John Miles, a spokesman for Eco2 Systems LLC, which makes the SANCO2 heat pump, says the current model works down to –26 degrees Fahrenheit (–32 Celsius). He adds that it has various means of checking for frost build-up and that any ice that does form will, eventually, melt away.
Terry Chapin, an ecosystem ecologist and professor emeritus of the University of Alaska, Fairbanks, has a heat pump but notes that his model—designed to work down to –13 degrees Fahrenheit (–25 Celsius)—struggles in the winter months. “It doubled our electricity use when I was using it at very low temperatures,” he says. When the temperature drops below 0 degrees Fahrenheit, he switches back to his oil heating system instead.
Vanessa Stevens, a building science researcher at the National Renewable Energy Laboratory in Fairbanks, says that the latest heat pumps are increasingly cold-hardy.
“We’re actually testing a heat pump in our lab this spring where the cutoff temperature is –31 degrees Fahrenheit,” she says. “That was unheard of 10 years ago.”
Demand in Alaska appears to be rising strongly because heat pumps are becoming more efficient and cost effective, she suggests, adding that there are now companies solely dedicated to heat pump installations—a relatively new development.
Heat pumps have great decarbonization potential, but this depends on context, says Meredith Fowlie, an economist at UC Berkeley. They will be most beneficial as a climate solution when they run on electricity generated predominantly from low-carbon sources—and when manufacturers move away from the least climate-friendly heat pump refrigerants. New homes, or homes requiring a brand-new heating system, should opt for a heat pump as standard now, according to Fowlie. But as heat pumps continue their spread, there must be enough properly trained tradespeople to install them, as well as building codes that promote the use of more efficient systems, says Fowlie.
“There’s a sense of urgency that needs to be balanced against some of the practical, pragmatic challenges that we need to overcome.”
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