You have decided on a heat pump. The remaining question is where it takes its heat from: the outside air, or the ground under your property. Both move heat rather than create it, which is why either one beats resistance heating, and our article on how a heat pump works covers the mechanism they share. Five criteria separate them.
1. Where the heat comes from. An air-source heat pump draws heat from the outdoor air, which is free and available everywhere but gets colder exactly when you need it most. A geothermal system draws from the ground instead, and below about six metres the ground in Quebec holds roughly 8 to 10 °C all year regardless of the weather. In cooling season the difference reverses in an interesting way: an air-source unit dumps your house’s heat into the outdoor air and loses it, while a geothermal loop puts it back into the ground, where a good part of it is still there for the heating season.
2. Efficiency, and what happens in deep cold. This is where the comparison is usually described badly, so to be precise: an air-source heat pump delivers roughly two to four units of heat per unit of electricity, and that ratio falls as the outdoor temperature drops. A geothermal system holds roughly three to five and holds it all winter, because its source does not get colder. Neither is a one-to-one machine. One-to-one is what electric baseboards and electric furnaces do, and it is the thing both of these are designed to beat. Our guide to heat pump efficiency ratings explains how to read the numbers on a spec sheet.
3. Maintenance and exposure. An air-source unit sits outdoors and lives through everything a Quebec winter does: snow, ice, freeze-thaw, road salt if it is near the driveway. A geothermal loop is buried and sees none of that, and the heat pump itself sits indoors in conditioned space. Both still need servicing twice a year, once before the heating season and once before the cooling season, and what that covers is much the same for either.
4. How long each one lasts. Expect roughly fifteen years from an air-source unit and closer to twenty-five from geothermal equipment, with the buried loop itself lasting far longer than the machine it feeds. That gap matters when you compare the two, because you are not comparing one purchase against another, you are comparing one purchase against a purchase and a replacement.
5. What your property allows, and the shape of the investment. This is usually the criterion that decides it. Geothermal needs a loop in the ground, which means drilling and a lot that can take it, and it is the larger investment at the outset in exchange for the lowest running cost available. An air-source unit needs a spot outside the house and can be installed in a day or two. Our article on what to check before buying a geothermal heat pump goes through the property side, and how profitable a geothermal system is goes through the money side. Both qualify for government rebates, which changes the comparison more than people expect.
So which one. On efficiency, stability in deep cold and lifespan, geothermal is the stronger system, and where a property suits it and the owner is staying, it is the one we recommend. On most lots, and for most owners, a cold-climate air-source heat pump is the practical answer and a very good one: it does the same two jobs, installs quickly and costs far less to get in the ground. The honest version is that this depends on your lot and your horizon, not on which technology is better in the abstract.
We install both, so we have no reason to steer you toward one. Talk to one of our specialists and we will tell you which of the two your property is actually a candidate for.
