Away for the Winter? Thermostat and Humidity Settings for an Empty House

Turning the heat down while you’re away saves money, but a cold house and humid air are a bad mix. Natural Resources Canada’s Keeping the Heat In (Section 9) gives a clear limit and a condition for going below it.

The 17°C rule

NRCan says it’s worthwhile to turn the temperature down if you’ll be away for more than three or four hours, and that a 1°C drop over eight hours can save about 2% on heating energy. But “in general, it is best not to reduce the temperature lower than 17°C (63°F), as there is a risk of moisture build-up in the exterior walls.”

If you want to go lower, for example when you’re away for a week or longer, NRCan says you must keep humidity levels low. It recommends measuring relative humidity throughout the house with a hygrometer. If levels aren’t low, reduce moisture sources or add an ENERGY STAR certified dehumidifier.

Before you leave: cut the moisture sources

NRCan’s list of first steps for high humidity or condensation fits a pre-trip checklist well:

• Disconnect any humidifiers.
• Don’t leave laundry drying indoors or firewood stored in the house.
• Make sure there’s no standing water in the house or against the foundation, and fix any basement leaks.
• Cover exposed earth floors in basements or crawl spaces with a moisture barrier.
• Check that the ground slopes away from the foundation and eavestroughs are working.

Health Canada’s mould guide adds: keep window coverings open so warm air reaches the windows, keep baseboards and heating vents clear of furniture, and leave interior doors open so air can move.

Safety and checking in

NRCan reminds homeowners that a home with a combustion appliance or attached garage needs carbon monoxide detectors, and that their batteries should be replaced regularly. A hygrometer that logs or reports remotely lets you see whether humidity stays low while you’re gone. When you get back, Health Canada’s guide suggests looking for condensation on windows and pipes, stains, and musty odours, and dealing with any small mould patches promptly.

Sources: Natural Resources Canada, Keeping The Heat In – Section 9; Health Canada, Guide to addressing moisture and mould indoors (2023). Both read in full.

Originally published at https://dry-glass-notes.surge.sh/articles/away-for-winter-thermostat-humidity.html (AI-assisted, sources cited). If this helped, zaps go to hollisvarrow3753@coinos.io.