The commonly recommended range
Most guidance for an unoccupied home in a Canadian winter lands between about 13 °C and 18 °C, with 15 °C the figure that appears most often. If your insurance policy specifies a minimum, that figure governs regardless of any general recommendation.
Why not lower
The thermostat reads air temperature at one location, typically a hallway on the main floor at about 1.5 metres. That is close to the warmest, most centrally circulated air in the building.
The plumbing does not run there. It runs in exterior walls, through unheated garages, along basement ceilings, and into bathrooms on corners. Those locations can be 5 to 10 °C colder than the thermostat reading, and in a wind event with poor insulation, more.
So 15 °C on the thermostat may mean 8 °C or lower where a supply line actually is. Setting 10 °C to save money can put that same line near freezing.
The economics are not close. The heating saving from dropping a few more degrees over a winter is modest. A single burst supply line is a five-figure event.
Making the setting actually work
- Set a minimum floor rather than a schedule, and confirm any smart-thermostat away or eco mode does not override it downward.
- Leave interior doors open so air circulates rather than stratifying.
- Open cabinet doors under sinks on exterior walls.
- Keep registers open in every room, including ones normally closed off.
- Photograph the thermostat before leaving so there is a record of the setting.
- Have interior temperature recorded at multiple points on every visit, not just at the thermostat.
If you are draining instead
With the water shut off and the system properly drained, the freeze argument for heating largely disappears — there is nothing left to freeze. Some owners in that situation lower the temperature substantially or shut heating off entirely.
That is a bigger decision than it looks. An unheated building through an Alberta winter experiences condensation and moisture cycling, stress on finishes and materials, and potential problems with anything left in the property. Boiler and in-floor systems cannot simply be shut down without proper procedure.
And again, check the policy. Several insurers require one or the other specifically.
Related questions
At what temperature do pipes freeze?
Water freezes at 0 °C, but pipes inside a building do not freeze the moment the air outside hits that figure. What matters is the temperature at the pipe, which depends on where it runs, how well that space is insulated, how long the cold persists, and whether wind is driving heat out of the assembly.
A pipe in a heated interior wall may be fine at −30 °C outside. A pipe in an uninsulated exterior wall, an unheated garage, or a crawlspace can freeze with the interior at a nominally reasonable temperature, because the pipe is not experiencing the interior temperature.
The commonly cited threshold for concern is a sustained outdoor temperature below about −6 °C, with risk rising sharply as temperature drops and duration extends. Wind matters a great deal — it accelerates heat loss from the building envelope.
The practical approach is to identify the vulnerable locations in your specific property rather than watching a single number: exterior walls with plumbing, unheated garages, basements with poor insulation, rooms above unheated spaces, and anywhere with a history of freezing. Those are the places a visit should check.
What temperature should I leave my house at when I go away?
The most commonly recommended minimum for an unoccupied home in a Canadian winter is around 15 °C, though recommendations range from about 13 °C to 18 °C. Some insurance policies specify a figure — if yours does, that number governs, not a general recommendation.
The reasoning behind keeping it that high rather than lower: the thermostat reads the air temperature at one location, usually a hallway on the main floor. Temperatures elsewhere in the building — exterior walls, the basement, above the garage, in a bathroom on a corner — run meaningfully colder. Setting 15 °C at the thermostat may mean 8 °C or lower where the plumbing actually is.
Setting it much lower to save on heating is a poor trade. The savings over a winter are modest; the cost of a single burst supply line is not.
A few practical points. Leave interior doors open so heat circulates. Open cabinet doors under sinks on exterior walls. Keep registers open in every room, including ones you would normally close off. If the property has a smart thermostat, set a floor rather than a schedule, and check that any away mode does not drop below your intended minimum.
And ask your insurer whether your policy specifies a minimum temperature during absences. Several do.
Can I turn the heat off completely?
Only if the water supply has been shut off and the system properly drained, and even then it is a bigger step than most owners realise.
With water fully drained there is no plumbing left to freeze, so the freeze argument for heating disappears. But an unheated building through an Alberta winter has other consequences: condensation and moisture cycling in the structure, stress on finishes, adhesives and materials from repeated freeze-thaw, and potential problems with anything left in the property.
A property with a boiler or in-floor heating cannot simply be shut down — those systems have their own fluid that needs handling, and shutting down without proper procedure risks damage to the system itself.
Your insurer likely has a view on this. Many policies require either maintained heat or a drained system during heating-season absences, and some are specific about which. Confirm before deciding.
For most owners leaving for a season, maintaining a minimum temperature is the simpler and safer choice. Full shutdown makes sense for genuinely long-term vacancy — an estate property with an uncertain timeline, or a property awaiting redevelopment — and is worth setting up properly with a plumber rather than improvising.