What a space heater really costs to run in Canada

The formula

Cost per hour = power in kilowatts × your rate per kilowatt-hour. A 1 kW heater running for one hour uses one kilowatt-hour. If your rate is 12 cents, that hour costs 12 cents. If it is 18 cents, it costs 18 cents.

Your rate is printed on your hydro bill. Use the total cost divided by total kilowatt-hours rather than the headline energy rate, because delivery and regulatory charges are real money too.

Why your real cost is lower than the formula

That calculation assumes the heater runs flat out for the whole hour. A heater with a thermostat does not: it heats until the room reaches your set temperature, then cuts the element and only cycles back on as the room cools.

In a normal insulated bedroom, a thermostat-controlled heater often draws power for a third to a half of the time it is switched on. That is the single biggest difference between a cheap coil heater and a properly specified one.

A worked example

Say you run a heater in a home office for eight hours a day, and the thermostat means the element is actually on for about 40% of that — roughly three and a quarter hours of full draw.

At 12 cents per kilowatt-hour that is about 39 cents a day. At 18 cents it is about 59 cents. Over a 22-day working month, somewhere between about $9 and $13 to keep one room comfortable all day.

Compare that with raising the central thermostat by two degrees for the whole house, all day, and the arithmetic usually favours the small heater by a wide margin.

Rates vary hugely by province

• Quebec, Manitoba and British Columbia have some of the lowest rates in North America
• Ontario has time-of-use pricing — running the heater off-peak costs noticeably less
• Alberta and Saskatchewan sit in the middle and move with the market
• Atlantic Canada and the territories are typically the most expensive

Five habits that cut the cost

• Close the door to the room you are heating
• Turn the central thermostat down while you zone heat
• Target 18–20°C rather than 23–24°C
• Use the timer so nothing heats an empty room
• Fix the draught under the door before buying anything at all

The arithmetic, shown in full

Electricity is billed per kilowatt-hour. A 1,500 W heater at full draw uses 1.5 kWh every hour, so cost per hour at full draw is simply 1.5 multiplied by your rate. At Ontario's roughly 15.4 cents that is about 23 cents an hour.

But a thermostat-controlled heater is not at full draw for most of the hour. In a normal insulated room it cycles at around half duty once the room is up to temperature, so 0.75 kWh an hour is the realistic average — about 12 cents an hour in Ontario.

Over a month at four hours a day that is 90 kWh, or roughly $14. The table below runs the same calculation for every province.

What changes your number

• Room size and ceiling height — more air to warm means more running time
• Insulation and windows — a cold-wall room keeps pulling heat out
• Your set temperature — every extra degree adds running time all evening
• Outside temperature — a −25°C night costs more than a 0°C one
• Whether the door is shut — an open door doubles the volume you are heating
• Your provincial rate, including time-of-use pricing where it applies

Space heater versus turning up the furnace

This is the comparison that decides whether a space heater saves you money. Heating one 12 m² room costs what the table shows. Raising a whole-house thermostat by two degrees heats every room, including the ones nobody is in, and in most Canadian homes that costs several times more over the same month.

The rule is simple: a space heater saves money when it replaces central heating, and costs money when it is added on top of it.

Five ways to cut the number

• Drop the central thermostat one or two degrees and heat the occupied room instead
• Use the timer rather than leaving the heater on
• Set the lowest comfortable temperature — 20°C rather than 23°C is a large difference over a winter
• Close the door and block the draught underneath
• Check whether your utility has time-of-use pricing, and shift heavy use off the peak window