How many BTU does it take to heat a house in Canada?
Why the BTU-per-square-foot rule gets it wrong, and what really sets heat pump size: climate, insulation, windows and airtightness.
The question always comes up: how many BTU for 1,000, 1,500 or 2,000 sq ft? The honest answer: it depends mostly on four things, and floor area comes second.
What really sets the size
- Climate. We size for your city’s design temperature: −23 °C in Montreal, −18 °C in Toronto, −32 °C in Edmonton. The colder it gets, the bigger the gap to fill.
- Insulation. A 1965 wall lets through roughly twice as much heat as a wall built after 2010.
- Windows. Even new ones lose four to five times more heat than an insulated wall of the same area.
- Airtightness. In an older house, air leakage can be a quarter to a third of all heat loss.
Ballpark figures
The tables below use the same method as the calculator (simplified CSA F280) for a two-storey house with a finished basement. They show the effect of climate and house age at equal floor area.
| Living area | Montreal (-23 °C) | Toronto (-18 °C) | Edmonton (-32 °C) |
|---|---|---|---|
| 800 sq ft | 16,300 | 14,500 | 19,500 |
| 1,200 sq ft | 21,800 | 19,400 | 26,100 |
| 1,600 sq ft | 26,800 | 24,000 | 32,000 |
| 2,000 sq ft | 31,500 | 30,000 | 37,700 |
| 2,400 sq ft | 36,100 | 36,000 | 43,100 |
| 3,000 sq ft | 45,000 | 45,000 | 51,200 |
| Living area | Montreal (-23 °C) | Toronto (-18 °C) | Edmonton (-32 °C) |
|---|---|---|---|
| 800 sq ft | 32,200 | 28,600 | 38,500 |
| 1,200 sq ft | 43,100 | 38,400 | 51,600 |
| 1,600 sq ft | 53,000 | 47,100 | 63,500 |
| 2,000 sq ft | 62,400 | 55,600 | 74,800 |
| 2,400 sq ft | 71,500 | 63,700 | 85,700 |
| 3,000 sq ft | 85,000 | 75,700 | 101,800 |
What about 20 to 30 BTU per sq ft?
That rule comes from window air conditioners and gives a ballpark for cooling a room. For heating a house in Canada it can overestimate a newer house by a factor of two or underestimate a poorly insulated older one. The only reliable way is a component-by-component heat loss calculation.
Run the numbers for your house
The calculator builds your house on screen, applies your city’s temperature and your home’s features, then picks the Kanartic system that covers your need without oversizing.