Furnace and heat pump sizing in Nova Scotia
Halifax runs about 4,189 heating degree-days a year, which puts it in the moderate band at roughly 40 BTU per square foot of heating. The rest of the province sits in the same band.
Nova Scotia is moderated by the ocean on every side, which shortens the extremes at both ends. Winters are long but the design condition is milder than the latitude implies — a useful margin for heat pumps, which hold more of their capacity here than in the interior.
Heating degree-days and January temperatures in Nova Scotia
Degree-days below 18 °C and January temperatures from the Environment and Climate Change Canada Canadian Climate Normals 1991–2020. The band column applies the mapping described on the Canada index.
| City | Heating degree-days (18 °C) | January daily mean | January daily min | Band | BTU/sq ft |
|---|---|---|---|---|---|
| Halifax | 4,189 | -5.7 °C | -10.1 °C | Moderate | ~40 |
| Sydney | 4,415 | -5.0 °C | -9.1 °C | Moderate | ~40 |
How the province compares to itself
Worked example
Take a 1,500 sq ft home in Halifax. At the moderate band of 40 BTU per square foot:
1,500 sq ft × 40 BTU/sq ft = 60,000 BTU/h
A gas furnace is rated by input, so divide the output by the AFUE to get the rating you shop for: at 95% AFUE that is about 63,000 BTU/h of input. That falls between the standard 60,000 and 80,000 BTU/h sizes. Which one you should buy is exactly the question a load calculation answers and a rule of thumb cannot — rounding down leaves the house short on the coldest nights, and rounding up brings the short-cycling problems of an oversized furnace. Run your own numbers in the furnace-size calculator, and use AFUE typical bands if you do not have the nameplate.
Heat pumps in Nova Scotia
A heat pump loses capacity as the outdoor temperature falls, exactly when the house needs the most heat. The temperature where its output equals the house load is the balance point; below that, backup heat makes up the difference. Halifax averages a January daily minimum around -10.1 °C, and the design condition is colder still.
A cold-climate air-source heat pump is a reasonable primary heat source at these degree-days, with backup sized to cover the coldest stretch. The question worth asking a contractor is what capacity the unit still delivers at your design temperature — not its rated capacity.
The heat-pump-size calculator works from the same band, the balance-point calculator finds the crossover temperature. Dual fuel and the balance point explains where backup heat takes over.
A note on units
Canadian homes are almost always described in square feet and equipment is rated in BTU/h or tons, but outdoor temperature is in °C and degree-days are on the 18 °C basis rather than the American 65 °F. The two degree-day scales are not interchangeable: an American HDD65 figure is about 1.8× the Canadian HDD18 number for the same place. Every degree-day figure on this page is the Canadian 18 °C basis. If you have a floor area in square metres, multiply by 10.76 to get square feet before using the calculators.