| City ↕ | Prov/State ↕ | Country ↕ | HDD (65°F) ↕ | CDD (65°F) ↕ | Climate Zone ↕ |
|---|
| Month | Days | Mean Temp (°F) | HDD | CDD |
|---|---|---|---|---|
| Annual Total | — | — | ||
Heating and Cooling Degree Days in HVAC
Degree days are a measure of cumulative temperature departure from a base temperature over a period of time. They are used to estimate annual energy consumption, compare climates, evaluate energy efficiency improvements, and correlate utility bills with weather. Every HVAC energy analysis starts with degree days.
How Degree Days Are Calculated
For each day: HDD = max(0, Base Temp − Mean Daily Temp). CDD = max(0, Mean Daily Temp − Base Temp). Annual HDD is the sum of daily HDD values over the year. The base temperature (18°C / 65°F) represents the outdoor temperature below which heating is typically needed. Above this temperature, internal gains from people, lighting, and equipment are assumed to maintain comfort without mechanical heating.
Using Degree Days for Energy Estimation
The degree-day method estimates annual heating energy: E_heat = (Q_peak × HDD × 24) / (ΔT_design × η), where Q_peak is peak heating load from the heat load calculator, HDD is annual heating degree days, ΔT_design is the design temperature difference, and η is system efficiency (AFUE). This is an approximation — actual consumption varies with occupancy, thermostat setbacks, and weather year-to-year. Use the payback period calculator for full energy economics.
Degree Days Across Canadian Cities
Canadian cities range from approximately 2,200 HDD (Vancouver) to over 10,000 HDD (Yellowknife) on a base 18°C. Toronto averages about 3,900 HDD, Edmonton 5,200, Montreal 4,400, and Calgary 5,000. These dramatic differences mean a home in Edmonton requires roughly 2.3× more annual heating energy than the identical home in Vancouver — illustrating why insulation levels in NBC Canada vary by climate zone. Compare cities using the lookup table above and use the energy estimator to quantify the impact on your specific project.
Frequently Asked Questions
Canada uses 18°C (64.4°F) as the standard base temperature, compared to 65°F (18.3°C) in the United States. The difference is small (0.6°C) but worth noting when comparing data sources. Some Canadian utility programs and NRCan energy tools use 18°C; ASHRAE data typically uses 65°F. This calculator lets you set any base temperature. For most practical purposes the difference between 18°C and 65°F base results is under 2%.
The degree-day method provides a reasonable first-order estimate — typically within 15–25% of actual consumption for well-characterized buildings. Accuracy improves when: the building has no significant internal gains (pure envelope-dominated load), the thermostat is not set back significantly at night, and the climate is not extremely variable. For more precise energy modelling, hour-by-hour simulation using actual weather files is required. The degree-day method is excellent for comparing retrofits, sizing equipment alternatives, and benchmarking utility bills against expected consumption.
Vancouver's coastal location on the Pacific gives it an oceanic climate — mild winters heavily influenced by the Pacific Ocean. Mean January temperature in Vancouver is about 3–4°C, compared to -12°C in Edmonton and -8°C in Toronto. The Rocky Mountains block Arctic air outbreaks. This results in only ~2,200–2,500 HDD (base 18°C) vs. 5,200 HDD in Edmonton. However, Vancouver has high humidity and significant heating season length — heating loads are spread across many months at moderate ΔT rather than intense cold snaps.