⚡ Energy Efficiency

Degree Day Energy Calculator

Convert heating and cooling degree days to annual energy use and fuel cost. Compare any two Canadian cities, normalise utility bills by degree days, and estimate savings from efficiency upgrades.

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Project / Client

Address

Prepared By

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🏠 Building Details

Conditioned Floor Area *

m²

Construction Standard

Heating Efficiency

AFUE

🌍 Climate & Fuel

City *

HDD (18°C base)

HDD

CDD (18°C base)

CDD

Heating Fuel

Fuel Rate

$/m³

Cooling SEER (if AC installed)

SEER

Enter 0 for no cooling

Electricity Rate (cooling)

$/kWh

📈 Degree Day Results

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Canadian HDD & CDD Reference Data

Heating degree days (18°C base) and cooling degree days (18°C base) from Environment and Climate Change Canada (ECCC) long-term climate normals. Winter design temperatures come from the design temperature lookup, which is what a load calculation should use instead of degree days for sizing equipment.

City	Province	HDD (18°C)	CDD (18°C)	Winter Design Temp
Vancouver	BC	3,015	250	−4°C
Victoria	BC	3,827	130	−2°C
Kelowna	BC	4,796	350	−15°C
Prince George	BC	8,278	80	−28°C
Calgary	AB	10,268	120	−29°C
Edmonton	AB	10,647	100	−29°C
Lethbridge	AB	9,200	180	−24°C
Saskatoon	SK	12,874	180	−33°C
Regina	SK	12,440	210	−33°C
Winnipeg	MB	10,679	270	−28°C
Thunder Bay	ON	10,050	180	−29°C
Toronto	ON	6,761	370	−16°C
Ottawa	ON	8,957	280	−19°C
London	ON	6,650	320	−16°C
Windsor	ON	5,800	480	−12°C
Montreal	QC	9,218	320	−19°C
Quebec City	QC	10,150	240	−22°C
Halifax	NS	8,123	180	−13°C
Moncton	NB	9,741	210	−20°C
Charlottetown	PEI	9,200	180	−18°C
St. John's	NL	7,600	100	−13°C
Whitehorse	YT	11,500	60	−40°C
Yellowknife	NT	14,555	50	−43°C

How to Use the Degree Day Energy Calculator

HDD/CDD to Energy and Cost

Estimates annual heating and cooling cost from degree day data, applying an envelope intensity factor by building age and floor area, scaled by your city's HDD and CDD. For a more detailed model including hot water and plug loads, use the annual energy cost calculator; for the duct-specific share of that heat loss, the duct heat loss calculator breaks out losses from unconditioned attics and crawlspaces separately.

Compare Two Cities

Takes one home spec and calculates heating/cooling cost in two Canadian cities, useful for relocation planning. HDD ratio is the primary driver: moving from Toronto (6,761 HDD) to Edmonton (10,647 HDD) increases heating cost by a factor of 1.57, about 57%.

Normalize Your Utility Bill

Enter actual fuel consumption and HDD for each year to see if efficiency upgrades genuinely worked, adjusted for weather. If normalized consumption per HDD drops year over year, that's a real efficiency gain, not just a mild winter. This is the same method NRCan and energy auditors use to verify retrofit performance.

Heating Degree Days in Canada: How Climate Drives Energy Costs

Canada has one of the most extreme ranges of heating climate in the world. The difference in heating demand between Vancouver (3,015 HDD) and Yellowknife (14,555 HDD) is nearly five-to-one. Understanding how degree days drive energy costs, and how to use them to analyse your home's performance, is one of the most practical tools available to Canadian homeowners and building professionals.

How Degree Days Are Calculated

A heating degree day (HDD) is calculated for each calendar day by comparing the daily mean outdoor temperature to the base temperature of 18°C. If the mean temperature is 10°C, that day contributes 18 - 10 = 8 HDD to the annual total. If the mean temperature is above 18°C (e.g. a summer day at 25°C), it contributes 0 HDD. The annual total is the sum of all daily values. Canada uses 18°C as the base temperature: this is the temperature below which most occupied buildings require active heating, accounting for internal gains from occupants, appliances, and solar. The United States uses 65°F (18.3°C), giving nearly identical results.

Cooling degree days (CDD) work the same way in reverse: each day the mean temperature exceeds the base, the difference is added to the CDD total. Canadian cities have far fewer CDD than HDD; Toronto has 370 CDD vs 6,761 HDD. Windsor, Ontario has the highest CDD in Canada at around 480, while Yellowknife has almost none.

Using Degree Days to Predict Energy Use

For a given building, heating energy use is approximately proportional to HDD. This is because the rate of heat loss through the building envelope is proportional to the temperature difference between inside and outside, and HDD is precisely the cumulative sum of those temperature differences over time. So if a home uses 20,000 kWh of heat in a year with 6,761 HDD, its heat loss rate is roughly 20,000 / 6,761 = 2.96 kWh/HDD. The same home in a year with 8,000 HDD would use approximately 2.96 × 8,000 = 23,680 kWh.

This relationship has limits: it assumes a constant thermostat setpoint, constant internal gains, and no solar contribution changes. For most practical purposes, planning, budgeting, and year-to-year comparison, it's accurate within 5-10%. For detailed energy modelling, NRCan's HOT2000 software runs hour-by-hour simulations using actual weather data.

Degree Day Normalisation: Separating Weather from Efficiency

Suppose your gas bill dropped from 2,200 m³ to 1,850 m³ after you insulated your attic. Did the insulation work, or was it just a milder winter? Degree day normalisation answers this. Divide each year's consumption by that year's HDD: 2,200 / 7,200 = 0.306 m³/HDD vs 1,850 / 6,800 = 0.272 m³/HDD. The normalised rate dropped by 11%, which is the real efficiency gain; the rest of the apparent saving was weather. NRCan uses this approach to verify energy savings in home retrofit programs. For a full air sealing savings analysis that uses the same principle, see the air sealing savings calculator.

Why Base Temperature Matters

The 18°C base is standard in Canada, but the right base temperature actually depends on the building's balance point, the outdoor temperature at which internal and solar gains exactly offset envelope losses, so no active heating is needed. A very well-insulated, south-facing passive solar home might have a balance point of 12-14°C, meaning it doesn't need heat until outdoor temperatures fall below that level. For such a building, HDD calculated with an 18°C base would overstate heating demand. Some energy models use a 15°C base for modern high-performance homes. This calculator uses the standard 18°C base consistent with ECCC and NRCan data.

Frequently Asked Questions

A heating degree day (HDD) is the difference between a base temperature (18°C in Canada) and the daily mean outdoor temperature, summed over all days where the mean is below the base. A day with a mean of 10°C contributes 8 HDD. The annual total reflects the cumulative heating demand of the climate. Vancouver has roughly 3,015 HDD (mild, maritime), Toronto 6,761 HDD (moderate continental), and Yellowknife 14,555 HDD (extreme subarctic). HDD are published by Environment and Climate Change Canada (ECCC) as 30-year climate normals.

Heating energy use is approximately proportional to HDD for a given building. If you know your annual heating consumption and the HDD for that year, you can calculate your home's heat loss rate in kWh/HDD. Multiplying by the HDD of any other city or year gives an estimated energy use under those conditions. This works within about 5-10% accuracy for planning purposes. For precise analysis, use HOT2000 or a detailed energy model. The proportional relationship is the basis for degree-day normalisation, which removes weather effects when comparing year-to-year energy use.

Canada uses 18°C (approximately 64.4°F) as the standard base temperature for heating degree days, written as HDD18, following Environment and Climate Change Canada's degree-day methodology. This is the same base used by ECCC, NRCan, and the National Building Code. It represents the approximate balance point of a typical occupied building, the outdoor temperature below which active heating is needed. The US uses 65°F (18.3°C), giving nearly identical results. Some high-performance building analyses use 15°C or 10°C bases to better reflect buildings with low heating balance points.

Divide your annual heating fuel consumption by the HDD for each year to get a normalised rate (e.g. m³/HDD or kWh/HDD). Compare the normalised rates before and after your upgrade. A reduction in the normalised rate is a genuine efficiency improvement, independent of weather variation. For example: 2,200 m³ in 7,200 HDD year = 0.306 m³/HDD. After insulating: 1,800 m³ in 7,400 HDD year = 0.243 m³/HDD. Real improvement = (0.306 - 0.243) / 0.306 = 21%. This is the same normalisation method NRCan uses to verify retrofit performance in home energy programs. Use the Bill Normalisation mode in this calculator to do this calculation automatically.