The Energy Cost Comparer estimates what six kinds of water heater cost to run for a year at your own energy prices. It multiplies litres of hot water per day by 365 days, the temperature rise and the heat needed per litre, divides by a representative efficiency (UEF) for each technology, converts electricity at 277.8 kWh per GJ, and ranks the annual costs from lowest to highest.
- Annual energy (GJ) = litres per day × 365 × (set − inlet temperature) × 4.186 ÷ 1,000,000 ÷ UEF.
- Defaults: 60 L per person per day, inlet 7 °C, set 55 °C; gas price in $/GJ and electricity in ¢/kWh are yours to enter.
- Representative UEFs: gas tank 0.62, power vent 0.66, condensing tank 0.85, gas tankless 0.93, electric tank 0.92, heat pump 3.0 (2.5 in a cold basement).
- At $8/GJ gas and 20¢/kWh electricity for three people, a gas tank runs about $170 a year, a heat pump about $244 and an electric tank about $797.
- Change the prices and the ranking can flip: at $14/GJ and 9¢/kWh the heat pump becomes the cheapest to run.
Energy Cost Comparer
01 /What does the Energy Cost Comparer calculate?
It answers a question that marketing rarely answers honestly: with the energy prices I actually pay, which type of water heater costs least to run? It takes the heat your household's hot water needs over a year, divides it by each technology's efficiency to get the energy each one would buy, and multiplies by your price for that energy. The result is a table of annual running costs, ranked lowest first.
Running cost is only half of the decision. A heater that is cheap to run can be expensive to buy and install, and the reverse. Use this tool alongside the replacement cost guide and, if you rent, the rent or buy calculator. Water heating is a large share of a Canadian home's energy: Natural Resources Canada puts it at 19.3% of the average household's energy use, second only to space heating.
02 /What do you enter?
| Input | Default | Notes |
|---|---|---|
| Hot water per day (litres) | People × 60 | Edit it if you know your use; NRCan reports Canadians use an average of 75 litres of hot water at home each day |
| Inlet temperature | 7 °C | Cold water entering the heater; lower in late winter |
| Set temperature | 55 °C | The temperature the water is heated to |
| Natural gas price | Your $/GJ (example: 8) | Use the variable rate per GJ on your bill, including delivery charges that scale with use |
| Electricity price | Your ¢/kWh (example: 20) | Use your all-in rate per kWh, including variable delivery charges |
Prices vary widely between provinces, utilities and retailers, and they change. The example prices are illustrations only, not a statement about any province's rates. Pull the variable parts of your own bill, not the fixed monthly charges, which do not change with how much hot water you use.
03 /How does the calculation work?
Annual energy (GJ) = L/day × 365 × ΔT × 4.186 ÷ 1,000,000 ÷ UEF, where ΔT is set temperature minus inlet temperature. Water needs 4.186 kJ to warm one litre by one degree Celsius, so litres × degrees × 4.186 gives kilojoules, and dividing by one million turns that into gigajoules. Dividing by the uniform energy factor (UEF) converts the heat that ends up in the water into the energy the heater has to buy, including its standby and combustion losses.
Gas technologies are priced at your $/GJ directly. Electric technologies convert at 1 GJ = 277.8 kWh and are priced at your ¢/kWh.
| Technology | Representative UEF | Why it sits there |
|---|---|---|
| Gas tank (atmospheric) | 0.62 | Flue losses up the chimney and standby losses through the flue |
| Power vent | 0.66 | Fan-assisted venting cuts some flue and standby loss |
| Condensing gas tank | 0.85 | Recovers heat from water vapour in the exhaust |
| Gas tankless | 0.93 | Condensing, no standby tank losses |
| Electric tank | 0.92 | All element heat enters the water; the loss is standby |
| Heat pump | 3.0 (2.5 in a cold basement) | Moves heat from room air; less heat is available in colder spaces |
These are representative values chosen for comparison, not ratings for any model. Real UEFs vary by model, size and draw pattern and are printed on the specification sheet and, for certified products, in NRCan's ENERGY STAR listings. A heat pump value above 1 is not a mistake: it moves heat rather than making it, which is why NRCan describes certified heat pump water heaters as up to four times more efficient than a standard electric water heater.
04 /Worked example: three people, $8/GJ gas, 20¢/kWh electricity
Three people at the default 60 litres each use 180 litres a day. With inlet water at 7 °C and a set temperature of 55 °C, ΔT is 48. The heat delivered to the water is 180 × 365 × 48 × 4.186 ÷ 1,000,000 = 13.2 GJ a year. Each technology then divides that by its UEF.
| Rank | Technology | Energy bought | Annual cost |
|---|---|---|---|
| 1 | Gas tankless (0.93) | 14.19 GJ | ~$114 |
| 2 | Condensing gas tank (0.85) | 15.53 GJ | ~$124 |
| 3 | Power vent (0.66) | 20.00 GJ | ~$160 |
| 4 | Gas tank (0.62) | 21.29 GJ | ~$170 |
| 5 | Heat pump (3.0) | 4.40 GJ = 1,222 kWh | ~$244 |
| — | Heat pump in a cold basement (2.5) | 5.28 GJ = 1,467 kWh | ~$293 |
| 6 | Electric tank (0.92) | 14.35 GJ = 3,986 kWh | ~$797 |
At these prices, gas is much cheaper per unit of heat: $8 per GJ against $55.56 per GJ for electricity at 20¢/kWh (277.8 × $0.20). Even a heat pump's efficiency of 3.0 does not close that gap entirely, although it cuts the electric tank's cost by about 70%.
05 /Worked example: the same house with different prices
Now keep everything the same but enter an illustrative gas price of $14/GJ and electricity at 9¢/kWh, the kind of mix you see where gas costs more and electricity costs less.
| Rank | Technology | Annual cost |
|---|---|---|
| 1 | Heat pump (3.0) | ~$110 |
| — | Heat pump in a cold basement (2.5) | ~$132 |
| 2 | Gas tankless (0.93) | ~$199 |
| 3 | Condensing gas tank (0.85) | ~$217 |
| 4 | Power vent (0.66) | ~$280 |
| 5 | Gas tank (0.62) | ~$298 |
| 6 | Electric tank (0.92) | ~$359 |
The ranking flips. The heat pump goes from fifth to first, and the gap between an ordinary electric tank and a gas tank shrinks to about $60 a year. This is why the answer to "gas or electric?" differs across Canada, and why the tool asks for your prices instead of assuming them. The Across Canada page explains the regional patterns, and gas vs electric water heaters covers the non-price differences.
06 /How to read the result, and its limits
- Hot water use drives everything. A household using 300 litres a day at a 55-degree rise needs about 25.2 GJ of delivered heat, nearly double the example. Reducing use (low-flow showerheads, cold-water laundry) cuts every row equally.
- Set temperature is not free to lower. Public health guidance is to store water at 60 °C to limit Legionella and mix it down to about 49 °C at the tap. The default of 55 °C is a calculation default, not a recommended setting; see temperature setting.
- Heat pumps borrow heat from the house. In a heated space, some of the heat a heat pump moves into the water comes out of your furnace's work in winter; in summer it cools and dehumidifies. The comparer does not model that interaction, so treat the heat pump rows as optimistic for winter operation inside a heated space.
- Only energy is compared. Purchase, installation, maintenance, lifespan, rental fees and incentives are not in this table.
- Fixed charges are excluded. Switching a house entirely off gas can remove a fixed monthly gas charge; switching a water heater alone usually does not.
Once you know the running-cost gap, compare it with the difference in installed price in the replacement cost guide, check programs in the rebates guide, and read efficiency, UEF and EnerGuide to compare real model ratings. When you are ready, you can request quotes.
FAQQuestions people ask
Is it cheaper to heat water with gas or electricity in Canada?
It depends on your prices. At $8/GJ gas and 20¢/kWh electricity, a gas tank costs about $170 a year to run for three people and an electric tank about $797. Where gas is dear and electricity cheap, a heat pump can be cheapest.
How much does it cost to run a heat pump water heater?
With three people, a 48-degree rise and a UEF of 3.0, a heat pump uses about 1,222 kWh a year: about $244 at 20¢/kWh or $110 at 9¢/kWh. Enter your own rate in the comparer.
What is UEF?
Uniform energy factor: the share of the energy a water heater buys that ends up as useful hot water under a standard test, including standby losses. Higher is better; heat pumps exceed 1 because they move heat.
Why is the default set temperature 55 °C and not 60 °C?
It is only a calculation default. Public health guidance is to store water at 60 °C and use mixing valves at the tap. Set the value you actually use.
Does a tankless water heater save money?
On energy, usually some, because a condensing tankless unit has no standby losses. In the first example it runs about $56 a year less than a gas tank. The higher installed cost often takes many years to recover.