How much does it cost to run a natural gas heater in a NB garage through winter?

Running a natural gas heater in a New Brunswick garage through the full winter heating season (October through April) typically costs $500 to $1,500, depending heavily on your garage's insulation level, the thermostat setting, and how frequently the garage door is opened. A well-insulated two-car garage kept at workshop temperature (12 to 15 degrees Celsius) will cost roughly $80 to $200 per month, while an uninsulated or poorly insulated garage can easily cost $250 to $400 per month and still never feel warm.

The math behind these numbers starts with New Brunswick's natural gas rates, which as of 2025-2026 run approximately $0.35 to $0.50 per cubic metre through Enbridge Gas New Brunswick (Liberty Utilities). Natural gas contains approximately 37.5 megajoules per cubic metre, and a modern 80% efficient unit heater converts about 30 megajoules of that into usable heat. A high-efficiency condensing unit heater (90-95% efficient) extracts 34-36 megajoules per cubic metre, reducing fuel consumption by 10-15% compared to a standard unit.

To estimate your specific costs, consider the main variables. Garage size is the obvious one — a single-car garage (roughly 300 square feet) requires about half the heating energy of a standard two-car garage (576 square feet), and a three-car garage (800+ square feet) requires proportionally more. Insulation level is the factor that most dramatically affects cost. A well-insulated garage (R-20 walls, R-40+ ceiling, R-16 garage door, sealed and weatherstripped) might lose heat at a rate of 15,000 to 25,000 BTU per hour when the outside temperature is -20 degrees Celsius. An uninsulated garage of the same size loses heat at 50,000 to 80,000 BTU per hour under the same conditions — three to four times as much, which means three to four times the fuel consumption.

The thermostat setting has a larger impact than most people realize. Every degree Celsius you raise the garage temperature increases heating costs by approximately 5-8%. Keeping a garage at 18 degrees Celsius (comfortable shirtsleeve working temperature) costs roughly 40-60% more than maintaining 10 degrees Celsius (above-freezing storage temperature). Many NB homeowners use a two-stage approach: maintain a baseline temperature of 5 to 8 degrees Celsius overnight and when away to prevent freezing, then boost to 12 to 16 degrees Celsius during active workshop use. This approach can cut seasonal heating costs by 30-40% compared to maintaining a constant workshop temperature.

Garage door openings are the hidden cost driver in NB's cold climate. Every time you open the garage door on a -20 degree day, you dump the entire volume of warm air and replace it with frigid outdoor air in under a minute. For a two-car garage, that is roughly 140 cubic metres of air that must be reheated from -20 to your setpoint — each door opening costs approximately $0.50 to $2.00 in natural gas depending on the temperature differential and your setpoint. If you open the garage door 4 to 6 times per day during winter (two vehicles, morning and evening), door openings alone can add $40 to $100 per month to your heating bill. Minimizing unnecessary door openings and using the service door for pedestrian access makes a measurable difference.

Here is a realistic seasonal cost breakdown for a well-insulated two-car garage in the greater Moncton, Saint John, or Fredericton area, heated to 12 degrees Celsius during the day and 5 degrees overnight, with a modern 90%+ efficient unit heater:

October and April (mild months): $40-$80 per month. November and March: $80-$150 per month. December through February (peak cold): $120-$200 per month. Full-season total: approximately $500 to $1,200. For an uninsulated garage at the same settings, double these figures. For a garage maintained at 18 degrees Celsius for full-time workshop use, add 40-60%.

Compared to other fuel sources, natural gas is the most affordable heating option for NB garages where service is available. Propane costs roughly 40-60% more per BTU than natural gas. Electric resistance heating costs approximately 2 to 3 times more than natural gas at current NB electricity rates. A cold-climate heat pump offers operating costs comparable to natural gas but with higher equipment costs upfront.

The best way to reduce your garage heating costs is to invest in insulation before you invest in a bigger heater. An insulation upgrade costing $2,000 to $4,000 for a two-car garage typically pays for itself in 3 to 5 years through reduced heating costs, and it makes the space dramatically more comfortable. Find qualified heating and garage contractors through the New Brunswick Construction Network at newbrunswickconstructionnetwork.com.