How to Cut Summer Cooling Costs

If you want to cut summer cooling costs, start with the sun and the thermostat. Most of the heat your air conditioner removes comes in through windows and the roof. Shading, a slightly higher setpoint and a well-maintained system typically save more than any gadget.

In most of Canada, cooling is a smaller share of yearly energy use than heating. Hot summers in southern Ontario, Quebec and the BC interior still push bills up. A central AC in a typical home might use roughly 1,000 to 2,500 kWh over a season, depending on climate, house size and habits.

What summer cooling typically costs

Rates are approximate all-in residential figures. Ontario customers on Time-of-Use pay more for afternoon use, which is when AC runs hardest. Use the home energy estimator to see your own split.

Keep the sun out

• Close blinds and curtains on east windows in the morning and west and south windows in the afternoon.
• Use exterior shading where you can. Awnings, exterior shades and deciduous trees stop heat before it reaches the glass, which works better than interior blinds.
• Consider reflective window film on west-facing glass that bakes in the afternoon.
• Check attic insulation and ventilation. A hot attic radiates heat into upper floors. See our attic insulation guide.
• Seal air leaks. The same gaps that leak heat in winter let hot, humid air in during summer. Our air sealing guide covers where to look.

Set the thermostat smarter

Many households are comfortable at about 24 to 25 °C when home. Each degree higher typically trims cooling energy by a few percent. Raise it by 2 to 4 °C while you are out, and let a programmable or smart thermostat bring it back down before you return. Our smart thermostat guide explains schedules, and the thermostat savings calculator estimates the effect.

• Use ceiling fans counter-clockwise. Moving air feels a few degrees cooler, so you can set the thermostat higher. Turn fans off in empty rooms.
• On cool nights, turn off the AC and open windows, then close up early in the morning.
• In Ontario, on Time-of-Use or Ultra-Low Overnight plans, pre-cool the house a little before peak hours. See our Ontario price plans guide.
• Avoid using the oven and dryer in the hottest part of the day.

Get your AC sizing right

Many Canadian homes have air conditioners that are too big. An oversized unit cools the air quickly and shuts off before it removes much moisture. The house feels cold and clammy, and frequent starts wear the equipment and waste energy.

If you are replacing a system, ask for a heat-gain calculation rather than matching the old unit's size. As a very rough guide, many Canadian homes need about 1 ton (12,000 BTU/h) of cooling per 600 to 1,000 sq ft, depending on insulation, windows and shade. A proper calculation can come out well below the old unit. Our guide on questions to ask installers covers what to request.

Maintain what you have

• Replace or clean the filter every 1 to 3 months during cooling season.
• Rinse the outdoor coil gently with a hose and keep plants at least 60 cm away.
• Make sure supply and return vents are open and unblocked.
• Have the refrigerant charge and airflow checked if cooling seems weak.

Use a heat pump as your AC

A heat pump is an air conditioner that can also run in reverse to heat your home. If your AC is 15 years or older, or needs a major repair, replacing it with a heat pump is often the better choice. Cooling efficiency is similar to or better than a new central AC, and you also get efficient heating for most of the winter. That second benefit is where the real savings come from.

Ductless mini-splits are a good option for homes without ducts or for a hot upstairs. See our central AC vs heat pump guide and ductless mini-split guide. In Ontario, the Home Renovation Savings Program offers up to $7,500 for an eligible cold-climate air-source heat pump. Check other provinces on our rebates page.

Window and portable units

If you only cool one or two rooms, a window AC or a mini-split zone can be cheaper than running central air for the whole house. Single-hose portable units are usually the least efficient choice, because they pull warm outdoor air back into the room.