Quick Answer: Running a typical window air conditioner overnight in Ontario costs roughly 80 cents a night on the off-peak rate of 9.8 cents per kilowatt hour set by the Ontario Energy Board. Night cooling is the cheap kind: off-peak pricing runs 7 p.m. to 7 a.m. on weekdays. A bedroom fan costs pennies. The expensive mistake is cooling an empty room at 2 p.m.
Time-of-use pricing is the billing system most Ontario households are on, where electricity costs more at busy hours and less overnight. On May 1, 2026, the Ontario Energy Board moved the summer on-peak window to the middle of the day, 11 a.m. to 5 p.m. on weekdays, because that is when air conditioning load now peaks. For sleepers, this is quietly good news. The hours you actually need cool, the ones you spend in bed, sit entirely inside the cheapest block on the bill.
At Mattress Miracle in Brantford, we spend a lot of the summer talking with customers about sleeping cooler, and the honest version of that conversation always includes what things cost to run.
"People assume the fix for hot sleep is a big purchase, and often it is a 6 dollar a month fan and a cotton sheet. I have fit mattresses for over four decades, and I will tell you the same thing in the store: a mattress is not an air conditioner. Get the cheap cooling right first, then let the bed do the part a bed can actually do, which is hold less heat against you."
Brad Grose, founder, Mattress Miracle, family owned in Brantford since 1997, with 40+ years in the mattress industry
The tiered pricing change matters too. Tiered pricing is the alternative plan where every hour costs the same but the price steps up after a monthly usage threshold. For summer 2026 that threshold dropped from 1,000 to 600 kilowatt hours. A household running central air hard can cross 600 kilowatt hours well before month end, which pushes the rest of the month to the higher tier.
In This Guide
Reading Time: 6 minutes
What Changed in Ontario Electricity Pricing on May 1, 2026?
Ontario's summer electricity pricing changed in two ways on May 1, 2026, according to the Ontario Energy Board. First, the time-of-use on-peak window moved to 11 a.m. to 5 p.m. on weekdays, with mid-peak hours at 7 to 11 a.m. and 5 to 7 p.m., and off-peak covering 7 p.m. to 7 a.m. plus all weekend and holiday hours. Second, the tiered plan's summer threshold dropped from 1,000 to 600 kilowatt hours per month before the higher tier price kicks in.
The rates themselves stayed where they were set in November 2025. Time-of-use pricing is 9.8 cents per kilowatt hour off-peak, 15.7 cents mid-peak, and 20.3 cents on-peak. Tiered pricing is 12.0 cents up to the threshold and 14.2 cents past it. There is also an ultra-low overnight plan with a 3.9 cent rate between 11 p.m. and 7 a.m., aimed mainly at electric vehicle owners, with a much higher evening peak rate as the trade-off.
For anyone deciding how to stay cool at night, the practical takeaway is simple. Overnight electricity is the cheapest electricity you can buy in Ontario, on every plan. Midday is the most expensive. Cooling strategy should follow that shape.
What Does It Cost to Run a Fan or AC All Night?
Running a fan or air conditioner overnight in Ontario costs less than most people guess, because the whole sleep window sits in off-peak hours. The table below uses typical appliance wattages and the current 9.8 cent off-peak rate over an eight hour night. Your unit's label will give you its exact draw, and central air varies with house size, so treat these as honest ballparks rather than promises.
Typical Cost per Eight Hour Night, Off-Peak (9.8 cents/kWh)
- Ceiling fan (about 50 watts): 0.4 kWh, roughly 4 cents a night
- Box or tower fan (about 75 watts): 0.6 kWh, roughly 6 cents a night
- Window AC, bedroom size (about 1,000 watts, cycling): 5 to 8 kWh, roughly 50 to 80 cents a night
- Portable AC (about 1,200 watts, cycling): 6 to 10 kWh, roughly 60 cents to a dollar a night
- Central AC, whole house (3,000 watts and up, cycling): 12 to 18 kWh, roughly 1.20 to 1.80 a night
Two things jump out of that table. A fan all night for a whole month costs about what one fancy coffee does. And cooling only the bedroom with a right-sized window unit costs about a quarter of what whole-house central air does overnight. If the budget is tight, cool the room you sleep in and let the living room fend for itself until morning.
Why Spend Anything on Night Cooling?
Because warm nights measurably cost you sleep. A 2022 study in One Earth analysing over 7 million wristband sleep records found that hot nights delay sleep onset and shorten total sleep, with the effect growing as night temperatures climb (Minor et al., 2022). Related research on heat and sleep, summarized on PubMed, shows heat cuts into deep sleep and REM specifically. This is general information, not medical advice, but a cooler bedroom is one of the better-evidenced sleep upgrades there is.
How to Pre-Cool a Bedroom Around the Peak Window
Pre-cooling means doing your cooling in cheap hours so you buy less of it in expensive ones. With on-peak now sitting at 11 a.m. to 5 p.m., the routine that works looks like this.
Step 1: Cool hard before 11 a.m.
If you run AC, let it work in the morning mid-peak or overnight off-peak hours, and get the bedroom a degree or two cooler than you need. You are banking coolness at 9.8 to 15.7 cents instead of buying it at 20.3.
Step 2: Seal and shade through the peak
From 11 to 5, blinds closed on sunny windows, bedroom door shut, AC eased off or up a few degrees. The room coasts on the morning's work.
Step 3: Resume at 7 p.m., not 5 p.m.
The 5 to 7 p.m. block is mid-peak. If the house is bearable, waiting until 7 to restart serious cooling buys the same comfort for a third less.
Step 4: Run the sleep window guilt-free
From 7 p.m. to 7 a.m. you are on the cheapest rate. A fan across the bed or a bedroom AC on a moderate setting all night is the best value cooling of the whole day.
The Zero-Electricity Options: Bedding and the Bed Itself
Bedding and the mattress surface are the part of night cooling that draws no power at all, and they deserve an honest framing. No mattress or sheet lowers the room temperature. What they change is how much of your own body heat stays pressed against you. Dense memory foam wraps close and holds warmth. Coil-based builds move air through the mattress core, and latex (a springy foam tapped from rubber trees, with a naturally open cell structure) releases heat faster than dense synthetic foams.
That is why we point hot sleepers toward breathable builds first. In our Brantford showroom the side-by-side test is simple: ten minutes on a dense foam bed, ten on a coil or latex build like the options in our Restonic lineup, and your own back tells you which one runs warmer. A breathable mattress protector and a cotton or linen top sheet finish the job. None of it shows up on your hydro bill.
The Honest Math, Brantford Edition
Mattress Miracle is family owned on West Street in Brantford, and we would rather save you money in the right order. Fan first, shade second, right-sized bedroom AC third, and a breathable bed surface underneath it all. Our team is non-commission, so if the answer to your hot bedroom is a 30 dollar fan and better sheets, that is exactly what we will tell you.
Frequently Asked Questions
Is it cheaper to run AC all night or cool the room before bed and turn it off?
All night at a moderate setting usually wins on comfort per dollar, since the whole night is off-peak. A pre-chilled room with the unit off tends to drift warm by 3 a.m., which is when warm-night waking hits hardest. If you do switch off, a fan can carry the second half of the night.
Does the 600 kilowatt hour tier change affect me?
Only if you are on the tiered plan rather than time-of-use. Check your bill for the word tiered. If you are on it and run central air, you will likely cross 600 kilowatt hours mid-month in summer, and shifting cooling into the night does not help on that plan. Time-of-use rewards night owls; tiered does not.
Do cooling sheets and gel toppers actually work?
Cool-touch fabrics feel cold for a few minutes, then your body warms them. Breathability over the whole night matters more than a cold first touch. Cotton, linen, and open-structure surfaces beat gel gimmicks in our experience fitting Brantford sleepers.
Is the ultra-low overnight plan worth it just for summer cooling?
Usually not on its own. The 3.9 cent overnight rate is great for sleep-hours cooling, but the plan's steep evening peak rate can eat the savings unless you also charge an electric vehicle or can shift most household use past 11 p.m. Run your last three bills through the Ontario Energy Board's plan comparison before switching.
What does Mattress Miracle actually recommend for hot sleepers on a budget?
A fan aimed across the bed, cotton or linen bedding, and blinds down through the midday peak. If your mattress itself sleeps hot year round, come try a coil or latex build in the Brantford showroom before spending anything. Call us at (519) 770-0001 and we will be straight with you about what helps.
Visit Our Brantford Showroom
Mattress Miracle
441 1/2 West Street, Brantford
Phone: (519) 770-0001
Hours: Mon-Wed 10-6, Thu-Fri 10-7, Sat 10-5, Sun 12-4
Wondering whether your mattress is part of why you sleep hot? Come lie on the breathable builds and feel the difference for yourself. No pressure, no commission, honest answers since 1997.
Related Reading
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- How to Sleep in Summer Heat Without AC
- How to Sleep During an Ontario Heat Wave