What Temperature Should You Set Your Thermostat in Fall?

There is a very specific kind of madness that takes over Ontario homes around mid-October. You wake up freezing, throw on three layers of fleece, and by 2:00 PM you are throwing open the windows because the afternoon sun has turned your living room into a sauna. It is a daily headache.

Whether you are trying to keep a drafty older home cozy in Markham, Richmond Hill, or Scarborough, or dealing with uneven heating in a newer build in Vaughan, Mississauga, or Newmarket, you are caught in the middle of this autumn weather rollercoaster. And honestly, the story is exactly the same from Ottawa down to London, and all across Waterloo, Barrie, Hamilton, Burlington, and Kanata. You want to stay warm, but nobody wants to wince when they open their next utility bill.

So, what is the actual sweet spot for your thermostat when the leaves start piling up? Let's skip the dry technical manuals and look at a realistic, comfortable setup for your home.

Finding Your Household’s Comfort Sweet Spot

First off, forget the idea of setting one temperature and leaving it alone all day. That is just pouring money down the drain. Your body—and your home's structure—needs different temperatures at different times.

• When you’re active during the day (20°C to 22°C): This is the sweet spot for general awake hours. If you're wearing a light sweater and moving around, you'll be perfectly cozy without your furnace working overtime.
• If you have babies or seniors at home: You'll want to tweak things slightly here. Babies can't regulate their own body temperature very well, so keeping their space right around 20°C to 22°C is best. For older family members, sitting closer to 22°C or 24°C is much better for circulation and keeping joint stiffness at bay.
• When everyone is asleep (17°C to 19°C): Do not pay to heat a house while you are unconscious under a heavy duvet. Letting the temperature drop a few degrees at night actually helps your brain fall into a deeper, more restorative sleep cycle. Plus, you'll shave about 2% off your heating costs for every single degree you drop.
• When the house is empty during work hours (17°C): If everyone is out of the house, let the thermostat drop. But don't let it plunge too low—keeping it at 17°C ensures your furnace doesn't have to work in absolute overdrive to warm the place back up when you get home.
• The absolute danger zones (16°C and below): It might be tempting to set the thermostat to 14°C to save a buck, but please don't do it. When your home drops below 16°C, the air holds more relative humidity, which causes condensation to pool on your windows and walls. Hello, mold. And if you go away for a fall weekend, never go below 12°C or 13°C. One unexpected cold snap and your pipes will freeze and burst inside the walls.

Stop Playing "Thermostat Tug-of-War"

We have all done it. It’s a chilly morning, so you crank the heat. By afternoon, it feels like mid-July, so you switch the thermostat straight to AC.

This is one of the worst things you can do to your HVAC system. Rapidly toggling between heating and cooling places massive physical stress on your blower fans, compressor valves, and electrical relays. If your system is running a cycle and you abruptly force it to switch directions, it can short-cycle, which ruins its efficiency and can lead to a sudden, expensive breakdown.

Try to let your system finish its active cycle completely before you make any adjustments. Ideally, try to pick one mode and stick to it for the day.

When should the furnace officially go on for the year?

A good rule of thumb is to fire it up when overnight outdoor temperatures consistently start hovering around 10°C. Doing this early gives you a chance to run the system, make sure the burners ignite cleanly, and catch any weird rattles or smells before the freezing winter rush begins.

And don't forget your outdoor taps! Go into your basement, shut off the indoor water valve connected to your outside faucets, and then open the outside tap wide so any leftover water can drain out. That stops ice from expanding and splitting your pipes inside your walls.

Let Technology Do the Chores

If you're still adjusting a manual dial on your wall every few hours, you are fighting a losing battle. Smart thermostats—like Nest, Ecobee, Honeywell, or Lennox—take the human error out of the equation. In fact, an Energy Star-certified smart thermostat can cut your heating bills by 8% or more just by being smart.

Here is what they actually do behind the scenes:

• They use geofencing to track your phone's GPS, automatically dropping the heat when you walk out the door and warming things up right before you pull into the driveway.
• They use remote sensors to balance out multi-level homes. If your second-story bedrooms are freezing while your living room is warm, these sensors average the temperature out so you don't get drafty cold spots.
• Some can even link with your local Ontario utility rates, running your heat pump or furnace during off-peak hours when electricity is cheapest. You can even sign up for Ontario's Peak Perks program, which rewards you for letting the grid make minor, unnoticeable adjustments during high-demand times.

Ontario’s Home Renovation Savings Program (Free Money on the Table)

If you want to grab a smart thermostat or upgrade to a high-efficiency system, you can get some serious financial help right now. The provincial Home Renovation Savings (HRS) program runs until November 30, 2026, and it is packed with great rebates.

The program splits into two straightforward paths:

• Path A (The Bundled Path): This requires a professional home energy assessment before and after you do the work. You have to complete at least two qualifying upgrades—like combining insulation with new doors—to unlock up to $7,700 in rebates, plus a $600 credit to fully cover the cost of your energy audits.
• Path B (The Standalone Path): This is the best part—no home energy assessment needed! You can just get single, targeted upgrades done. You can get $75 to $100 back for an Energy Star smart thermostat, up to $7,500 for a cold-climate air-source heat pump, up to $12,000 for geothermal heat pumps, $500 for a heat pump water heater, and up to $10,000 for rooftop solar panels and battery storage.

Just remember: your home must be connected to the Ontario electricity grid to qualify (Cornwall Electric customers are out because their power comes from Quebec). Also, homes occupied for less than six months and stacked townhouses don't qualify. And while the federal Canada Greener Homes Loan closed for new applications on October 1, 2025, anyone who was already approved still has a 12-month window to finish their projects and claim their funds.

The "Attic Trick" That Stops You from Burning Money

The best thermostat in the world won’t save you a dime if your home’s insulation is paper-thin.

If your home was built before 2010, you probably have attic insulation between R-10 and R-32. Today’s Ontario building code requires a minimum of R-60. Upgrading your attic insulation can stop up to 25% of your home's heat from floating right out of your roof, slashing your overall energy bills by 20% to 50%.

Under the standalone Path B rebates (no assessment required), you can get cash back just for topping up your attic to at least R-50 using an approved contractor:

• If your attic is currently sitting at R-12 or less, you qualify for a $1,250 rebate.
• If you are between R-12 and R-25, you qualify for a $1,000 rebate.
• If you are between R-25 and R-35, you get an $800 rebate.

Combine that with professional air sealing—which stops hidden drafts from bypassing your insulation altogether—and your home will feel like a completely different space. Constant Home Comfort can get your attic insulated starting at just $799 after your rebates are applied.

Your Quick Fall Prep Checklist

Before the freezing winter weather settles in, spend a weekend running through these quick tasks to make sure your system is ready to work efficiently:

• Swap your air filters: Clean filters let air flow freely, which stops your furnace from working twice as hard and keeps your bills low. Change them every three months.
• Reverse your ceiling fans: Switch them to run clockwise on a low speed. This draws cool air upward and gently pushes the warm air pooled at the ceiling down to where you are actually sitting.
• Bleed your radiators: If you use a boiler, bleed the trapped air out of your radiators once or twice a year so they can fill completely with hot water.
• Clear the vents: Double-check that furniture, area rugs, drapes, or pet beds are not blocking any heating registers or return vents.
• Get a professional tune-up: A licensed tech should clean your burners, check the heat exchanger for dangerous micro-cracks, test gas connections, and lubricate moving parts to keep everything running safely.

Let Constant Home Comfort Handle the Hard Part

Trying to navigate energy programs, deal with energy audits, and calculate R-values can feel like a full-time job. That is where Constant Home Comfort comes in.

We are an approved, registered contractor under Ontario's Home Renovation Savings Program. We will verify your eligibility, help you map out the best upgrades, and submit your entire rebate application for you at absolutely no extra cost.

Whether you need a quick seasonal furnace tune-up, a brand-new high-efficiency system, a versatile ductless heat pump starting at just $49.99 a month, or an insulation top-up starting at $799 after rebates, we have got you covered. We carry top-tier brands like Lennox, KeepRite, Goodman, and Gree, and offer flexible rent-to-own or $0 down, 0% interest financing options on approved credit (O.A.C.).

Keep your home comfortable and your bills low this season. Give Constant Home Comfort a call today at 1-888-675-5907 for your fast, hassle-free quote!