Best Thermostat Settings for Summer to Save Energy and Stay Cool

When Ontario summers heat up, your air conditioner becomes one of the biggest line items on your hydro bill. The encouraging part: dialing in your thermostat is one of the easiest, no-cost ways to cut cooling costs while staying comfortable.

Here are the settings our technicians recommend, plus the habits that make them work.

The Best Summer Thermostat Settings

The right temperature depends on whether you are home, away, or asleep.

When you are home

Set the thermostat to 24°C (75°F). This hits the sweet spot between comfort and efficiency, keeping you cool without the AC running flat out.

When you are away

Bump it up to 26 to 27°C (78 to 80°F). There is no reason to cool an empty house, and raising the setpoint while you are out is one of the simplest ways to lower your bill.

At night

Set it to 22 to 23°C (72 to 73°F). A slightly cooler bedroom helps most people sleep better, and overnight outdoor temperatures mean your system isn’t fighting peak afternoon heat to get there.

Why These Settings Matter

Your thermostat directly controls how long and how often the AC runs. Setting it lower than you need doesn’t cool the house any faster — it just makes the system run longer, burning more electricity and adding wear. Using sensible setpoints lets you:

• Lower your monthly hydro bill
• Reduce wear on the compressor and other parts
• Keep the home comfortable without overworking the system
• Extend the lifespan of your cooling equipment

Simple Tips to Cut Cooling Costs Further

Pair smart setpoints with these habits and the savings compound:

1. Use a programmable or smart thermostat to automate the home/away/night changes.
2. Keep blinds and curtains closed during peak afternoon sun.
3. Seal windows and doors so the cool air you paid for stays inside.
4. Don’t crank the thermostat way down — it won’t cool faster, it will only run longer.
5. Keep up with routine AC maintenance so the system runs at peak efficiency. Our AC maintenance checklist covers the essentials.

Should You Upgrade Your Thermostat?

If you are still using a basic manual thermostat, switching to a smart model is one of the highest-value small upgrades available. It adjusts temperatures automatically around your schedule, so you capture the savings without thinking about it.

The takeaway: 24°C at home, warmer when you’re out, slightly cooler at night — automated with a smart thermostat — is the simplest recipe for a comfortable home and a lower summer bill.

If your system still struggles to hold a setpoint or your bills stay stubbornly high, it may be time for a professional look — our guide on why your AC is raising your energy bills explains the usual culprits. Ready for help? Book a free quote and we will get your cooling system dialed in.