When summer hits Ottawa, keeping your home cool becomes a top priority. But while AC brings relief from the heat, it raises a key question: what temperature should you actually set the thermostat to?
The goal is balancing comfort and energy efficiency. The right setting keeps you comfortable without overworking the system or your budget.
The ideal AC temperature
For most households, the ideal AC temperature in summer is between 24°C and 26°C (75°F to 78°F). This range is recommended by energy authorities and HVAC professionals because it maintains comfort while keeping electricity use in check.
It is tempting to set the thermostat to 20°C on a scorching day, but that usually means more energy use and a heftier electricity bill.
Adjust based on your day
When you are home. Stick to 24°C–26°C. That is the sweet spot for comfort and savings.
When you are away. Raise the setting to 28°C–30°C, or turn it off if no one will be home for hours. You can save real money on electricity without giving up comfort when you return.
At night. Lowering slightly to 23°C–24°C helps with sleep. Use eco mode or a programmable timer to ease the temperature down gradually.
Keep indoor and outdoor within 12°C
A major tip from health experts: avoid drastic indoor/outdoor temperature differences. A gap of more than 12°C can shock your system and your body. If it is 34°C outside, keep indoor air around 24°C–26°C, not lower.
Boost comfort without overcooling
Lowering the thermostat is not the only path to feeling cooler:
- Use ceiling or oscillating fans to circulate air
- Keep blinds or curtains closed during the hottest hours
- Seal windows and doors so the cool air does not escape
- Add a dehumidifier to cut humidity and raise apparent comfort
These work together to support your AC and reduce its load.
Smart thermostats and energy savings
A smart thermostat is a step change. It learns your schedule, adjusts when you are away, and can even respond to outdoor temperature shifts. Many models track energy usage and flag maintenance reminders. Connected to your phone, you can manage the AC remotely so you never cool an empty house.
Is it OK to sleep with the AC on all night?
Yes, smartly. Set the thermostat around 23°C–24°C, turn on night mode if your system offers it, and make sure airflow is not blowing directly at your bed. Pair it with fans to maintain comfort while easing the load on the system.
What if it is 30°C+ outside?
Do not drop the thermostat to extremes just because it is hot. AC is designed to cool steadily, not instantly. Overcooling wastes energy and causes wear. Focus on air circulation, humidity control, and reducing heat gain through windows.
Is 20°C too low?
In most cases, yes. Going below 24°C typically increases energy use by 3 to 5% per degree and can leave you with a dry throat or chills. Unless medically necessary, moderate cooling is better for both your comfort and your bill.
When the unit struggles
If your system struggles to hold temperature, or your bills are unusually high, it may be time to look at a higher-efficiency replacement. Modern units use less energy, cool more effectively, and qualify for several Ontario rebate programs.
If you are seeing uneven cooling, strange noises, short cycling, or rising energy bills, those point to clogged filters, low refrigerant, worn components, or a failing compressor. Catching it early prevents a peak-summer breakdown. Our AC repair team diagnoses quickly and gives you the honest read on repair versus replacement.
Finding the right temperature
Every home is different, comfort is personal. But keeping the thermostat between 24°C and 26°C during the day, adjusting around your routine, and supporting the AC with the basics will keep you cool without overspending.
