Oh, those Ontario summers – hot and humid, the excellent combination that makes those high temperatures feel even higher. So, whenever possible, you remain inside and enjoy the chilling effect of the AC, right?!
However, running the AC non-stop is definitely not too healthy, not to mention the high energy bills. That’s why opening your windows from time to time is recommended. Nonetheless, you should do this strategically – otherwise, you actually risk spending more on energy bills! We’ll explain everything, don’t worry!
So, if you’re wondering when to turn off AC and open windows for the best indoor comfort and energy consumption, read on!
Key Takeaways
- Turn off the AC and open your windows in the early morning, late evening, or at night when outdoor temperatures are cooler than indoors for natural cooling.
- Monitor outdoor temperature and humidity levels before turning off the AC; keep windows closed during high heat and humidity.
- Switching off the AC can improve indoor air quality and save energy, but avoid common mistakes like leaving windows open during peak heat.
- If your AC is struggling to keep your home cool, it may be time to assess the condition of your windows or equip them with insulating layers, like Magic’s thermal blinds.
Best Time to Turn Off AC and Open Windows
The best time to turn off AC and open windows is in the evening, at night, and early morning. Obviously, there are exceptions to this rule. Here are some general guidelines to consider:
- You should only open windows in the evening when the outside temperature is lower than the temperature on your thermostat. This method is usually effective when evening temperatures drop to around 70 degrees or less, which is common for later summer or early fall.
- If you like to sleep with open windows at night, make sure to wake up early and close them before the sun rises or shortly after to avoid warm air getting inside.
Does Turning Off the AC and Opening Windows Save Money?
Turning off the AC and opening your windows can help you save money on energy bills, but only under specific conditions. Let’s say the temperature inside your house is 75.2 degrees after running the AC all day. It’s a late summer evening, the temperatures have slightly dropped, and you want to open windows to let fresh air in and give your AC a break. The outside temperature is 80.6 degrees. In this case, turning off the AC and opening all the windows won’t help you save money.
Even if the difference between indoor and outdoor air temperature seems insignificant, the air outside your house is still warmer than the air inside your house. So, it will enter your home and obviously warm it up. You may not notice it at first, but if you keep the windows open all night and in the morning, when the sun starts shining bright, your air conditioning systems will have to work twice as hard to reach the desired temperature.
However, temperature isn’t the only thing to consider. Let’s talk humidity.
Turning Off AC: Indoor Temperature vs. Outdoor Temperature vs. Humidity Levels
Turning off the air conditioner and opening all windows when outdoor humidity levels are higher than 50%-60% is not a good idea. Let’s see why.
Let’s say the temperature inside your house is 75.2 degrees, and the outdoor temperature is 71.6 degrees. At first thought, opening the windows may seem like a great idea, right? Not so fast. You should check the humidity first. Why? Because if the outdoor air is humid, it will enter the house. Consequently, your AC will work twice as hard the next day. We’ll explain in a bit why.
Over the night, you’ll feel just fine. When the house starts warming up in the morning, the high humidity acquired during the night will make the house feel much hotter. Why? Our bodies thermoregulate by sweating, which means that sweat keeps us cool. However, this is only valid when sweat evaporates. When humidity levels are high, sweat doesn’t evaporate as easily, so air feels hotter.
Therefore, if you run the AC when the air is humid at the same level as when it is dry, you won’t get the desired effects. You simply won’t notice that the temperature drops. To get the desired cooling effect, the AC will have to run harder and for longer.
Studies have shown that when homeowners turn off the AC at night, the electricity use drops by approximately 30%. However, if outdoor humidity levels are high, the electricity use during the day when the air conditioner is on increases by 21%.
Now, let’s see how humid the air is in Ontario to understand if it’s worth it to turn the AC off.
Humidity Levels Ontario
Without a doubt, winters in Ontario are quite humid, reaching an average relative humidity of 94.05%, but summers aren’t far behind, reaching an average relative humidity of 72.42% in August. Considering that Ontario is bordered by Hudson Bay in the North-East and Lake Superior and Lake Huron in the South and South-West, it’s unsurprising that most of its territory has humid air. Not to mention how many smaller lakes there are in the entire territory of Ontario.
According to climatologists’ observations, the air is much more humid in the morning than in the afternoon, which is why leaving the windows open at night is not a great idea in this case. In some regions, like Peterborough, Ontario and Thunder Bay, Ontario, the morning humidity levels can pass 90%.
Benefits of Turning Off AC and Keeping the Windows Open
If turning the air conditioner off is an option, considering outdoor temperature and humidity, go for it! Without a doubt, fresh air is a necessity if we want to stay healthy.
By opening your windows, you contribute to reducing the concentration of pollutants such as mold spores, dust, and bacteria. This can notably improve the quality of indoor air. While some air conditioners do keep pollutants and debris out of the air, opening your windows from time to time is still recommended. Additionally, air circulation can enhance overall comfort and well-being by introducing a natural breeze into your home.
Using natural ventilation instead of an air conditioning unit can lead to substantial energy savings. By relying less on your AC during the cooler parts of the day or night, you can reduce your energy consumption and lower your utility bills. This approach not only saves money but also extends the lifespan of your AC unit by reducing its workload.
Common Mistakes to Avoid
Here are some common mistakes you should avoid when it comes to running air conditioning units and opening all the windows:
- Don’t keep your windows open when the air conditioner is on. This will make the system work harder because the cool air will escape the house quickly. If the thermostat is close to the window that stays open, the AC will find it very difficult to cool the air because of the heat that enters through the window.
- Keep your air conditioner on during the day unless there are extra measures that help maintain the air cool. For example, if you have thermal blinds and curtains that serve as an insulating layer, you can definitely give your air conditioning system a break.
- Don’t set the AC at a very low temperature to run it for a few hours and then switch it off. This will make the air conditioner work twice as hard, and the energy costs will increase.
- Don’t let your AC run all day if you’re not at home. If you have a programmable thermostat, you can make sure the air conditioner will turn on automatically 30 minutes or 1 hour before you arrive.
Tips for Keeping Your House Cool During Summer
In the end, the main reasoning behind the turning off AC and opening the windows debate comes down to energy efficiency and insulation. Besides letting fresh air in, our primary goal is to lower the estimated energy savings and contribute to environmental efforts, right? That’s why we’ve prepared some tips for keeping your house cool during summer (and warm during winter!), so read on!
Replace Your Windows If They’re Old
Windows are directly linked to ensuring a comfortable indoor environment. Alongside doors, they are the main entrance points for heat and cold. Therefore, if your windows are old and drafty, it may be time to replace them. This can be an expensive investment but it’s definitely worth it in the long run, especially if you pick windows with a good energy rating.
Magic windows are by far the most energy-efficient windows in Ontario. Why so? Because they’re tailored specifically to the Ontario weather. We have the possibility to customize all our products according to the climate of your region, personal preferences, and design needs.
Our Insulated Glass Units have the best-performing warm-edge spacers and 35% more gas fills than other windows on the market. In addition, you can equip your windows with Low-E coatings, which contribute significantly to energy savings by preventing hot air from entering the house.
Install Thermal Blinds
High-quality thermal blinds can truly make a difference. Magic’s fully retractable thermal blinds, for example, improve a window’s energy efficiency by 40%. This translates into lower energy bills. Since Magic’s thermal blinds are built into the window frame, you don’t need to sacrifice window aesthetics for energy-saving performance!
Let’s say you leave your windows open during the night because temperature and humidity conditions favor it. Without thermal blinds, you’ll have to close the windows early in the morning and turn on the air conditioner because the sun can quickly warm the house up. If you have thermal blinds, you can simply open them in the morning, and your house will stay cool for much longer because they prevent any sun rays and UV radiation from getting in.
Home Insulation
The walls, the roof, and the floor also absorb heat during the summer. Therefore, you may want to check how well your home is insulated and solve any related issues as soon as possible. This can help you save money on energy bills in the long run. In the end, insulating your house isn’t only beneficial during summer. It will also keep your house warm during winter.
Summary
In conclusion, you should only turn off the air conditioner and open your windows in the evening, at night, and in the morning, when the outdoor temperature is lower than the indoor air temperature and when outdoor humidity levels are at most 60%. During the day, keep your windows closed and your air conditioning unit on at a stable temperature.
If you notice that your AC starts working harder during the day, there may be an issue with your windows’ insulation. If they’ve outlived their life expectancy, you may want to consider installing new energy-efficient windows. In this case, you can book a free consultation with Magic – one of our project managers will assess the condition of your windows and advise you if a replacement is indeed recommended.
Frequently Asked Questions
When should I open my windows instead of AC?
The best time to open windows for cooling is early morning and late evening when outdoor temperatures are cooler than indoor air temperatures. Make sure to check outdoor humidity levels – if they’re higher than 50%-60%, keep the windows closed.
What temperature to open windows at night?
Turn off the air conditioners and open your windows in the summer when nighttime temperatures are below 70 degrees and humidity levels are below 50%-60%.
When is it too humid to open windows?
If outdoor humidity levels pass 50%-60%, you should keep the windows closed. You can only open them for around 5 minutes to let some fresh air in.
Should I open my windows at night if I have no AC?
If you do not have an AC system, you can open your windows at night, especially if the temperature outside is lower than the temperature inside. During the day, keep your windows closed and use blinds or curtains to keep your house cool.
Can opening windows improve indoor air quality?
Yes, opening windows can reduce indoor air pollutants and improve overall air quality by increasing ventilation. It’s a simple and effective way to freshen up the air in your home.
What are common mistakes to avoid when using AC and windows?
Make sure to avoid leaving windows open during hot weather and keep an eye on humidity levels, as these can lower the cooling efficiency of your AC.