During summer, many enjoy getting some fresh air whenever they can—especially if that also means cutting costs on air conditioning bills. But when is the best time to get that fresh summer air into your home?

Read on and learn more about when to turn off the AC and open your windows.

The Best Time to Open Windows in Summer and Turn Off the AC

You can balance your cooling efficiency and indoor air quality by choosing the right time to open your windows. The best time is:

  • When the temperature and humidity outside are lower. It’s a common misconception that turning off the AC and opening windows at night in summer is more cost-effective. But this isn’t always the case. As a general rule, if humidity levels are above 65% outdoors, then it’s best to keep your windows shut. Otherwise, the next day your AC will have to work harder to manage that additional humidity, and it may still feel muggy indoors.

  • During cooler periods of summer. In Muncie, this means that early June and late August or early September are the best times to open the windows and turn off the AC. If temperatures and humidity drop low enough at night, though, you may be able to benefit from doing this throughout the entire summer.

  • When indoor air feels congested. Indoor air can be filled with dust, dirt, debris, smoke, viruses, and bacteria. Pollutants inside the home can be two to five times higher than outdoors. For this reason, we recommend you open your windows at the start of summer and periodically throughout the season to relieve some congestion and help with your overall indoor air quality (and your health)!


Related Content: How to Make a Room Cooler Without Air Conditioning

Does Opening Windows Increase Humidity in Summer?

As mentioned previously, this is generally only an issue if the air outside is warmer or more humid than the air inside your home.

If your AC is struggling to keep up with the humidity inside your home, you may either need AC repairs, ventilation installation, or a dehumidification system.

Is It Bad to Run the AC with Windows Open?

Yes. Running your AC and leaving the windows open can strain your air conditioning system. Your AC unit is responsible for circulating air and keeping your home at a set temperature.

When you open the windows, not only can that cool air escape and hot air enter, but it also interrupts the overall airflow inside your home. This can result in your AC system straining to keep your home at a consistent temperature.

Overworking your AC in this way can lead to:

  • Premature AC repairs or replacements

  • High energy bills

  • Humidity control issues

  • Hot and cold spots

  • Incorrect thermostat readings


That being said, you shouldn’t avoid ever opening your windows when the AC is on. Letting in some fresh air every so often is good and necessary. But keeping your windows open for longer than a few minutes while the AC is on isn’t advised for the reasons above.

What About Running the AC Fan Only with Windows Open?

If the temperature and humidity outside are low enough to open your windows, but the breeze isn’t quite strong enough to keep you comfortable, utilizing just the AC fan can help that air circulate better. Your AC fan by itself doesn’t consume much energy, making it a cost-effective way to keep your home cool. If you want to keep air moving while the windows are open, set your thermostat to “fan only.”

Should I Open My Attic Windows in the Summer?

It’s not recommended that you open your attic windows in summer if you plan on running your air conditioner. This will only let more hot air in, further straining your AC and trapping excess moisture inside. Instead, point a few fans upward at the ceiling in your attic to help some of that cool air circulate upwards. Or place the fans near any vents to help filter that hot air out.

Related Content: Attic Ventilation Has a Role in Air Conditioner Efficiency

Keep Cool in Muncie This Summer With Professional AC Services

If your AC is failing to keep your home cool this summer, count on the professionals at One Hour Heating & Air Conditioning of Muncie for air conditioning or heat pump solutions. Call (765) 204-1218, or contact us online to schedule air conditioner maintenance or repair in Muncie, Indiana.