Can Sleeping With the Windows Open in Summer Save Energy?

April 14, 2022
Open Windows in Colorado Springs, CO

Ensuring your home stays cool throughout the summer is obviously important. The only issue is that running your air conditioning all day and night can quickly add up to huge energy costs. Therefore, many people attempt to reduce their cooling costs by turning off their AC at night and sleeping with the windows open instead. While this may sound good in practice, the reality is that it may not make nearly as big of a difference as you might expect depending on the climate where you live. To understand why let’s look at how much energy an air conditioner typically uses at night and the impact of temperature and climate on energy use.

How Much Energy Does an AC Use at Night?

As you might imagine, air conditioners tend to use much less energy at night than they do during the day. Your air conditioner will obviously have to run much less frequently during the cooler evening than it does during the hottest parts of the afternoon and evening. On average, approximately two-thirds of an air conditioner’s daily energy usage occurs between noon and midnight, with the remaining one-third being used between midnight and noon.

On the face of things, this would seem to indicate that turning off your air conditioning at night could potentially reduce your energy usage by somewhere around 33%. However, this isn’t always the case as outdoor temperatures and high humidity levels can drastically reduce this number in some cases. In fact, for people who live in a hotter, more humid climate, opening windows at night will usually result in decreased comfort without doing much to reduce your energy costs.

Temperature and Humidity Factors

Most studies that have been done on this subject have focused on hot, humid climates like those found in the southern U.S. In one such study, researchers showed that turning off the air conditioner and opening windows at night resulted in an approximately 30% decrease in energy consumption. However, because the open windows allowed excess heat and humidity to get inside the home, daytime energy consumption rose by around 21%. The reason is that the air conditioner then had to work much harder when it was turned back on to eliminate the excess humidity from the home and bring the temperature back down. The humidity was an especially big factor since air conditioners don’t function nearly as efficiently in more humid conditions.

Turning off your AC at night will always save you at least some money. Nevertheless, the two most important factors are how warm or cool the nighttime temperatures are and how humid the air is. If the nighttime temperatures are below the temperature, you have your thermostat set to, opening your windows at night instead of using your AC is always a smart option.

This is great news for people in Colorado Springs since the average nighttime temperatures even during the hottest months of the year are still usually in the 50s. This means that opening your windows at night will usually cool off your house even more than if you left your AC running all night. As a result, your air conditioner generally won’t have to turn on again until later in the day when the temperature starts to heat up again.

Colorado Springs is categorized as an alpine desert climate, which means you generally will never have to worry about excess humidity. For these reasons, turning off the AC at night is something you may want to consider if you’re looking for ways to reduce your energy bills. People who suffer from allergies or other respiratory issues are probably better off leaving the windows closed throughout the summer. Opening your windows does replenish the fresh air inside your house and can reduce the concentration of airborne pollutants. However, it also enables pollen, mold spores, and other allergens to get inside the home and potentially cause or worsen your allergy symptoms.

Professional Heating and Air Conditioning Services

With more than 30 years of experience serving customers in Colorado Springs and the surrounding area, Home Heating Service, Inc. is the one to trust for all your home’s heating and cooling needs. Our NATE-certified HVAC technicians can service and repair all types of heating and cooling equipment or install any new equipment you may need. We also specialize in indoor air quality, gas fireplaces, insulation and attic sealing, home energy audits, and much more. Contact us today if you have any questions or want to schedule an appointment.