April 14, 2022
Open Window in Amherst, NY

Ensuring your home stays cool and comfortable during the summer can be costly. For this reason, many people attempt to reduce their cooling costs by only running their air conditioner as little as possible. One such option is to open your windows at night instead of using the AC. Still, the question is whether or not this will actually save you money?

Estimated Energy Savings from Turning AC Off at Night

It probably won’t surprise you to learn that a central AC system uses far more energy during the day than at night. In hotter, more humid climates, somewhere around two-thirds of the system’s total energy consumption occurs between the hours of noon and midnight. This percentage can be even greater in milder climates like Upstate New York since the evenings tend to be fairly cool. In this case, as much as 75% of the total energy consumption will occur during daytime hours.

Studies have shown that, on average, shutting off your air conditioner at night will reduce your total cooling costs by somewhere around 30% compared to leaving it turned on 24 hours a day. However, this depends in large part on how warm it is at night as well as the humidity level.

Factoring in Outdoor Temperatures and Humidity Level

If the nighttime temperature is similar to or below what you have your thermostat set to, opening your windows at night is generally always a better option than running your air conditioning. On the other hand, if the nighttime temperature is still into the 80s or the weather is especially humid, shutting off your AC at night won’t make all that much of a difference in terms of your total energy consumption.

If the outdoor temperature is much hotter than what you have your thermostat set to, opening the windows will end up heating the house instead of cooling it. In this situation, your AC will have to work a bit harder the next day to cool the house back down. Still, this added load won’t be nearly enough to cancel out the energy savings you’ll get by turning the AC off at night. This means that the bigger issue in this situation is the effect that opening the windows will have on your comfort.

A much bigger issue is if it is especially humid out. If the humidity level outside is much above 65%, you are usually much better off keeping your windows closed at night and using your AC instead. The reason is that opening your windows allows all of that humid air to get inside the house and soak into your furnishings.

Air conditioners have to work much harder when the humidity level inside the house is higher. This means that when you turn the system back on in the morning, it will need to run for much longer to dehumidify the air and cool the house. Studies have shown that in humid environments, leaving the windows open and the AC off at night can increase the system’s daytime energy consumption by more than 20%. This means that opening your windows at night will not only negatively impact your comfort but also potentially cancel out any energy savings you got by turning the AC off.

Ensuring You Stay Cool and Comfortable at Night

As long as the weather outside isn’t excessively hot or humid, keeping your AC switched off while you sleep is a great way to reduce your energy costs. In fact, even in the nighttime temperatures are still in the 80s, this is still a good option as long as it isn’t too humid outside. After all, you could simply use a fan or two in your bedroom to help ensure you stay cool as you sleep.

Compared to a central AC system, running a fan all night will use approximately 1% of the total energy that the AC system would use. In fact, a central AC system will generally use more energy in 10 to 15 minutes than a fan would if it was left on for 24 hours. This means you could easily use multiple fans in every bedroom or every room of the house at night and still save money compared to running your AC at night.

Expert Cooling Services and More

At Heatwave Heating & Cooling, we understand the importance of keeping your home cool during the summer and are here to help you in any way we can. We have been providing professional heating and cooling services to customers in Amherst for more than 15 years, and our NATE-certified HVAC technicians have the knowledge and skills to ensure your home remains comfortable all year long. We specialize in all types of heating and cooling installations, repairs and maintenance, and we work on all makes and models of HVAC equipment. To learn more about your cooling options or any of our other services, give Heatwave Heating & Cooling a call today.

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