The Open and Shut Case on Windows and A/C in Spring & Fall
June 22, 2023
When it comes to the fluctuating temperatures of spring and fall, many people find themselves in a house divided: those who want to run the air conditioning early and often and those who want to keep windows open. Many times there is a compromise and families switch between running the A/C during the day’s warmer hours and opening windows in the cool of the night.
There are certainly advantages to letting the fresh air in, but there are also some very real considerations related to the operational performance and lifespan of your HVAC system.
While we may not be able to totally referee the seasonal debate at your home, we can run through the pros and cons of this practice and give you some good information to make the best decision where you live.
To be clear, this is not an article to ward you off of opening your windows and enjoying the outside breezes, so we’ll start there with the benefits of fresh air circulation:
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Say goodbye to stale air:
The recycled air in your home can become a host to potential toxins including mold spores, dust, smoke, viruses and bacteria. If you don’t let fresh air cycle in periodically, you may be at a higher risk of becoming sick. Inhaling stale air can also make you feel drowsy and in more severe cases can cause headaches, dizziness, nausea, and irritation in your eyes, nose, and throat.
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Your lungs will thank you:
Fresh air generally contains higher levels of oxygen than indoor air. Extra oxygen allows your lungs better dilation for more effective tissue repair and filtration, as well as improves your heart rate and blood pressure.
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No more “weeping windows”:
Does your home suffer from weeping windows? When windows are kept closed and there’s insufficient air circulation inside, condensation can form on the panes. If ignored, this moisture can create serious problems. Mold, bacteria, and other toxins can start to build up and possibly cause illness in those living in the home. When these indoor toxins are present, you need to take steps to remove them. Opening a window for a few minutes daily can prevent the condensation from forming in the first place.
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Reduce or eliminate radon gas:
Radon is a colorless, odorless radioactive gas that is naturally found in trace amounts within the atmosphere. Outside, the gas disperses naturally and doesn’t pose a health risk. However, radon can become trapped indoors after it enters through cracks and other holes in the foundation. Breathing radon over time increases your risk of lung cancer. Radon is the second leading cause of lung cancer in the United States. Opening your windows allows fresh air to cycle through your home and mitigates the impact of radon gas. You can also have your home professionally tested for radon gas, and your local One Hour Heating and Air professionals are expertly trained in how to provide this service.
“Sounds like shutting off the A/C and opening windows is the way to go!”
In some energy savings studies, it was found that shutting off your air conditioning unit at night can reduce energy usage by up to 30%. On the surface, that’s a notable savings and a compelling reason to give your A/C a rest. However, there are important considerations on the other side of that coin.
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Extra effort = more wear & tear:
The extra energy needed to lower your home’s temperature after leaving your windows open all night means your air conditioning unit is working harder and using up to 20% more energy. This greatly narrows the benefit margin of the 30% savings on your energy bill. If this A/C restart happens often enough during milder months it can negatively impact the average lifespan of your unit with faster wear and tear.
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Humidity and your A/C:
Moist air carries more heat than dry air and depending on where you live, leaving windows open will let in a lot of humidity. Cooling that air and cycling out the moisture takes a toll on air conditioning. One study found that open-window ventilation at night increased the amount of moisture by about 5 gallons a day versus a house that kept its windows closed at night. Now, imagine the strain an A/C unit as it works to overcome that higher moisture and warmer temperatures to bring the home to daytime comfort levels.
“Wait…so are you saying I shouldn’t open my windows at night then?!”
Not at all! As with most things in life, moderation is key. The off-again-on-again practice of A/C by day and open windows by night can reduce your system’s performance if it’s done constantly over a long period of time. There are a few ways to strike a better balance.
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Set a schedule:
If you’re going to take this approach, choose days when the outside temperature is close to the desired indoor temperature of your home, usually within 3-degrees. Perhaps choose one or two days a week to do this, based on your local forecast, and allow your system to run at peak efficiency with closed windows the rest of the week. This will provide periodic fresh air circulation benefits, while reducing strain on your A/C units. If you leave your windows open at night, close the windows AND the blinds (or curtains) in the morning so the A/C doesn’t have to fight outside light and heat while cooling your house.
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Thermostat settings:
You can save about 10% on your energy bills by turning your thermostat back between 7 and 10 degrees for 8 hours a day from its normal setting, according to the Department of Energy. That’s good news for customers in the milder climates like the southeast; your savings will be greater than those living in harsher climates.
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Automate your energy savings:
Energy.gov suggests keeping your summer thermostat set at 78 degrees (F) when you’re home and raising it when you know you’ll be away. The easiest way to do this is to install a programmable smart thermostat that can operate on a pre-set schedule or even sense when rooms aren’t being used and adjust your A/C to ideal settings accordingly. In this same sense, you can program your thermostat to anticipate and respond to periods of fresh air circulation by having it raise the temperature while windows are open and then cool the air slowly during the day, versus a total shut-off while windows are open and restart when they are closed.
To achieve the maximum operational performance of your air conditioning system, let One Hour Heating and Air professionals conduct a comprehensive seasonal tune-up and inspection. Our highly-skilled technicians can also install smart HVAC technology and help you find the optimum settings for your home and energy bills.
Warmer weather is coming soon, act now before summer starts. Our professionals are your go-to HVAC team in North and South Carolina!
Visit www.onehourac.comfor our weekly and monthly specials. Call our 24/7 customer service line today 704-251-0610.