April 25, 2023
HVAC Technician Talking to Customer in Salem, OR

When you feel a cool evening breeze outside, you might wonder: Is your home’s AC system really necessary? Many people think that shutting off the air conditioning and opening windows at night can be a great way to save on electric bills. Technically, opening your windows at night can cool your home, but it might not be as energy efficient as you hope it will be. Before you turn off your AC and fling open your windows, there are a few things you need to know.

Open Windows Let Damaging Humidity Into Your Home

One of the biggest concerns with open windows is humidity. Salem gets about 45 inches of rain each year, which is well above the national average. This creates a damp, humid climate that can wreak havoc inside your home. Every night that you sleep with the windows open, you could be letting a lot of humidity into your home.

Unfortunately, with the air conditioning switched off, you’re also interfering with your home’s ability to dehumidify itself. Modern homes control indoor humidity by running the AC. When the AC is turned off, the humidity just builds up. Excess humidity can be bad for your home and your health, and there’s no way to avoid it unless the weather is nice and dry that evening.

When your home’s indoor humidity levels are consistently above 50% humidity, the risk of mold starts to increase. Mold and mildew can discolor your walls, cause your home to smell musty, and increase the risk of respiratory problems. High humidity levels can also wreak havoc on electronics and damage upholstery and paper products.

There is one easy way to keep indoor humidity levels under control: Keep your windows closed at night.

Many People End Up Getting Too Hot as the Sun Rises

It might be cool and breezy when you go to bed, but if you follow a modern sleep schedule, sleeping with open windows is not always comfortable all night long. The problem is that your home starts heating up the second the sun rises. Unless you’re waking up around 6 a.m., you will end up finding that your house is already too warm by the time you get up.

AC units are helpful because they automatically adjust to manage your home’s temperature. However, if you turn your air conditioner off before bedtime and opened your windows, you have no way to easily adjust the temperatures. While you’re sleeping, your house will start to warm up. This can make it hard to stay comfortable and sleep well. If you don’t like waking up in a tangle of sweaty sheets, you’ll be better off closing the window and letting the air conditioner do its job. Unlike the great outdoors, your thermostat can keep tabs on the temperature and respond to rising temperatures, turning the air conditioner on and off as needed to keep your home cool and comfortable.

Your System Might End Up Working Harder Overall

Keep in mind that opening windows at night might not save as much energy as you hope. When temperatures are cooler outside, your AC does not need to work hard at all. Most of the time, your AC will only kick on once or twice throughout the night. The residual coolness from the outdoors allows your home to easily maintain a comfortable temperature.

However, if you open your windows, you could be letting humidity or heat into your house. Your AC might not run for a few minutes during the night, but by the time you close your windows, your home might be warmer and damper than it otherwise would have been. Your AC will need to run for a few extra hours each morning to dehumidify and cool the house. Ultimately, the power you save at night doesn’t usually compensate for the extra energy during the day. Research has found that in humid environments, opening windows and shutting off the AC at night could increase your daytime energy consumption by over 20%.

Keeping Your AC On and Windows Open Never Works

Some homeowners try to compromise by setting their AC temperature a little higher and opening windows as well. They hope that the open windows will take on some of the air conditioner’s workload while the running AC will keep humidity levels down. The truth is that this will not provide you with the best of both worlds.

Unfortunately, this is one of the least efficient options you can choose. Your AC is designed to work in a closed system. AC size and fan size are carefully calculated to move air around inside your home. When the windows are open, your AC cannot circulate air properly. Cooled, dehumidified air will easily float outside while moist outdoor air rushes in. This makes it run longer and struggle to keep your home at a comfortable temperature.

Sleeping With Open Windows Has Other Potential Risks

As you can see, sleeping with open windows usually only keeps your home cool and comfortable if the weather is unusually cool and dry and you can wake up in time to turn on your AC at sunrise. However, even in these situations, the pros of saving a few cents on your electric bill don’t outweigh the potential cons of sleeping with your window open.

You might worry about other unrelated issues as well, including safety concerns or increased worries about pollen and other airborne allergens and irritants. Depending on the types of pests around your home, open windows can also let in clouds of gnats, disease-carrying mosquitoes, or other bugs.

Ways to Cool Your Home More Efficiently at Night

If you’re tired of high electric bills and want to save money, what can you do? For many homeowners, one convenient option is running a fan. Ceiling fans can help circulate air and provide a cooling breeze while you sleep. You might find that you can turn off your AC and get by with a fan just fine at night. As long as you keep your windows closed, you won’t face any issues with humidity.

You can also try switching to a programmable thermostat and adjusting your air conditioning system to accommodate your preferred temperature. A programmable thermostat lets you set up your AC to switch to a higher temperature once you fall asleep. Just bumping your thermostat temperature up by 7 degrees while you sleep reduces your cooling costs by 10%, and since it happens after you fall asleep, you’re less likely to notice the change.

Ultimately, most homeowners are better off just running their air conditioning system. Unless the weather happens to be particularly perfect, the benefits don’t outweigh the risks. If you’re looking for ways to save, Woodward Heating Air Plumbing can help. We’re happy to install an energy-efficient system or service your current system so it runs better. Our team also provides Salem residents with a variety of other HVAC repairs, installations, and maintenance. Give Woodward Heating Air Plumbing a call today to learn more about our services.

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