Does Opening Windows in Summer Increase Humidity?

Many people believe that opening a window in the summertime is the best way to ventilate their home and keep it cool. However, opening your windows, especially when it is hot outside, will add more humidity to your house and potentially increase your HVAC bill.

Opening your windows in the summertime increases the humidity in your home. Your HVAC will have difficulty removing the moisture in your home efficiently as the open window will constantly circle in fresh air.

So, let’s get into the details and talk more about how opening a window in the summertime will affect the temperature and humidity in your home.

Why Does Opening the Windows in Summer Increase Humidity?

When your home is hot in the summer, most peoples’ first instinct is to open the window. However, that’s not usually the best way to cool off your space.

Opening your windows in summer may increase the humidity in your home since warmer summer air is more humid. AC units also strip the moisture from the air in your building, and when you bring in more air from outside, the unit will have to work overtime to deliver your intended results.

You may be wondering what factors affect the humidity in your home and why opening your windows in the summertime is not always the best idea if you want to keep your home cool and dry. Well, let’s talk about that.

Warmer Air Is More Humid

When the weather outside is hot, the air is generally more humid.

That’s because water evaporates more quickly in hot weather, changing from liquid to gas in the heat of the sun.

In addition, when water and air are both hot, their particles vibrate more quickly, causing them to rise. That’s how clouds form– hot air and moisture rise until they get colder in the sky and condense.

The same thing happens in your home when you open the window. Air from the outdoors will enter your home, bringing in warm humidity.

Still, the amount of humidity that enters your house will differ depending on the climate of the area you live in and how much sunlight your house’s location is exposed to. If you live in a naturally humid place, and if your home gets a lot of sunlight, you can expect the air to be more humid.

So, since there is so much humidity in the summer air, you will likely make your home warmer and more humid by opening your windows.

Air Conditioning Units Filter Out Humidity

AC units work by circulating air throughout your home.

AC units constantly use the same air that is already in your house, keeping it trapped inside to make sure that the indoor air stays cool. When your unit is on, the air conditioner pulls in air, cools it, then seals it inside your house, keeping warmer, more humid air outside.

As your AC unit recirculates the air inside your home, it removes moisture using an air condenser. Most AC units are connected to a condensate pump, which drains all of the water from the air in your home, pumps it out, and deposits it in the sewage system.

So, since AC units strip the moisture from the air in your home and reuse that air to keep the entire building cool, opening a window will introduce more humidity to your house and make your AC less efficient.

Opening windows, even with your AC turned off, will add more moisture to your home.

That means when you turn your air conditioning unit back on and close your windows, it will have to run for a while before it can adjust the temperature and remove the humidity from the air. Usually, this results in a 21% increase in how hard your AC has to work to filter out the moisture when you turn it back on, costing you extra money and using more electricity. 

So, even though it may seem like you would be saving money and electricity by turning your AC unit off and opening a window instead, it doesn’t work that way. When you turn it back on, your AC will have to work harder to correct the humidity that you introduce to your home, causing it to run for a longer time to get your home dry again.

When Is It Better to Open Windows Than Use Your AC?

Although opening your windows almost always increases the humidity in your home, there are some occasions when opening your window may cool your home off more than an AC will.

If the air inside your home is hotter than the air outside, you may want to open your windows.

Cooler air is not nearly as humid as warm air, so it is usually more efficient to open your windows on cool days where the temperature inside your home is hotter than the temperature outdoors.

Still, this may introduce more moisture to your home, so if you have an AC, it is usually better to let the air conditioning unit cool the air for you.

How to Keep Humidity Out of Your Home in the Summertime

Cutting down on humidity in your home will help your AC run more efficiently, and it will keep you cooler in the summertime.

To keep humidity out of your home and keep coolness in during the summer:

  • Keep your windows and blinds closed during peak heat
  • Use exhaust fans to remove moisture
  • Use a dehumidifier

Keep Your Windows and Blinds Closed in the Peak Heat

Keeping your windows closed in the heat of summertime may seem like it would make your home hotter, but it keeps humidity lower, preventing the temperature from rising in your space.

Most people believe that a breeze will cool off their buildings, but often, that breeze only offers an illusion of coolness. In a hot room, you will sweat. When a breeze hits your sweat, you will feel cooler, even though that breeze may be warmer than the air inside your home.

Keeping your windows closed will keep warm humidity from entering, which will keep you much cooler than if you left the windows open.

For the best results, use blinds when the sun shines on your windows. That way, the sun can‘t turn your room into a greenhouse.

You can also use a fan to create a cool breeze inside your home without opening your windows.

Use Exhaust Fans to Remove Moisture

When you take showers or boil water in your kitchen, ventilating the area will keep humidity low, which will keep your home cooler.

Always turn on your bathroom vent when you shower, and if you want to keep the area dry, use it every time you use your bathroom. That way, the fan can help your AC unit remove the humidity from your home.

It would be best if you also used your kitchen exhaust fan when cooking to keep the steam from adding unnecessary moisture to the air in your home.

Use a Dehumidifier

Like exhaust fans, dehumidifiers will remove excess humidity from your air. They also work a bit like fans since they keep air circulating through your home, so they are fantastic for keeping your home cool.

Keep dehumidifiers in the hottest areas of your home or where insulation is the weakest. Empty them regularly and ensure that the filter is kept clean. That way, you can be sure that all of the moisture in your air will be gone even faster, leaving you with a cool space.

Final Thoughts

Opening your windows in the summertime increases the humidity in your home, which could also make your home much warmer in the long run. Opening your windows won’t save you money, either, since your AC will have to work harder to remove humidity from your home when you leave the windows open. So, generally, it is best to keep your windows closed, especially on the hottest days.

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