Does A Dehumidifier Work With Windows Open?

Opening windows is a simple and natural way to bring in fresh air. Whenever we want to improve indoor air quality, we will think about doing it. The indoor humidity level is an essential factor in air quality. When the air is too humid, we will use a dehumidifier to remove excess moisture.

Since opening windows and using a dehumidifier are both ways to control air quality, it isn’t unusual for some people to wonder if a dehumidifier can work with windows open.

No, it is not recommended to use a dehumidifier with windows open. It will reduce the efficiency of your dehumidifier, making it difficult to achieve the proper humidity level in the room. To increase airflow, use a fan or open a window for a few minutes each day.

To delve deeper into the subject, I’ll walk you through everything you need to know about “dehumidifier and open windows” in this post, including why open windows work against a dehumidifier.

Much useful information awaits; let’s get started!

Why can’t you leave your windows open when using a dehumidifier?

why you can't run a dehumidifier with windows open

As I said at the beginning, running a dehumidifier with windows open isn’t advisable. In this section, I want to explain the reasons behind it. 

Whatever type of dehumidifier you use, it will dry out the room by removing moisture from the air.

Every dehumidifier has a different capacity. Some, for example, are suitable for 5000 square feet, whereas others can only handle a 500 square foot room. That is, each model can only handle a certain amount of moisture in a certain amount of time.

When you leave the windows open while running it, it can constantly increase the amount of moisture. Typically, a dehumidifier can gradually reduce humidity and does not need to run continuously.

In this case, the moisture dispersed through the window will offset some of the moisture removed by your dehumidifier, lowering its efficiency and forcing it to work harder and longer.

As a result, running a dehumidifier with windows open is not a good idea.

Effect of open windows on a dehumidifier

Until now, we have already known opening windows have an effect on a dehumidifier, but how much impact it will have? 

In fact, many factors will affect the result.

1. The amount of airflow entering through the windows

The amount of airflow from the outside is a crucial factor to determine the effect on dehumidifiers. 

If there is only one small window in the room and you open it only slightly, it will have little effect on your dehumidifier.

On the contrary, if the room has a few large windows and you fully open them, the performance of the dehumidifier will be greatly reduced.

Aside from that, the airflow will increase on a cloudy day. The natural fan blows out more air to your house.

2. Humidity outdoors

Generally, outdoor humidity has a big impact on your indoor environment. In other words, whenever you use a dehumidifier, the air outdoors is likely moist at the same time.

However, the difference can amplify when you turn your HVAC system on or run your dehumidifier or humidifier for an extended period. 

Therefore, opening the window can reduce or increase the moisture level significantly when it is too humid or too dry.

3. Do you open the door at the same time?

Keeping the door open at the same time will improve air circulation. However, it will increase the workload on your dehumidifier. The impact can vary depending on the size of the door opening.

4. Dehumidifier capacity

Assume you place a powerful modern dehumidifier in a small room, which can regulate the humidity effortlessly even though you keep the windows opening.

You will be satisfied as long as it lowers the humidity level, even if it takes a little longer to work.

Can opening windows help dehumidify the room?

While you’d better keep the window closed while running a dehumidifier, it doesn’t mean that you can’t open windows to dehumidify the room. 

In fact, opening windows could be a free way to remove the excess humidity indoors under some circumstances. 

For example, in the winter months, the relative humidity outdoors could be higher than the one indoors since the temperature is lower outside. In this case, opening the window allows some dry air to enter. Nevertheless, it will also cool down your room.

In addition, when your home is overcrowded, the humidity rises. You can get some fresh, dry air by opening the window.

When using a dehumidifier, what can you do if you want fresh and cool air?

The main reason why people want to use a dehumidifier with windows open is that they require fresh air or want the air to cool down the room. 

These requirements are absolutely necessary, but they can be met without leaving windows open.

At first, a dehumidifier can’t reduce the room temperature, but it can make you feel cooler.

This is because we adjust our body temperature through sweating. When the environment is humid, such as in the summer months, the sweat can’t evaporate quickly, making our bodies overheat and feel sticky. 

When your dehumidifier lowers the humidity level, you will feel much better as the evaporating speed goes up.

As for fresh air, you can increase the ventilation in the whole house by operating the exhaust fans in other rooms. Besides, it is OK to open the window for a few minutes daily to eliminate some odors.


Running a dehumidifier with windows open is not a sensible idea. While it will not make the machine stop working, it can affect its performance. The device will take a longer time to dry the room out.

You can, however, open the window for a few minutes each day to let some fresh air in. When you run a powerful model, the impact of window opening can be limited. Sometimes simply opening a window without running a dehumidifier is enough to remove excess moisture from your home.

About The Author

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Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested dozens of products in person, like humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

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