Many New Zealanders experience a common problem both at home and in the office: condensation on windows. This is usually caused by excessive moisture and differences in temperature, the latter of which can be exacerbated by New Zealand’s highly varied climate.

Condensation on windows forms more often during the winter when the air outside is cold and dry while the air inside is warm and humid. However, it can also happen during the summer (in reverse) when many people crank up the air-conditioning to combat the heat.

Do note that while it may be annoying, this kind of moisture is generally harmless. In fact, it’s a good indicator that the windows are forming a good seal and preventing air leakage. What you have to really worry about is when the condensation forms in between the window panes.

That said, while your trusted commercial cleaners can remove stubborn dirt, water stains, and other nasty things from your windows, they can’t really stop condensation from forming. However, you can employ a lot of simple solutions to prevent this situation from happening. Here are a few tips:

Turn Down the Humidifier

Some people use humidifiers to combat dry air, which can trigger allergies and worsen some respiratory conditions. However, too much humidity can result in condensation in windows. It can also make the air feel a little heavy and uncomfortable.

Most experts agree that the ideal humidity levels indoors would be around 30% to 50%. Turn down your humidifier (including those that come with furnaces) to these settings to reduce the condensation.

Use a Dehumidifier

If you’re not using a humidifier but the air is still a bit damp, a dehumidifier can help fix things. Just make sure to check the features of the appliance. Some dehumidifiers operate automatically depending on the humidity levels of the environment. Meanwhile, some models may have a timer or need to be turned on and off manually

Get an Air-to-Air Exchanger

Another appliance that can help you minimise condensation on windows is an air-to-air exchanger. The way it works is simple: it brings air from the outside and sends the indoor air back out. In the process, the exchanger removes pollutants and moisture content from the air.

Do note that an air-to-air exchanger, as well as a humidifier and dehumidifier, must be the right size so it can work as intended.

Improve Air Circulation

Sometimes, all you need is a fan to move indoor air properly and reduce humidity. Even a strategically placed pedestal fan can work wonders! Meanwhile, if you have a ceiling fan, make sure it’s moving in a clockwise direction. This will move warm air that’s sitting near the ceilings down, and the cooler air up.

Ensure Proper Ventilation

In relation to the above-mentioned tip, you also need to make sure that areas that are prone to accumulating moisture are well-ventilated. These areas include the bathroom and kitchen, as well as the laundry room. Use exhaust fans in these locations or pop a window open while you are using them to let the air out.

Install Storm Windows During Winter

If you only experience increased window condensation during the winter, installing storm windows over your existing windows may be a good idea. This will help seal in the air and retain warmth, thus eliminating condensation. As a bonus, the storm windows can also reduce noise.

Do note that the storm windows themselves may experience condensation build-up, but they will certainly prevent condensation in interior windows.

Move Plants Away from the Windows

Do you have indoor plants? It’s best to move them away from your windows. That’s because plants release moisture into the air; as such, placing plants near (closed) windows can increase condensation build-up. Even firewood still contains and releases moisture, so it’s best to keep them outside to control indoor humidity.

How to Prevent Exterior Window Condensation

Condensation on exterior windows can be quite annoying, especially since it can affect your home’s aesthetics. However, they disappear quite quickly once the sun comes out and dries it off. If you don’t want the moisture to build-up in the first place, you can try applying a water repellent coating onto the exterior of your windows like the ones used for car windshields.

What to Do With Condensation Between Window Panes

If you notice condensation between the sheets of dual- or triple-pane windows, it’s possible that the seals are broken; the desiccant may also already be saturated. In short, you may need to have the window replaced.

Try to clean the windows first, though, and see if the glass is just hazy or there’s a build-up of cleaning product. If it doesn’t work, get in touch with the company that installed your windows and have them check if they can replace only the window panes. This will help save you a bit of money. Otherwise, the entire window will have to be replaced. While this can be a little more expensive, most modern windows utilise technologies that can make them last longer and even provide extra benefits.


At the end of the day, a little bit of condensation on your windows isn’t that big of a deal. However, if it happens often, it’s an indicator that there may be something wrong with the humidity indoors. Make sure to address the issue immediately before things lead to musty odours, peeling paint, mould infestations, and other costly problems.