Window Condensation in Summer? Don’t Sweat It

Just as your brow starts to get beads of sweat in humid air, your windows may also show beads of water vapor in the summer months. If you see moist air gathering on your window glass, don’t panic. Although it can seem concerning, condensation is a fairly typical occurrence—especially when Wisconsin gets a humid heat wave in July and August.

Many of us are well-versed in the perils of winter weather, but here in Southeastern Wisconsin, we get a taste (albeit short) of all four seasons. Here’s how to make sure your windows are doing their job.

Condensation in the Summer?

Many Wisconsin homeowners think of condensation as an occurrence for the winter months. However, as we go into the warmer months of the year and turn on the air conditioner (hopefully!), we may see excess moisture or condensation forming, causing windows to sweat on the exterior. Let’s explore how and why you see water droplets on the outside of the window on a sunny summer day.

​When cold weather hits, we turn up the heat to get some warm air to beat the chill. When the heat goes up, so does the indoor humidity level in the home. The indoor air is warmer than those frigid outdoor temperatures we see here along Lake Michigan—during the winter, “sweating” or condensation forms inside your windows.

In the summer, we may experience the reverse. When there are high humidity levels outside of your windows and cool air on the inside, you’ll see water build up on the cooler surfaces like panes of glass. So outdoor temperatures can impact your windows any time of year—no matter which season we’re in. It’s not a sign that your replacement windows are defective or lacking efficiency—it’s just the science of summer condensation.

Glass conducts heat, and as the sun heats up the exterior of your windows on warmer days, the Low-E coating helps keep the outdoor air outside. The entrapment of heat outside is a positive aspect of having energy-efficient windows on your home.

When the sun goes down, and we settle in for a cooler night of the summer season, the surface of the window also begins to cool. Again, the Low-E coating minimizes the heat transfer. So, the outside glass surface may cool notably below the outside air temperatures. When the right combination of cool inside temperature and warm outdoor air comes together with outdoor humidity, windows with the Low-E shield can develop condensation.

​The Benefits of Low-E Window Coatings

What are Low-E window coatings anyway? Low-E stands for “low-emissivity.” It refers to thin, transparent layers applied to the window surface. The coatings reduce the infrared and ultraviolet light that passes through glass without compromising the visible light in the space. Low-E coatings are microscopically thin and aren’t noticeable. The coating is durable and can withstand cold air in those long winter months.

Low-E coatings reduce heat loss in the winter by deflecting heat back into the room. That means the air inside stays warmer, and your heating and energy bills stay low. When the air outside is hot, the windows reflect heat away from the room. Again, the process helps keep the indoor temperature comfortable. Low-E windows are one of the energy-efficient products we carry at Weather Tight to help your home stay comfortable all year long.

The reason we highlight the Low-E coated windows in condensation is to point out the contrast. An energy-efficient window is doing its job. Inefficient, older windows may be poorly insulated. In older homes, we often don’t see signs of condensation because the windows aren’t performing as they should. Energy-efficient windows make it nearly impossible for the heat and cold air to transfer through the glass. This means that condensation is actually a very good thing.

​Can Condensation Damage My Home?

Is too much moisture bad for your home? Properly installed windows are meant to withstand significant moisture (hello, summer rainstorms) inside and out. Even with excess humidity, interior and exterior condensation won’t be likely to damage your home. Between the hot shower, cooking, and washing dishes, there’s a lot of moisture that goes into the average home’s air circulation. If your home has a higher humidity level, you may want to run the kitchen, ceiling fans, and bathroom exhaust fans regularly and ensure your HVAC system is working properly.

​As for outdoor condensation, it’s most likely a good indication that your Weather Tight windows are doing their job. Most homeowners find that condensation appears during the early morning hours and when the sun sets later at night. As the day progresses and temperatures climb, condensation dries up on its own. If you notice water stains, Weather Tight windows are easy to clean (most from the inside of your home).

The place condensation shouldn’t appear between the glass panes on your window. If windows are foggy or seem always to have a clouded appearance, there may be a seal failure. We tend to see this in old windows, and it’s often a sign that you need to consider replacing them. Water damage around windows may indicate a more significant issue with leaks and insulation problems, so it’s best to address them immediately.

​If you’re experiencing a persistent issue with inefficient windows, please reach out for a free consultation and price quote. We can help you explore your options and find the ideal windows for your situation.