Building Sustainable Homes: Window Design, Condensation & Exhaust Fans - North Twin Builders

Incorporating sustainable elements into your home construction or renovation can provide you with long-term cost-savings that are paid back through reduced heating and electric bills.

Why is there condensation on my windows?

Much like a cold drink sweats when you take it out of the fridge, windows can sweat in the winter. You might view condensation on your windows as a bad thing, but in reality it often means you are living in a relatively air tight home. The condensation is forming as a result of moisture producing elements within your home: the pasta you cook, the interior plants you water,  or when you take a shower without turning on an exhaust fan.

The condensation on your windows, especially in older homes or older windows, are a sign of high humidity levels. This water vapor in the air condenses on cold window surfaces and other areas throughout your home. The excess moisture can lead to mold and mildew, which can impact your health and damage your home.

You can reduce condensation in your home by turning off your humidifier, using a dehumidifier, running fans to help circulate the air, and turning on exhaust fans each time you boil water or bathe. In the winter months, it is recommended to run your ceiling fans clockwise to push the warm air down. If you live in a home with older windows, it may also be time to consider switching to double-paned windows, which will improve both thermal comfort and reduce the likelihood of condensation.

What windows are the right ones?

Shopping for windows can be overwhelming. We recommend beginning your search with Energy Star certified windows, which can reduce utility bills by up to 15 percent! Window frames should be made of fiberglass, vinyl, aluminum, wood, or a combination and should always be multi-paneled. Options for multi-paned windows also include a special spectral coating that keeps your home a comfortable temperature by reflecting incoming light.

The experts and Energy Star certified home builders at North Twin Builders use thermal imaging equipment and decades of experience to identify drafty windows or other sources of air leaks, like poorly installed dryer vents, and introduce ways to enhance the energy efficiency of your home.

Watch for air leaks

If you are seeing abnormally high heating bills, we encourage you to check all your windows to ensure they are not only closed, but locked, latched, and secure. Unlatched windows allow for air leakage, open your home to cold air, prevent the window weather stripping from working properly, and create higher heating bills. We recommend avoiding the blustery drafts by doing a window check to verify latches.

If you observe gaps in your windows (or doors), these can be filled in with caulk or weather stripping. If you are sitting in your home on a blustery winter day and hear your windows rattling, we encourage you to have a home construction expert out to check if your window frames are secure.

As part of your summer maintenance schedule, you can have a home energy audit completed through Focus on Energy to check for air drafts, leaks, and other ventilation problems.

Optimizing Humidity Levels

Moisture is a natural part of every environment. A family of four adds between 2-3 gallons of water to the interior of their home each day. This combined with unproperly vented homes and insulation issues can add to the moisture in your home and increase the humidity.

We are often called into home remodels and renovations for issues with exhaust fans. We find that they are often misplaced and misrouted. Ideally exhaust fans in bathrooms should be placed over the shower at the source to immediately pickup the condensation. In addition, the ducting used to route exhaust fans shouldn’t have extra length on the interior of the home. Any extra material on the hoses used for routing should go directly outside.

In kitchen environments, you should ideally have a vented range hood that brings the condensation to the exterior, rather than an unvented hood that blows the moisture toward the ceiling. In both bathroom and kitchen environments, the exhaust fan should run 30 minutes after use to remove the excess humidity. We sometimes add humidity control devices to run such fans long enough to remove moisture, but no longer than needed, so that heating and AC are not burdened by leaving the exhaust fan on for too long.

Your dryer vent should also exit to the exterior of your home to remove the moisture from your interior home environment. When checking on these vents, watch for cracks in the sealant which can allow moisture into your home.

We also encourage home owners to open their blinds regularly so the warm air can flow past the window and avoid trapping an air pocket, which can lead to condensation.

Controlling Moisture

Are you building a new home? Make sure you are relying on a builder that pairs building science with building code. Your selected contractor should be able to explain their chosen solutions, and the effect of each choice. Air barriers should be brought up as part of the discussion to ensure your builder is considering the implications of their designs and materials on the interior and exterior environment of your home.

A home contractor needs to look at both the indoor and outdoor movement of air and moisture. Designing homes for the best indoor air barrier for the given home environment by preventing moisture movement through the walls isn’t the solution, nor is caulking spots for air leaks.

A trusted and energy conscious home builder will develop a plan for proper moisture drainage and ventilation, while also considering air barriers when looking at how air will move around the home. Building your home right the first time is the best way to ensure optimal air flow, ventilation, moisture control, and energy efficiency.

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