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What You Need to Know About Energy Efficiency and Your Windows

Windows beautify your home, bring the outdoors in and let you bathe your interior décor in glowing natural light. That said, they can also cost you — and that doesn’t just mean the cost of installation and maintenance. Window spaces in the average home take up roughly 15 to 20 percent of the entire wall surface. That provides plenty of places for air to get in or out. When it comes to letting a spring breeze in, you’re thrilled to let the outdoor air pass through. And when it comes to letting the smoky air of a burning stovetop dinner out, you’re also happy to have the ventilation. But when it comes to losing heat or AC cooling, window leaks aren’t your friend. Before you cover your home in plastic or decide on a total redesign, check out what you need to know about your home’s windows and energy efficiency.

What Causes Heat/Cooling Loss?

There are many factors that play into heat loss through your home’s windows. To start with, heat and cooling can get in or out directly through the glass or glazing. Think about how chilly old windows feel to the touch. If the window itself is freezing, it’s likely your home will be too.

Along with losing heat or cooling through the glass itself, everything around your window can let air in and out. A gap in the frame, cracked or failing caulk or a lack of insulation (or old insulation that isn’t standing up well to the test of time) can all decrease your home’s energy efficiency.

Are All Windows the Same?

It’s not exactly breaking news that older windows don’t perform as well as newer ones. Technological innovations have led to the development of materials and processes that are more energy-efficient and reduce the overall heat/cooling loss. But that doesn’t mean every “newer” window is the same. Some fair better than others when it comes to what comes in and out of your home.

The National Fenestration Rating Council (NFRC) administers a program (this is a voluntary program and is not required for all window manufacturers) that evaluates, certifies and labels windows. Certified labels are found on all Energy Star qualified windows and designate that the product is energy efficient.

What Else Goes into An Energy-Efficient Window?

Understanding what makes a window more or less energy efficient can help you to choose wisely when you’re updating your home. Modern windows are made of layers of glass that are filled with a gas or a combination of gases. They are then sealed, creating an insulated system within the window itself. The more glazings a window has, the better insulated it is. And the better insulated a window is, the less energy you’re likely to lose.

Older homes may have single-glazed windows. These have one pane of glass and typically lose energy at the highest rates. Better insulated windows come in double, triple and even quad glazings.

The number of layers alone isn’t the only factor feeding into energy efficient windows. Different materials transmit visible light while blocking heat from coming in. The light-to-solar gain (LSG) number is the ratio between the solar radiation (heat) that comes in and the visible transmittance (VT) light that gets through. A higher number means that the window lets in more light without letting in even more heat. That makes it more energy-efficient and helps to keep your summer cooling bills down.

What Else Is There to Consider?

You can pick the best window available, with the highest energy efficiency ratings, and still have heat or cooling loss. How is this possible? If the window frame is warped, breaking down or in some way not wellinsulated, it’s likely that you’ll lose energy. This is what makes professional installation absolutely essential. A pro can evaluate your window spaces and help you to make decisions about the frames as well as the glass. Whether you’re replacing both the windows and the frames or just the windows, an expert contractor can also make sure that the installation is done right (and is energy tight) the first time.

If you’re considering replacing your windows, call Arch Design at 513-367-0737 for a consultation.

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