When shopping for replacement windows, the buyer really is spoiled for choice. There’s a lot of stuff out there! We know it can be hard to make a decision, especially when you’re not entirely sure what you should be looking for, and what you should avoid. The following are some key points to help you make an informed decision on your new windows.
• The Frame: You want to look for a good strong frame. The rigidity of a windows very important to the over-all unit. A window that flexes too much will eventually have seal failure and you will be back at square one. However a super rigid frame is not always the best; you also want to understand how the window is made. Windows that are mechanically fastened (screwed together) have more possibility to flex than a welded window. So even though fiber-glass as a material is very strong, it may be weak at the joints. Vinyl window frames are welded to make one uni-body frame. If you do go with vinyl, look for a strengthening insert wherever the lock mechanism is. Windows with a strong insert in the meeting rail will have less opportunity to sag or lose their shape.
• Air Infiltration / Weather-stripping: Air infiltration ratings are very low on vinyl windows because they have welded corners. On any type of window you want to look at the weather-stripping. The strip is usually felt, fiberglass, or in crank operated windows it can be rubber. The strip acts as a barrier for air and dust, and is an important part of a window. Windows that have two weather strips will block more from the outside than a window with just one layer. Windows that are triple and quadruple weather-stripped are even more effective against blocking air and dust. You want to have at least two layers of protection around any operable part of the window.
• The Glass: The glass in a window directly affects how well it performs. You may get the most efficient frame available but if it has clear glass without a protective coating, you will not have an efficient window. Low-E glasshas a film applied to it to block harsh UV rays, radiant heat, and direct heat from sunshine. There are a lot of different types of Low-E, and a lot of choices out there. Soft-coat Low-E glass is the most efficient and you do not have to worry about the coating as it will be on the inside of the two-panes. Hard coat Low-E glass has the coating on an exterior, touchable surface, and may be harder to keep clean. There are varying degrees of strength and darkness in Low-E glass, and it usually comes down to personal preference. Having any type of Low-E is better than none at all. The thickness of the glass itself is also important. You want to look for windows that have double-strength, or 1/8th inch glass. Stronger glass has less ability to flex or droop, and therefore less opportunity to have seal failure.
• Ratings: Looking directly at the ratings will tell you exactly what you need to know, if you know what they mean! Windows are not rated with an R-Value like other construction materials. They are rated by the National Fenestration Registration Council for things specific to windows.
o U-Factor: This factor measures the heat from INSIDE a room that can’t escape. The lower the number, the better the window is at keeping heat in. This factor is especially important during winter months when you are running your heater.
o SHGC: The Solar Heat Gain Coefficient measure the amount of OUTDOOR heat than can enter a room. The lower the number, the better your window is at keeping heat out. This comes into play during the hot months, especially for windows that get direct sunlight.
o VT: Visible transmittance is a measurement of how much natural light can come into a room. A higher number here means more natural light. However windows with a very high VT number usually fall short in the other categories.
o AL: Air Leakage or Air Infiltration rates measure how much air will enter a room through the window. The lower the number, the better the window is at keeping air and dust out. This is an optional rating, and not all companies include it on their labels, or even test for it at all. At Glass-Rite we think it is an important part of the windows efficiency and it is included on all our NFRC stickers.
o U-Factor: This factor measures the heat from INSIDE a room that can’t escape. The lower the number, the better the window is at keeping heat in. This factor is especially important during winter months when you are running your heater.
o SHGC: The Solar Heat Gain Coefficient measure the amount of OUTDOOR heat than can enter a room. The lower the number, the better your window is at keeping heat out. This comes into play during the hot months, especially for windows that get direct sunlight.
o VT: Visible transmittance is a measurement of how much natural light can come into a room. A higher number here means more natural light. However windows with a very high VT number usually fall short in the other categories.
o AL: Air Leakage or Air Infiltration rates measure how much air will enter a room through the window. The lower the number, the better the window is at keeping air and dust out. This is an optional rating, and not all companies include it on their labels, or even test for it at all. At Glass-Rite we think it is an important part of the windows efficiency and it is included on all our NFRC stickers.
• Value: Last but not least, how well the window will perform in the long run. Ideally most of us are looking for something energy efficient as well as cost efficient. You want a window with excellent ratings that will last and look good for years to come. Check out a company’s warranty before you buy to see what is really covered. Also consider the personal value the windows will have to you. You’re the one who will be looking through them, so it is important to get something that you like.
We’ve taken you through what makes a good window, but what makes a window fail? From what we’ve seen over the years is that there are two common culprits.
• The insulated glass unit in a window really is all important. If you can get a window that has a glass unit sealed at your altitude that is the best way to go. Windows being shipped from sea level to our altitude will have a much higher chance to fail than units sealed here. The pressure difference will be too much, and the seal around the glass unit will break or pop, allowing moisture inside the glass unit. Thin glass that is poorly sealed with have the same problems.
• Installation matters! You may have the best window ever but if it is installed incorrectly you will have problems with it forever. If a window is not level it will not operate properly. If it is not insulated or sealed properly you will have water and air leaks. A good installation team is paramount when getting new windows. Look for a company that does not use subcontractors, but rather one who has a full time employed staff. This means that you’ll get installers that know the product they’re working with, and they will be backed by the company that sold the windows.
We hope this information was helpful. We want to give you the knowledge you’ll need to make the best decision on your new windows. If you have any questions, or want to know even more about windows, please call or visit us at our factory showroom and we’d be happy to show you around!
