SAVE $100 
by Rachel Lyon, Editorial Director for The House Designers
Extensive window designs have been featured in large luxury homes for years, but you’ll find them making their way into plans of all sizes nowadays. Whether they simply accentuate and brighten spaces or really make a statement on the walls of two- and three-story foyers and great rooms, deciding to generously incorporate windows is an investment that repays in natural light, enhanced beauty, and overall style.
Despite the obvious pros, people are wary of one very big con: the potential risk of reduced household efficiency. Stand next to windows during winter and you might feel the chill from outside creeping in, and nobody wants to deal with a drafty home that costs more to keep comfortable. It might seem that the answer is to limit windows in favor of efficiency, but this is contrary to the aesthetics that so many people love and you might be surprised to learn that large windows can actually be an environmentally and wallet-friendly choice. Here are the benefits you can expect from a fantastic window design, provided you choose windows that meet your expectations in terms of performance.
Understanding Window Efficiency
If you’re building a house, you’ve probably heard various professionals talk about R-values and why choosing products with higher ones offers the best insulation and, in return, efficiency. While this measure works for things like walls and doors, windows function differently and use other terms to describe how they act as an intermediate between the interior of a home and its environment.
U-factor – Describes the rate at which heat is lost through the window to the outdoors
Solar Heat Gain Coefficient (SHGC) – Describes the amount of heat from the sun that passes through a window to the indoors
Maybe you’ve heard that you should always choose the highest R-value to best control your interior climate, but the same can’t be said for windows. A professional will always ask for information about your house before offering suggestions, because the perfect window in Maine would actually be a huge problem in Florida. What remains constant across all locations is the need for high quality seals and weather stripping—you don’t want to have to think about air movement through a closed window negating all the good that the right type of glass does for your home’s efficiency.
Choosing the Right Glass
The rules of balancing U-factor and SHGC are fairly straightforward. Think about a frigid northern climate where keeping warm is the priority; you want a low U-factor to minimize the loss of heat through the window and a high SHGC to let in more free solar heat. On the other hand, homeowners in hot southern areas might not be as concerned with U-factor and instead invest more heavily in a product with a low SHGC to prevent heat from entering the house. Visible transmittance (VT) becomes something else to consider in these cases, because the whole point of a window is to let in light and allow you to view the surroundings, but it can be darkened by heat-reducing measures. Select a high VT to allow more light inside while the low SHGC blocks heat.
There are three variables that go into the construction of efficient windows: number of panes, insulating gases, and low emissivity (Low E) coatings. Most modern windows are made with two panes, although triple pane options are popular among those especially concerned with keeping interior and exterior climates separate. Insulating gases including argon and krypton help to slow heat transfer between the panes, resulting in a better thermal barrier. Low E coatings are basically metallic glazes that you can’t see, but that play an integral role in directing heat where you want it to go; depending on the number of panes, the number of coatings, and the surfaces that are coated, you can control just how radiant heat is reflected and absorbed. You can see that there is a lot to consider, and there are plenty of ways to tailor the best window for your needs.
Making the Most of a Great Window Design
The orientation of the house and which direction windows face are also critical to maximizing efficiency, and this is where those large, beautiful designs can make or break your efforts. Windows can become more than just a source of loss in terms of heating and cooling—with the right insulating features, they can actually improve your home’s performance and work for you rather than just prevent the inevitable.
Take, for instance, a house in an area that experiences harsh winters. Large windows might seem like a bad idea, but if they are oriented due south, where the sun shines all day, windows with a Low E1 coating will maximize solar heat gain to help passively heat your interior. The glaze helps prevent heat from escaping, too, and paired with insulating gases that also increase U-factor, you have a window solution that lets you appreciate the beauty of the outdoors, take advantage of natural light, and stay comfortable. On the other end of the spectrum are homes in very hot, sunny places where the goal is to keep cool. Avoid having large windows face east, northeast, west, and northwest here, as that’s where the harshest summer sun will shine. Low E3 and ERS coatings reflect the sun’s rays away to prevent houses from baking, so you can enjoy the views of your paradise without suffering for it. Overhanging eaves and exterior shades also cut solar heat gain, so you definitely don’t have to resort to living like a mole to keep from overheating.
Visit Integrity® from Marvin® Windows and Doors to discover stunning windows in every style that you’ll love to use in your own home. Integrity® offers ENERGY STAR® certified products and can help guide you to the best windows for your exact situation. While it’s fairly easy to select the most efficient options for other construction materials by yourself, it’s in your best interest to consult with a professional when it comes to windows. Find a local dealer to learn about what will work best for your home!
