It’s easier to shop for new or replacement windows if you know the same things the window manufacturers know. This is the second part of a series on options and features that can make new windows more efficient.
Things To Know About Energy Efficient Glass Choices
Here’s a list of glass or glazing choices that can make windows more efficient. Quality replacement windows will offer these features.
Unless they are handmade in a local shop, virtually any windows you buy today will be at least double pane, which is two layers of glass sealed with an air space in between. This is also known as insulating glass, or sometimes double glazing. Some window companies fill the air space with argon, a nontoxic gas used to increase energy efficiency and lower the amount of heat the glass will conduct. Insulating glass is a great first step in improving efficiency. Plus, added benefits of insulating glass include cutting down on outside noise and making your home more secure from glass-breaking intruders.
Better window brands also offer tri-pane insulating glass, which is also known as triple pane or triple glazing. We’ll get back to this in a second. But first, here are some upgrades to insulating glass.
LoE-272 glazing (glass) is a double metallic coating that is applied to the inside glass surface in between the panes. It reflects heat into the room in winter and keeps out the sun’s heat in summer, optimizing room comfort and reducing utility usage. How does it know the difference? The sun is higher in the summer, so the coating is especially engineered to block these rays. This can significantly lower air conditioning bills. In the winter, when the sun’s rays are lower, the coating will allow the light through, naturally warming rooms. This warming is enough to make a difference in your heating costs.
In addition, this coating decreases the damaging effects of UV rays. Benefits of LoE-272 glass include both an enhanced U-factor and improved Solar Heat Gain Coefficient. (U-factor is the amount of heat loss to the outside, and Solar Heat Gain Coefficient is how much heat from the sun your windows let in.)
LoE-366 glazing (glass) is three metallic layers of silver, and like LoE-272, it allows heat into the room in winter and keeps out the sun’s heat in summer. The difference is, LoE-366 glazing is tweaked to block more heat so it is recommended for warm climates, such as Georgia, where cooling costs are high and also for areas where intense exposure to the sun is an issue, such as a large wall of windows facing a southern exposure.
Tripane glazing, offered in Marvin window products, provides advanced energy efficiency. The air spaces between the three panes of glass are filled with argon gas or, for even better insulating value, krypton gas, and that it is available with LoE coatings to match a variety of climate requirements.
Energy Panels are sometimes confused with storm windows. Actually, this glazing option is a removable exterior glass panel finished on the edges by a frame. Energy panels cover the outside glass surface of each sash, and can further increase energy efficiency for wood windows with single glazing, such as those used in historical homes.
Storm and Screen combinations are two movable glass panels and one movable screen panel. The individual panels can be set up multiple ways depending on the season and homeowner’s needs, and can be easily removed from the interior for cleaning.
Framing Your Choices for Window Materials
Besides the glass, what your window frames and sashes are made of also makes a difference. Since the frames and sashes represent 10-30% percent of the total area of each window, the frame properties will definitely influence overall efficiency.
Wood and aluminum clad wood are naturally better insulators than vinyl and aluminum. This means wood windows do not pass temperature extremes through their frames as readily as, say, aluminum windows. Ever stand near the interior of an aluminum window when it’s cold outside? They can feel very cold! Stand near a wood window, and you won’t notice the cold as much.
From a thermal point of view, wood-framed windows have a positive influence on a window’s overall U-factor (see below for the definition of U-factor). Well-built and well-maintained wood windows from a good manufacturer can have a very long life. Paint protects the exterior surface and allows you to change the color easily.
Wood windows with a clad aluminum exterior are another excellent choice for improving home efficiency. They possess the same properties as wood windows, and the sturdy exterior aluminum cladding acts like a coat of armor against the elements. Considered to be among the best, Marvin clad windows’ exterior color finish is extremely fade resistant and strong so they are a great choice for low maintenance good looks that last for decades.
Fiberglass Windows (Composite)
Another strong choice you can make in upgrading your energy efficiency is composite or fiberglass windows. As a window and door material, fiberglass comes closest to perfection. A quality fiberglass, such as Ultrex used in Integrity and Infinity replacement windows, is extremely strong and warp resistant much more so than vinyl. Besides helping your replacement windows last a lifetime, the strength of fiberglass keeps the shape of your windows intact for decades to come. The more your windows stay in shape, the better that layer of air sealed in between the insulating panes of glass can do its job.
What’s more, fiberglass expands and contracts very little, unlike vinyl, which can grow and shrink measurable amounts in the temperature extremes that windows and doors endure. The low rate of thermal expansion in fiberglass, again keeps your windows sealed tight, to prevent energy-robbing air leaks from finding their way in over the years. And finally, fiberglass is 500 times less thermally conductive than aluminum, which means it doesn’t allow in the heat or cold extremes from the outside.
With this knowledge under your belt, you can shop for replacement doors and windows and feel confident that they will add newfound comfort and energy efficiency to your home.
In case you missed it, please read GET THE FACTS ON ENERGY EFFICIENT WINDOWS Part 1.