There are many glass options for windows for your home. Most residential windows today come with two panes, or lites, of glass in the frame. Some super-energy-efficient windows have three or even four pieces of glass, though the latter is fairly rare (and expensive).
If you’re shopping for windows for your home on Glass.com, our affiliates will be able to present you with a huge range of options to choose from. Let’s take a look at what you’re most likely to encounter as you hit the market.
The glass in most residential windows sold in the U.S. has many similar characteristics.
Typically, glass in these windows is sealed together in a vinyl, wood or metal frame with an airspace in between the two pieces of glass. Sometimes that airspace is filled with a gas such as argon or krypton. The use of gases can boost the energy efficiency of the windows. These are commonly called “insulating glass units” by window professionals. “Double pane,” “dual pane” and “double glazed” are other terms you might have heard. (Glazing is another term for glass.)
The glass on most windows today features a low-E coating. (E stands for emissivity, which is the ability of a material to radiate energy.) Low-E coatings are applied in a very thin layer on the surface of the glass. These coatings can reduce the amount of ultraviolet and infrared light that passes through glass and maintain the level of visible light. (Ultraviolet light is the kind that can fade your curtains or carpets, while infrared light is the kind that can cause your house to become hotter.)
Demand is strong for low-E glass, and it’s expected to get stronger as energy efficiency becomes more important.
Here’s a useful way to think about low-E glass. According to Vitro Glazings, a leading glass maker, low-E glass works a lot like a thermos. The low-E coatings reflect interior temperatures back inside, helping a room to stay warm or cold. That, in turn, can help lower your energy bills.
In a typical double-pane insulating glass unit, there are four surfaces that can get receive the low-E coatings: the first surface, which faces outdoors; the second and third surfaces, which face each other inside the window unit and are separated by the insulating air space; and the fourth surface, which is the one inside your home. Some low-E coatings work best on the third or fourth surface. Others usually go on the second surface.
Regardless of the type of low-E coating used on the glass, professionals in the window industry use two main ratings to determine how well a window performs.
The U-Value shows how much heat it can lose from inside the house. The solar heat gain coefficient (SHGC) shows how much solar radiation comes through a window. The lower the SHGC, the less heat it transmits.
Low-E glass is a type of reflective glass. Other types of glass are typically used in windows.
Annealed glass is glass that has been cooled slowly during the production process to relieve internal stresses and to prevent it from cracking when exposed to changes in temperature. However, annealed glass will break into large, dangerous shards when it’s broken, so it’s not often used in windows.
Heat-strengthened glass is annealed glass that’s been heated to 1,300 degrees Fahrenheit and then rapidly cooled. This produces a product that can handle greater swings in temperature. Heat-strengthened glass is about twice as strong as annealed glass, but it will break in to medium-sized shards when shattered, so it can be unsafe.
Tempered glass, also called safety glass, is frequently used in windows. It breaks into small pieces when it’s shattered instead of large, dangerous shards.
Laminated glass is glass that’s designed to stay together when it’s shattered. A chemical interlayer holds two or more layers of glass together even after being shattered, preventing it from breaking into large sharp pieces. If you’ve seen a window with a “spider web” pattern where it suffered an impact, then you’re looking at laminated glass.
A growing subset of laminated glass is impact-resistant glass or hurricane glass. These insulating glass units can minimize damage from the kind of flying debris that homeowners might experience in a hurricane. Impact-resistant glass can also reduce the sound levels coming into a home in areas that aren’t prone to severe storms.
Decorative glass is a product used in or around windows to create eye-catching visual effects. This can include patterns and colors, or the use of metal embedded in the glass. Decorative glass can provide a point of visual interest to increase to curb appeal of a home.
While these might not be typical of the glass options for windows you’re shopping for, these advances happening in glass that could show up in your windows in the future.
Dynamic glazing is a type of glass that can tint itself light or dark depending on the sunlight outside or based on an occupant’s individual preferences. While it’s currently more of a high-end product, advances could lower the cost of this type of glass.
Photovoltaic glazing is a type of glass that can generate electricity. The glass has transparent semiconductor-based photovoltaic cells sandwiched between two sheets of glass.
Photovoltaic glass has the potential to help buildings generate some of their own electricity through the windows. That would reduce the carbon footprint of the structure.
Vacuum glazing is a technology in which the air between two pieces of glass in an insulating glass unit is removed. That creates a vacuum, which research indicates could greatly increase the energy efficiency of a window.
Another promising development is a thin, lightweight triple-pane window. This patented process would involve dropping a very thin piece of glass into the middle of an insulating glass unit. The gaps would then be filled with krypton gas.
According to Steve Selkowitz, a senior advisor at the Lawrence Berkeley Lab, all double-pane windows could be converted to triple-pane products without a major redesign of existing windows.
However, this potential product is still on the drawing board.
Glass is a versatile, beautiful and useful product, and it comes in a vast range of colors and configurations. Navigating your way through all the glass options for windows can be confusing, but if you use one of the experts available on Glass.com, the trip could be a lot easier. They are experts in glass for all kinds of applications, but especially for the home.
We’ll connect you with a reputable glass and window dealer in your area who can help you find just the right product for your home and give you a high-quality, professional installation.