You walk in a window showroom, and start talking to a salesperson about energy efficiency. He explains all the advantages and intricacies of the IG unit to you. If you are like most of us, he has lost you already with that acronym. IG stands for insulating glass and it’s what keeps the heat from coming in through your window in the summer and the cold out in the winter.
Insulating glass refers to glass that is made to prevent significant heat transfer into or out of a home or building. It consists of multiple pieces of glass separated by spacers made of either metal, such as aluminum, or structural foam. The space between the glass is sometimes filled with a noble gas, such as argon or krypton. Insulating glass is often abbreviated IG and is sometimes called double-glazed or double-pane glass. As technology evolves, triple-paned or quadruple-paned glass is now available as well.
Insulating glass is comprised of several components: multiple pieces of glass, materials that create and maintain space between the glass and any gas added to the space between the glass. All of these pieces are assembled into a single, sealed unit that holds the entire system together and helps prevent changes, especially to the air (or gas) between the glass. These complete units are called insulating glass units, or IGUs.
Your IG unit will typically be made with low-E glass, which has a coating that reduces the ultraviolet and infrared light that passes through a window. It helps regulate temperature (and energy consumption) within a home by redirecting heat back in the direction from which it is coming. Low-E coatings are made of microscopically thin coatings of materials that reflect heat much better than it absorbs or emits it. (For more definitions of windows and glass lingo, visit the Glass.com dictionary.)
When looking for new windows and an efficient IG unit, where you live plays a major role. For example, windows in Michigan will need to focus on keeping that cold weather out in winter while in Florida the focus will be on keeping the heat out. What plays a major role in both of those scenarios is the solar heat gain coefficient and the U-factor.
U factor, in essence, is the rate of heat transfer and a measure of how well the window insulates. They generally range from .25 to 1.25. The SHGC is how much solar radiation is admitted through a window, and ranges between 0 and 1. The lower the number the less heat it transmits.
If there is a certain area of your house that gets a great deal of sun for example, you could even choose different window types for the various units in your home based on these factors.
If purchasing an energy-efficient window is your main priority then you will want to choose a window frame that will aid in that goal. There are many variables to consider when choosing a window frame, but here we will just look at how well it helps insulate contributing to the overall efficiency of the window.
It is difficult to determine the payback associated with an energy-efficient window purchase but there are several items that go into this evaluation:
The site also states that you can reduce your energy bills at an average of 12 percent through a purchase of Energy Star windows.
Now that you are armed with what factors go into an energy-efficient window purchase don’t get confused by multiple sales pitches. Know what you want, listen to the information you are given and then re-evaluate once more before making that final purchase. Don’t get swayed by pitches for triple pane units with krypton gas if these are not needed for your home. Focus on the IG basics, look for that low-E coating and consider your climate.
More article on energy efficient windows can be found on Glass.com as well as how to find a window dealer near you. Good luck shopping!