Energy efficiency has become an increasingly hot topic among home owners over the years. The environment, your energy bill, and your comfort are all factors that energy efficiency affects, and an overall increase in energy efficiency can drastically improve all three. Windows are one of the most overlooked improvements when people start to talk about energy efficiency. However, in residential buildings, such as homes, apartments, and condos (especially older buildings) can lose a lot of efficiency through their windows. In fact, over 70% of all lost efficiency of your home occurs through your windows and doors, with almost 90% of that coming from the glass of the windows. This makes the average window the greatest contributor to your increasingly large electric bill during the peak of summer or winter months.
How to Prevent Loss of Efficiency in Windows
When preventing the loss of efficiency in your windows, a lot of it will come down to the type of window you have installed and the accessories you’ve added to the glass or frame. There are tons of different types of windows that involve increased number of panes, different coatings, spacers, and placement of the windows—all factors that affect how much energy is lost throughout the day via the glass. What sort of window you end up getting will depend a lot on the room that you want to put it in, and the resulting effect you want your windows to have. You’ll want to have an idea in mind for the room before settling on a window, to avoid needless replacements and potentially unusable rooms.
There are generally seven specific factors that should be taken into account when choosing an appropriate window:
Double or Triple Panes
Double or triple-paned windows help prevent thermal transfer into the house by providing a buffer space between the glass. Often, the space is filled with a spacer pane or insulator pane that further helps reduce thermal transfer, but there are windows that have two or three panes with no insulating pane between them. The added second or third pane helps further insulate the inside providing less thermal movement from the outside in.
Glass coatings further enhance the glass’ resilience to heat. Windows are graded on their efficiency through U-values and R-values. U-values are the measurement of heat gain or loss between the outdoor and the indoor side of the window. Lower U-values means more energy efficient glass with less heat transfer. R-values measure the overall resistance to heat flow. The higher the R-value, the less heat that is transferred through the glass. Adding a coating to the glass can help lower the U-value and raise the R-value through blocking out part of the UV light and reflecting part of the heat inducing light off of the glass, while improving the overall thermal abilities of the glass.
Solar Heat Gain Coefficient (SHGCs)
The solar heat gain coefficient is another measuring term for glass panes. Simply put, SHGCs is the shading ability of the glass, or how well it transmits solar energy through itself. The lower the value, the better the shading ability of the glass. Adding a coating to the glass helps block or reflect portions of the solar energy that hit the glass, preventing more of it from passing through.
Visible Transmittance (VT) Rating
A visible transmittance rating is a measurement of the visible light that the glass allows through. An example would be comparing a pair of sunglasses to your living room windows. The sunglasses work by limiting the amount of light that is allowed through the glass, while most home windows want to maximize daylight hours, and thus let more daylight in. The scale is between 0 and 1, where 0 would be “no visible light gets through,” and 1 would be “no resistance to visible light.” Most double or triple paned windows are between 0.3 and 0.7 on the VT rating.
Frame material actually plays a big part in the efficiency of your windows. Having a metal frame will allow more heat to seep through to the inside because of how well it conducts heat compared to other material. Fiberglass, wood, or vinyl frames are some of the bests at preventing heat from seeping in from around your windows. They are better insulators than metal, making them more energy efficient in the long run.
How To Choose The Best Window For Your Home
Now that you know more about how windows operate and what sort of additions and measurements go into them, knowing what window is right for you becomes a lot easier. Your choice of window will depend heavily on the room in which it is located and what the primary functionality of the window should be. If you are simply looking at upgrading your windows, finding a highly energy efficient window is pretty simple; just choose how well you want them to interact with the visible light that seeps through. Double or triple pane glass windows are typically more energy efficient but they might not let as much visible light in or they might not be able to be opened, depending on the kind you have.
You won’t find a one size fits all window, so customization and choosing what is best for your needs for the given window location are important. An experienced contractor who knows what they are doing can help you decide what sort of window—and what measurement—would be right for the location and purpose of your room. They will also know more about the intricacies of installing a window in certain locations to help improve the overall desired effect you have for the room. For instance, most people who install windows in a sunroom primarily focus on insulating during the winter months, forgetting that the suns heat will be magnified in the sunroom without the proper protection. This results in a completely unusable sunroom during the summer that lets a ton of heat in from the outside. Always make sure that you use a professional window installer for any window replacing needs you might have.