Windows are a different story. If your windows are more than 20 years old, or you notice significant drafts from your windows even if they’re sealed well, it’s time to replace them. Newer windows are light years ahead of older windows in terms of energy efficiency.
How to Choose the Right Windows
Windows are rated primarily by their U-values, which are a measure of the rate at which heat passes through the material. Another factor used to rate a window is by its R-value. In contrast to a U-value, an R-value is a measure of the window’s resistance to heat. The lower the U-value and the higher the R-value, the more energy-efficient the window is. Look for a U-value of 0.25 or lower, and an R-value of 4 or higher. It’s particularly wise to choose ENERGY STAR–qualified windows, which could save you some money in energy bills (as much as $450 per year per window) and you may qualify for a tax rebate. Other features to look for are:
- Glazing: Windows with double or triple glazing (which refers to the number of layers of glass used) have higher R-values.
- Low-e coatings: Made of thin semiconductor film, low-e coatings reduce incoming heat and keep your house cool, making them ideal if you live in a warm climate.
Several types of home windows are available on the market. If you want to be truly energy-efficient, casement windows are the way to go. Casements open outward on a side hinge and usually are the best-sealed and most energy efficient windows available. Awning windows, which open outward on a top hinge, and sliding windows, which slide open horizontally, are moderately efficient. Double-hung windows, which slide open and closed vertically, are the least efficient type of window because they don’t seal well. Ironically, double-hung windows are the most common. Replacing double-hung windows with casements will save you a significant amount of energy.
If you’re on a budget (who isn’t?), you can usually replace double-hung single pane windows with replacement double pane windows. Double pane windows have two panes of class with an air space between them for greater energy efficiency. Air is actually a great insulator when it doesn’t move. When your replacement windows are installed, take the opportunity to add insulation around the jambs if possible.
New windows won’t help you save energy if they’re installed incorrectly. Unless you’re relatively handy, pay a professional install your new windows, and after the work has been completed, check each window yourself with the draft test explained above. No matter how efficient the windows are, they won’t be able to do their job of keeping your house airtight if there are cracks and spaces between the windows and the walls.
Old Barn Window Photo by Feodora Umarov