There are many ways you can bump up energy efficiency in your home but your windows are one of the most crucial elements you can focus on. This is because between 10 and 25% of heating and cooling requirements in an average American home are affected by heat lost and gained through windows, which translates to a loss of $35 billion every year, according to the U.S. Department of Energy.
When you opt for an energy-efficient window, you can save anywhere between 7 and 15% of energy that you would hav e otherwise lost, according to ENERGY STAR, translating to savings as well on your energy bill. How does an energy-efficient window do this? It’s all thanks to the sum of its parts.
What Makes a Window Energy-Efficient
Consider the following:
- Glass – The type of glass used can greatly affect a window’s energy efficiency. Insulated glass, for instance, features spacers that create a moisture and thermal seal for enhancing thermal performance, keeping the level of heat that passes through a window down. Low-emissivity glass, or low-E glass, on the other hand, is fitted with a thin, transparent layer of tin oxide or silver that lets a window reduce solar heat gain without affecting visible transmittance. Double-glazed windows are also more energy-efficient than their single-glazed counterparts.
- Frame – Like glass, frame materials can affect the level of energy efficiency a window has. Wood, for instance, remains a popular option because it provides good insulation while offering great aesthetic. However, it requires serious upkeep to keep performing well. Vinyl is more affordable and easier to maintain than wood but offers decent insulation that’s why it became a favorite as an alternative to wooden frames, Composite, on the other hand, combines the appearance and performance of wood with the ease of maintenance afforded by vinyl, which is why it is steadily gaining popularity as a replacement window option.
Understanding Energy-Efficiency Labels
By default, getting an ENERGY STAR label means a window is energy-efficient because it has met standards set by the Environmental Protection Agency. Windows will still differ in just how energy-efficient they are, however, depending on the rating on its label, but generally the higher a rating is, the more energy-efficient a window will be.
ENERGY STAR labels can stand alone as a measure of window performance but they are typically included alongside the National Fenestration Rating Council’s own label, which outlines more specific performance ratings, like:
- U-factor – Measures how well a window keeps indoor heat in.
- Solar Heat Gain Coefficient (SHGC) – Gauges how much solar heat a window lets in.
- Air Leakage – Determines the amount of air that a window lets through.
- Visible Transmittance – Lists the level of natural light that a window lets in.
Now that you’ve covered the basics, it’s time to move on to debunking common myths and misconceptions about window energy efficiency. Head on over to Part 2 to learn more!