If you want your home to be extremely energy efficient, then fill in all of your windows so you have only solid walls. I kid. But there's no arguing that windows are the "weakest link" in the construction of a wall. But we love a good view - so what to do?
Installing vinyl replacement windows is not always the most eco-friendly or attractive option. Fortunately, they aren't your only option when it comes time to replace your old windows with more energy efficient models. In order to choose the best replacement windows, look for these qualities:
1. Multiple Panes
A single pane window inevitably leaks a lot of air. You may as well not even bother installing a window, as far as energy efficiency goes. However, when you install windows will double panes, or better yet, triple panes, the insulation factor skyrockets. (Unfortunately, so does the price...but you'll recoup it)
2. Insulating Gases
Obviously you can't stuff fluffy pink batt insulation between those panes of glass as you would in a wall; but thanks to the existence of certain gases that are more dense than air, but still invisible, it is possible to insulate between panes. Several window manufacturers use Argon, Krypton and Xenon for this purpose.
3. Low-e Coating
Low-emissivity glass is coated with metal, but don't worry, it won't block your view. Instead, this super-thin coating is placed on one side of the glass in the airspace between panes. Its location depends on your climate; it can either reflect radiation from the sun into your space to warm it, if you live in a cold climate, or reflect it back outside if you live in a hot climate.
4. Sustainable Frame Materials
Look for window frames made of FSC wood, ideally. If real wood is out of your price range, find those made of recycled or composite materials. Be sure that whatever materials they are made from, the windows you are purchasing won't offgas harmful chemicals like VOCs.
5. Energy Star Label
Consider the Energy Star label a seal of approval. According to guidelines, these windows much attain an "NFRC certified U-Factor and, where applicable, Solar Heat Gain Coefficient (SHGC) ratings." You don't have to know precisely what those terms mean (they relate to the window's tendencies to transfer heat and block heat from the sun), but they are a good thing. If the window manufacturer has reached these high standards, you can rest assured that little blue and white label will translate into extra cash you can spend on something besides your energy bills...like more windows!