Environmentally Friendly Windows

There’s so much to consider when “greening” a home, and one of the most important factors is windows.  There are several eco-friendly window options for new homes, historic homes, and everything in between.  We’re here to break it down for you.

This contemporary cottage in Vancouver, Washington features multi-glazed windows with a Low-E coating and argon fill. 

One option to consider is double- or triple-pane windows (also known as double-glazed).  The basic principal here is that the thicker the glass, the better the insulation, thereby maximizing energy efficiency (and lowering your electric bills!).  

Multi-pane windows are usually made with Low-E (low emissivity) glass, which has been treated with an invisible metallic oxide coating (thinner than a human hair!) that reflects heat/ultraviolet light, while still allowing visible light in. This type of glass lessens energy consumption and also reduces fading of interior fabrics.  In warmer climates, the Low-E layer is applied to the oustide of the window, to prevent heat from entering the home, and in colder climates it's applied to the inside of the window, to keep heat inside.  Don't have windows with a Low-E coating? The films are available for purchase separately to be applied to existing windows. They're inexpensive and can last up to 15 years.  

Another element usually incorporated into multi-pane windows is argon gas, which is placed between the panes.  Argon (or inert) gas is denser than air, so it aids in reducing the transfer of heat or cold air through the window. 

 

A wooden window frame in the process of being rebuilt. 

The type of window frame is also very important when considering the eco-friendliness of a window. Wood frames insulate very well, 1,800 times better than aluminum in fact.  Fiberglass frames insulate the same as wood, but won't warp in extreme temperatures like wood can sometimes do.  They also have air cavities that can be filled with additional insulation. Vinyl frames are typically made of PVC (polyvinyl chloride) and have UV stabilizers that prevent sunlight from wearing down the materials. They, too, have cavities for insulation. 

Aluminum and metal frames conduct heat very rapidly, and therefore, are not the greenest choice.  However, if you're not in the market to take on a large window restoration project, there are some small things you can do to maximize their efficiency.  The first is weather stripping.  The addition of this sealant around window edges can save on energy bills. There are many weather stripping options available, from felt to foam tape to rubber and metal.   

Other quick-fix options are techniques most people are already using without even knowing it.  Blinds and shades can keep out heat, and adding screens reduces the need for air conditioning.  

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