Energy Efficient Windows

Energy Efficient Windows
Energy Efficient Windows - Andersen 400 Series

Until quite recently, a home's windows were one of the biggest sources of energy loss in the entire structure. Over the last few decades however, major advances in window technology have largely rectified this; since the early 1980s, the energy performance of a typical window has been improved by over 50%.

Doing some research into the windows you select for your home can save a great deal of energy (and money!) over the lifetime of your house. There are a lot of window companies and choices out there, all promising energy savings. What are some of the things to look for when shopping for windows?

Energy-Efficient Windows: Multiple Panes

Many older homes still have original windows with only one single pane of glass. Today's windows have double-paned glass to increase the window's efficiency. The space between the panes acts as a thermal barrier between the indoors and outdoors. More expensive windows can contain triple-paned glass to increase efficiency even further.

Energy-Efficient Windows: Low-E Glass

Energy Efficient Windows

The use of low-e glass can greatly increase the r-value of new windows. Low-e glass contains invisible layers of special coatings, typically tin dioxides or thin silver layers. These coatings reflect radiant energy, keeping that heat on the same side of the glass from which it originated, while still letting visible light pass.

During hot periods, the heat (and UV rays) of the sun is reflected away, lowering cooling costs. On the flip side, during cooler months, the low-e window keeps heated air on the inside of the house, lowering heating costs.

The premium price of low-e windows, usually 10-20% higher than traditional windows, will pay for itself in just a few years in energy savings.

Energy-Efficient Windows: Fill 'em Up with Gas

Many efficient windows today inject an inert, low-conductivity gas in the space between layers of glazing to greatly improve thermal performance. Most use argon gas, though some ultra high-efficiency windows use krypton or a mix of argon and krypton between the glazing layers.

Energy-Efficient Windows: Frames Are Important, Too

The material used for a window's frame can also improve it's efficiency. Vinyl frames have a good thermal performance, but can be prone to warping and sagging. Weather sealing can also be a problem with low-quality vinyl windows due to the expansion and contraction of the vinyl plastic from temperature variations.

Other efficient window frame materials include fiberglass with foam insulation and composites made from recycled plastic and wood. The 'original' window framing material, wood, is still the best for energy efficiency. Many manufacturers add vinyl cladding to a wood window's exterior side for lower maintenance.

Energy Star Windows

A great way to start your search for windows is to simply look for the Energy Star label. Energy Star was established by the U.S. government to effectively measure and rate home products, and make it easier for consumers to identify energy-efficient products that offer savings on energy bills without sacrificing performance.

Energy Efficient Windows
Pella Windows - Center-Of-Glass Insulation Values

An Energy Star product will save energy and money, and also reduce greenhouse gas emissions and other pollutants caused by the inefficient use of energy. Energy Star approved windows are certified to:

Energy-Efficient Windows and Green Home Source

All green home plans designed by Green Home Source specifically call for efficient windows certified by Energy Star and The National Fenestration Rating Council (NFRC). These ratings provide a useful tool when comparing and choosing windows for your home and will ensure that your home is as energy-efficient as possible.

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