Glazed Window Energy Efficiency
October 11, 2010
Windows can make up 25 percent your heating and cooling bill. How can you bring that cost down? The more energy efficient your windows are, the less your bills will be. The style and materials of a window will affect its energy efficiency. Generally, wood, vinyl, or fiberglass frames are better insulators than metal, so they're more energy efficient. The window material that goes in that frame is called the glazing. Several factors can improve glazed windows energy efficiency.
To understand why the glazing material matters, you need to understand a bit about energy efficiency ratings. Ratings include three factors. One is non-solar heat transference through your window. Number two is the heat gained from the sun shining through that glazing. The third is airflow, which can happen when you open the window or from leakage.
The glazing itself can greatly affect solar and non-solar heat transference. Though most glazing material is glass, plastic glazing materials such as acrylic and polyethylene are widely available. Some plastics have higher solar transmittance, which makes them less energy efficient.
Instead of using clear glass, glazed windows energy efficiency can be increased by using heat-absorbing glass that can absorb 45 percent of incoming solar energy, "low-e" glass that is coated to reflect 40-70 percent of heat, and reflective glass, which reduces heat and light.The number of panes in glazed windows as well as what fills the space between them affect a window's energy efficiency. Glazed windows energy efficiency depends on the style of window, the glazing and frame material, and the quality of the installation.