You’ve decided to replace those old rotting windows, and you’ve chosen the perfect window frames to match your home on the inside and on the outside.
Now comes a decision that’s just as important as picking new energy efficient frames. Now it’s time to consider what type of glass or glazing you should use to improve your home’s energy efficiency even more. And depending on the climate, your home’s design, window orientation and other factors, you might choose different types of glazing for different windows throughout your home.
Let’s talk about tinting
One way to improve the thermal performance of windows with insulating glazing is to fill the space between the panes with inert gas, like argon, that has a higher resistance to heat flow than air.
Heat-absorbing window glazing contains special tints that change the color of the glass. Tinted glass absorbs a large fraction of the incoming solar radiation through a window, reducing the solar heat gain coefficient (SHGC) and glare. The SHGC is the fraction of incident solar radiation admitted through a window, both directly transmitted and absorbed and subsequently released inward. SHGC is expressed as a number between 0 and 1. The lower a window’s solar heat gain coefficient, the less solar heat it transmits.
Some heat, however, continues to pass through tinted windows by conduction and re-radiation.
Inner layers of clear glass or spectrally selective coatings can be applied on insulated glazing to help reduce these types of heat transfer.
Tinted, heat-absorbing glass reflects only a small percentage of light, so it does not have the mirror-like appearance of reflective glass.
Insulating window glazing
With windows that have two or more panes, the glass panes are spaced apart and sealed to insulate the window, which leaves an insulating air space. Insulating window glazing primarily lowers the U-factor, but it also lowers the SHGC.
Low-emissivity (low-e) coatings on glazing or glass control heat transfer through windows with insulating glazing. Windows manufactured with low-e coatings can reduce energy loss, according to energy.gov.
A low-e coating virtually invisible and lowers the U-factor of the window, and different types of low-e coatings have been designed to allow for high solar gain, moderate solar gain, or low solar gain.
Reflective coatings on window glazing or glass reduce the transmission of solar radiation, blocking more light than heat. Therefore, they greatly reduce a window’s glare (interior), as well as reduce a window’s SHGC.
Reflective coatings usually consist of thin, metallic layers, and come in a variety of colors, including silver, gold, and bronze.
Reflective window glazing is commonly used in hot climates to control solar heat gain. The reduced cooling energy demands can be offset by the need for additional electrical lighting, so reflective glass is used mostly for special applications.
Customize your glaze
Special coatings can be applied on various types of tinted glass to produce “customized” glazing systems capable of either increasing or decreasing solar gains according to the aesthetic and climatic effects desired.
According to energy.gov., computer simulations have shown that advanced window glazing with spectrally selective coatings can reduce the electric space cooling requirements of new homes in hot climates.
Pella Omaha’s glazing options
Pella offers a wide variety of insulating glass options for Architect Series®, Pella® ProLine, Pella Impervia®, and Encompass by Pella® products, plus dual- or triple-glazing solutions for Designer Series® products.
Glass options from Pella Omaha include:
- Advanced Low-E insulating glass with argon (Optional high-altitude Low-E insulating glass is available with or without argon on most products. Please see your local Pella representative for more information.) — features a Low-E coating made from two layers of thermal protection for exceptional energy efficiency.
- SunDefense™ Low-E insulating glass with argon — features a unique Low-E coating made from three layers of thermal protection that greatly reduce solar heat gain while maximizing visible light.
- NaturalSun Low-E insulating glass with argon — features a single layer low-E coating that provides a low U-Factor and high Solar Heat Gain Coefficient (SHGC) that make it the ideal glass for passive solar applications.
- Solar-E — offers superior reduction in solar heat gain.
- Spandrel glass or panels
Designer Series Exclusive Glazing Systems
- Designer Series aluminum-clad wood products are available with three-pane systems that allow for a variety of between-the-glass options including blinds and shades.
- Designer Series products with Advanced Low-E triple-pane glass have superior NFRC U-Factors and SHGC ratings) and noise reduction among top national wood brands. (When compared to top national brands with similar glazing, Pella’s triple-pane glass significantly reduces sound transmission.)
Dual glazed Designer Series is primarily used in Commercial applications.