There are two types of low-e coatings: soft-coat (sputtered) and hard-coat (or pyrolytic) coatings. The type of coating can affect other window properties, such as how well it blocks heat from the sun (called solar heat gain coefficient(SHGC) The fraction of solar gain admitted through a window, expressed as a number between 0 and 1., or SHGCSolar heat gain coefficient. The fraction of solar gain admitted through a window, expressed as
a number between 0 and 1.) or how much light it allows (visual transmittance, or VT). Double-glazed or triple-glazed low-eLow-emissivity coating. Very thin metallic coating on glass or plastic window glazing that permits most of the sun’s short-wave (light) radiation to enter, while blocking up to 90% of the long-wave (heat) radiation. Low-e coatings boost a window’s R-value and reduce its U-factor. windows can be ordered with either a low SHGC or a high SHGC. In most climates, south-facing windows should have high SHGC glazingWhen referring to windows or doors, the transparent or translucent layer that transmits light. High-performance glazing may include multiple layers of glass or plastic, low-e coatings, and low-conductivity gas fill., while west (and in some cases east) windows should have low SHGC glazing.
Certain low-e coatings can give windows a bluish or reddish tint, most noticeable when looking at the glass from an angle. Since everyone has their own sensitivity to color filtering, it is best to discuss the issue with your clients and make sure they see and approve of the window selection.
For more information on low-e coatings:
Building Science.
For more information on glazing choices, see All About Glazing Options and High-Solar-Gain Glazing.
For the best overall information on residential window properties:
Efficient Windows Collaborative.
For product information on high-performance windows:
Green Building Advisor.