Glass Performance

UV - click for more info.
UVA energy is the primary component responsible for fading of furnishings and overall deterioration of fabric quality. The more a window product can reject or absorb the sun's UV energy, the longer the life and quality of the furnishings being protected. All window products should strive for the lowest UV transmission value possible.

VISIBLE LIGHT - click for more info.
Light Transmission percentage represents the actual visible light from the sun the window lets pass through.  Allowing too much light causes glare and eye strain, but blocking too much light defeats one of the main purposes for having windows in the first place.

INFRARED - click for more info.
Transmission percentage represents the amount of heat from the sun that your window allows to pass into your home.  You can save money on their energy bills by blocking the sun's heat.  Different coatings and films on glass will function differently regarding infrared energy. For Far Infrared (FIR), both soft coat and hard coat Low E coatings reflect thin long-wave infrared energy (heat) back inside a home, thus reducing heat loss through the windows. For Near Infrared (NIR), spectrally selective coat Low E coatings prevent significant portion of the NIR energy transmitting through a window. The NIR energy is reflected away from a window, thus reducing the amount of NIR energy that is permitted into a building to be converted to long-wave (FIR) heat.

SOLAR HEAT GAIN COEFFICIENT (SHGC) - click for more info.
The SHGC is the fraction of incident solar radiation admitted through a window, both 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.

If you have moderate air conditioning requirements, select windows with a SHGC of 0.55 or less. While windows with lower SHGC values reduce summer cooling and overheating, they also reduce free winter solar heat gain.


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