National Fenestration Rating Council

Window Performance Guide
for Human Thermal Comfort

This glass guide covers four important areas of window performance, providing comparative
performance information and selection criteria for the following critical areas of performance:

Winter insulating performance
WINTER: ENERGY
EFFICIENCY AND
COMFORT 		summer solar control
SUMMER: PROTECTION FROM SEARING
SOLAR HEAT 		Sound Control
ALLOWING YOU
TO SEE
THE WORLD 		ultra violet protection
EXTENDING THE LIFE AND
BEAUTY OF YOUR HOME'S
FURNISHINGS
Glass Temperature Recommended U-factors

U Factor map U Factor chart
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