Terminology for Different types of Window
Air Infiltration
This test measures air infiltration through a window or door, excluding air that passes between the frame of the unit and the wall. The units are tested as specified in AAMA/NWWDA 101/1.S.2-97: cfm (cubic feet/minute) per square foot of overall frame dimension.
Glazing (IG)
IG refers to insulating glass (dual panes separated by a spacer). IG glass is offered in clear (no special coating or gas filling) and high-performance (HP), which has a special low-emissivity coating for exceptional energy efficiency.
Outdoor-Indoor Trarsmission Class
OITC is a single-number rating that represents the acoustical performance of a product exposed to an exterior noise environment. The test evaluates a product’s ability to reduce air and ground transportation noises, such as from an aircraft, freeway or railroad. The frequency range for this test is 80-4000Hz (1/3 octave bands).
Solar Heat Gain Coefficient (SHGC)
This is a measurement of the amount of heat from solar radiation that makes it through a piece of glass or a fenestration product.
Sound Transmission Classification (STC)
STC is a single-number rating that represents the acoustical performance of a product exposed to an office noise environment. The test evaluates a product’s ability to block common interior noises, such as speech, radio and television. The frequency range for this test is 125-4000Hz (1/3 octave bands).
Visible Light Transmittance (VT)
VT is an energy performance rating that measures the amount of visible light transmitted through the total fenestration system. VT is expressed as a dimensionless number between 0 and 1. VT is influenced by the type of glazing and the ratio of glazing and frame area. The higher the VT, the more daylight a product lets in. Are you Looking for Structural SticK Glazing?
U-Factor
A window’s U-factor is the measure of heat loss through the window. The lower the number, the greater a window resists the transfer of heat.
U-Factor of Unit
NFRC-rated U-factors are determined using NFRC 100-01. The average U-factor is an area weighting of the center of the glass and the frame heat loss for the entire unit. The U-factor is the overall coefficient of heat transmission or thermal transmittance (air-to-air) in BTU/hr./sq. ft./ degrees Fahrenheit. Winter night U-factors are calculated for an outdoor air temperature of 0°F, indoor air temperature of 70°F, outdoor air speed of 15 mph, indoor air speed of 0 mph, and a solar intensity of 0 BTU/hr./sq. ft.