UV Transmission (UVT)

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Last Updated: July 31, 2024

Ultraviolet Transmission (UVT) is a measure of the percentage of ultraviolet (UV) light that passes through a material, such as glass. UV light, which has wavelengths ranging from approximately 300 to 400 nanometers (nm) at the Earth’s surface, can have harmful effects on skin, eyes, and interior materials, causing fading, discoloration, and degradation. UVT is an important metric for understanding how well a material filters out UV radiation.

Understanding UVT helps when selecting window and door glass where UV protection is a concern. Lower UVT values indicate better UV filtration and protection against the harmful effects of UV radiation.

UVT vs. ISO-CIE Fade Measurement (Tdw-ISO):

UVT is a more well-known measurement to measure fade potential. But ISO-CIE Fade Measurement, or Tdw-ISO, offers a broader assessment of fading potential, accounting for the whole spectrum of light that contributes to fading, including UV and visible light, in the range of 300 to 700 nm. The Tdw-ISO value calculates transmitted daylight weighted by the ISO-CIE damage function, which assigns specific damage-weighted transmittance to each wavelength according to its contribution to fading. Lower Tdw-ISO values indicate better overall fade protection. Both metrics, UVT and Tdw-ISO, are important for evaluating materials’ UV and fade protection properties.

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