Standard: NFRC 203 – Procedure for Determining Visible Transmittance of Tubular Daylighting Devices

Scope: This test applicable to both residential and commercial Tubular Daylighting Devices (TDD).

Applicable Products: Tubular Daylighting Devices (TDD)

Test Procedure: This test uses a Large Diameter Integrating Sphere (LDIS) operated per ASTM E1175. The device tracks sun position and maintains prescribed incidence angles with the sun. Photometric sensors measure the amount of light passing through the TDD into the interior space.

End Result: The Visible Transmittance (VT) of the Tubular Daylighting Device is determined. The VT can be used to determine the natural light coming through the TDD. This typically is used to certify windows, doors, skylights and curtain walls for VT. This is almost always done in conjunction with ANSI/NFRC 100 testing for U-Factor and NFRC 201 testing for SHGC.

Special Notes: When NFRC 203 is required for VT, NFRC 201 will be applicable to determine Solar Heat Gain Coefficient (SHGC) of those products.


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