Standard: NFRC 102 – Procedure for Measuring the Steady-State Thermal Transmittance of Fenestration Systems

Scope: This test is applicable to both residential and commercial fenestration products.

Applicable Products: Windows, Doors, Skylights, Curtain Walls

Test Procedure: The test utilizes an apparatus known as a guarded hot box. The guarded hot box consists of a cold room and a warm room. The cold room contains refrigeration coils to maintain temperatures as low as -22ºF (-30ºC) and fans to replicate wind speeds of 15 mph (24 kph). The warm room contains electric heating elements to maintain temperatures up to 100ºF (38ºC). The warm room is enclosed within a second room, known as the guard room, with the same heating capabilities.

In the NFRC 102 test, the product is placed in a wall between the warm and cold rooms. Temperatures of 70ºF (21ºC) and 0ºF (-18ºC) and a wind speed of 15 mph (24 kph) are maintained in the two rooms until steady-state conditions have been met for temperature on both sides and energy input to the warm side. The heat flow through the product is measured to determine the U-Factor of the product.

End Result: The thermal transmittance (U-Factor) of the product is determined. The U-Factor can be used to determine energy losses through products. This test is used in conjunction with the NFRC 100 simulation methods to prove the validity of the simulation results for the product. This typically is used to certify windows, doors, skylights and curtain walls for U-Factor.

Special Notes: Alternative U-Factor methods which may be appropriate are NFRC 100, AAMA 1503, CSA A440.2, ASTM C1199, and ASTM C1363.


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