This test method details the calibration and testing procedures and necessary additional temperature instrumentation required in applying Test Method C 1363
4.2 The thermal transmittance of a test specimen is affected by its size and three-dimensional geometry. Care must be exercised when extrapolating to product sizes smaller or larger than the test specimen. Therefore, it is recommended that fenestration systems be tested at the recommended sizes specified in Practice E 1423
Since both temperature and surface heat transfer coefficient conditions affect results, use of recommended conditions will assist in reducing confusion caused by comparing results of tests performed under dissimilar conditions. Standardized test conditions for determining the thermal transmittance of fenestration systems are specified in Practice E 1423
Likewise, it would be desirable to have a surround panel that closely duplicates the actual wall where the fenestration system would be installed. Since there are such a wide variety of fenestration system openings in North American residential, commercial and industrial buildings, it is not feasible to select a typical surround panel construction for installing the fenestration system test specimen. Furthermore, for high resistance fenestration systems installed in fenestration opening designs and constructions that have thermal bridges, the large relative amount of heat transfer through the thermal bridge will cause the relatively small amount of heat transfer through the fenestration system to have a larger than desirable error. For this reason, the Calibration Transfer Standard and test specimen are installed in a homogeneous surround panel constructed from materials having a relatively high thermal resistance. Installing the test specimen in a relatively high thermal resistance surround panel places the focus of the test on the fenestration system thermal performance alone. Therefore, it is important to recognize that the thermal transmittance results obtained from this test method are for ideal laboratory conditions, and should only be used for fenestration product comparisons unless the thermal bridge effects that have the potential to occur due to the specific design and construction of the fenestration system opening are included in the analysis.
4.5 This test method does not include procedures to determine the heat flow due to either air movement through the specimen or solar radiation effects. As a consequence, the thermal transmittance results obtained do not reflect performances that may be expected from field installations. It is possible to use the results from this test method as input to annual energy performance analyses which include solar, and air leakage effects to get a better estimate of how the test specimen would perform when installed in an actual building. To determine the Solar Heat Gain Coefficient of fenestration products, refer to NFRC 2010. To determine air leakage for......
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