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Uncertainty Analysis of Thermal Transmission Properties Determined by ASTM C 177



Robert R. Zarr


An uncertainty analysis for steady-state thermal transmission properties determined by the National Institute of Standards and Technology (NIST) 1016 mm Guarded-Hot-Plate apparatus is presented for fibrous-glass blanket and expanded polystyrene board. The uncertainties are presented for the guarded-hot-plate apparatus in the single-sided mode of operation covering specimen heat flows from 0.5 W to 5 W. The relative expanded uncertainties for thermal resistance increase from 1 % to 3.5 % for thicknesses of 25.4 mm to 254 mm, respectively. Although these uncertainties have been developed for two thermal insulation materials, the results are indicative of other insulation materials measured at a mean temperature near 297 K (23.9 °C). This assessment of uncertainties is of particular interest for users of Test Method C 177 that operate similar apparatus at low heat flows (i.e., near or less than 1 W). Implications for laboratories that develop secondary standards from NIST calibrations are discussed.
Journal of Testing and Evaluation


building technology, calibration, expanded polystyrene board, fibrous glass blanket, guarded hot plate, heat flow, thermal conductivity, thermal insulation, thermal resistance, standard uncertainty, expanded uncertainty


Zarr, R. (2010), Uncertainty Analysis of Thermal Transmission Properties Determined by ASTM C 177, Journal of Testing and Evaluation, [online], (Accessed February 27, 2024)
Created March 1, 2010, Updated February 19, 2017