Reliability study on adoption of conversion factors in the design values for thermal conductivity parameters: Effect on a mineral-fibrous material.

Building components in terms of thermal protection are being addressed with standard requirements to related thermal performance design. In this relation, thermal conductivity parameters play a highly relevant role that may affect heat transfer greatly. This represents a key factor in building performance assessments for steady-state conditions and corresponding calculation models on thermal effectiveness as well as temperature distribution of building components. Generally, these parameters are known from declared values given by their producers. For this purpose, standard tests are performed to provide data under steady-state conditions. However, limitations may occur in real cases due to not constant and changing thermal conductivity that is temperature, moisture, and time-depending variables. Therefore, in the design process, several governing factors should be carefully considered in thermal calculations. Accordingly, a standard methodology using the transformation of declared values to design values is adopted in practice. In this paper, the usefulness of transformation formulas based on standard methods is demonstrated and discussed as compared with real subjections obtained in the laboratory. One of the representatives of thermal insulation based on mineral fibrous material was used and studied experimentally to obtain transformation factors on both moisture and temperature relations. Based on the data measured, coefficients of transformation formulas were derived from experimental measurements. Results identify a certain discrepancy between experimental data and theoretically calculated values used by available standard methods. [ABSTRACT FROM AUTHOR]