What Property Do We Measure— Considerations on a Decade of ISO/TC 163

Abstract

In April 1973 Subcommittee C-16.30 of ASTM Committee C-16 presented the milestone paper "What Property Do We Measure?" recognizing that a single measurement on an insulating material could not represent a material property. Since that paper a lot of research has been done and in the meantime ISO Committee 163 on Thermal Insulation was established, soon becoming an excellent international forum for new ideas and concepts In this paper, that is not an official statement from ISO/TC 163, we first analyze what a figure means that we get from a guarded hot plate or heat flow meter appara tus. Two concepts can be stressed: (1) a material can possess an intrinsic property but this may need more than one number to be assigned and (2) a test result, in many in stances, is not a measure of a material property, but it is rather a more or less complex function of material properties and testing conditions. A change in testing philosophy is then proposed: instead of asking for as many measurements as those duplicating all end use conditions, the minimum number of measurements to foresee all conditions of practical interest should be defined. To be consistent with the concepts just outlined, new parameters, and hence new terms, are needed to unambiguously describe thermal performance of insulating ma terials.