ABSTRACT
The paper describes a method to determine the so-called design value of the thermal conductivity of insulation materials. The procedure involves determination of moisture conversion factors to convert between the so-called declared values, which are obtained directly or indirectly from measurements, and the design values that are characteristic of the in-use conditions of the products. The declared and design values of thermal conductivity, as well as the moisture conversion factor are introduced in the international standard EN ISO 10456, but it is left open how to determine the design values for materials at the conditions under which they are typically used in building constructions. The paper presents a proposal, using numerical prediction of the hygrothermal conditions of the materials, of how to estimate the design value.
