25/30530701 DC

This standard 25/30530701 DC BS EN 12664 Thermal performance of building materials and products - Determination of thermal resistance by means of guarded hot plate and heat flow meter methods - Dry and moist products of medium and low thermal resistance is classified in these ICS categories:

• 91.100.01 Construction materials in general
• 91.120.10 Thermal insulation of buildings

This document specifies principles and testing procedures for determining, by means of the guarded hot plate or heat flow meter methods, the thermal resistance of test specimens either in the dry state or conditioned to equilibrium with moist air, having a thermal resistance of not less than 0,1 m2·K/W and a (hygro)thermal transmissivity or thermal conductivity up to 2,0 W/(m·K). NOTE The lower limit for measurable thermal resistance is due to the effect of contact thermal resistances, which require special testing techniques described in this document. Although this document can be used for testing dry specimens of high and medium thermal resistance, i.e. on products having a thermal resistance, that is, on products with a thermal resistance of at least 0.5 m².K/W, the simpler procedures of EN 12667[3] are available for such specimen. This document does not cover methods to assess the hygrothermal transmissivity of materials in the over-hygroscopic range (i.e. when free liquid water occurs in the material in general above 95% of moisture). It applies in principle to any mean test temperature, but the equipment design in Annex D is essentially intended to operate between a minimum cooling unit temperature of -100 °C and maximum heating unit temperature of +100 °C. This document does not supply general guidance and background information (e.g. the heat transfer property to be reported, product-dependent specimen preparations, suggested materials for vapour-tight envelopes when testing moist specimens, procedures requiring multiple measurements, such as those to assess the effect of specimen non-homogeneities, those to test specimens whose thickness exceeds the apparatus capabilities, and those to assess the relevance of the thickness effect).