An intercomparison of guarded hot plate apparatus used by UKAS accredited testing organisations

An intercomparison has been carried out between the seven organisations accredited by the United Kingdom Accreditation Service for measurement of thermal performance of thermal insulations and other low conductivity materials by means of the guarded hot plate method. Measurements were made at 10 degreesC and/or 23 degreesC on samples of two thicknesses of an expanded polystyrene, an extruded polystyrene and a high density mineral fibre board, according to ISO 8302 [1] and following a strict protocol. These materials had been chosen for a supplementary intercomparison of the seventeen heat flow meter apparatus currently used within the UK and Ireland. The aim of these investigations was not only to check that a consistent level of current measurement technology was being maintained to declared precision limits but also to provide information to assist all organisations that intended to improve their measurements capabilities. The investigation showed that the overall consistency obtained is well within +/-3%. This confirms the results of internal audits within the testing organisations and is compatible with the levels expected when complying with the standard procedure ISO 8302 [1].