Validation of measurement techniques and the determination of data required for thermal modelling of moist masonry walls

摘要

A comprehensive programme of measurements involving twelve organizations has been carried out as part of a project partially funded by the European Community under the "Competitive and Sustainable Growth" Programme (1998-2002), relating to the thermal and moisture performance of masonry walls and the measurement uncertainty associated with those measurements. The basic thermal and moisture transport properties of several types of masonry materials and mortars have been obtained, an extended series of measurements have been made using different types of hot box measurement apparatus of the thermal performance of wall systems fabricated from these materials in the dry and carefully controlled moisture content conditions. To assist in the final analysis, a series of measurements of "idealized" wall systems with sheets of polymethylmethacrylate replacing the mortar was also included. Over 200 hot box tests were carried out for three main reasons. Firstly to quantify the repeatability, reproducibil-ity and uncertainty limits of guarded and calibrated hot box measurements according to ISO 8990. Secondly, to establish and verify the efficiency and possible equivalency of the more recently developed EN1934 procedure that utilises a heat flow meter attached to the surface of the test element. Thirdly, to validate a mathematical model used to derive the U-value of walls built of hollow blocks and mortar, with specific moisture contents, from the thermal properties of its components in the dry state. The results are presented and discussed with respect to the equivalency requirements and to the verification of performance of each type of hot box. In addition, comparisons are made of the effects of moisture on performance between tests made on the composite system. Finally, the overall data were analysed in order to validate the mathematical model of complex moist masonry structures and to produce a software tool to facilitate the determination of thermal properties using a procedure based on EN 6946.