In situ measuring of thermophysical properties of building materials and wal configurations

摘要

The thermal properties of building materials are of great importance for many technical questions. The thermal insulation characteristics of external wall constructions decisively determine the utility value and the runnign costs in housing and public buildings. In this paper possibilities are represented to record such values by means of in-situ-measurement. A measurement arrangement is introduced to determine the thermal resistance of external wall structures and/or the thermal conductivity of material layers. This method works with a heating system transmitting a definite steady heat flux through the objects. The generated temperatures determine the thermal resistance and the thermal conductivity. When a periodical intermittent heat flux is generated, the storage capacity or the specific heat can also be determined. To measure the thermal properties of each layer of multi-layered constructions, like thermal conductivity, thermal diffusivity or specific heat, it is advantageous to use temperature and flux gradients existing there in according to the prevailing initial- and boundary-conditions.