A thermal conductivity meter was assembled and the thermal conductivity of two materials was
measured. We have done standards rewiev which are describing the measurements of thermal
conductivity of building materials and the main working principles of the thermal conductivity meters currently available on the market. In order to calculate a thermal conductivity of homogeneous material we measured a heat flux through sample of known thickness and a temperature gradient. The assembled thermal conductivity meter consists of a heater, two heat flux sensors, data logger and a fan. The precision of the apparatus was estimated by comparing the thermal conductivity determined by
certified thermal conductivity meter, with our result. Finally, we measured the thermal conductivity of two insulating building materials: aerated concrete and extruded polystyrene. The aerated concrete was measured in various humidity conditions. The thermal conductivity of aerated concrete increases approximately linearly with the relative humidity increasing of the sample.