Nowadays to reduce the energy loss as well as to minimize the emission of the green house gases of buildings can be solved by thermal insulating. Silica aerogels have a promising potential in the building and construction sector as thermal insulation due to their excellent thermal conductivity. At the present time the applications of silica aerogel blankets are truly widespread. This study focuses on the moisture induced degradation of the thermal conductivity of the above mentioned insulation slabs. Experimental studies show that the thermal conductivity of the aerogel blankets can be increased significantly (approximately 20-40%) after wetting them. For this case different types of investigations were carried out to investigate the changes in the thermal conductivity derived by the moisture content. Firstly, in order to see the temperature sensitivity of the moisture up-taking, sorption isotherm curves were registered at 283, 293 and 303 K after 24h after drying and wetting at 5 different relative humidities. Secondly, the decrease of the thermal conductivity was followed with a Holometrix type heat flow meter of individual aerogel slabs after wetting the dried samples for 0, 4, 8, 12, 16, 20 h at 293 K and 90% relative humidity in a Climacell type climatic chamber. Finally, the change in the thermal resistance of a brick based wall covered with 0.013 cm thick aerogel insulation was registered by calibrated chamber method in function of the quantity of sprayed water. From the measurement results calculations were executed to see the changes of the thermo-physical properties of the aerogel samples due to the water absorption. The novelties of the article can be found in the comparison of the measurements of the same values and properties carried out by different methods Moreover, the measurement results formed the basis of Building Energetic Simulations in order to show roughly the effect of the moisture. (C) 2017 Elsevier B.V. All rights reserved.