Hygro-thermal performance of hollow bricks and current standards

Hygro-thermal performance of building components is a result of the interaction of several influencing factors (i.e. vapour and liquid transfer, driving rain, solar radiation, etc.), but national and international standards are still based on Glaser-type methods of calculation. A mono-dimensional moisture transfer resistance of each layer must be evaluated in a many-layered wall. When the layer is non-homogeneous such as an hollow brick numerical calculations are due to its two-dimensional performance. Numerical results are mesh dependent, but two-dimensional numerical analysis is able to predict in-wall condensation not evident from standard mono-dimensional calculations. Experimental measurements of water-vapour transfer resistance are reported and results are compared with numerical and standard ones.