Modeling heat and moisture transfer in promising timber envelope structures.

The account of dependence of moisture conductivity coefficient, thermal conductivity coefficient and heat capacity on temperature and moisture is the main peculiarity of the new physico-mathematical model of combined heat and moisture transfer in walls of low-rise wooden insulated timber buildings. This study is aimed at refining and testing such model, including preliminary evaluation of influence of moisture transfer processes on moisture accumulation in insulated timber structures with connectors at low outside temperatures. The study provides approximation dependences that illustrate variation in thermal characteristics of wooden structures made of timber, plywood and insulation. The results of numerical simulation of heat and mass transfer processes occurring in a representative wall fragment made of high-strength profiled timber are given. Temperature and moisture fields are calculated in a selected inhomogeneous fragment. Maximum humidification in insulated profiled timber walls is located on the external surface of the wall. It is found that the use of additional internal longitudinal lamellae in timber with vertical connectors leads to significantly uneven moisture distribution. Based on the calculation results one may conclude that the wall fragment under study has no areas where free moisture can be possibly accumulated. [ABSTRACT FROM AUTHOR]