This paper focuses on the issue of integrating two or three dimensional models of heat and moisture transfer in porous materials with whole building HAM model-ing. To assess this aim, this paper proposes a reduced order model to simulate 2D Heat, air and moisture (HAM) behaviour in porous material. The reduction method used is the proper orthogonal decomposition. The method is applied on a block of concrete. Reduced order model and large original model are compared. The results illustrate the significant value of model re-duction for modelling 2D heat and mass transfers.