An investigation of moisture migration through building envelopes has been made using the simulation software UMIDUS of transfer of heat and mass within porous walls in 13 Brazilian cities. Both diffusion and capillary regimes are taken into account; that is, the transfer of heat and mass through the material can be analyzed simultaneously for multi-layer walls. Both conditioned and unconditioned rooms are studied. The contribution of moisture migration to the ratio of latent heat flux to the total flux through the wall is calculated, and the importances of the role that moisture plays within the building envelope is analyzed. The effect of paint on the internal surface of the wall is investigated, and rain effects on the heat transfer are also discussed. It was found that an impermeable paint on the internal surface reduces the total heat transfer through the wall as it restricts moisture movement from the wall into the room.

Authors: Nathan Mendes, Dr. Eng.; Roberto Lamberts, Ph.D.; Paulo Cesar Philippi, Dr. Ing.

Citation: Thermal Performance of the Exterior Envelopes of Buildings VIII

Keywords: December, Florida, 2001