Moisture proof calculation of envelope in severe cold zone

The permeability of building materials significantly influences the thermal performance and structural safety of walls. Checks the envelope moisture proof performance in some cities of severe cold zone in China by dew point method widely used in engineering projects. The results show that in severe cold zone of China, the thermal insulation materials installed on the outside of the main structure is helpful to reduce the risk of water vapor condensation inside the structure. Clay bricks widely used in the existing buildings have good permeability. In the new buildings, increasing the thickness of the concrete block structure rarely contributes to protect the walls from the water vapor condensation. Increasing the thickness of the thermal insulation materials helps to reduce the risk of condensation. The rise in indoor dry bulb temperature or relative humidity will increase the risk of condensation, and the higher the indoor temperature, the more obvious the effect of the relative humidity. Proposes a dimensionless physical parameter—condensation factor, which simplifies the traditional calculation, according to the calculation results.