Experiment And Simulation Research Of Moisture Transportation In Wall Composed With External Thermal Insulation

For buildings in severely cold zone, the insulation performance of buildingenvelope will directly affect the level of energy consumption. And moisture content ofwall materials has an important influence on the thermal performance of the buildingenvelope. Besides, moisture accumulation inside the wall will have a negative impacton the durability of the structure. Therefore, study on water migration in the wall isnecessary.This paper is devoted to the study of the moisture transportation in wall composedwith external thermal insulation EPS. The law of moisture migration inside the wall wasobtained through the test of hygrothermal performance of EPS, and the ecperiment ofmoisture transportation in wall specimen, the comparison of simulation and test of heatand moisture conditions of external wall in Harbin.First, by heating steam and immersion in water, the EPS board was humidified.The influence of water content on thermal conductivity of EPS was studied by steadystate test method. The simulation of testing process of thermal conductivity results showthat the moisture distribution inside EPS has changed a lot during the test. Thus thesteady state test method is not well applicable to the thermal conductivity test of moistporous building materials.Then the moisture transportation in wall specimen experiment was conductedbased on the temperature field and humidity field made by freezer and humidifier. Forthe hot end, the temperature is at room temperature, relative humidity is99%RH and70%RH, respectively; the cold end was controlled by freezer Specimens was subjected totemperature and humidity gradients, and hydration occurred in concrete, thus theinternal humidity field changed greatly. The IRH value in concrete layer near the hotend increases a little, and those away from hot end decrease continuously. And the IRHof the air layer continues to decrease. There are differences between two groups invariational amplitude. The simulation results by CHAMPS are in good agreement withthose of experiments.And moisture conditions for wall with EPS as external insulation in Harbin wassimulated by CHAMPS. The results shows that it takes five years for wall materialswater content to get steady state. And the IRH can hardly come to a steady state.Condensation in air layer is highly likely to occur in the first year. And little impact ofmoisture conditions of materials on the heat transfer coefficient is observed since thecompletion of3years.Finally, several practical wall was monitored. The IRH of the concrete layer washigh, and decreased rapidly.since completion of the wall. After the completion of twoyears, the indoor and outdoor environment became the main factors that affect the IRH of the wall. There is a big difference between the test results and the simulation results.As the ultimate state, simulation results is still valuable to provide reference.