COMPUTER SIMULATION OF MOISTURE TRANSPORT IN WALLS OF RESIDENCES

摘要

Well insulated walls of residences experiencerntemperature depression in their outer layers during coldrnweather, causing moisture to condense on the surfaces. Arnpredictive model capable of identifying the conditions thatrnpotentially lead to condensation or high moisture levels hasrnbeen developed. The model utilized includes both moisturernstorage and distribution effects by utilizing the general form ofrnthe thermal energy and moisture conservation equations forrneach layer of a wall of typical residential construction, utilizingrnmaterials such as wood siding, insulation, and gypsum board.rnA finite difference numerical solution produces the transientrntemperature and moisture profiles for each material. The modelrnpredicts that the wood layers offer most of the storagerncapacity for moisture, exhibiting large delays betweenrnchanges in the external conditions and response of thernmoisture content. When walls are exposed to various outdoorrnclimates, the wall moisture content is greater for mild and moistrnclimates than for cold and dry climates. Simulation of an airrnleak in the wall, such as that found around an electrical outlet,rnshow that the wood moisture in the region adjacent to the leakrnis substantially greater than with no air leak.