Choice of indoor standard in hygrothermal simulations of external walls – Three swedish case studies.

When assessing the moisture damage risks of different external wall designs using hygrothermal simulation software, the user of said software can choose between different inputs for the determination of the indoor climate. This paper aims to compare results from field measurements in three Swedish buildings using different standards available in a widely used commercial hygrothermal simulation software, WUFI Pro. In this project, field measurements on external walls were conducted before the implementation of interior insulation. Measurements were conducted indoors, outdoors, and on the exterior and interior surfaces of the external walls. Comparing measurement and simulation results shows that on-site measurements give more accurate modelling of an existing external wall. However, the results also show that, when needed, any of the current standards can be used as replacements for actual measurements regarding indoor air temperature. The comparisons show that the most accurate results regarding the relative humidity are generated when ASHRAE Standard 160 is applied with an intermediate approach and a higher air change rate than in the nominal case. However, several parameters must be known for such an approach, such as the actual air change rate and the number of bedrooms. If such parameters are not known, the standard that gives the best fit between measured and simulated relative humidity is EN15026. [ABSTRACT FROM AUTHOR]