Predicting hygrothermal performance in cold roofs using a 1D transient heat and moisture calculation tool

Stricter Swedish building regulations require a moisture safety design process to be carried out before houses are built. In order to predict moisture-critical conditions, a properly verified, user-friendly and reliable calculation tool that could be used in this design phase, is required. This paper initially presents a blind method that could be used in order to verify hyg-rothermal calculation tools in a reliable manner. Furthermore, general results and findings from blind validations of a transient heat and moisture calculation tool carried out in cold roofs are summarized and presented. The comparisons include measurements and calculations of temperature and relative humidity and were carried out in Northern European climates. In general, the results show a good correlation between measured and calculated values. Comparisons show that the studied tool can be used during the design phase to predict moisture risks. However, factors such as the influence of impaired temperature measurements on relative humidity have to be taken into account. There is also a need for outdoor climate boundary conditions that take into account critical periods. Measurements and calculations also established that the most moisture-critical conditions in general occurred in the tongued and grooved wooden roof boarding located under the roof membrane. (C) 2015 Elsevier Ltd. All rights reserved.