Climate data for hygrothermal simulations of Brussels.

Moisture is a dominant agent in the degradation of building components. To assess degradation phenomena in building envelopes, hygrothermal simulations are performed. The hygrothermal behaviour of building envelopes depends on the outdoor climate conditions. Therefore, it is important to use climate data near the location of interest when running hygrothermal simulations. There are no appropriate climate data for hygrothermal simulations of Belgian cities. Therefore, we created two types of climate files for Brussels, i.e. the capital of Belgium. This paper presents the climate data that are selected based on the framework developed by Vandemeulebroucke et al. The first climate file is a long-term 30-year climate file. Using this climate file is the most reliable, but computationally expensive. This climate file is recommended for academics having sufficient computational power. The second file is a Moisture Reference Year (MRY), which is one year of climate data that represents the 90th percentile of moisture stress on building envelopes. The MRY is selected based on a climate index that is critical for many applications, i.e. the free wind-driven rain load. The reference year is called a generic climate-based MRY. The latter climate file is recommended for building consultants or academics performing very large studies, as it requires less computational power at the cost of a lower level of detail.

Impact of the urban heat island on freeze-thaw risk of natural stone in the built environment, a case study in Ghent, Belgium.

Freeze-thaw cycles are important in the weathering behaviour of natural building stones in humid, cold to temperate climates. It is expected that the elevated air temperatures in urban environments, the so-called urban heat island (UHI), will have an impact on freeze-thaw weathering. In this study, the impact of the urban heat island on the potential freeze-thaw risk is assessed by parameterization of climatic data of 1 year (07/2016-06/2017) from the MOCCA (Monitoring the City's Climate and Atmosphere) project, which studies the urban heat island in Ghent, Belgium. The dose-response of Savonnières, a French limestone often used as building stone, is investigated in laboratory and by HAM simulations. Analysis of the MOCCA data demonstrates that the urban heat island phenomenon decreases the number and intensity of freeze-thaw cycles in an urban environment with 42% and 41% respectively for the studied year in Ghent. This decrease suggests a mitigation of frost risk in urban environments. Laboratory tests and computational simulations confirm that this leads indeed to a decreased freeze-thaw risk in urban landscapes compared to the surrounding rural environment.