Abstract
Parts of the building envelope that frequently receive high amounts of rain are usually exposed to a higher risk of deterioration due to moisture. Determination of such locations can thus help with the assessment of moisture-induced damage risks. This study performs computational fluid dynamics (CFD) simulations of wind-driven rain (WDR) on the Parliament buildings in Ottawa, Canada. Long-term time-varying wetting load due to WDR and potential evaporation are considered according to several years of meteorological data, and this cumulative assessment is proposed as a fast method to identify critical locations and periods. The results show that, on the Center Block of the Parliament buildings, the façades of lower towers facing east are the most exposed to WDR, together with the corners of the main tower. Periods of high WDR wetting load larger than the potential evaporation are observed, indicating that deposited rain may lead to moisture accumulation in the envelope. During these critical periods of up to several months, air temperature may repeatedly drop below freezing point, which poses a risk of freeze–thaw damage. First assessment on future freeze–thaw damage risks indicates an increase in such risks at moderate increases in temperature, but a lower risk is found for larger increases in temperature.
Highlights
Wind-driven rain (WDR), referring to raindrops carried by wind and deposited on building façades, influences the hygrothermal performance and durability of building façades significantly
In order to evaluate moisture-induced damage risks, it is common to perform onedimensional hygrothermal simulations of building envelope assemblies to assess their long-term performance [1]. While this approach resolves the moisture transport in the actual structure of building envelopes, WDR load is mostly simplified by the use of semi-empirical models, which are prone to deficiencies and large uncertainties, unable to capture the effects of local wind-flow features correctly, and defined only for a limited number of common building geometries [18,19,20]
Based on the computational fluid dynamics (CFD) simulations, the highest WDR exposure on the Center Block was observed on the smaller towers, which cause a limited disturbance to the approaching wind flow, i.e., lower wind blockage
Summary
Wind-driven rain (WDR), referring to raindrops carried by wind and deposited on building façades, influences the hygrothermal performance and durability of building façades significantly. In order to evaluate moisture-induced damage risks, it is common to perform onedimensional hygrothermal simulations of building envelope assemblies to assess their long-term performance [1]. While this approach resolves the moisture transport in the actual structure of building envelopes, WDR load is mostly simplified by the use of semi-empirical models, which are prone to deficiencies and large uncertainties, unable to capture the effects of local wind-flow features correctly, and defined only for a limited number of common building geometries [18,19,20]. The numerical model for WDR is implemented into a solver based on OpenFOAM v6 (download available, windDrivenRainFoam [30]), and has been validated in numerous studies [25,26,27]
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