Aerodynamic Loading of Lightweight Green Roof Systems on Industrial Buildings: A Case-Based CFD Study of an Existing Industrial Hall

Abstract

Large low-rise industrial halls offer extensive roof areas for adding vegetated roof assemblies (VRAs) as part of reconstruction. However, existing structures often require lightweight VRAs to avoid overloading. To assess the wind resistance of such lightweight systems, atmospheric boundary layer simulations were conducted in OpenFOAM using Reynolds-Averaged Navier-Stokes approach for a cuboid industrial hall in a low-density built environment, representative of many industrial facilities worldwide. Additional roof geometries and adjoining-building cases were analysed to cover configurations not addressed in prior studies. Compared with a simple cuboid, a combined cuboid-bevel geometry experienced notably higher roof underpressure. The presence of an adjoining building further intensified corner-zone suction, increasing peak local suction from 608 Pa to 830 Pa (37%). For an extreme air velocity of 43.1 m/s recorded at the Brno (Czech Republic) meteorological station, the computed pressures were compared with the European standard for wind actions on structures. The peak suction reached approximately 4 kPa at the roof corner for a 45° wind direction, about twice the allowable limit for components with effective area 1 m2, indicating that perpendicular-wind (0°) analyses may underestimate the risk for modular systems. The results have implications for the long-term green-roof performance, because wind-induced uplift or substrate displacement can alter VRA thermal behaviour; maintaining aerodynamic stability is therefore essential to sustain the intended thermal performance. The findings highlight potential failure mechanisms, particularly in unanchored lightweight VRAs, and support more resilient green-roof design and standards for industrial buildings.