Effects of façade and rooftop greening on the surface pressure distribution of an isolated cubic building with side wall apertures

Greening is considered a sustainable and environmentally friendly policy for urban development but despite the progress made so far, the aerodynamic implications of building embedded greening have yet to be determined. Greening may have a variety of implications on wind loads, natural ventilation and air exchange, all related to the pressure distribution on buildings’ external surfaces. In the present study, a wind tunnel investigation deals with the qualitative and quantitative effects of building greening on the external surface pressure distribution of a model building. Greening was considered to fully cover the external windward façade and the roof under various permeabilities and thicknesses. Openings on the side walls allow for indoor–outdoor air exchange. The position and the thickness of greening were found to be decisive parameters for the overall pressure distribution but attention was also directed towards the fluctuating pressures near the openings, which are expected to be the driving mechanism for air exchange in this configuration. Effects of rooftop greening were confined mainly to the roof and the wake but for windward façade greening, mean and fluctuating pressure differences of up to 35%, compared to the bare building, were observed in the vicinity of the openings. The major effect was a damping of the lower frequencies of pressure fluctuations and it had a stronger dependence on the thickness rather than the material properties of the windward façade greening.