Simulation of the cooling effect of a lightweight vegetated structure

The prevalence of built structures in urban areas has led to the emergence of heat islands, intensifying the impact of climate change. Hence, introducing vegetation in cities is key to regulate urban micro-climates, reduce heat-risks, and improve the physical and mental well-being of urban residents. Green infrastructures can help mitigate urban overheating via two main mechanisms: (1) direct shading, which reduces the amount of solar radiation absorbed by the urban surfaces, and (2) evapotranspiration, which regulates the partitioning of latent and sensible heat fluxes within the urban fabric. Yet, planting and managing vegetation in cities face several challenges, from limited space, to plant damages, and conflicts with other infrastructure (e.g., pipes, cables).

To address these problems, we investigate the potential cooling effect of an innovative lightweight structure (bamX) made of bamboo canes weaved together and vegetated with hops. We use the PALM model to run high resolution (0.5 m) computational fluid dynamics simulations in idealized conditions and for different stages of plant maturity. Preliminary results show that the greatest cooling potential of these lightweight vegetated structures is associated with shading and depends on the leaf area density of vegetation. Evapotranspiration processes, despite slightly increasing relative and specific humidity locally, do not significantly alter human thermal comfort within and around the structure.