Thermal assessment of spray evaporative cooling in opaque double skin facade for cooling load reduction in hot arid climate

Opaque ventilated façades have gained attention in the last years due to their cooling load reduction. The double skin façade (DSF) is a well-known device and is an ideal system to combine with evaporative cooling solutions, like water spray systems. The aim of the present study is to determine the façade air cavity width and spray water characteristics (the spray water droplet size, and the number of spray nozzles) through a numerical simulation. The temperature at the centre of the cavity and the cooling efficiency are employed as the design variables to improve the thermal performance of an opaque double skin facade. The CFD simulations showed good agreement with experimental measurements. The performed numerical method is a valuable tool to design and evaluate double skin façades, considering buoyancy effects and water particles evaporation simultaneously. According to the results, the best arrangement of the DSF for hot-arid condition with an evaporative cooling strategy is an air cavity of 0.4 m, a droplet size of 25 μm and a separation of 0.6 m between each nozzle. •The CFD model was experimentally validated for hot-arid climate condition.•Coupled momentum and heat transfer numerical simulation.•Evaporative Opaque Ventilated Façcade geometric configuration defined.•Spray droplet size and nozzle number defined for best thermal performance.•Evaporative Opaque Ventilated Façade showed a max. cooling efficiency of 31.9%.