Wind tunnel analysis of artificial substrates used in active living walls for indoor environment conditioning in Mediterranean buildings

In this paper, a low-speed wind tunnel was used for experimental analysis of water volume retained, pressure drop, saturation efficiency and water consumption for three types of synthetic substrates used in active living walls: polyester (PR), polyurethane (PU) and polyamide–polypropylene (PA–PP) The substrates were of a similar thickness and were tested for different water and air flows. The water retained increases with higher water flow. The pressure drop increases with the presence of vegetation and when air speed and water flow is higher. Cooling efficiency is enhanced with vegetation and low air speed. Specific consumption of water is greater with vegetation at higher air speeds. Therefore, low air (between 0.25 and 0.5 m s−1) and water flows are recommended to ensure a homogeneous wetting of the substrate surface. PA–PP has the greatest pressure drop of the three, but also presents the best saturation efficiency, with an average water retention capacity and less specific consumption. PU offers the least resistance to air flow, with an intermediate efficiency level and high water consumption and water retention capacity. PR presents the worst saturation efficiency, a medium level of pressure drop and high water consumption.