Improving the thermal performance of indirect evaporative cooling by using a wet fabric device on a concrete roof in hot and humid climates

This study investigated an indirect evaporative cooling system (IECS) to control latent heat loss on roof ponds by increasing the evaporation rates on wet fabric membranes. The cooling potential of the proposed system was experimentally tested in a real environment and it was compared against a roof pond and a floating fiber (gunny bags) to provide an efficient model for buildings in hot and humid climates. Dry bulb temperatures (DBT) are presented for four experimental models. Solar irradiance, ambient and indoor dry bulb temperatures, and relative humidity (RH) were measured for seven days in each of the following climate conditions: hot sub-humid (mean DBT 27.3 °C and mean RH 72%), hot humid (mean DBT 27.1 °C and mean RH 81%), and warm sub-humid (mean DBT 25.2°C and mean RH 68%). There were no significant variations in thermal performance between the examined devices under hot humid conditions; however, the wet fabric device had superior thermal performance under sub-humid conditions when compared to the other IECSs. In the three climatic scenarios where the proposed system was tested, the wet fabric managed to reduce the indoor air temperature by 6.6 °C, 5.3 °C, and 5.1 °C, respectively, as compared to the outdoor air temperatures.