Effect of Parapet Lattice on Alteration of Airflow for Convective Cooling of the Roof Surface

Abstract

For reducing the thermal stress in the environment, studies are being conducted to articulate the building elements for increasing their efficacy. These elements, which are like shading devices, balcony, veranda, walls, windows, etc. are associated with superstructure but are positioned below the roof level[1][2][3]. Here, parapet, which is primarily designed for safety and aesthetics, has been explored for its ability to reduce roof surface temperature. Any modification in the design of a parapet directly influences the amount of solar gain or the pattern of airflow on the roof surface. Though the limited height of a parapet does not have much influence on the amount of solar gain or shade, it can alter the incoming airflow. Traditionally voids have been provided in parapet to facilitate passing air to get in touch with roof surface for convective cooling. So, the paper focus on designing and evaluating an array of generic voids with opening ranging from 0 to 80 per cent for the active cooling of the adjoining roof surface. For the broader benefit of the study, elements like dwelling unit size, climatic conditions, choice of building material, contemporary designs of parapet etc. have been taken consideration. Sixteen generic modules were formed, which were examined in two phases; these include CFD simulation and three-dimensional physical model study. The results established a notable difference in the rate of heat loss among themselves with respect to the timeline. On this basis, the sixteen scenarios were rearranged and grouped following the descending order of the heat loss. The application of this outcome will not only enhance the rooftop living environment but will also facilitate enhanced thermal comfort, especially to those who have either no access or have limited economic resources to manage mechanical appliances.