A numerical Study of the Effect of Façade Opening on Nighttime Ventilation of a Low-Energy Building

Natural ventilation is an effective passive design strategy that delivers fresh air to space, improving indoor air quality and reducing energy consumption in buildings. This article performs a numerical simulation on the influence of façade opening and window-to-wall ratio (WWR) on natural ventilation performance of a low-energy building in Johor Bahru, Malaysia. Field measurements were first conducted for five days to obtain the values of air velocity, air temperature, relative humidity, and mean radiant temperature. ANSYS Fluent is used in this study to conduct 3D steady-state computational fluid dynamics (CFD) simulation. The simulation results showed that façade opening and WWR significantly influence the thermal comfort of occupants. The improvement in the modified predicted mean vote (PMVm) index for case 4 (façade opening of 9.26 m2) compared to the base case (façade opening of 1.04 m2) was between 11.66 % and 55.81 %. The PMVm index for Case 4 was between 0.41 and 0.51, which is within the range recommended by ASHRAE Standard-55.