Simulation research on the performance of natural ventilation in buildings

• Main Author: Lew, Ruenn Shen
• Other Authors: Li Hua
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Mechanical engineering
• Online Access: http://hdl.handle.net/10356/71319
• Institution: Nanyang Technological University

Natural ventilation is the exchange air between a building and the environment by natural means such as the forces from the wind and temperature variations. Although the forces from the wind may appear as the dominant driving mechanism of natural ventilation, the effect of temperature differences should not be overlooked as directional buoyancy force greatly affect the air flow patterns inside the building [1]. Natural ventilation has been labelled as a “green” technology and has attracted great attentions because it reduces energy consumption and at the same time provides ventilation at an acceptable rate comparable to most of the mechanical ventilation strategies [2]. Tantasavasdi et al. studied the applicability natural ventilation strategies in houses located in a hot and humid climate region and concluded that a minimal indoor air velocity of 0.4ms-1 is essential for comfortable indoor environment [3]. The objective of this research is to simulate and analyse the effects of different placement of openings and incoming air velocity on the effectiveness of natural ventilation. The computational fluid dynamics (CFD) simulations are generated to obtain information on the indoor air parameters such as the pressure, velocity and temperature. The variables studied are the configurations of the placement of both the inlet and outlet pair and the incoming air velocity. The effectiveness of the natural ventilation strategies could be deduced qualitatively from results of contours and vectors in the CFD simulations. Based on the CFD simulations, it has been found that the most effective natural ventilation strategy is by placing the inlet at lower altitude compared to the outlet on walls opposite to each other across the building. The CFD simulations also indicate that the effectiveness of natural ventilation increases with increasing incoming air velocity. Nevertheless, extremely high velocity is not ideal because the level of comfort of the occupant in the building reduces due to fast moving air. The CFD simulations results could be utilised to generate an intuition ii among the readers on the pattern of indoor air flow due to the interaction of wind and temperature variations.