Modeling of the Impact of different Window Types on Single-sided Natural Ventilation

Abstract

Natural ventilation can reduce the building energy consumption for cooling and improve indoor air quality. Thus it has gained popularity in recent years. Natural ventilation can be classified as single-sided ventilation and cross ventilation. Cross ventilation can provide higher ventilation rate, however, it can only be used in thin buildings and no large obstacles in the air path. Single-sided ventilation has little restriction and can be easily implemented in buildings. The ventilation rate of single-sided ventilation is hard to predict due to the strong turbulence effect and bi-directional flow occurred at the openings. Our previous study has quantified the effect of mean flow, pulsating flow and eddy penetration on single-sided ventilation rate for simple openings. However, other types of windows such as awning, hopper and casement windows are more commonly used in buildings. To find the impact of different types of windows on single-sided ventilation, this study used Computational Fluid Dynamics (CFD) Large Eddy Simulation (LES) to simulate three different types of windows (awning, hopper and casement) with different opening angles under various wind conditions. The study found the impact of different types of windows on the ventilation rate varied greatly with wind directions, which was due to change of flow pattern introduced by the windows and turbulent effect. This investigation has further developed empirical models for predicting ventilation rate for these types of windows. The models are based on the orifice model and our previous study for simple openings. The model predictions showed good agreement with the CFD simulations.