Enhanced Single-Sided Ventilation with Overhang in Buildings

Jinsoo Park,Gwang Rhee,Jung-Il Choi

doi:10.3390/en9030122

Abstract

Enhancing the ventilation performance of energy-efficient buildings with single-sided openings is important because their ventilation performance is poor and strongly depends on the wind conditions. We considered an overhang as a potential building facade for improving the single-sided ventilation performance. We performed numerical simulations of three-dimensional unsteady turbulent flows over an idealized building with an overhang in order to investigate the effect of the overhang on the ventilation performance. Parametric studies were systematically carried out where the overhang length, wind speed, and wind direction were varied. The numerical results showed that the overhang drastically enhanced the ventilation rate in the windward direction regardless of the wind speed. This is because, for windward cases, the overhang produces a vortex with strong flow separation near the tip of the overhang, which promotes a net airflow exchange at the entrance and increases the ventilation rate. However, the ventilation rates for the leeward and side cases are slightly decreased with the overhang. Using an overhang with single-sided ventilation greatly reduces the local mean age of air (LMA) in the windward direction but increases it in the leeward direction.

Highlights

Ventilation promotes an airflow exchange in indoor environments and is important for providing better indoor air quality and thermal comfort
We performed 45 simulations using different values for the parameters of the wind speed, wind direction, and overhang length to evaluate the effect of the overhang on the single-sided ventilation performance
We performed numerical simulations of three-dimensional turbulent flows over a generic isolated building model with an overhang in order to investigate the effect of the overhang on the single-sided ventilation performance

Summary

Introduction

Ventilation promotes an airflow exchange in indoor environments and is important for providing better indoor air quality and thermal comfort. Natural ventilation is an eco-friendly method for providing fresh air, but its performance heavily depends on outdoor environmental factors such as the wind conditions and building shape, including openings and windows [1]. Cross ventilation may be the most effective natural ventilation technique, in which two open surfaces are aligned with the wind direction. Single-sided open surfaces (e.g., the entrance door), which are frequently encountered in commercial buildings may cause a poor ventilation performance. The poor ventilation rate of single-sided ventilation buildings causes indoor air quality problems; additional energy is needed to run the mechanical ventilation system [3,4]. Enhancing the ventilation performance is important to achieve energy-efficient commercial building clusters with single-sided openings

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Conclusion