Cross-ventilation in a generic isolated building equipped with louvers: Wind-tunnel experiments and CFD simulations

Katarina Kosutova,Twan Van Hooff,Christina Vanderwel,Bert Blocken,Jan Hensen

doi:10.1016/j.buildenv.2019.03.019

Abstract

Natural ventilation can be used to improve indoor air quality, remove contaminants from spaces and to remove heat from a building during the day, or during the night. In some cases, openings for natural ventilation are equipped with shading devices – such as louvers – to reduce solar heat gains while allowing natural ventilation. This study presents wind-tunnel experiments and computational fluid dynamics (CFD) simulations of a cross-ventilated building equipped with louvers. Four opening positions are studied: (i) openings in the center, (ii) upper or (iii) lower part of the windward and leeward facades or (iv) one opening in the upper part of the windward facade and one opening in the lower part of the leeward facade. The 3D steady Reynolds-averaged Navier-Stokes (RANS) simulations are performed with three turbulence models (RNG k-ε, SST k-ω, RSM) and validated with the wind-tunnel experiments. The experimental results show that the largest velocities occur in a building with openings in the upper part of the facade. The best agreement with experimental data is provided by RSM. In addition, CFD simulations for buildings without louvers are conducted for the same opening positions to evaluate the effect of louvers on the dimensionless volume flow rate, age of air and air exchange efficiency. The highest dimensionless volume flow rate at reduced scale (0.69) is obtained in the building with louvered openings in the upper part of the facade and the highest air exchange efficiency is achieved for a building with louvered openings in the center of the facade (45%).

Highlights

Natural cross-ventilation is a commonly used technique to maintain a comfortable indoor environment and to remove pollutants
This study presents wind-tunnel experiments and computational fluid dynamics (CFD) simulations of natural cross-ventilation in a generic isolated cubic building equipped with louvers for four different window opening positions
The jet passing through the windward opening is directed upwards under an angle of about 19° due to the louver slats, the jet hardly reaches the ceiling of the room

Summary

Introduction

Natural cross-ventilation is a commonly used technique to maintain a comfortable indoor environment and to remove pollutants (e.g. refs. [1,2,3,4]). Natural cross-ventilation is a commonly used technique to maintain a comfortable indoor environment and to remove pollutants [1,2,3,4]) It can be used as a passive cooling technique to reduce the cooling demand of buildings The performance of natural ventilation is heavily influenced by the design of the facade openings, such as windows. Practical concerns, such as prevention against rain, burglary or excessive solar radiation have to be addressed. Using architectural louvers can be an efficient solution as these can reduce the entrance of direct solar radiation (especially when they are opaque) and prevent rain penetration. Louvers can have an impact on the amount of airflow penetrating through the openings [8] as well

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