Numerical evaluation of the effects of different types of shading devices on interior occupant thermal comfort using wind tunnel experimental data

Abstract

In this study, it is aimed to determine the effects of shading device alternatives on the thermal sensations of occupants in a cross-ventilated office zone by considering changing indoor airflow velocities in summer conditions. Interior airflow velocities on 3 vertical profile heights were measured for 5 cases in a wind tunnel. The effects of alternatives on simulated occupant thermal comfort conditions in a modelled environment at different time intervals were investigated by comparing the results of mean radiant temperature, predicted mean vote, predicted percentage of dissatisfied calculations, conducted by EnergyPlus, considering the measured airflow velocity values, calculated angle factors defining the location of the occupants and their interaction with interior surfaces. The results show that the effect of shading devices on thermal comfort changes due to geometry and the location of the element on the facade. Shading devices lower dissatisfaction ratios at all measurement points. The most satisfaction is obtained near the backward window in the morning hours changing among D and B Category defined in ISO 7730. Dissatisfaction ratios are much higher in the morning hours than afternoon hours. The alternatives having lower cavity area for airflow intake and stimulating lower airflow velocity while also enabling the access of solar radiation throughout the open windows provide more satisfaction when the outside temperature is low. The optimum shading device among the alternatives derived for the study, providing the lowest MRT, PPD is “3.1-CDE-CPK-90” (Perpendicular to facade, slat angle: 90°) at all occupant locations, especially in the middle of the zone.