Lightwell or deep courtyard is commonly used in high-rise deep layout plan buildings and are usually implemented to admit daylight and to induce natural ventilation into targeted spaces. Upward flow in the lightwell is dominant due to buoyancy effect; however, direct connection to the outdoor through horizontal void may assist or oppose the upward airflow in the lightwell. This article mainly investigates the effect of different vertical and horizontal positions of the void connected to the lightwell on the upward flow with different wind directions. Computational Fluid Dynamics (CFD) was employed to simulate the airflow inside the lightwell. The simulation results were validated and confirmed a good agreement with the experimental data. The configuration of the lightwell connection clearly indicate the strong influence on upward flow in the internal lightwell; however, the double-level void in cross-flow configuration was found more effective than other configurations in terms of airflow velocity and temperature. Wind direction is an important parameter which influences air flow patterns and velocity in the lightwell. This study provides proper guidelines to predict ventilation performance and to improve the design of naturally ventilated high-rise buildings. (C) 2014 Elsevier B.V. All rights reserved.