Evaluating thermal comfort and air quality in buses with different ventilation strategies in Hong Kong

•Study impact of air supply velocities, directions and exhaust positions for buses.•Air supply velocity of 1.5 m/s balances bus's thermal comfort and air quality.•Changing air direction boosts comfort, altering exhaust position has minimal effect.•HVAC ensures uniform fresh air distribution when blowing air laterally.•Moving exhaust forward improve air quality in whole cabin, especially for driver. This study employed computational fluid dynamics (CFD) simulations to investigate the influence of air-conditioning exhaust position, supply velocity and direction on air quality and thermal comfort in a fully occupied bus. Air quality was evaluated employing CO2 concentration as an indicator, while thermal comfort was assessed via the Predicted Mean Vote (PMV) index. The findings reveal that air supply velocity and direction have significant impacts on passengers’ thermal comfort. In winter, a closed air supply can maintain thermal neutrality in the cabin (|PMV|