Ventilation and fluid dynamics in built environment aims to enhance energy efficiency, promote occupant health and comfort, and facilitate climate-responsive and sustainable built environments. This research area focuses on design, control and modelling of natural (hybrid) and smart adaptive ventilation systems in buildings, and on wind and thermal comfort in neighborhood communities. Our research is conducted by using onsite field tests, laboratory experiments, wind tunnel testing, and numerical modelling such as Computational Fluid Dynamics (CFD) modelling. Our research advances the automation of indoor environmental control, develops mitigation strategies for heat stress and ventilation-related technologies for abating emissions in livestock buildings, and contributes to research-based public consultancy. Additionally, we develop CFD-based models of heat and mass transfer, and ventilation rates in naturally ventilated buildings, which serve as key components in decision-support tools to inform decarbonization strategies in the built environment.