This study examines the evolution of the ‘wet markets’ in Hong Kong and Singapore, focusing on some of their recent retrofits in Hong Kong, in which traditional and hybrid-ventilation methods with open facades are upgraded to mechanically ventilated systems with sealed and closed facades. The upgrades from open air to air-tight impacts not only the architectural expression and tectonic representation of these markets buildings, the façade’s openness expressing architectural tenets for civic provisions in the modern city. The upgrades also increases the energy consumption for air exchange and cooling, while challenging the balance of hygiene maintenance, thermal and olfactory comfort in a multiphysics environment. By measuring the particulate concentration in the newly-retrofitted wet markets in Hong Kong that have recently transitioned to mechanical ventilation within sealed facades, and comparing them with the hybrid-ventilated wet markets with open facades, still prevalent in Hong Kong in Singapore, this analysis quantitatively assesses the impacts of different ventilation strategies on the indoor environmental quality of these markets. A significant aspect of our study is the development of a framework to evaluate the benefits and drawbacks of the retrofit strategies for aging wet markets, which were designed with open air, in both cities. Our goal is to offer evidence-based insights and recommendations that can guide future retrofits, as well as shape regulatory policies, ensuring that these vital urban public spaces continue to thrive while adapting to modern standards of health, comfort, and sustainability. The findings will contribute to the still little-studied discussion on urban market renovations.