Study on the impacts of occupant distribution on the thermal environment of tall and large public spaces

In tall and large (T&L) public spaces, occupant distribution and its variation may impact the thermal environment and thus the operation of heating, ventilation, and air conditioning (HVAC) systems. Such studies are rare in previous literature, so in-situ tests were conducted to demonstrate dynamic occupant distribution characteristics and the potential impact on the thermal environment in the waiting room of a high-speed railway station. The building energy model (BEM) and the computational fluid dynamics (CFD) model were then co-simulated to analyze the impacts under different occupant distribution scenarios. To improve the indoor thermal environment affected by occupant distribution, the thermal coupling relationships between different subzones were considered and identified, and a supply air reallocation optimization based on occupant distribution was proposed for T&L-space public buildings. The results showed that both the temporal and spatial variations of occupants in different subzones easily led to the thermal non-uniformity of an entire large space with a difference over 1.5 °C. Meanwhile, the thermal coupling effect between different subzones should not be neglected in the distribution of supply air since the thermal uniformity of the case building was improved by 15.89%–20.03%, effectively reducing local overcooling and overheating.