Integrating CFD and thermoregulation models: A novel framework for thermal comfort analysis of non-uniform indoor environments

Occupant-centric radiant cooling strategies have the potential to enhance thermal comfort and reduce energy consumption by influencing the operative temperature and creating a non-uniform environment around the occupant instead of conditioning the entire indoor space. However, current literature shows significant limitations: environmental and physiological parameters are often estimated at a few spatial points and averaged to calculate comfort metrics, hindering the study of local comfort in non-uniform environments; the human body is often represented by fixed mean heat rates or temperatures, neglecting thermoregulation responses. To advance the state-of-the-art, this paper presents a novel numerical framework to evaluate the impact of non-uniform indoor environments on physiological responses, heat balance, and thermal comfort. Using an efficient and scalable co-simulation protocol, the framework integrates a thermoregulation and a computational fluid dynamics model. Further, the framework introduces two novel metrics: Reference Heat Deviation and Reference Heat Deviation Temperature. The former quantifies changes in human heat balance by measuring deviations in metabolic and sensible heat from a reference condition, while the latter translates this information into equivalent temperatures. A case study demonstrated the framework’s application by studying the performance of a personal radiant cooling system. Results indicate that at 28 °C air temperature, the heat balance is not restored to comfort levels at 25 °C, but latent heat exchange is minimised, and radiant asymmetry remains low. Further, the perceived temperature is up to 2 °C lower than the air temperature. Finally, this work’s limitations, potential applications, and outlook are discussed.