Towards a Child-specific Outdoor Thermal Comfort Index for Tropical Environments: A Numerical Proof of Concept

Abstract

Background: Outdoor thermal comfort indices are predominantly based on adult physiological models, although children differ in body geometry, activity patterns, exposure height, and age-related thermoregulatory characteristics. Aims: To establish a transparent, field-oriented biophysical architecture and numerical proof of concept for assessing outdoor thermal comfort in children, shifting focus from adult-based models to child-specific microclimatic exposure in tropical environments. Study Design: Numerical modeling and algorithmic stress-testing using a structured synthetic matrix of theoretical microclimatic scenarios. Place and Duration of Study: Pierre PAGNEY Laboratory: Climate, Water, Ecosystems and Development (LACEEDE), Université d'Abomey-Calavi, Benin, between 2025 and 2026. Methodology: The study constructed a structured synthetic matrix comprising 720 independent simulated situations to evaluate a prototype algorithm across four age classes (0–12 years), three child-height microclimatic measurement heights, four surface types, three activity levels, and five shading/ventilation configurations. Performance metrics including Root Mean Square Error (RMSE), pseudo-R², and categorical classification accuracy were computed against the internal theoretical response structure. Results: The internal evaluation of the synthetic proof-of-concept matrix yielded a pseudo-R² of 0.68, an RMSE of 0.68 scale points, and a categorical classification accuracy of 76%. The prototype successfully captured near-ground thermal gradients and surface material impacts on children's simulated heat balance without relying on uncalibrated adult coefficients. Conclusion: The proposed biophysical framework serves as a rigorous numerical foundation and prospective decision-support tool rather than an empirical population-validated index. A detailed 6-phase empirical validation roadmap is established to guide future field data collection, external validation, and necessary paediatric ethical safeguards.