Analysis of a radon mitigation system using sub-slab air chamber: CFD model development and validation in an...

Radon is a radioactive gas produced by uranium decay in soil, and its infiltration and accumulation indoors at high concentrations pose a significant lung cancer risk. Mitigation strategies based on depressurized or ventilated sub-slab air chambers have proven highly effective. This study aims to develop and validate a Computational Fluid Dynamics (CFD) model to analyze radon transport, entry, and mitigation performance using sub-slab air chambers under two configurations: depressurization and forced-air ventilation. The model incorporates key inputs-geometric parameters, modeling simplifications, and estimation of unknown factors-and is validated against experimental data from two case studies. Parametric analyses explore the influence of chamber height, airflow rate, and building length on mitigation efficiency. For depressurization systems, increasing chamber height enhances pressure reduction, while higher flow rates yield diminishing returns in radon reduction. Across building lengths, radon concentration decreases by 45-90%, with smaller structures achieving the greatest reductions. Conversely, in forced-air ventilation systems, increasing chamber height and injection flow rate induces overpressure, raising indoor radon levels, whereas larger building lengths mitigate this effect. These findings provide insights for optimizing radon mitigation designs, supporting the development of efficient systems with minimal construction effort.