Models of radon exhalation from building structures: General and case-specific solutions

Assessing the radon activity that exhales from building structures is crucial to identify the best strategies to prevent radon from entering a building or reducing its concentration in the inhabited spaces. The direct measurement is ex-tremely difficult, so the common approach has consisted in developing models describing the radon migration and ex-halation phenomena for building porous materials. However, due to the mathematical complexity of comprehensively modelling the radon transport phenomenon in buildings, simplified equations have been mostly adopted until now to assess the radon exhalation. A systematic analysis of the models applicable to radon transport has been carried out and has resulted in four models differing in the migration mechanisms - only diffusive or diffusive and advective - and the presence of inner radon generation. The general solutions have been obtained for all the models. Moreover, three case-specific sets of boundary conditions have been formulated to account for all the actual scenarios occurring in buildings: both perimetral and partition walls and building structures in direct contact with soil or embankments. The corresponding case-specific solutions obtained serve as a key practical tool to improve the accuracy in assessing the contribution of building materials to indoor radon concentration according to the site-specific installation condi-tions in addition to the material inner properties.

Automated summary

Assessing radon activity in building structures is crucial for preventing radon from entering buildings or reducing its concentration. Due to the difficulty of direct measurement, models describing radon migration and exhalation have been developed. Simplified equations have been mostly used to assess radon exhalation. A systematic analysis of radon transport models has resulted in four models with different migration mechanisms and the presence of inner radon generation. Case-specific solutions have been formulated for different scenarios in buildings to improve accuracy in assessing building materials' contribution to indoor radon concentration.