Simplified prediction method for fungal growth risk in indoor environment coupled with heat and moisture transfer in building materials

In the present study, a mathematical model that reproduces fungal proliferation and morphological colony formation was developed on the basis of a reaction diffusion modeling approach. In this modeling, fungus was separated into two states, active and inactive, and it was assumed that active fungus moves by diffusion and reaction while generating and producing inactive fungus. The effects of temperature and humidity on fungal growth were explicitly incorporated in the reaction term of nutrient consumption/generation of active fungus in this governing equation. The damping function, which reproduces the effects of temperature and humidity on fungal growth, was developed and explicitly based on the fungal index proposed by K. Abe. The fungal index expresses the growth response of three representative fungi as a function of atmospheric temperature and relative humidity. In order to estimate the sensitivity of the proposed numerical fungal growth model, fungal growth on the surface of building materials was analyzed for four types of building materials, and the prediction results were compared with the results of WUFI-Bio and the fungal index proposed by Abe. In the three prediction models, fungal index expressed high sensitivity for atmospheric temperature and humidity and the prediction results of the reaction diffusion model and WUFI-Bio model were reasonably consistent with each other.