The aim of this study is to evaluate a simplified parameter to characterize green roofs summer dynamic thermal performance through a mathematical approach. The inside face surface conduction in a green roof component is calculated through the Fast all-season soil strength (FASST) model. A parametric analysis is carried out to evaluate which roof design options have the greatest effect on the green roof Thermal behavior during the summer period. The results show the relevance of the leaf area index of the vegetation layer and of thickness of the soil, which is the key factor regarding the growing media