Thermal modelling of Green Roofs

Urban changes highlight the need for expand vegetated spaces in built environments. In this sense, green roofs represent a valuable opportunity due to their potential to provide ecosystem services. Among the components of green roofs, substrates are essential and can be optimized to enhance their thermal properties, thus influencing heat transfer into buildings. Using additives in substrates for thermal optimization is a promising approach, especially when these additives include environmental by-products that make the substrates lighter and more cost-effective. The thermal performance of green roofs is also influenced by meteorological conditions that regulate substrate temperatures. This study conducted thermal modeling of the internal temperature of five green roof substrates by using generalized additive models and linear models based. Data collected during the summer months of 2021 and 2022 from five identical green roofs, except for their substrate composition - local soil (SOIL), commercial substrate (SCOM), and three mixtures incorporating carbonized rice husk, construction waste, vermiculite, and vermicompost into the local soil (SC2, SC4 and SC5) - were assessed. The correlation between monitored temperatures and meteorological variables was also assessed. The results showed correlations ranging from moderate to strong between the internal temperature of the substrates and climatic variables, especially temperature and humidity. It was proposed a predictive model for the internal temperatures of green roofs, achieving a Nash-Sutcliffe coefficient of up to 0.86, effectively evaluating the thermal benefits of green roofs under different meteorological conditions.