Moderating thermal load on a multi-residential building block through integrated green roofs

Urban environments are facing the challenges posed by climate change. As the urban heat island effect intensifies, the need for implementing strategies in the context of energy resilience is also growing. The aim of this study was to investigate the impact of integrating green roofs within the existing green infrastructure of an urban area on moderating microclimatic conditions, and consequently the thermal load on buildings. The concept of thermal load is addressed through temperature-based indicators, reflecting the buildings’ exposure to outdoor thermal conditions. The microclimatic simulations for the multi-residential urban block (Block 22) in Belgrade were conducted under two scenarios: the “existing-state” scenario, representing the base condition, and the “integrated-green-roofs” scenario, representing the implementation of green roofs across all roofing systems. The ENVI-met software was used as a tool for predicting microclimatic conditions, i.e., outdoor air temperatures and façade surface temperatures. The results regarding variations in temperature distribution within the urban block, analyzed through eight horizontal sections, showed slight reductions in the “integrated-green-roofs” scenario, up to 0.20°C in maximum temperatures at the highest section including buildings. Regarding variations in façade surface temperatures, reductions ranged from 0.15-0.36°C, also favoring the second scenario. Overall, despite some inconsistencies observed in the study, the indirect positive impact of green roofs in moderating thermal load on entire building envelopes, not only on the roofing systems, was confirmed.