Assessing the thermal performance of green walls for solar shading: Model validation and implementation

In response to rising urban temperatures and growing energy demands, green walls have gained attention as passive solutions that enhance building performance and urban sustainability. However, the detailed design of green walls and their integration into building simulations remains a methodological challenge due to the complex thermal and moisture dynamics they involve. This study aims to address this gap by developing and validating a simplified, dynamic thermal model based on a grey-box approach using electrothermal analogy. The objective is to provide a practical and scalable tool for assessing the thermal performance of green façades during summer conditions. The model was developed in MATLAB/Simulink and validated using field data recorded on an experimental prototype of green façades installed on a case study building in the north of Rome, Italy. Simulations were then conducted across three summer days every three years (2019, 2021, 2022) and five different wall assemblies, comparing configurations with and without the green façades. Results show that the green wall reduces thermal wave amplitude by 24–39 % and incoming heat flux by 35–48 %, with indoor temperature reductions reaching up to 5.2 °C. The effect on phase shift instead was minimal, increasing delay by no more than 1.5 h. The model also performed well across wall types, with greater impact observed on lightweight and non-insulated assemblies. This validated tool, in addition to its derived coefficients (AF*, Kv, t*), can support designers and policymakers during early-stage decisions, encouraging broader adoption of green walls as a strategy to enhance building resilience within warm climates.