A computational approach to assess the effects of ecological building envelopes on outdoor thermal comfort

• Ecological building envelopes support microclimate regulation in dense urban areas. • Outdoor thermal comfort vary depending on NbS configuration on the building envelope. • PFGs microclimatic performance can be calculated through CFD simulations. • Geometry, urban density, and NbS are key parameters for microclimate regulation. Rapid urbanization and the progressive reduction of green spaces in urban areas are among the main causes of the Urban Heat Island (UHI) effect. Nature-based building envelopes can effectively support the mitigation of UHI and the improvement of microclimate conditions. This paper aims to identify the most efficient computational method(s) to be included in a parametric optimization process for evaluating outdoor thermal comfort (OTC), considering the contribution of design parameters and plants. In addition, the performance of ecological building envelopes is evaluated, identifying the most relevant design and context parameters for OTC improvement. Specifically, building height (up to Δ6,95 °C between high-rise and terraced houses), geometric form (up to Δ11,9 °C between multi-storey building and terraced houses), urban density (up to Δ6,31 °C between high and low density), and the presence of trees (up to Δ6,13 °C configuration with and without trees) are among the most influential factors. Furthermore, perimeter blocks and multi-storey buildings constitute the most promising building types due to the high variation of OTC conditions (up to Δ8.78 °C). Finally, the results of the study enable the foundation for the future integration of plants features and performance into microclimate modelling approaches.