Environmental and Climate-Responsive Redesign of Public Outdoor Spaces within Historic Mediterranean Urban Fabrics

Public outdoor spaces play a key role in the environmental performance and thermal resilience of contemporary cities. Mediterranean cities are increasingly affected by climate change, particularly through the intensification of the urban heat island (UHI) effect. The historic city of Piraeus, Greece, characterized by its Hippodamian urban grid and layered urban landscape, represents a critical case where urban densification, limited vegetation, and extensive surface sealing have significantly altered local microclimatic conditions, resulting in increased thermal stress during the summer period.

This study investigates the potential of environmental redesign and climate-responsive urban planning strategies to improve thermal comfort in selected public outdoor spaces within the Municipality of Piraeus. An integrated methodological framework combining urban morphology analysis, environmental assessment, microclimatic evaluation, and digital simulation tools was employed. Public spaces and green infrastructure were analyzed according to spatial, climatic, social, and environmental criteria. ENVI-met simulations were conducted to assess air temperature, Mean Radiant Temperature (MRT), and thermal comfort indices, including PET and UTCI, under existing and proposed redesign scenarios. The proposed interventions incorporated bioclimatic and nature-based solutions such as increased vegetation and tree canopy coverage, permeable and high-albedo materials, shaded seating areas, and water-sensitive landscape elements. Simulation results demonstrated significant reductions in ambient and surface temperatures, with Potential Air Temperature decreasing by up to 10.4 °C during peak afternoon hours. UTCI values in shaded and vegetated areas improved by approximately 6–8 °C compared to baseline conditions, with the most significant thermal improvements occurring between 12:00 and 16:00 during peak summer conditions.

The findings confirm that climate-responsive redesign strategies can effectively mitigate urban heat stress while enhancing environmental resilience, ecological quality, and social sustainability in historically layered Mediterranean cities. Small- and medium-scale green interventions emerge as particularly effective tools for improving thermal comfort and supporting climate adaptation in urban environments.