Microclimate design for open spaces: Ranking urban design effects on pedestrian thermal comfort in summer

• Microclimate studies of an urban square and a courtyard in summer conditions.
• Simulations with selected computational tools tested against measured data.
• Assessment of the effects of geometry, materials, soil humidity, vegetation, water.
• Ranking design parameters based of their influence on pedestrian comfort indices.
• Significant impact of trees, soil humidity, albedo, spatial and temporal variations.

The paper presents a study on the influence of urban morphology and urban design parameters such as street and building geometry, landscape elements including vegetation types, water surfaces and material properties and their effects on pedestrian thermal comfort in cities. The data provided by the paper are based on simulations using selected computational tools (ENVI-met, RadTherm and Fluent) and performed for two typical urban spaces, a square and a courtyard. The paper focuses on summer conditions which include increasingly uncomfortable periods. It draws upon studies initiated in the city of Thessaloniki in northern Greece. However, the findings apply to many other cities with similar morphological characteristics and summer design conditions. The results are ranked according to the influence each of the design parameters considered can have on pedestrian thermal comfort. Spatial and temporal variations are highlighted. Special mention is given to the high impact of trees and soil humidity and the contrasting effects of pavement albedo. The paper provides data for use by urban designers in specifying appropriate microclimatic interventions to improve pedestrian comfort.