Microclimate walk for Outdoor Thermal Comfort assessment of four Old and New Urban Configurations in a Mediterranean Climate

Outdoor thermal comfort has become a major challenge in dense urban areas, where rising temperatures and limited shading intensify heat stress during summer. In Mediterranean cities such as Algiers, the interaction between urban morphology and microclimatic conditions strongly shapes pedestrians’ thermal perception. This paper investigates outdoor thermal comfort and its impact on perceived thermal stress in Algiers, Algeria by explicitly examining how urban form modulates both measured microclimate and user perception during summer conditions. An empirical study was conducted using the micrometeorological session method, which combines synchronized in-situ microclimatic measurements and perception surveys collected during pedestrian movement. The protocol integrates radiant temperature, air temperature, air velocity, and relative humidity. Twelve measurement points were selected within four representative urban fabrics (Old, Colonial, Mixed Old and Colonial, and Postcolonial.) composing Algiers’ safeguarded sector. Both objective and subjective data were collected to evaluate thermal ambiances and identify the factors governing perceived comfort and discomfort. The micro-meteorological session identified four main factors affecting thermal perception: (1) architectural and urban, (2) natural, (3) socio-cultural and psychological, and (4) other comfort aspects (olfactory and visual). The results highlighted contrasted thermal performances across urban fabrics, highlighting both advantages and limitations of each configuration. Compact and shaded environments in the old and mixed fabrics were associated with lower solar exposure and higher thermal satisfaction (Maximum globe temperature Tg=34.7°C), however, open and weakly shaded colonial and postcolonial spaces generated high thermal stress and dissatisfaction (maximum Tg=43.4°C). Overall, solar load control emerged as the dominant driver of outdoor thermal comfort, modulated by wind and sociocultural use of space. The proposed micro-meteorological session method can be easily replicated in various global contexts to facilitate citizen participation and in situ diagnosis, especially in Mediterranean and comparable climates.