​In the urban fabric of Athens, and more specifically at its centre, the high density and the geometry of the buildings can be the main reason for the diurnal temperature deviations that can be observed. The high global incident radiation as well as the storage capacity of the surrounding materials in a street and its surroundings, such as concrete, brick, concrete tiles and asphalt, converts the built environment to a radiator which releases its heat at night. Additionally, anthropogenic heat due to the intense use of private means of transportation as well as due to the use of mechanical cooling systems during summer, may exacerbate the problem. Moreover, the lack of vegetation and hence the lack of shading and evaporation usually leads to creation of unpleasant areas, especially for the inhabitants at the centre. Regarding the potential of occupying the outdoor spaces in such a climate, which could be more than half of the year, there might be a possibility of transforming low traffic streets into pedestrian zones, providing in this way a more comfortable and friendly environment

This dissertation deals with the thermal comfort of a pedestrian within the urban fabric and, more specifically, within the network of pedestrian roads in the centre of Athens during summer time. The environmental factors, as well as thermal comfort outdoors, depend on various parameters like the geometrical characteristics of the urban fabric, materiality, distribution of vegetation together with heat emission and anthropogenic heat release. Regarding the typology of pedestrian roads in Athens, streets surrounded by buildings and streets with the ‘open’ typology were examined equally. Primary factors which were analysed were street geometry, orientation, vegetation distribution, transmittance of diffuse and direct solar radiation as well as air flow within the urban fabric. How can all these parameters affect thermal comfort outdoors? All these issues were examined and analysed through the theoretical background of this dissertation.