C. Georgakis, S. Zoras and M. Santamouris
Bibliographic info:
Proceedings of the 34th AIVC - 3rd TightVent - 2nd Cool Roofs' - 1st venticool Conference , 25-26 September, Athens 2013

Surface temperature measurements were performed in a deep street canyon, during summer period, in the center of Athens. Surface temperature was measured on an hourly basis, at several spots, in the external facades of buildings, pavements and at ground level inside an urban canyon. At the same time experimental data of air temperature were collected through extensive monitoring at four different heights in the center of the urban canyon. Based on these measurements air temperature vertical stratification was analyzed and interpreted as a function of the coating used.
Computational fluid dynamics (CFD) simulation were performed for evaluating surface temperature in the external facades of the buildings and at ground level in the urban canyon, for the coating used in the urban street canyon. CFD simulations based on the orientation of the street, the geometrical characteristic of the street (Height/Width), together with the type of coating used to define the surface temperature at different spot inside the canyon. At the same time air temperature was calculated in the center of the canyon for the specific four heights. Computational results were compared to field data in order to validate the accuracy of the CFD model used for the prediction both of surface and air temperature inside an urban street canyon. Secondly, by the means of the computational fluid dynamics model for the various types of “cool” coatings used for the buildings facades and smart materials for the ground level, i) air temperature was calculated at four different heights inside the urban canyon and ii) surface temperature in the canyons facades and at ground level. The calculated data have been thoroughly analyzed.

Aim of the work was the comparison between measurements of the vertical stratification of air temperature inside a deep street urban canyon with the calculated ones for different “cool” coatings and smart materials and give evidences for the possible mitigation of the heat island effect. The use of “cool” coatings in buildings has been estimated as crucial for the energy  consumption and thermal comfort conditions in cities. Their albedo to solar radiation and emissivity to long-wave radiation, are very important parameters for the reduction of absorbed solar radiation and air temperature inside street canyons.