Simultaneous integration of urban heat island mitigation technologies in the existing urban fabric in Athens, Greece

This research studies the possibility of introducing combinations of specific mitigation techniques for the urban heat island effect (UHI) in Athens, Greece. A variety of factors, such as surface cover, dense traffic, anthropogenic heat release and urban characteristics including geographic features and climate conditions interact with one another to create UHI, which is becoming increasingly evident also due to the changing climate, which in this region is expected to increase the duration of hot spells and the frequency of heat waves.
Mitigation techniques can contribute highly to improve the urban thermal environment, decrease the energy consumption of buildings and also decrease urban air temperatures. Proper mitigation technologies involve, among others, new building envelope technologies and the use of highly reflective materials to decrease the absorption of solar radiation by urban surfaces, the use of advanced materials adapted to the local climate, the additional use of urban green spaces and the use of appropriate heat sink technologies. Advanced mitigation techniques have been applied quite recently in many urban rehabilitation projects around the globe and have succeeded in improving the local microclimate significantly. However, each mitigation measure is often being implemented as a unique element. The focus of this research study is on their relationship and the actual feasibility for their simultaneous integration into the urban environment.
To this end this study focuses on urban architectural dynamics and the development of a methodology for the optimal simultaneous architectural integration of high performance heat-island mitigation technologies in the urban fabric. The methodology can be applied at city block or neighbourhood level and is based on the geometric characteristics and the orientation of the site, but also on the microclimatic conditions of the site. In order to achieve the aim of this study, a small typical neighbourhood in Athens, representative in terms of orientation, building height, road width etc, is analyzed as a case study. After recording each feature that describes the urban cityscape, the study presents feedback, regarding the feasibility for the integration of UHI mitigation technologies, as well as their interaction with various smart materials. Mitigation technologies studied in the present research include, but are not limited to, the reduction of anthropogenic heat release, such as the use of cooling towers, the retention of water through materials, the improvement of the reflectivity of urban surfaces, the use of green spaces, the effect of open spaces, the improvement of land usage and orientation, the use of appropriate shading, the use of natural heat sinks etc.
Finally, the study presents whether the above mentioned factors can reduce the air temperature at street level, how they affect the UHI effect and provide good air quality at the neighbourhood scale, whereas at the same time analyze possible problems or merits for their simultaneous integration.