Dissertation committee:
Κωνσταντίνος Καρτάλης, Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ (επιβλέπων)
Ματθαίος Σανταμούρης, Καθηγητής, New South Wales, Australia
Δημοσθένης Ασημακόπουλος, Ομότιμος Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ
Μαργαρίτα-Νίκη Ασημακοπούλου, Αναπληρώτρια Καθηγήτρια, Τμήμα Φυσικής, ΕΚΠΑ
Χρήστος Τζάνης, Επίκουρος Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ
Κωνσταντίνος Μουστρής, Αναπληρωτή Καθηγητή, Τμήμα Μηχανολόγων Μηχανικών, ΠΑΔΑ
Νεκτάριος Χρυσουλάκης, Διευθυντή Ερευνών, Ίδρυμα Τεχνολογίας & Έρευνας
Summary:
The Urban Heat Island is an atmospheric phenomenon that occurs in urban and semi-urban environments where, due to the dense construction of buildings, heat is trapped, resulting in an increase in air temperature in urban areas compared to the surrounding rural areas. The study of the phenomenon of the Urban Heat Island and in general, the urban climate, is particularly important because, due to the phenomenon of urbanization which is showing a dramatic increase (it is estimated that until 2030 more than 60% of the world population will be live in cities ) affects millions of people every day.
The purpose of this thesis is:
• to present the phenomenon of the Urban Heat Island in the basin of Attica, within the building boundary layer (BCL), for the summer months of 1996, 1997 and 1998 using a total of 27 autographic meteorological stations, οn an hourly air temperature basis, related to the CORINE land use categories.
• to study the air and surface temperature regime of 9 urban canyons with different geometric characteristics over different places of the city of Athens, for the summer season of 1997 in order to present in detail the generative causes of the phenomenon
• to examine the effect of the undisturbed wind intensity over the basin on the urban heat island phenomenon and
• finally, to highlight the effect of the phenomenon on the cooling energy requirements of a building, which is one of the most important and immediately understandable effects.
In this context, the average monthly intensity of the heat island phenomenon in the city of Athens, was determined at 6.3°C and 5.4°C during the day and night time respectively, with the highest values being found in the urban areas, characterized as a continuous urban fabric according to the Corine categorization of land uses, while the spatial mapping of the phenomenon, highlighted for the first time, the extension of it, towards the western and southern suburbs of the city of Athens. The study of the temperature regime inside the urban canyons showed the direct dependence of the air temperature on the surface temperatures, when it is measured close to them, while the air temperature in the middle of the road, during the day time is generally lower about 1.5 o C than that recorded above the urban canyon and systematically higher(up to 2°C), during the night period. These differences, as well as the intensity of the phenomenon directly depends on the wind. intensity. The intensity of the urban heat island shows an inverse correlation with low wind speed, while for intensities above 5 to 7 m/s there is a minimization of the phenomenon.
Finally, the effect of the urban heat island is catalytic in the cooling energy. The phenomenon affects both the degree of efficiency of the air conditioning units (COP), the effect of which can vary by up to 14%, and the required latent cooling energy (kWh/m2). where the obtained in the basis of the “Standard Meteorological Year” was 15% to 50% less than that calculated over various areas of Western Athens
Keywords:
Urban heat island, urban canyon, wind speed, cooling energy consumption
