A first experimental survey on the urban heat island in Padua (Italy)

The Urban Heat Island effect concerns the higher air temperature in urban environment with respect to the rural one. This phenomenon is well known by hundreds of years, but it has been experimentally studied only in the last few decades and in large metropolis. Very different possibilities concerning the measurements are possible (fixed ground based meteorological stations, “transept” measurements, satellite-based infrared sensors), with different difficult and quality of the data measured. The paper reports on the experimental results obtained by a research group of the University of Padua (Italy) in 2010 and 2011 springs-summers in Padua city. The main thermo-hygrometric variables (dry-bulb temperature, relative humidity, global solar radiation) have been measured along some different paths fixed in advance. The paths have been selected in order to cross different zones of the fabric of the city: urban, sub-urban and rural. The high number of “transepts” implemented in different time bands during the day and after the sunset allows to characterize the phenomenon in different meteorological conditions. The results indicate a presence of the UHI in urban zones of the city up to 5 °C. This work is intended to be developed during 2012 by the research group of the Department of Management and Engineering of the University of Padua, in cooperation with Co.Ri.La. (Venice) in the European Project “UHI - Development and application of mitigation and adaptation strategies and measures for counteracting the global Urban Heat Islands phenomenon” (3CE292P3). The paper reports the analysis of data recorded by two fixed meteorological stations (in the centre and out of Padua) during the period 1994-2011, that show some increase in the UHI effect during this period. Some guidelines concerning the choice of the experimental measurements settings are supplied by the Authors. The future measurements will be used also to calculate some outdoor comfort index and to verify how the latter will change modifying some characteristic parameters (buildings placement, thermal properties, trees presence, etc.) by a simulation model.