Marco Noro

Urban heat island in Padua, Italy: experimental and theoretical analysis

This paper reports the study of the urban heat island (UHI) phenomenon in Padua, a medium size city in the North-East of Italy, one of the most industrialized and developed parts of the country. Data recorded by two fixed meteorological stations (in the centre and out of Padua) during the period 1994–2011 were analysed, showing some increase in the UHI effect during this period. Experimental measurements were carried out during 2012 summer. The main thermo-hygrometric variables (dry-bulb temperature, relative humidity and global solar radiation) were measured by a mobile survey along an exact path, selected in order to cross different zones of the city area: urban, sub-urban and rural. The results indicate the presence of UHI effect in urban zones of the city up to 6 ℃. Some measurements in situ had been carried out in order to evaluate the mean radiant temperature (besides the other meteorological variables) in some characteristic sites of the city area: historic centre, high- and low-density populated residential zones, industrial zone and rural zone. Two simulation models were used to calculate some outdoor comfort indices and to evaluate the effect of some mitigation strategy in characteristic sites of the city.

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 Urban Corridor of Venice and The Case of Padua

Urban Heat Island effect was widely studied in large cities around the world, more rarely in medium size ones. The chapter reports on the study of the UHI phenomenon in Padua, a medium size city of the North-East of Italy, one of the most industrialized and developed parts of the country. Experimental measurements were carried out during 2012 summer, recording the main thermo-hygrometric variables (dry-bulb temperature, relative humidity, global solar radiation) by a mobile survey along an exact path crossing different zones of the city area: urban, sub-urban and rural. The analysis of the data highlights the presence of UHI effect with different magnitudes in function of the zone of the city. In the city centre, an historical zone, the effect was up to 7 °C. In the meantime, some measurements in situ were carried out in order to evaluate other thermal comfort indexes rather than air temperature and humidity only: wind velocity and mean radiant temperature (besides the other meteorological variables) in some characteristic sites of the city area like historic centre, high and low density populated residential zones, industrial zone, rural zone, were recorded. In particular, a very famous square of the city (Prato della Valle) was analysed: it can be considered representative of the phenomenon because of the size and the very different characteristics from the UHI effect point of view. RayMan simulation model was used to calculate some outdoor comfort indexes and Envimet model was further used to evaluate the effect of some mitigation strategies in characteristic sites of the city.

Multisource Heat Pump System: The Case Study of a New School Building

The concept of a low energy building in the temperate climate (according to the Koppen climate classification) is based on the reduction of heat losses through a better insulation, the heat recovery on mechanical ventilation and the use of high efficiency heating/cooling systems integrated with renewables. It is very difficult to achieve good results in terms of global energy efficiency if one of these elements is missing. In 2009 a new school building, integrating those three elements, started its operation in Agordo town, northern Italy. Its main features concern a well insulated envelope and a space heating and ventilation system driven by an innovative multisource heat pump system concept. Outdoor air is a common heat source, whose limits are well known. Heat pump features can take advantage of better sources than air, as for instance the ground heat, solar heat, and heat recovery. These sources are those used by the analyzed system. A multisource system aims to enhance the performances of the heat pump, both in terms of heating capacity and of efficiency, of the heat pump. The present work shows data monitoring and analysis for a real working application, for a period of about two heating seasons, during which the behavior of the system can be analysed and the eventual malfunctioning of the plant can be identified. The energy balance indicates that the integration of different sources not only increases the thermal performance of the system as a whole but also optimizes the use of each source, thus leading to a lower stress on the ground and to a higher utilization of the solar system. The results are then compared to those could have been obtained with the use of a single source system, i.e. the ground, taking no advantage from the heat recovery and the solar system.