The widespread overbuilding, the prevalence of asphalt surfaces on green areas, the use of building materials with low ability to heat dissipation, are among the main causes of Urban Heat Islands. In summer, the presence of this phenomenon leads to numerous problems: peak demand of energy consumption, cost of air conditioning and greenhouse gas emissions. Within urban areas, evapotranspiration and plants shade can reduce, significantly, the heat that would be re-radiated from the buildings. Green roofs are building systems that can play a decisive role in this direction. As part of the Research Project PON "Integrated and Sustainable Management Services for the Water-Energy Cycle in Urban Drainage Systems”, a scale model of green roof has been installed at the University of Calabria, in order to evaluate the influence of green roofs on rainwater management and energy consumption for air conditioning in the Mediterranean area. In order to facilitate the comparison of different design solutions, the test site was organised in four sectors defining three sectors with different stratigraphy and a sector as a reference made with the classic waterproof membrane. Subject of this work is the analysis of the measurements taken on two sectors with vegetated roof differentiated by types of crops planted and by irrigation of one. The energy aspects of this study focus on roof temperature and heat flux dynamic comparison between two green roof and on evapotranspiration’s flow effects on heat flux. Data monitoring provided the measurement of parameters such as temperature and water content at different depths in the growing medium, air temperature, total horizontal solar radiation, rainfall and wind speed. The proposed data refer to the summer period and indicate significantly lower peak roof surface temperatures for the irrigated green roof. Initial heat flux estimates have also been made for each of the two roof measurement locations for the same period. Heat flux is lower for irrigated vegetated roofs examined. Between the two types of vegetated roof the difference must be attributed to the culture medium’s composition and, therefore, to the different evapotranspiration’s flow. The determination of hourly evapotranspiration flow, through water soil balance, allows to verify that coverage with selected vegetation and irrigated (sector 1) has a lower surface heat flux compared to the coverage with native vegetation and not irrigated (sector 3).
Effects of evapotranspiration in the energy performance of a vegetated roof: first experimental results
Garofalo G.;Carbone M.;Nigro G.;Piro P.
2015-01-01
Abstract
The widespread overbuilding, the prevalence of asphalt surfaces on green areas, the use of building materials with low ability to heat dissipation, are among the main causes of Urban Heat Islands. In summer, the presence of this phenomenon leads to numerous problems: peak demand of energy consumption, cost of air conditioning and greenhouse gas emissions. Within urban areas, evapotranspiration and plants shade can reduce, significantly, the heat that would be re-radiated from the buildings. Green roofs are building systems that can play a decisive role in this direction. As part of the Research Project PON "Integrated and Sustainable Management Services for the Water-Energy Cycle in Urban Drainage Systems”, a scale model of green roof has been installed at the University of Calabria, in order to evaluate the influence of green roofs on rainwater management and energy consumption for air conditioning in the Mediterranean area. In order to facilitate the comparison of different design solutions, the test site was organised in four sectors defining three sectors with different stratigraphy and a sector as a reference made with the classic waterproof membrane. Subject of this work is the analysis of the measurements taken on two sectors with vegetated roof differentiated by types of crops planted and by irrigation of one. The energy aspects of this study focus on roof temperature and heat flux dynamic comparison between two green roof and on evapotranspiration’s flow effects on heat flux. Data monitoring provided the measurement of parameters such as temperature and water content at different depths in the growing medium, air temperature, total horizontal solar radiation, rainfall and wind speed. The proposed data refer to the summer period and indicate significantly lower peak roof surface temperatures for the irrigated green roof. Initial heat flux estimates have also been made for each of the two roof measurement locations for the same period. Heat flux is lower for irrigated vegetated roofs examined. Between the two types of vegetated roof the difference must be attributed to the culture medium’s composition and, therefore, to the different evapotranspiration’s flow. The determination of hourly evapotranspiration flow, through water soil balance, allows to verify that coverage with selected vegetation and irrigated (sector 1) has a lower surface heat flux compared to the coverage with native vegetation and not irrigated (sector 3).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.