In recent years there has been a significant change of values in society with an increment of sensitivity towards the environmental issues. In the case of the building industry, the so called Sustainable Construction tends to close the cycles of materials, water and energy, so that the efficient use of resources is fundamental in any of these three areas. In this sustainable approach, the increment of vegetation cover in urban areas, for example, with green roofs and facades, can contribute significantly to improve the build environment. The two main mechanisms that regulate the thermal behavior of a green roof are the shadow effect produced by plants, and the insulation effect provided by the materials of the below layers, especially the substrate and drainage. Several authors have also stated that there is a cooling effect which can be done due to evapotranspiration from plants substrate. In this sense, the moisture content of the substrate also influence the energy-saving that green roof can provide to the building. The thermal behavior of a green roof also strongly depends on the weather conditions of the location where it is installed. Moreover, the thermal performance of green roofs is influenced by the design: plants selection (solar radiation shading effect), materials of the different layers (thermal properties) and thicknesses of the support and substrate layers. The objective of this study is to compare the thermal behavior of two green roofs located in Mediterranean climates, continental and hot temperate, with different compositions (number of layers, materials, thicknesses, plants, etc.). The first green roof is a 2000 m2 extensive green roof and is a part of a renovation project located in the Gardeny Science and Technology Park in the city of Lleida (Spain). Moreover, the results of two 3x3 meters experimental extensive green roofs placed in a pilot plant located in Puigverd de Lleida (Spain) will be also considered. In these green roofs the energy savings and the thermal behavior has been investigated for 3 years. The second one is an experimental extensive green roof of 200 m2, located on the 400 m2 roof of the Department of Mechanical, Energy and Management Engineering at the University of Calabria (Italy). The green roof surface is divided into four plots: one is the reference traditional roof, while the other three provide specific stratigraphies. Two of them, without thermal insulation, have equivalent stratigraphy but are built using different commercial materials. The third one, initially without vegetation, includes a thermal insulation layer. The study carries out the comparison of experimental results obtained from the different construction systems in different locations. The main parameters considered to monitor and evaluate the energy performance of the green roofs are: the surface and layers temperatures, the indoor temperatures, the water content variation in the substrate and the energy savings achieved. These data are used to define the thermal behavior of different materials of the green roof, and how the climatic conditions (rainfall and moisture in the substrate) influence the overall thermal performance and development of plants.
Green roofs for building energy savings. A comparative study
Bevilacqua P;DE SIMONE, Marilena;
2014-01-01
Abstract
In recent years there has been a significant change of values in society with an increment of sensitivity towards the environmental issues. In the case of the building industry, the so called Sustainable Construction tends to close the cycles of materials, water and energy, so that the efficient use of resources is fundamental in any of these three areas. In this sustainable approach, the increment of vegetation cover in urban areas, for example, with green roofs and facades, can contribute significantly to improve the build environment. The two main mechanisms that regulate the thermal behavior of a green roof are the shadow effect produced by plants, and the insulation effect provided by the materials of the below layers, especially the substrate and drainage. Several authors have also stated that there is a cooling effect which can be done due to evapotranspiration from plants substrate. In this sense, the moisture content of the substrate also influence the energy-saving that green roof can provide to the building. The thermal behavior of a green roof also strongly depends on the weather conditions of the location where it is installed. Moreover, the thermal performance of green roofs is influenced by the design: plants selection (solar radiation shading effect), materials of the different layers (thermal properties) and thicknesses of the support and substrate layers. The objective of this study is to compare the thermal behavior of two green roofs located in Mediterranean climates, continental and hot temperate, with different compositions (number of layers, materials, thicknesses, plants, etc.). The first green roof is a 2000 m2 extensive green roof and is a part of a renovation project located in the Gardeny Science and Technology Park in the city of Lleida (Spain). Moreover, the results of two 3x3 meters experimental extensive green roofs placed in a pilot plant located in Puigverd de Lleida (Spain) will be also considered. In these green roofs the energy savings and the thermal behavior has been investigated for 3 years. The second one is an experimental extensive green roof of 200 m2, located on the 400 m2 roof of the Department of Mechanical, Energy and Management Engineering at the University of Calabria (Italy). The green roof surface is divided into four plots: one is the reference traditional roof, while the other three provide specific stratigraphies. Two of them, without thermal insulation, have equivalent stratigraphy but are built using different commercial materials. The third one, initially without vegetation, includes a thermal insulation layer. The study carries out the comparison of experimental results obtained from the different construction systems in different locations. The main parameters considered to monitor and evaluate the energy performance of the green roofs are: the surface and layers temperatures, the indoor temperatures, the water content variation in the substrate and the energy savings achieved. These data are used to define the thermal behavior of different materials of the green roof, and how the climatic conditions (rainfall and moisture in the substrate) influence the overall thermal performance and development of plants.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
