Suchergebnisse

Green façades consist of the application of vegetation on buildings' vertical enve-lope. The integration of vegetation into the building fabric improves not only the aesthetic appearance, but also the energy performance of the building itself. The introduction of green façades mainly aims at a passive thermal control of build-ings' for enhancing sustainability of the built environment. An experimental green façade was tested at the University of Bari, in a Mediterranean climate context. The experimental green façade was south-exposed and realized with evergreen plants, following the characteristics of the indirect typology. A portion of the south wall was left bare to be used as a control for comparison. The contribution of the green façade in terms of passive climate control was particularly relevant during summer. Vegetation affects the boundary climatic conditions and the surface temperature. A reduction in sensible air and surface temperature of up to 2.2°C and 6.7°C, respectively, was recorded. The wall behind vegetation received 95.6% less solar radiative energy than the bare wall. These results were a direct conse-quence of the two main cooling mechanisms that characterize the green façade, the evapotranspiration and the shading effect. These effects affected the heat transfer reducing the energy input through the covered wall. The reduction of the incoming heat through the covered wall was read as energy saving, since it inevita-bly affects the building energy demand for cooling. It was found that the green fa-çade allowed a mean daily energy saving of 1.1 MJ m-2 and that 90.9% of this was obtained at daytime. These findings contribute to increasing the knowledge of en-ergy functioning and of the real advantages provided by green façades.

A sustainable and environmentally alternative to commonly used air conditioning systems can be the solar cooling system due to the use of renewable and clean energy. Solar absorption systems can be used for greenhouse cooling in areas with high outdoor temperatures and solar radiation levels. These systems take advantage of the simultaneity between the solar energy availability and the greenhouse cooling demand allowing the reduction of conventional electricity and water consumption. This paper presents the results of the application of a solar cooling plant for the climate control of a greenhouse at the University of Bari, Italy. The experimental plant consists of a Mediterranean greenhouse, having a surface of 300 m2, and of a single effect LiBr-H2O absorption chiller fed by evacuated-tube solar collectors. Two different localized systems were chosen for the distribution of cold inside the greenhouse: the first system presents pipes placed centrally on the cultivation vessels; the second consists of pipes in contact with aluminium plates and of a transparent EVA film, used to border an area close to plants. The distribution system of cold with pipes, plate and EVA film provided a slightly higher cooling capacity due to the presence of the plates which increases the ability to dissipate energy.