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Greenhouse microclimate depends on climatic parameters, such as solar radiation, air temperature, relative humidity and wind speed. The management of the greenhouse environment aims to ensure suitable growing condition for the crop, energy savings, and also safety condition for the workers. Solar absorption systems, exploiting renewable energy sources, can be applied for greenhouse cooling in regions with high values of solar irradiation in which evaporative systems are generally used; nevertheless evaporative systems require large quantity of water that is often a scarce natural resource in Mediterranean areas. The paper presents the technical considerations on the application of thermal solar collectors and an absorption system for cooling a greenhouse in the Mediterranean area. The simulation study was realized based on the data collected at the experimental centre of the University of Bari, Southern Italy, aiming to control the air temperature of a greenhouse having a surface of 300 m2. The study aims to delineate the solar collector surface related to the greenhouse cultivated area and the potential of the system in terms of cooling capacity and energy consumption. The designed system consists of 60 m2 of evacuated-tube solar collectors, a single-effect absorption chiller having a cooling capacity of 18 kW and a pilot distribution system, which provides the cooling power for the air volume surrounding the crop. The simulation showed that the delivered yearly cooling capacity for the greenhouse was 113 GJ, the required solar energy 157 GJ and the available solar energy 234 GJ.

The phenomenon of urban warming, known as urban heat island, negatively influences outdoor comfort conditions and pollutants concentration and as well increases the environmental impact due to the energy demand for air conditioning. Urban warming can be attenuated by reducing the solar heat gain that increases building’s temperature during the hot season. Solar heat can be mainly reduced by increasing the insulation between the exterior and interior of the building, as well as by shading the building surface from direct sun exposure. A sustainable technology for improving the energy efficiency of buildings is the use of green roofs and green walls that: allow the physical shading of the building and promote evapotranspiration in summer; increase the thermal insulation in winter. An experimental test was carried out at the University of Bari (Italy, 41 ° 05 'N, 16 ° 53 'E). Three prototypes of building vertical wall, made with perforated bricks, were designed: two vertical walls were covered with plants (one with Pandorea jasminoides variegated, the second with Rhyncospermum jasminoides) while the third wall was kept uncovered and was used as control. A system composed by a data logger and sensors was used to measure and record the following parameters: temperature of the wall surface under solar radiation and of the surface on the other side of the wall, solar radiation falling on the wall, external air temperature and wind speed. During summer 2014 the diurnal temperatures of the control surface exposed to the solar radiation were higher by about 4 °C compared to the temperatures recorded on both the vertical walls covered with Rhyncospermum jasminoides and Pandorea jasminoides variegated. The thermal wave propagated with a phase shift of about 2 hours and half.