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A sustainable technology for improving the energy efficiency of buildings is the use of urban greening in order to reduce the energy consumption for air conditioning in summer and to increase the thermal insulation in winter. A worldwide growing interest in urban green is encouraging the application of the greening technology for more sustainable buildings. Building indoor air temperature depends on several different parameters related to the climate of the region, the building itself and its use. The main parameters influencing the microclimate are: external air temperature and relative humidity, incident solar radiation, long wave radiation exchange between the building surfaces and its surroundings, wind velocity and direction, air exchanges, physical and thermal properties of the building's envelope materials, design variables such as building dimensions and orientation, presence of artificial light, electrical equipment. Green façades can allow the physical shading of the building and promote evapotranspiration in summer and increase the thermal insulation in winter. External wall surface temperature is a parameter useful to assess the effectiveness of green façades. An experimental test was carried out at the University of Bari (Italy) for three years. Three vertical walls, made with perforated bricks, were tested: two were covered with evergreen plants (Pandorea jasminoides variegated and Rhyncospermum jasminoides) while the third wall was kept uncovered and used as control. Several climatic parameters concerning the walls and the ambient conditions were collected during the experimental test. The experimental data were used for developing a multiple regression equation regarding the dependence of the difference of external surface temperature between the green façades and the control wall and the weather conditions. The model shows a good predicting ability.

Green facades can represent a sustainable solution for construction of new buildings and for retrofitting of existing buildings, in order to reduce the energy demands of the cooling systems, to mitigate the urban heat island and to improve the thermal energy performance of buildings. Green facades can allow the physical shading of the building and promote evapotranspiration in summer, and increase the thermal insulation in winter. An experimental test was carried out at the University of Bari (Italy) for two years. Three vertical walls, made with perforated bricks, were tested: two were covered with evergreen plants (Pandorea jasminoides variegated and Rhyncospermum jasminoides) while the third wall was kept uncovered and used as control. Several climatic parameters concerning the walls and the ambient conditions were collected during the experimental test. The daylight temperatures observed on the shielded walls during warm days were lower than the respective temperatures of the uncovered wall up to 9.0 °C. The nighttime temperatures during the cold days for the vegetated walls were higher than the respective temperatures of the control wall up to 3.5 °C. The thermal effects of the facades at daytime was driven by solar radiation, wind velocity and air relative humidity. The highest cooling effect of such parameters occurred with a wind speed of 3–4 ms−1, an air relative humidity within the range 30–60% and a solar radiation higher than 800 Wm−2. The long-term experimental test demonstrated that both Pandorea jasminoides variegated and Rhyncospermum jasminoides are suitable for green facades in the Mediterranean climatic area. The results shown in the present research allow to fill the gap in literature concerning the lack of data for all the seasons of the year, in order to obtain a complete picture of the building thermal performance in the Mediterranean climate region.

Energy performance of a double-skin green facade in Mediterranean climate was investigated. Experimental data were collected at a green facade prototype realized at the University of Bari. The green facade thermal behaviour was assessed under different summertime weather scenarios. To point out the plants influence, a comparison was carried out between microclimatic conditions and energy transfer at the covered wall, behind the vegetation, and at an un-vegetated wall. Experimental data concerning the walls surface, the air gap in the green facade and the external air were used to perform statistical analyses and to evaluate the heat fluxes. At daytime, the green facade provided a reduction of the wall surface temperature up to 9.9 °C, while air relative humidity behind the vegetation rose up to 18.7%. Surface and air warming were found at night-time. A time-shift was detected between the maximum surface temperature of the covered and of the bare wall. The analysis of the energy flux through the two walls highlighted a sensible reduction in the covered wall, equal to 62% during daytime. Solar and LWIR radiative and convective fluxes were generally lower in the covered wall. Latent heat due to evapotranspiration was evaluated, as well. Net radiation was found to be the most influencing parameter for latent heat transfer. A simplified relationship was proposed to quantify latent heat due to evapotranspiration. The formula based on the net radiation, as input parameter, was found to be the most suitable. The findings of this research contribute to the knowledge of the effects provided by green facades in terms of cooling and heating, influence on the proximity microclimatic conditions and overall energy transfer.

Increasing urban green infrastructure (UGI) in a city contributes to improve urban air quality and urban climate in summer, reducing buildings surface temperature, especially in southern Europe. UGI includes green walls and their correct application requires the knowledge of the energy performance of the applied green system. The effects of the green walls application on the building depend on the local climate, water availability, building shape. The presence of green walls affects the building microclimate all day, by reducing heat waves during the warm periods and heat losses from the building in cold periods. The heat and mass transfer between the external environment, the green wall and the building surface determine the building microclimate. Solar radiation, long wave infrared radiation, convective heat transfer and evapotranspiration are the main mechanism of heat transfer in a green wall. The paper describes the main parameters concerning heat flow in green walls that can be used in simulation models for predicting temperatures in buildings using the external weather conditions as model inputs. The green wall system was described by a schematic representation, the following layers were defined: the green wall, the gap air, the external surface of the building wall, the internal surface of the building wall, the air inside the building. The energy balance was defined for each layer and all the terms involved in the energy exchange between the layers were defined.

Green technology can represent a sustainable solution for construction of new buildings and for retrofitting of existing buildings, in order to reduce the energy demands of the buildings’ cooling systems, to mitigate the urban heat island and to improve the thermal energy performance of buildings. Green walls can allow the physical shading of the building, promote evapotranspiration in summer and increase thermal insulation in winter. An experimental test was carried out at the University of Bari (Italy) for 2 years. Three vertical walls, made with perforated bricks, were tested: two were covered with evergreen plants (Pandorea jasminoides and Rhyncospermum jasminoides), while the third wall was kept uncovered and used as a control. Several climatic parameters concerning the walls and the ambient conditions were collected during the experimental test. Daylight temperatures observed on the shielded walls during warm days were lower than the respective temperatures of the uncovered wall by up to 9.0°C. Night-time temperatures during cold days for the vegetated walls were higher than the respective temperatures of the control wall by up to 6.0°C. The absence in the literature of data concerning different seasons of the year is overcome in order to obtain a complete picture of building thermal performance in the Mediterranean climate region. © 2018 International Society for Horticultural Science. All Rights Reserved.

Building greenery systems can represent a sustainable solution for new buildings design and for existing buildings retrofitting, in order to improve the thermal energy performance of buildings, to decrease building energy loads and to contrast the Urban Heat Island. Green façades can influence thermal properties of a building by means of different important mechanisms: the shading, the cooling, the insulating and the wind barrier effect. Moreover, green façades accomplish heating effect in the cold season and at nighttime. An experimental test was developed at small scale at the University of Bari (Italy) from 2014 to 2016 for testing two different green façades. The plant species chosen were Pandorea jasminoides variegated and Rhyncospermum jasminoides, two evergreen climbing plants. A third uncovered wall was used as control. The thermal behaviour of the plants was analysed during the 2016 summer season, by keeping in consideration the external surface temperature of the building and the temperature of the airgap behind the green vertical systems. The daylight temperatures observed on the plant-covered walls during representative days were lower than the respective temperatures of the uncovered wall up to 7.0°C. During nighttime, the temperatures behind the plants were higher than the respective temperatures of the control wall up to 2.2°C. The results shown in the present research allow delineating the behaviour of the two plant species during summer in the Mediterranean climate region.

Green technology can represent a sustainable solution for construction of new buildings and for retrofitting of existing buildings, in order to reduce the energy demands of the cooling systems of buildings, to mitigate the urban heat island and to improve the thermal energy performance of buildings. Green walls can allow the physical shading of the building and promote evapotranspiration in summer and increase the thermal insulation in winter. Three vertical walls, made with perforated bricks, were tested at the University of Bari (Italy): two were covered with evergreen plants (Pandorea jasminoides variegated and Rhyncospermum jasminoides) while the third wall was kept uncovered and used as control. Several climatic parameters concerning the walls and the ambient conditions were collected during the experimental test. The daylight temperatures observed on the shielded walls during warm days were lower than the respective temperatures of the uncovered wall up to 8.4°C. The night-time temperatures during the cold days for the vegetated walls were higher than the respective temperatures of the control wall up to 3.6°C. © ISHS.

The thermal potential of vertical greenery systems in buildings can be fully explored through modelling. Models support designers in choosing between different technical solutions. This study analyses the cooling effect of two plants suitable for the Mediterranean area. A regression model simulating the difference of the wall external surface temperature between the wall covered with vegetation and an uncovered wall was developed. In order to overcome the gaps in literature, the model was fitted and validated on long period experimental data. It was based only on the use of climatic conditions as input variables, without making assumptions about the plants. Climatic data were grouped in solar radiation slots; the most significant predictors were selected for each slot. The adoption of this method allowed to obtain, during validation, coefficients of determination (R2) higher than 0.95 and low values of the root mean square error (0.4–0.6 °C). It was found that the vegetated walls recorded surface temperatures lower than the uncovered wall up to 7.7 °C in summertime. The results showed that the model developed with a statistical approach can efficiently be used for simulating the thermal effects of a green facade in a similar Mediterranean climate.

Building indoor air temperature depends on several different parameters related to the climate of the region, the building itself and its use. The main parameters influencing the microclimate are: external air temperature and relative humidity, incident solar radiation, long wave radiation exchange between the building surfaces and its surroundings, incidence and speed of the wind, air exchanges, physical and thermal properties of the building's envelope materials, design variables such as building dimensions and orientation, presence of artificial light, electrical equipment. A sustainable technology for improving the energy efficiency of buildings and to mitigate urban heat island is the use of green roofs and walls. The green technology can allow the physical shading of the building and promote evapotranspiration in summer and increase the thermal insulation in winter. An experimental test was carried out at the University of Bari (Italy). Three vertical walls, made with perforated bricks, were tested: two were covered with plants (one with Pandorea jasminoides variegated, the second with Rhyncospermum jasminoides) while the third wall was kept uncovered and 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, and external air temperature. The use of the green walls during cold months allowed increasing the thermal insulation performance of the walls by keeping the external surface temperature in nighttime hours up to about 2.8°C over the surface temperature of the wall not covered with plants. © 2017 ISHS.

Monitoring and controlling environmental parameters inside a greenhouse are required to reach high yields and low environmental impacts. Ventilation, shading, evaporative cooling and refrigeration are methods of controlling air temperature and relative humidity in Mediterranean greenhouses. Nevertheless ventilation and shading are often not sufficient to remove the excess heat, refrigeration is generally expensive and evaporative cooling is based on the exploitation of high quality water, a resource to be preserved in the Mediterranean areas. In order to enhance the sustainability levels of the greenhouse sector, renewable energy sources can be exploited with the application of solar absorption systems for greenhouse cooling in areas with high outdoor temperatures. These systems take advantage of the simultaneity between the solar energy availability and the greenhouse cooling demand allowing the reduction of conventional electricity. This paper presents the simulation and optimization of a solar cooling system designed for a Mediterranean greenhouse, having a surface of 300 m2, using 68 m2 of evacuated tube solar collectors, a LiBr absorption unit with a cooling capacity of 17.6 kW and a pilot distribution system providing the cooling power for the volume surrounding the crop. The simulation study, predicting the performance of the unit, was based on the experimental data collected at the experimental centre of the University of Bari, Southern Italy. The results of the simulation indicated that the system is seasonally in phase with the climatic data; the delivered yearly cooling capacity for the greenhouse was 113 GJ, the required solar energy 157 GJ and the available solar energy on the 68 m2 capturing surface, with a slope of 30°, was 265 GJ. The simulation can be used as a forecasting tool of the effects of the changes on the parameters of the system before applying them on the greenhouse system. © 2017 ISHS.