• Energy Research

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.

Abstract 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.

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.

Green infrastructures inside cities represent an effective strategy to face with the increasingly urgent environmental problems. Green systems applied to building envelope are among the most applicable and useful solutions. These provide many significant advantages at different scales. Green façades (GF) are a typology of vertical green systems, applied to the vertical components of the building envelope. GF allow to save energy for air conditioning, by improving the envelope thermal performances. Energy behaviour of GF has been more deeply studied in warm periods, than in cold ones. This paper aims to analyse wintertime energy performances of GF. Evaluations were carried out based on the experimental data collected on two GF, in Bari (Italy), under mediterranean climatic conditions. The experimental set-up included also a bare wall (BW), used as control. The heating effect provided by the greenery was pointed out through statistical and energy analyses. At night-time, the covered walls (CW) were warmer than the bare one up to 3.5°c. The dependence of night-time heating effect on microclimate parameters, as external air temperature, relative humidity and wind speed, was studied. External air temperature was found to be the most influencing factor: as it dropped, the heating effect increased. Overall energy transfer through the CW was lower than through the BW at night-time. The long-wave infrared energy radiative losses were reduced thanks to the green layer, which acted as a thermal barrier. These findings proved that GF improve winter night-time thermal performance by reducing energy losses.

The use of plastic materials in agriculture, for greenhouse covering, soil mulching, irrigation pipes, containers and bags, generates a huge amounts of plastic waste that must be properly disposed of. An adequate waste management and disposal system requires the knowledge of the waste generation on the land. This paper presents the results of a research, based on the application of a Geographical Information System, for mapping the waste generation in the municipality of Trinitapoli, Italy. Aim of the research is to identify the points of waste generation and to quantify the waste. A dedicated geo-referenced database with data on the spatial distribution and amount of the plastic wastes was created; waste density ranged from 3.3 kg ha-1yr-1 to 861 kg ha-1yr-1. L’uso di materiali plastici in agricoltura, quali film per la copertura di serre, film per la pacciamatura del terreno, tubi d’irrigazione, contenitori di pesticidi e sacchetti di fertilizzanti, genera un enorme quantita di rifiuti plastici che devono essere correttamente smaltiti. Un sistema adeguato di gestione e smaltimento delle plastiche presuppone la conoscenza della produzione dei rifiuti sul territorio. Questo lavoro presenta i risultati di una ricerca, basata sull’applicazione di un Sistema di Informazione Geografica, per la mappatura della produzione di rifiuti nel comune di Trinitapoli, in Italia. Lo scopo della ricerca e quello di identificare i punti di generazione dei rifiuti plastici e di quantificarli. E stato creato un database georeferenziato dedicato, con i dati sulla distribuzione spaziale e la quantita di rifiuti di plastica generati. La densita dei rifiuti prodotti varia da 3,3 kg ha-1 a 861 kg ha-1 per anno.

A research is under development at the Department of Agro- Environmental Sciences of the University of Bari “Aldo Moro” in order to investigate the suitable solutions of a power system based on solar energy (photovoltaic) and hydrogen, integrated with a geothermal heat pump for powering a self sustained heated greenhouse. The electrical energy for heat pump operation is provided by a purpose-built array of solar photovoltaic modules, which supplies also a water electrolyser system controlled by embedded pc; the generated dry hydrogen gas is conserved in suitable pressured storage tank. The hydrogen is used to produce electricity in a fuel cell in order to meet the above mentioned heat pump power demand when the photovoltaic system is inactive during winter night-time or the solar radiation level is insufficient to meet the electrical demand. The present work reports some theoretical and observed data about the electrolyzer operation. Indeed the electrolyzer has required particular attention because during the experimental tests it did not show a stable operation and it was registered a performance not properly consistent with the predicted performance by means of the theoretical study.

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.