155,327 research outputs found
Building green covering for a sustainable use of energy
No full textNowadays the growth of the cities increased built and paved areas, energy use and heat generation. The phenomenon of urban warming, called urban heat island, influences negatively outdoor comfort conditions, pollutants concentration, energy demand for air conditioning, as well as increases environmental impact due to the demand of energy generation. A sustainable technology for improving the energy efficiency of buildings is the use of green roofs and walls in order to reduce the energy consumption for conditioning in summer and improve the thermal insulation in winter. The use of green roofs and walls can contribute to mitigate the phenomenon of heat island, the emissions of greenhouse gases, and the storm water runoff affecting human thermal comfort, air quality and energy use of the buildings. Recently, a number of municipalities started to adopt regulations and constructive benefits for renovated and new buildings which incorporate green roofs and walls. The aim of this paper is to describe the green roofs and walls plant technology. © Copyright C.A. Campiotti et al., 2013
Green walls for building microclimate control
No full textGreen 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 façades to enhance climate control inside buildings
No full textGreen 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
A comparison between two methods to control nutrient delivery to greenhouse melons grown in recirculating nutrient solution culture
No full textEnvironmental impact reduction in greenhouses heating: Biomass-fired absorption heat pump coupled with wood biomass boiler
No full textThis paper deals with an interesting application of different technologies to greenhouse heating systems. First, biomass boilers is a mature and affordable technology, showing high efficiency and long lasting devices. As wood biomass is considered as GHG neutral when converted to heat, it is logical to think about its application to greenhouse heating. Second, the thermally activated heat pumps, and more specifically the absorption heat pump, has reached a mature technology, as well. If the thermally activated heat pumps are coupled with short and long term heat storage, this can enhance the overall efficiency of the system. As greenhouse radiant, floor and bench heating systems can exploit low grade thermal energy, and these interconnections generate virtuous circles for the environmental impact reduction related to greenhouse heating systems. © 2016, SRAC - Societatea Romana Pentru Asigurarea Calitatii. All rights reserved
Solar absorption cooling system for greenhouse climate control: Technical evaluation
No full textEvaporative systems are generally used in warm regions for commercial greenhouse cooling, such systems require large quantity of water that is often a scarce natural resource in Mediterranean areas. Solar absorption cooling systems can be applied for greenhouse climate control in regions with high values of solar irradiation as alternative to evaporative systems by exploiting renewable energy sources. The paper presents the preliminary results of a research on the application of a solar absorption cooling system to a Mediterranean greenhouse. The aim of the research was to assess the potential of the system in terms of energy absorption related to the solar collector surface and to the greenhouse covered area. The simulation study was realized based on the experimental data collected at the experimental centre of the University of Bari, Southern Italy, in order to control the temperature of a plastic film covered greenhouse, having a surface of 300 m2. The cooling system was designed by adopting suitable technologies of energy saving, in order to reduce cooling energy needs. The designed system consists of an absorption chiller having a cooling capacity of 35 kW and of 80 m2 of evacuated-tube solar collectors
Estimation of hydraulic properties of growing media with a one-step outflow technique
No full textAn application of the improved iterative method for the simultaneous determination of the hydraulic properties of growing media using the one-step experiment is described for highly porous media. Substrate hydraulic properties were characterized by the Brooks and Corey equation for water retention, and by the Kozeny power equation for hydraulic conductivity. The iterative procedure has been tested with a particular class of growing media generally used for container plant cultivation, represented by pure peat, pumice, and a 25: 75 Peat: Pumice mix. The previously optimized One-Step method with Peat: Pumice ratio in the range from 1: 0 to 1: 1, was tested on five replications over the new range from 1: 3 to 0: 1. By analyzing the mean cumulative outflow curves recorded versus time, an estimation of hydraulic functions was derived. Estimated water retention was compared with nine experimental datasets and with estimation by the Van Genuchten model. Normalizing the saturated water content, the two models overlap except for the "wet" range near saturation. Estimated hydraulic conductivity was compared with the estimation derived from the Van Genuchten-Mualem equation involving 3 and/or 4-parameter analysis. Comparisons showed a good similarity between model estimations
Energy efficiency as option for improving sustainability of agrofood system
No full textAgrofood system embraces two closely related components: direct crop production (agriculture) and food industry which includes processing, retailing and products distribution. FAO reports that the agrofood system is one of the world's largest user of fossil energy, with around 20% of the total energy consumption in developed countries, and a 22% of total annual emissions, with the agriculture component as responsible of around 14% of total global GHG emissions. Agrofood system accounts for 17 % of the EU’s gross energy consumption in 2013, equivalent to about 26 % of the EU’s final energy consumption, producing approximately 11% of the EU agrofood GHG emissions. This paper focuses on the opportunities linked with the application of energy management measures complying with the EU 2012 Energy Efficiency Directive (EED), and with the target of the EC to reduce 20% of GHG by 2020. © 2016, SRAC - Societatea Romana Pentru Asigurarea Calitatii. All rights reserved
A sustainable energy for greenhouses heating in Italy: Wood biomass
No full textMore than 0.7 million ton of oil equivalent is the total requirement for thermal energy in the Italian greenhouse vegetable industry, derived mostly from fossil fuels, which corresponds to 2 Mt CO2 emissions. The technology of wood biomass system is a good candidate for heating greenhouses, since this resource is considered as 'greenhouse gas' (GHG) neutral when converted to heat, excluding the GHG generation during harvesting, transportation, and pre-processing of raw materials. Besides, the CO2 enrichment in greenhouses from the exhaust gas of a biomass heating system can bring benefits for greenhouse production, along with optimal management strategies to reduce fuel consumption. Unfortunately, CO2 enrichment from the exhaust gas of biomass boilers is still challenging and expensive, considering that wood biomass boilers generate a higher volume of particulate matters (PM) and ash emissions than other fossil fuels. However, wet scrubbers and other recent flue gas conditioning devices could help to reduce costs and make this process more feasible. In the Italian peninsula, the power energy load for greenhouses heating was estimated to be between 30 and 175 W m-2, while the thermal energy consumption varies between 21 to 546 kWh m-2 year-1 according with internal air temperature and climatic zones. In general, the total cost of a heating system with boiler, loading system, accumulator, control system and safety, installation, and heat delivering can vary from a maximum of 1400 € kW-1 for systems with power up to 100 kW, 600-800 € kW-1 for power over 100 kW, to a minimum of 400 € kW-1 for systems with power over 1000 kW. Thus, a techno-economic assessment is highly recommended to ascertain the economic feasibility of wood biomass boilers for the greenhouse industry, as related to the economic incentives by the National Decree of 28 December 2012, so-called "White Certifies". © 2017 ISHS
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