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Densely built areas are affected by higher air-pollutant concentrations, representing a significant risk to public health. At the same time, urban settlements have a remarkable environmental impact: cities are responsible for 70% of annual carbon emissions while buildings account for 37% of global energy and process emissions. Moreover, people living in urban areas are frequently exposed to extreme micro-climate conditions caused by the urban heat island effect, related to increased external air temperature and peculiarities of the built environment. Given this framework and considering the Sustainable Development Goals, it is necessary to point out some effective and strategical mitigation measures to ameliorate micro-climate conditions, reduce pollutants concentration and enhance building performance. This paper investigates the potential advantages of green roofs as retrofitting solutions and tree planting on several micro-climate parameters and particulate matter concentration, considering an industrial district located in Italy and using ENVI-met software. The influence of the extensive green roof on energy performance is further investigated at the building level recurring to Design Builder energy models. Results showed that an extensive green roof could reduce external air temperature by up to 1.5 °C, outer surface temperature by up to 15 °C and wind speed by 50% at roof level compared to current state conditions. The application of the green roof let also to achieve energy savings of 15% for both the summer and winter seasons. Focusing on the effect on particulate matter, intensive green roof solutions proved to be more efficient in capturing air pollutants. • Green roofs' impact on UHI and air pollutants is assessed at the district level. • Extensive green roof is an effective retrofitting measure for industrial buildings. • Tree planting mainly affects micro-climate parameters at a local level. • Outdoor air temperature is reduced by 1.5 °C following green roof adoption. • Heating and cooling energy demand in a manufacturing facility is lowered by 15%. [ABSTRACT FROM AUTHOR]

In recent years, Distributed Energy Systems (DESs) have been recognized as a good option for sustainable development of future energy systems. With growing environmental concerns, design optimization of DESs through economic assessments only is not sufficient. To achieve long-run sustainability of energy supply, the key idea of this paper is to investigate exergy assessments in DES design optimization to attain rational use of energy resources while considering energy qualities of supply and demand. By using low-temperature sources for low-quality thermal demand, the waste of high-quality energy can be reduced, and the overall exergy efficiency can be increased. Based on a pre-established superstructure, the aim is to determine numbers and sizes of energy devices in the DES and the corresponding operation strategies. A multi-objective linear problem is formulated to reduce the total annual cost and increase the overall exergy efficiency. The Pareto frontier is found to provide different design options for planners based on economic and sustainability priorities, through minimizing a weighted-sum of the total annual cost and primary exergy input, by using branch-and-cut. Numerical results demonstrate that different optimized DES configurations can be found according to the two objectives. Moreover, results also show that the total annual cost and primary exergy input are reduced by 20% - 30% as compared with conventional energy supply systems. [ABSTRACT FROM AUTHOR]

Solar thermal collectors represent one of the most widely used technologies for heat production from renewable energy sources. To increase efficiency and to not increase too much cost different type of solar collectors, and in particular of evacuated tube collectors have been realized. In order to compare performance, tests at different conditions and in different configurations have to be performed. The aim of this paper is to establish the performance of a new prototype via an experimental evaluation of the performance in different conditions and configurations of three collectors. The prototype is particular owing to his new head configuration that permits an innovative parallel configuration way. Therefore, parallel and series configurations have been analyzed applying the UNI-EN 12975, in a steady-state regime. The efficiencies of the two configurations have been tested for different flow rates and different inflow water temperatures. The experimental results show that, with the same input flow rate to the single collector, the parallel configuration has higher performance than the series one, reaching 15% higher level of efficiency. Thus, it seems that these prototypes in optimized configuration can lead to a systems improvement, thereby increasing the overall energy production or giving the same energy production with smaller collector area. [ABSTRACT FROM AUTHOR]

Solar thermal collectors represent one of the most widely used technologies for heat production from renewable energy sources. To increase efficiency and to not increase too much cost different type of solar collectors, and in particular of evacuated tube collectors have been realized. In order to compare performance, tests at different conditions and in different configurations have to be performed. The aim of this paper is to establish the performance of a new prototype via an experimental evaluation of the performance in different conditions and configurations of three collectors. The prototype is particular owing to his new head configuration that permits an innovative parallel configuration way. Therefore, parallel and series configurations have been analyzed applying the UNI-EN 12975, in a steady-state regime. The efficiencies of the two configurations have been tested for different flow rates and different inflow water temperatures. The experimental results show that, with the same input flow rate to the single collector, the parallel configuration has higher performance than the series one, reaching 15% higher level of efficiency. Thus, it seems that these prototypes in optimized configuration can lead to a systems improvement, thereby increasing the overall energy production or giving the same energy production with smaller collector area. [ABSTRACT FROM AUTHOR]

Abstract: The indoor climate control of buildings represents today the highest percentage of energy consumption in European Union. Hence the evaluation of the best performing HVAC system is a strategic target for both energy consumption and greenhouse gas emissions reduction. This paper presents a deep analysis of the performance of Renewable Energy Sources HVAC systems for buildings. The technologies considered are biomass boiler, aerothermal, geothermal and absorption heat pumps. The proposed method estimates all the parameters according to the theory of the “big is better”. For each parameter a function has been defined to evaluate how much the performance of each technology depends from it. The analysis take in account also the environment in which each technology operates. The result is a set of dimensionless parameters, through which it is possible to extrapolate the assessments of performance. It can include both cost-effectiveness and feasibility of a given technology and the contribution to the achievement of European objectives to 2020. [Copyright &y& Elsevier]

Abstract: With reference to a steel beam located at the ceiling of a small room irradiated by a burner located on the floor, that is the fire source, the Adiabatic Surface Temperature (AST) has been evaluated. Surface temperatures of the beam and the heat fluxes released to it (conjugate case) are then compared to those in a single beam with the AST as boundary condition (standalone case). Results show that, by assuming AST as the exchange parameter between fire and structural models, differences between conjugate and standalone case are strongly dependent on the convection coefficient assumed in the latter one. [Copyright &y& Elsevier]

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