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The increasing attention paid to climate change has boosted scientific research in the matter of energy refurbishment of existing public buildings. However, the design of the intervention must be integrated with structural upgrading when the constructions are located in seismic zones. Indeed, in Italy, as in other seismically active countries, the structural damage, observed after earthquakes, underlines the increase in economic losses for buildings retrofitted only for energy saving. In this framework, the paper introduces an integrated approach for selecting retrofit actions aimed at improving both the seismic and energy performance, starting from a detailed in situ analysis with which dynamic energy and structural simulation models are constructed. The case study is an auditorium erected in 1982 with a reinforced concrete structure inside a masonry ring wall of an ancient building. A step-by-step analysis of each component role in the structural and energy performance of the building is proposed. The results indicate that the proposed approach can help to determine the best technical solution, and the integrated design leads to saving 10% of the cost of the works.

The reduction of buildings energy demand represents one of the main goals in developed countries in order to achieve a sustainable future. In Italy a significant number of public administration offices are located in historical buildings, especially in small provincial towns. In this paper the analysis of the energy and environmental effects deriving from the plant renovation of the Palazzo San Giorgio, the building offices of the municipality of Campobasso (Southern Italy), is carried out. The simulation model of the building-plant system has been implemented with the TRNSYS software using data collected in the survey campaign. It has been calibrated on the basis of the billed electricity and gas consumption and then, further used to evaluate the reduction of the building primary energy demands and CO2 emissions deriving from some non-invasive energy refurbishment measures: led lighting, thermostatic valves, cogeneration system and photovoltaic plant. The latter was considered in two variants: the first one provides a system completely integrated into the roof, the second one high efficiency non-integrated panels. The interventions have been evaluated both individually and combined. A primary energy saving of about 47% and a reduction in CO2 emissions of 73% are obtained with the best combined renovation action.

In this paper two solar electric-driven air conditioning systems are compared and analyzed from an energy and environmental point of view. Both systems satisfy the electricity, space heating and cooling needs of an existing multi-purpose, multi-story building that is simulated with TRNSYS 17. The first one, considered as reference system, is based on a centralized electric heat pump coupled with a conventional photovoltaic plant installed 10 years ago. The second one, hereinafter proposed system, has a hybrid configuration, consisting of a ground-source heat pump, a low temperature thermal network and a series of electric heat pumps, one per apartment. In addition, the plant is connected to a high-performance commercial photovoltaic system equipped with a solar tracking system to the panels. Five different solutions realized with vertical, two horizontal orientations, polar and two-axis trackers are taken into account and compared with the standard fixed configuration. The last hybrid configuration can be seen as an upgrade of an existing decentralized air conditioning system in which the local electric heat pumps are converted in water-to-water devices that interact with the thermal grid representing the heat source/sink for them. In both solar electric heating and cooling plants the photovoltaic system is installed on the building roof and it produces electricity to feed the heat pumps and end-users. The electricity surplus or the load not covered by solar field is fed to/taken from power grid. The energy and environmental analyses have been performed by considering both average annual and monthly values of power grid efficiency and CO2 emission factor for electricity. By comparing reference system and proposed one equipped with a two-axis tracker system a primary fossil energy saving of 101.67% is achieved in summer period and 28.10% in winter period. These percentages are the highest values recorded, even if, for all configurations the energy analysis rewards the proposed system. The results of environmental analysis demonstrate that the reference system has the worst performances compared to proposed system with all solar tracker systems selected guarantying positive values for avoided carbon dioxide index up to 45.86%.

Electric air-conditioning systems driven by electricity from a wind turbine can be defined as wind electric and cooling systems according to the definition of solar-activated air-conditioners. They can potentially contribute to reduce primary energy demand and CO2 emission in the civil sector. In this paper, mini wind turbines are considered coupled with a ground source heat pump in order to serve an office building for air-conditioning and supply the electricity surplus for the pure electric load of the user. Different plant configurations are considered. First of all, assessments with two kinds of wind turbines (5&ndash, 5.5 kW), vertical and horizontal axis, are performed, also considering the coupling with one and two identical wind generators. Secondly, to better use on-site electricity, a parametric study is proposed taking into account different battery storage system sizes (3.2&ndash, 9.6 kWh). Finally, the plant is simulated in two locations: Naples and Cagliari. Simulation results demonstrate that the source availability mainly affects the system performance. In Cagliari, the primary energy reduction per kWh of final energy demand (for pure electric load, space heating, and cooling) is equal to 1.24, 54.8% more than in Naples. In addition, the storage system limits the interaction with the power grid, lowering the exported electricity from about 50% to about 27% for Naples and from 63% to 50% for Cagliari. The fraction of the load met by renewable energy accounts for up to 25% for Naples and 48% for Cagliari.

The dairy cattle sector is responsible of significant greenhouse gas emissions such as methane, carbon dioxide, nitrous oxide. The reduction of heat stress of dairy cows plays a crucial role in the improvement of dairy productivity and avoid greenhouse emissions. In this study a parametric analysis about several traditional or innovative passive solutions for building envelope of livestock housing is carried out, with the aim to achieve the thermal comfort of animals without active energy systems. The different energy efficiency measures designed for the building envelope are evaluated on the basis of different indexes for animal comfort, by means of the combination of the Building Energy Performance Simulations (BEPS) and computational fluid dynamics (CFD) simulations. The proposed method starts from the numerical model definition of a semi-closed, naturally ventilated, loose housing system, characterized by criteria traditionally recognized or accepted by the scientific community for designing a dairy cow housing. Different interventions, referred to the shape of the building and its envelope materials, are taken into account, such as cool materials or cross laminated timber, as well as polyurethane insulation or shading systems. Basing on the both temperature-humidity index (THI) and black globe temperature humidity index (BGHI) the optimal building envelope solutions are: opening ridge area with 1.8 m width, window to wall ratio equal to 79%, roof made by polyurethane foam with a slope of 15°. The environmental indexes calculated by means of BEPS numerical models simpler than CFD analysis bring a difference in results by a maximum of 18%. The results can support the decision-making process in the design of a sustainable barn for dairy cows taking animals welfare as reference. Moreover, the methodological approach could be easily replicated for other livestock type or other climatic zones.

The energy demand for the air-conditioning of buildings has shown a very significant growth trend in the last two decades. In this paper three alternative hygroscopic materials for desiccant wheels are compared considering the operation of the air handling unit they are installed in. The analyses are performed by means of the TRNSYS 17&reg, software, simulating the plant with the desiccant wheel made of: silica-gel, i.e., the filling actually used in the experimental plant desiccant wheel of the University of Sannio Laboratory, MIL101@GO-6 (MILGO), a composite material, consisting of graphite oxide dispersed in a MIL101 metal organic framework structure, Campanian Ignimbrite, a naturally occurring tuff, rich in phillipsite and chabazite zeolites, widespread in the Campania region, in Southern Italy. The air-conditioning system analyzed serves a university classroom located in Benevento, and it is activated by the thermal energy of a solar field for which three surfaces are considered: about 20, 27 and 34 m2. The results demonstrate that a primary energy saving of about 20%, 29%, 15% can be reached with silica-gel, MILGO and zeolite-rich tuff desiccant wheel based air handling units, respectively.

Solar-driven air-conditioning systems are an interesting solution to reduce greenhouse gas emissions as they are essentially powered with a renewable energy source. Among the solar heating and cooling systems, desiccant-based air handling units (AHUs) are a very promising alternative as they require low temperature thermal energy for operation in cooling mode. In this paper the experimental plant of University of Sannio (Benevento, Southern Italy), consisting of an AHU with a desiccant wheel using as hygroscopic material silica gel is coupled with solar thermal collectors. This AHU has been also simulated with a different material for the desiccant wheel, the MIL101@GO-6 (MILGO). It is a composite material, consisting of graphite oxide dispersed in the MIL101 metal organic framework network structure, that shows a better dehumidification effectiveness. The energy and environmental performance of a desiccant-based solar heating and cooling system with this new material have been evaluated with respect to the conventional AHU based on cooling dehumidification. Yearly based dynamic simulations of the plant serving a university classroom located in Benevento have been performed. Furthermore, a comparison with the air-conditioning system equipped the currently adopted material (silica gel) has been carried out too. The optimal plant configuration varying collector type (flat plate and evacuated tube), tilt angle and surface has been found.

A renewable-based system able to meet pure electric, space heating and cooling loads of a small office building located in Southern Italy is evaluated here. The proposed energy conversion system is based on a photovoltaic plant, an electric-driven heat pump and electrical energy storage. Energy and environmental performance of this system has been evaluated by means of a dynamic simulation software changing photovoltaic nominal power (4.5-7.5 kW), battery capacity (3.2-9.6 kWh), and reference electrical system. The aim of the paper is the energy and environmental comparison on monthly, as well as, on yearly basis between the proposed system and the reference conventional system. The conventional system is based on the power grid, a natural gas fired boiler and an electric-driven chiller. The analysis here reported shows how monthly variation of electric reference system, due to different monthly Italian electricity mix production, influences the energy and environmental performance of the solar-based system. The proposed system guarantees high primary energy saving and equivalent carbon dioxide emissions reduction up to about 93%.

The paper examines a solar electric driven heat pump serving an office building located in southern Italy. To satisfy space heating and cooling demand a heat pump activated by electric energy available from solar photovoltaic plant is here considered. In order to improve the self-consumption of electricity available from photovoltaic system different configurations were considered introducing an electric storage and an electric vehicle. Dynamic simulations to evaluate energy performance of the system varying photovoltaic peak power (4.5–7.5 kW) have been carried out. The proposed system achieves a fossil fuel primary energy saving up to about 96% in comparison to the reference conventional system based on a natural gas fired boiler, an electric chiller and the national electric grid. The results show that fossil fuel primary energy saving is higher when there are no storage battery and electric vehicle.

In this paper, three alternative layouts (scenarios) of an innovative solar-assisted hybrid desiccant-based air handling unit (AHU) are investigated through dynamic simulations. Performance is evaluated with respect to a reference system and compared to those of the innovative plant without modifications. For each scenario, different collector types, surfaces and tilt angles are considered. The effect of the solar thermal energy surplus exploitation for other low-temperature uses is also investigated. The first alternative scenario consists of the recovery of the heat rejected by the condenser of the chiller to pre-heat the regeneration air. The second scenario considers the pre-heating of regeneration air with the warmer regeneration air exiting the desiccant wheel (DW). The last scenario provides pre-cooling of the process air before entering the DW. Results reveal that the plants with evacuated solar collectors (SC) can ensure primary energy savings (15%–24%) and avoid equivalent CO2 emissions (14%–22%), about 10 percentage points more than those with flat-plate collectors, when the solar thermal energy is used only for air conditioning and the collectors have the best tilt angle. If all of the solar thermal energy is considered, the best results with evacuated tube collectors are approximately 73% in terms of primary energy saving, 71% in terms of avoided equivalent CO2 emissions and a payback period of six years.

A hybrid solar-assisted trigeneration system is analyzed in this paper. The system is composed of a 20 m2 solar field of evacuated tube collectors, a natural gas fired micro combined heat and power system delivering 12.5 kW of thermal power, an absorption heat pump (AHP) with a nominal cooling power of 17.6 kW, two storage tanks (hot and cold) and an electric auxiliary heater (AH). The plant satisfies the energy demand of an office building located in Naples (Southern Italy). The electric energy of the cogenerator is used to meet the load and auxiliaries electric demand; the interactions with the grid are considered in cases of excess or over requests. This hybrid solution is interesting for buildings located in cities or historical centers with limited usable roof surface to install a conventional solar heating and cooling (SHC) system able to achieve high solar fraction (SF). The results of dynamic simulation show that a tilt angle of 30° maximizes the SF of the system on annual basis achieving about 53.5%. The influence on the performance of proposed system of the hot water storage tank (HST) characteristics (volume, insulation) is also studied. It is highlighted that the SF improves when better insulated and bigger HSTs are considered. A maximum SF of about 58.2% is obtained with a 2000 L storage, whereas the lower thermal losses take place with a better insulated 1000 L tank.

Desiccant-based air handling units can achieve reductions in greenhouse gas emissions and energy savings with respect to conventional air conditioning systems. Benefits are maximized when they interact with renewable energy technologies, such as solar collectors. In this work, experimental tests and data derived from scientific and technical literature are used to implement a model of a solar desiccant cooling system, considering three different collector technologies (air, flat-plate and evacuated collectors). Simulations were then performed to compare the energy, environmental and economic performance of the system with those of a desiccant-based unit where regeneration thermal energy is supplied by a natural gas boiler, and with those of a conventional air-handling unit. The only solution that allows achieving the economic feasibility of the solar desiccant cooling unit consists of 16 m 2 of evacuated solar collectors. This is able to obtain, with respect to the reference system, a reduction of primary energy consumption and of the equivalent CO 2 emissions of 50.2% and 49.8%, respectively, but with a payback time of 20 years.

Desiccant-based air handling units allow significant reductions in greenhouse gas emissions and energy savings with respect to conventional air conditioning systems. Benefits are maximized when they interact with renewable energy technologies, such as solar collectors. Due to the high requirements of humidifiers, water consumption is a major issue for desiccant cooling technology. Therefore, a water consumption analysis should be also performed.In this work, experimental tests and data derived from scientific and technical literature are used to implement a model of a solar desiccant cooling system, considering three different solar caption technologies (air, flat plate and evacuated collectors). Simulations were then performed to compare the energy, environmental and economic performance and water consumption of the system with those of a desiccant-based unit in which regeneration thermal energy is supplied by a natural gas boiler, and with a conventional air handling device. A trade-off solution is chosen, consisting of 16 m2 of flat-plate solar collectors. This solution allows to obtain, with respect to the reference system, a reduction of primary energy consumption and of the equivalent CO2 emissions of 24.2% and 27.1%, respectively, with an acceptable pay-back time of 4.81 years, and a water consumption very similar to that of the reference system.

A new concept system is presented for the combined production of heat and electric power. Two renewable energy sources are used, i.e., direct solar (thermodynamic solar) and biomass (indirect solar energy). Biomass combustion is conducted using a fluidized bed combustor. A second source of energy, given by the direct irradiation of the bed with a concentrated solar radiation, is integrated in the same system. A Scheffler mirror is planned to carry out sunlight irradiation of the fluidized bed in a fixed focal point. A Stirling engine, integrated in the fluidized bed, converts heat into electricity. A working prototype, referred to as MEGARIS, has been developed very recently and is presently under test. The proposed paper is mainly devoted to automatic control and load regulation of the MEGARIS prototype. A simple dynamic mathematical model has been developed for the fluidized bed acting at the same time as solid biomass combustor, solar light receiver and heat exchanger toward the Stirling engine. For control and regulation purposes, the bed temperature has been taken as the controlled variable; the process variables acting as disturbances have been identified, e.g., the sunlight power; the main manipulated variable has been considered the solid biomass feed rate; the system parameters that are subject to uncertainty have been identified, e.g., the power dissipated through insulation. The control and regulation strategy relies on a feedback architecture. Different theoretical approaches and sophistication levels have been proposed and tested for the loop controller, i.e., PID, Fuzzy Logic and predicting model-based. Both the dynamic model and the controller algorithms have been developed in Matlab scripts and implemented in Simulink codes. A systematic simulation has been carried out for both the open loop and closed loop system responses to those changes that are realistically expected in the main process variables or in uncertain parameters. In parallel, the dynamical analysis of the mathematical model of the prototype has been carried out with Matcont. The results obtained so far are very encouraging to achieve flexibility and controllability of the MEGARIS prototype.