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32nd European Photovoltaic Solar Energy Conference and Exhibition; 3070-3072, While in the developed countries the transition from AC to DC systems is a topic related to the introduction of electric vehicles and residential energy storage, in the low-electrified countries this choice is becoming more and more logical and cost-effective for the energy development. Starting from small solar lighting systems, we have already met the target of powering small DC appliances such as TVs, fans, radios and computers with solar energy. Recently the order of magnitude has changed significantly: a few years ago the market of solar lanterns was about 1 Wp, this number grew to 10 Wp with Solar Home systems and now it is nearly 100 Wp with kits provided with additional appliances, in continuous current. Public programs such as Lighting Global or Global Leap are playing an important role for standardization and technical verification of the products. However, today in most of the countries where these applications could bring greater environmental, social and economic benefits, there are many practical barriers, presented in this study, that impede the process of distribution of the products. In this study, based on our direct experience in more than 40 markets in the last three years, we are going to present the most common problems that hinder various stakeholders: end users, manufacturers, importers and distributors. In this field we analyze the role of the NGOs that can be extremely significant or counterproductive, depending on the approach that is being adopted. Simple donation mechanisms are likely to destroy the development of small local businesses that would need to be supported financially instead. Finally, the study will present proposals to make the development of these markets healthier, while maintaining some understandable commercial tools, such as custom duties, which many countries, especially in Africa, cannot do without.

Rapid-response seismic networks are an important element in the response to seismic crises. They temporarily improve the detection performance of permanent monitoring systems during seismic sequences. The improvement in earthquake detection and location capabilities can be important for decision makers to assess the current situation, and can provide invaluable data for scientific studies related to hazard, tectonics and earthquake physics. Aftershocks and the clustering of the locations of seismic events help to characterize the dimensions of the causative fault. Knowing the number, size and timing of the aftershocks or the clustering seismic events can help in the foreseeing of the characteristics of future seismic sequences in the same tectonic environment. Instrumental rapid response requires a high degree of preparedness. A mission in response to a magnitude (Ml) 6 event with a rupture length of a few tens of kilometers might involve the deployment within hours to days of 30-50 seismic stations in the middle of a disaster area of some hundreds of square kilometers, and the installation of an operational center to help in the logistics and communications. When an earthquake strikes in a populated area, which is almost always the case in Italy, driving the relevant seismic response is more difficult. […]

The aim of this work is to analyse the energy contribution of a geothermal heat pump for heating and cooling in a Net Zero Energy Building (NZEB) used as B&B, through a dynamic energy simulation software (DesignBuilder). The case study building is virtually located in two Italian cities with different climatic characteristics. The energy savings related to the use of the geothermal heat pump are evaluated, compared to both an air-to-water heat pump and a condensing boiler coupled to a chiller. In literature there are few comparisons between air-to-water heat pump and geothermal heat pump. The paper evaluates how much this technology is convenient for NZEBs, from an energetic-economic point of view.

During the last decade, in the Mediterranean area, during the warm season, there is an increasing demand of cooling energy in domestic and small commercial sectors, generally satisfied by electrically-driven units. This trend has involved an increase of the power generation capacity of electric utilities and a summer peak load of electric energy consumption with the related problem of electric black-out. This problem has been the driving force to an increasing interest in small scale polygeneration systems fuelled by natural gas, especially in the South of Europe. These energy conversion systems are based on a prime mover that can drive in different ways (mechanically, electrically, thermally) electric generators and/or electric heat pump, absorption heat pumps, desiccant wheels, … allowing a wide range of operating conditions to match thermal (heating and cooling) and electric end-user requirements. In particular, in this paper, attention is paid to the description of a test facility, located in Southern Italy, designed and built to carry out experimental analysis on a small scale polygeneration system based on a natural gas-fired Micro- CHP and a hybrid HVAC (Heating, Ventilation and Air Conditioning) system equipped with a desiccant wheel. The MCHP supplies thermal power, recovered by engine cooling and exhaust gas, to the regeneration of the sorption material of the desiccant wheel and electric power for Air Handling Unit, AHU, self consumptions (fans, pumps, …), to drive the electric chiller and finally for the external units (computers, lights…). The hybrid HVAC system can also operate in traditional way, interacting with separate “production” systems (electric grid and gas-fired boiler). In this paper the first experimental results considering different operating modes are reported.

Net Zero Energy Buildings (NZEBs) play a key role to save energy. However, unpredictable scenarios and uncertainties about stability of energy production from renewables frequently cause measured performance of the building-plants system that differs from predictions. So, it is crucial to individuate the best alternatives in the early-stage design of the building and related energy systems, also considering uncertain circumstances. Hence, the aim of this paper is to enhance reliability of the building design process by providing an innovative workflow based on multi-objective optimization that encompasses robustness assessment of different design alternatives against uncertain scenarios. The standard genetic algorithm optimization routine has been deeply improved to set as a key performance indicator the robustness of energy performance of several building-HVAC system configurations, also considering the financial aspects optimization. Compliance with NZEB target of the obtained optimal solutions is then automatically verified by the algorithm. The new methodology combines open-source coding language Python and the dynamic energy simulation engine EnergyPlus. The robustness of each solution is evaluated through Taguchi method. First obtained results are related to energy-efficient solutions for the building envelope. Regarding the HVAC system, ground source (instead of air source) heat pumps and variable refrigerating flow systems are preferable. Finally, medium–high size of photovoltaic panels is preferred, although with high investment costs.

The theme of the energy requalification of historic buildings is addressed considering the Palaeontology Museum of Naples (Southern Italy). It is assessed whether, through non-invasive methods and without intervening on the building envelope, it is possible to obtain internal hygrothermal parameters suitable to allow both occupants’ thermal comfort and satisfactory conservation conditions for the archaeological finds. In addition, a relevant reduction of energy requirements and CO2 equivalent emissions is required. Dynamic energy simulations are conducted regarding both the current configuration and the various possible modifications concerning the air conditioning system; the model is calibrated by comparison with real energy consumption data. The electric and primary energy are compared for the various cases. Furthermore, the internal hygrothermal conditions for occupants’ thermal comfort and for conservation of the archaeological finds are analysed. Finally, the possibility of inserting a suitable and minimally invasive photovoltaic system is evaluated and an almost ‘Double Plus-Zero Energy Building’ is obtained.

The European Union introduced the concept of “Net Zero Energy Building” (NZEB) to promote competitive, sustainable, eco-friendly, and “decarbonised” cities. To these aims, mainly with reference to highly urbanized places, it is necessary to renovate existing buildings to achieve the NZEB target. Thus, this paper analyses the energy retrofit of an existing building considering two low enthalpy geothermal systems in the HVAC plants: the Ground-to-Air Heat eXchanger (GAHX) and the Ground Source Heat Pump (GSHP). These two plants are used in different retrofit strategies and compared from an energy, environmental and economic point of view. A dynamic simulation software based on EnergyPlus calculation engine is used. The results are very interesting and demonstrate how by using a low enthalpy geothermal plant, a very low value of primary energy requirement can be obtained (about 60 kWh/m2, i.e., −71% compared to the existing building, characterized by a gas boiler). Moreover, substantial savings on annual energy bills and reduction of CO2 emissions are obtained.

Photovoltaic (PV) systems are often used for the attainment of the NZEB (Net Zero Energy Building) target. The lack of sufficient roof area for the plant installation is, however, a common issue that limits the spread of this technology mainly in urban areas characterized by high density of buildings. This work evaluates the possibility of obtaining the NZEB target for residences and offices in Mediterranean area, using only “on site” PV systems, i.e., on the roof slab, considering different typologies of building. An in-depth analysis is provided for obtaining the building geometric parameters that would allow to establish, in the first stages of the design process and avoiding dynamic energy simulations, whether it is possible to achieve energy self-sufficiency for a certain building, taking into consideration the characteristics of the plans and the number of floors. The results show that, for the investigated square-based residential building, the energy self-sufficiency, and therefore the NZEB target, is obtainable up a maximum of 7 levels (6 levels for rectangular shape building, 5 for L and courtyard shapes), while, for another case study building intended for offices, the energy self-sufficiency is obtainable up to a maximum of 7 levels. For early design analyses about geometric characteristics and intended use of new buildings, it would be possible to use the results reported in this study to achieve a first evaluation of NZEB target attainment.

Nowadays, environmental and energy issues attract a lot of attention in the civil buildings sector, leading to the emergence of new technologies and new targets, which include Net Zero Energy Buildings (NZEBs). However, despite the great response in scientific research, the spread of NZEBs in Europe is quite limited. This is due not only to the lack of transposition of the related European Directives into the various national legislations, but also to the high initial cost of such high-performance buildings. The aim of this paper is to demonstrate how different energy retrofit strategies on existing buildings can lead to the achievement of the NZEB target if encouraged by tax incentives, at zero or almost zero cost. The introduction of tax incentives by individual EU member states would allow the spread of NZEBs that are still underdeveloped, especially in highly urbanized contexts. A suitable building energy dynamic simulation software has been used. The case study refers to a villa located in Southern Italy and for which different energy retrofit strategies are proposed to reach the NZEB target. For each case, an energy and economic evaluation is carried out to evaluate the feasibility of the interventions, exploiting the so-called “Super-Eco-Bonus 110%” incentive. The main results highlight that among the various solutions, the greatest energy cost reductions are obtained with the use of heat pump generators. Furthermore, the solution with the biomass boiler allows the use of a smaller number of photovoltaic panels to meet the yearly energy balance of the NZEB.

Earth-to-air (EAHX) and/or air-to-air (AAHX) heat exchangers can be conveniently inserted in heating, ventilation, and air conditioning (HVAC) systems to obtain relevant energy saving. In this article, the subject is analyzed for an office building located in two Italian localities: Milan (Northern Italy, with cold winters and hot summers) and Palermo (Southern Italy, with mild winters and very hot summers). A dynamic building energy performance simulation software is used to simulate a designed office building. The HVAC system is based on fancoils and primary air, with or without EAHX and AAHX. The seasonal analysis shows better energy results for AAHX in winter and EAHX in summer, respectively. The yearly analysis shows that the EAHX is preferable in hot or mild climates. Successively, the EAHX and AAHX are combined: based on the previous seasonal results, the first one is activated in summer, while the second in winter. The combination of the two technologies is preferable for Milan (energy saving up to about 75%) compared to Palermo (saving up to about 60%). Finally, the analyses of the equivalent CO2 emissions and discounted payback are reported.

This paper investigates air-to-air (AAHX) and earth-to-air (EAHX) heat exchangers, to reduce the energy requirements of air conditioning systems for office buildings. The AAHX considered is of static type with a partition wall and allows recovering both sensible and latent heat. The EAHX technology exploits the capability of the ground as energy storage, through a system of earthed air ducts laid horizontally. In summer, the ground usually presents temperatures lower than outside ventilation air temperatures, while in winter it could have, in some hours/days, a temperature higher than the outside air. Three European cities are considered: Palermo (southern Italy), with mild winters and very hot summers; Milan (northern Italy), with cold winters and hot summers; Berlin (Germany), with very cold winters and quite hot summers. The analysis is performed by means of EnergyPlus, a dynamic building energy simulation software, with reference to the same, newly designed office building, with or without heat recovery systems. The air conditioning system is based on fan-coils and primary air, and the EAHX (or the AAHX) is inserted in the first part of the primary air-handling unit. The research shows that in winter the use of the AAHX reduces the energy requirement much more than the EAHX, while in summer the EAHX is preferable. Moreover, the annual analysis shows that the use of the EAHX is more convenient in hot climates. The case of coupled heat exchangers (AAHX + EAHX) is also investigated. The evaluated discounted payback is about 6–9 years for the EAHX (3–5 years if an incentive of 20% is considered) and 1–3 years for the AAHX (less than 1 year with the incentive).

Delaying the analysis of the building performance to the final stages of the design process can often cause the actual results to differ from the expected ones, with the issue of significant redesign costs. The aim of this work is to improve the designer’s control on thermal and geometric variables of the building in the first stages of the design process, to obtain an optimized building from different points of view. An innovative computational performance-driven design optimization workflow is proposed. The integration of a parametric algorithmic modelling tool in a genetic algorithm powered performance optimization procedure allows to minimize energy need and construction cost of the building, and to optimize the natural illumination levels, affecting several geometric variables. This approach is tested on the early design stages for the new construction of an educational building located in the centre of Italy (L’Aquila). The results are post-processed in order to provide an innovative graphical visualization of the outputs to improve the decision-making process. Useful insights on the influence of different design choices on three key performance indicators can be drawn for the case study building, by comparison of the Pareto solutions: optimization results highlight the strongest influence of window-to-wall ratio, among the other variables, on energy need and useful daylight illuminance.

The costs of concentrating photovoltaic (CPV) and concentrating photovoltaic and thermal (CPV/T) systems are highly reduced in the last years because of their increasing diffusion. The unit power cost also depends on the plant size. Hence, the main aim of this paper is to analyze the feasibility of a CPV/T system adopted for users with increasing sizes located in Salerno (Italy): the house, the hotel, and the food industry. An experimental model was developed for an accurate evaluation of the electrical and thermal powers supplied by the CPV/T system when direct normal irradiation (DNI) and environmental temperature vary. A modular configuration of a line-focus CPV/T system was sized to match the electrical and thermal loads of each user. The current economic results, together with a forecast till the year 2025, were discussed. In 2025, for the same CPV system adopted for the domestic user, the net present value (NPVs) are expected to increase by 6.7% and 13% in pessimistic and optimistic scenarios, respectively, with reductions of its discounted payback period (DPBP) of 16% and 30%. For the same CPV systems adopted for the other two users, the NPVs are expected to increase by about 4.2% and 8.4% in pessimistic and optimistic scenarios, respectively, with decreases of its DPBP of 14% and 27%.

Highlights • Earth-to-Air Heat eXchanger uses geothermal energy for air conditioning systems. • A 2D mathematical model of the EAHX is developed to obtain the system performance. • A case study office building is analysed for eight worldwide localities. • Air temperature variation along the EAHX and EAHX efficiency are calculated. • Reduction of thermal capacity of the coils inside air handling unit is evaluated., A great fraction (20–40%) of primary energy is required for building air conditioning, so the use of renewable energy sources is increasing. The geothermal energy for Heating, Ventilating and Air Conditioning (HVAC) systems can be used considering an Earth-to-Air Heat eXchanger (EAHX). This work analyses the performance of an EAHX through a mathematical model (2D), as a function of diameter and length of the air ducts. The problem is solved with finite element method. A case study office building is analyzed. The air conditioning plant is characterized by fan-coil units and primary air; the EAHX is positioned upstream the Air Handling Unit (AHU) to pre-cool/pre-heat the air. The building is virtually placed initially in six Italian cities (different climatic zones according to Italian regulation DPR 412/93) and subsequently in eight worldwide cities according to Köppen climate classification. The following parameters are calculated: air temperature variation and thermal efficiency of the EAHX; the decreasing of cooling and heating capacity of the coils into the AHU. The best results refer to a duct length of 100 m for Ottawa (warm-summer humid continental climate, 65% capacity reduction), the worst ones for Rio de Janeiro (tropical wet and dry climate, maximum 24% reduction).

This paper is focused on the resort to geothermal energy, through the employment of an Earth-to-Air-Heat Exchanger (EAHX) positioned upstream of the air-handling unit of an air conditioning system, for an office building in Naples (South Italy). The aim is to evaluate the energy performances of this unusual system compared to the common solution of external air directly entering the air-handling unit. The EAHX is extensively designed and two-dimensionally modeled, and the analysis is solved with finite element method. The model is validated with experimental data and this comparison shows good agreement. With the requirement of providing the building with 1300 m3 h−1 of external airflow, different design solutions for the EAHX are studied, by varying the diameter (in the range 0.2–0.5 m) and length (between 20 and 140 m) of the buried pipes. The results indicate that: smaller tube diameters enhance the heat transfer; a tube length between 80 and 100 m is recommended. Using the EAHX, the reduction of the thermal power of the coils in the air-handling unit is greater than 40% in most cases. Finally, the efficiency of the EAHX is assessed as a function of the tube length and diameter, reaching values up to 0.9.

In this paper the energy performances carried out by an investigation conducted on a Heating, Ventilation and Air Conditioning (HVAC) system, composed by an Air Handling Unit (AHU) for the primary air coupled with a horizontal-pipes Ground-to-Air Heat eXchanger (GAHX) and fan-coil units, for an office building, supposed to be placed in four different cities (Rio de Janeiro, Dubai, Naples, Ottawa) belonging to four different worldwide climatic areas, according to the K&ouml, ppen climate classification. The investigation is performed by means of a two dimensional numerical model, experimentally validated, of an GAHX solved with finite element method. The results introduced in this paper are carried out by varying the length of the pipes and the air flow velocity, thus, also the number of tubes forming the GAHX is varied since the volumetric flow rate to be provided to the AHU must be kept constant. The energy performances of the above-mentioned HVAC system are analyzed, both in summer and in winter operation modes. Specifically, the reduction of the power of the heating and cooling coils in the AHU due to the pre-treatment of the air operated by the GAHX, the efficiency of the GAHX and the inlet-outlet temperature span are evaluated through a sensitivity analysis. These results lead to say that an GAHX for the geothermal pre-treatment of the air to be introduced into the AHU is energetically very convenient since it leads total thermal power savings in all the investigated cities, that makes this solution competitive. Specifically the best value of power reduction (61.5%) for a 100 m pipe-length GAHX is obtained in Ottawa, a city belonging to continental climate zone. The worst results in terms of power reduction are registered in Rio de Janeiro, a city belonging to the tropical or equatorial climates: this reduction, for a 100 m pipe-length ground to air heat exchanger, is 23.9%.

The increasing energy demand encourages the use of photovoltaic solar systems coupled to organic rankine cycle (ORC) systems. This paper presents a model of an ORC system coupled with a concentrating photovoltaic and thermal (CPV/T) system. The CPV/T-ORC combined system, described and modeled in this paper, is sized to match the electrical load of a medium industrial user located in the South of Italy. A line-focus configuration of the CPV/T system, constituted by 16 modules with 500 triple-junction cells, is adopted. Different simulations have been realized evaluating also the direct normal irradiance (DNI) by means of the artificial neural network (ANN) and considering three input condition scenarios: Summer, winter, and middle season. Hence, the energy performances of the CPV/T-ORC system have been determined to evaluate if this integrated system can satisfy the industrial user energy loads. In particular, the peak power considered for the industrial machines is about 42 kW while other electrical, heating or cooling loads require a total peak power of 15 kW; a total electric average production of 7500 kWh/month is required. The annual analysis shows that the CPV/T-ORC system allows satisfying 100% of the electric loads from April to September; moreover, in these months the overproduction can be sold to the network or stored for a future use. The covering rates of the electrical loads are equal to 73%, 77%, and 83%, respectively for January, February, and March and 86%, 93%, and 100%, respectively for October, November, and December. Finally, the CPV/T-ORC combined system represents an ideal solution for an industrial user from the energy point of view.

A passive strategy to reduce the energy consumption of existing buildings is to improve the thermal insulation of the opaque building envelope and insert windows with low thermal transmittance U. But what is the best compromise between cost of intervention and reduction of primary energy? The aim of this paper is to answer this question using the innovative cost-optimal methodology and a dynamic energy simulation software. The case study refers to an existing school in central Italy. Eight passive strategies are analysed, combining different insulation thicknesses and types of windows. Furthermore, a comparison between cost-optimal methodology and discounted payback analysis is reported. Finally, a sensitivity analysis on parameters influencing the cost-optimal method is conducted. The lowest primary energy is obtained considering an insulation thickness of 12 cm and windows with U of 1.10 W/m2 K, while the best case using the cost-optimal methodology refers to a low increase in insulation thickness.

This paper investigates the best strategies to reduce the energy requirements of air conditioning systems for office buildings by using two different types of technology: Air-to-Air (AAHX) and/or Earth-to-Air (EAHX) heat exchangers. The AAHX considered is a static type of heat recovery with partition wall, which allows recovering both sensible and latent heat by means of convection and conduction mechanisms via partition wall. Referring to EAHX, this technology exploits the capability of the ground as energy storage, through a system of earthed air ducts laid horizontally. In summer, the ground usually presents temperatures lower than outside ventilation air temperatures, while in winter it could have, in some hours/days, a temperature higher than the outside air. In the examined case, the air conditioning system is based on fan-coils and primary air, and the EAHX (or the AAHX) is installed upstream of the primary air-handling unit. The performance of the two examined technologies are analysed for three European cities with different climates: Palermo (Southern Italy), with mild winters and very hot summers; Milan (Northern Italy), with cold winters and hot summers; Berlin (Germany), with very cold winters and quite hot summers. The analysis is performed by means of EnergyPlus, a dynamic building energy simulation software, with reference to the same designed new office building with or without heat recovery systems. The research shows that, for all the analysed climates, in winter the use of the AAHX reduces the energy requirement much more than the EAHX, while in summer the EAHX is preferable. Moreover, the annual analysis shows that the use of the EAHX is more convenient in hot climates. The case of coupled heat exchangers (AAHX+EAHX) is also investigated. A further analysis is performed on the benefits that the two analysed technologies allow in different seasons.

Energy consumption for heating and cooling of Italian office buildings is growing. In particular, there is an increase in the demand for electricity for cooling in the summer. Thermal insulation on the external side of the buildings is a very usual strategy to reduce energy demand for air-conditioning systems. However, a too high thickness of insulating material, even if complying with current legislative requirements, can be disadvantageous in buildings characterized by great internal thermal loads and/or located in climatic contexts with mild winters and hot summers. In this paper, the energetic and economic influence of external thermal insulation is evaluated by using energy simulations under dynamic conditions (DesignBuilder software) for a case study. The analysis is performed for various cities (Palermo, Milan and Cairo) and for different values (10, 20, 30 W/m2) of internal thermal loads. According to the recent and innovative “cost-optimal” methodology, optimal insulation thicknesses are derived, and the results demonstrate the need to avoid excessive insulation of buildings to obtain the highest energy saving. Finally, an integration of the “cost-optimal” methodology is proposed considering also the topic of thermal comfort; this modification allows to obtain other optimal solutions compared to the basic calculation procedure.