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Ensuring optimum interior lighting is a topic of great importance, as this influences not only the well-being of users but also the optimal performance of visual tasks. Lighting can be natural, but if not sufficient, it can be compensated with artificial lighting. This study highlights a methodology for designing a new lighting system that takes into account both technical and economic aspects. The method was applied to an existing school located in southern Italy, in which the electricity consumption is related to the current lighting system. The school is chosen as being representative of the construction type and layout of many local schools. In addition, the coexistence of several visual tasks with different design requisites (e.g., illuminance levels) makes the school a very complex environment. The school lighting is modelled in Google SketchUp and imported into Daysim to simulate the yearly and hourly daylight indoor contribution. Dialux Evo has been used to simulate and design artificial lighting. The results show a reduction of energy consumption of 33% with the simple replacement of fluorescent luminaires with LEDs, while the LED lamp dimming and modulation for rows of luminaires leads to a 95% reduction in energy consumption compared with the current state.

Rising damp is considered one of the most widespread and damaging deterioration processes in buildings, architectural and cultural heritage. A widespread lack of knowledge of this phenomenon has often led to inadequate corrective measures with the consequent accelerated masonry deterioration. This work focuses on the dynamic evaluation of rising damp in two typical and widely used building stones in Southern Italy (Salento peninsula): Lecce Stone and Carparo. Under controlled and monitored microclimatic conditions, an experimental campaign has been carried out in laboratory, starting from two dry monolithic blocks. The blocks were periodically wetted, weighed and the height of rising damp measured in the tested materials. At the end of the campaign, the rising damp behaviour has been derived using the well-known mathematical model of Christopher Hall and William D. Hoff. Finally, the theoretical model was adapted to the case study, modifying the model constants based on the collected experimental data. The results were analysed, and the study showed a good agreement between the numerical and experimental data in both tested materials.

Greenhouse crops represent a significant productive sector of the agricultural system, one of the main problems to be addressed is indoor air conditioning to ensure thermal well-being of crops. This study focuses on the ventilation analysis of solar greenhouse with symmetrical flat pitched roof and single span located in a warm temperate climate. This work proposes the dynamic analysis of the greenhouse modeled in TRNsys, simultaneously considering different thermal phenomena three-dimensional (3D) shortwave and longwave radiative exchange, airflow exchanges, presence of lamps with their exact 3D position, ground and plant evapotranspiration, and convective heat transfer coefficients. Several air conditioning systems were analyzed, automatic window opening, controlled mechanical ventilation systems (CMV) and horizontal Earth-to-Air Heat Exchanger (EAHX) coupled with CMV, for different air volume changes per hour. In summer, the exploitation of the ground allows having excellent results with the EAHX system, reducing the temperature peaks of up to 5 &deg, C compared to the use of CMV. In winter, it is interesting to note that, although the EAHX is not the solution that raises the temperature the most during the day, its use allows flattening the thermal wave more. In fact, the trend is almost constant during the day, raising the temperature during the first and last hours of the day.

The European Energy Performance of Buildings Directive (EPBD) recast proposes, a comparative methodology to calculate cost-optimal levels of minimum energy performance requirements for buildings. This paper presents a method able to select the best retrofit action for lighting system, selectively analysing the daylight conditions and applying the cost-optimal methodology for different scenarios proposed for two existing educational buildings located in Italy. With the aim to improve both energy efficient and visual comfort conditions, the retrofit scenarios include lighting solutions with different combinations. They consider the replacement of lamps with more efficient lighting sources and the application of lighting control.

This paper investigates the performance of a 960 kWP photovoltaic (PV) system, located in southern Italy. Monitoring data over a 43 months period are used to evaluate the monthly average of energy yields, losses and efficiency. The performance ratio and the capacity factor were 84.4% and 15.6%, respectively. The yearly average module efficiency was 15.3% and the system efficiency was 14.9%, whereas the capture and system losses were 0.6 h/day and 0.1 h/day respectively. The degradation rate of the PV system, after continuous outdoor exposure, has been estimated at about 1.48%/year by applying the Classical Seasonal Decomposition (CSD) method. A comparison in terms of degradation rate is made with other PV plants installed in different climates to address the need of standard methods to determine this crucial parameter. The actual performance of the studied PV system is compared with the expected outcomes by using two widely used PV simulation tools, SAM and PVsyst. A detailed difference analysis is carried out to evaluate the accuracy of the SAM and PVsyst models. Results show that the yearly average energy injected into the grid was under-estimated by 3.0% by SAM and by 3.3% by PVsyst, but overall PVsyst outperforms the SAM tool. Results provide reliable data on the plant and demonstrate its good performance compared to other plants located in the same climate. The results can be used to improve the prediction of the performance of future PV of systems in the Mediterranean climate, and also provide a useful dataset for comparative studies.

There is not a real “storage market” and the range of technical solutions for electrical storage appears to be underdeveloped. The use of electrochemical batteries seems to be the easiest and cheapest way, but some problems related to disposal, average life span and storage capacity, still put a brake on their diffusion. The micro CAES-TES (Compressed Air Energy Storage – Thermal Energy Storage) systems with small renewable energy plants for cogeneration and trigeneration represent an important development perspective thank to the reuse of the heat generated at the stage of air compression (for heating) and air expansion (for cooling). This improves the complexity of the entire system because of the heat exchange and thermal storage units must match the capacities and performances of the air compression/expansion units. The paper presents a new mathematical model for micro CAES-TES systems, implemented in Matlab software environment. The novelty is the use of air compressed energy storage in small and residential applications, a trigeneration due to reuse of heat from air compression and expansion stage, only renewable energy used. By keeping the initial investment low, the analysis is extended to the optimal system configuration and identifies key parameters that have a dominant influence on improving system efficiency and provides useful guidance for CAES-TES system design. The results show that, for an air storage volume of 4 m3, the optimal configuration is with a compression ratio of 15 splitted in two stages, charging time 5 h, mechanical storage efficiency 48%, compression air flow rate 3.73 kg/hour. The proposed system has a possible future development overall if combined with new possible scenarios of direct use of compressed air in the residential sector.

This work proposes a new device for air treatment with dehumidification and water recovery/storage, with possible mitigation of indoor environmental conditions. The system is based on Peltier cells coupled with a horizontal earth-to-air heat exchanger, it is proposed as an easy-to-implement alternative to the heat pumps and air handling units currently used on the market, in terms of cost, ease of installation, and maintenance. The process provides the water collection from the cooling of warm-humid air through a process that leads to condensation and water vapor separation. The airflow generated by a fan splits into two dual flows that lap the two surfaces of the Peltier cells, one flow laps the cold surfaces undergoing sensible, latent cooling with dehumidification; the other flow laps the hot surfaces and heats up. The airflow undergoes thermal pre-treatment through the underground horizontal geothermal pipe that precedes the Peltier cells. In the water storage tank, which also works as a mixing chamber, the two air streams are mixed to regulate the outlet temperature. The system can be stand-alone if equipped with a photovoltaic panel and a micro wind turbine, able to be used in places where electricity is absent. The system, with different configurations, is modeled in the African city Kigali, in Rwanda.

Geothermal energy has a huge potential in building applications. This paper proposes the use of an Air-Source Heat Pump (ASHP) system coupled with a Horizontal Earth-To-Air Heat Exchanger (EAHX) to reduce energy consumption in buildings. The novelty is to geothermally pre-heat or pre-cool the air source of the ASHP through the EAHX, reducing the electric power needed, keeping constant heating/cooling capacity. The behaviour of ASHP-EAHX system has been investigated by a numerical model implemented in TRNSYS. A total of 54 combinations have been obtained and tested varying ground thermal properties, burial depth, air flow rate and pipe length. The model has been validated with a real case showing a good agreement between simulated and monitored data. The study is focused on the city of Turin (North of Italy), compared with Brindisi (South of Italy), and extremely cold and hot climates like Tromso (Norway) and Bechar (Algeria), respectively. The ASHP-EAXH performance has been investigated, by the comparison with the traditional ASHP, using different coefficients, such as the Coefficient of Performance (COP), the Energy Efficiency Ratio (EER), the Seasonal Coefficient of Performance (SCOP), and the Seasonal Energy Efficiency Ratio (SEER). The paper reveals how the ASHP-EAHX system show higher performance compared to the traditional ASHP, in all seasons. The overall merit is, for cold extremely climate, the reduction of the shutdown periods, when the outside temperature is below the limit operating temperature, and to allow the extension of the use of the heat pump to locations, where it is currently not convenient for the average outside temperature lower than the limit operating temperature of the heat pump.

A light pipe is an excellent solution to transport and distribute daylight into environments without or with little lighting, guaranteeing comfort inside the rooms. As stated in the literature, the evaluation of the performances of light pipes presents numerous complexities, making the work very difficult for technicians and designers. This study is aimed to present a methodology that is able to identify the potential of light pipes using indices such as daylight autonomy (DA), continuous daylight autonomy (DAc), and useful daylight illuminance (UDI). This paper presents an analysis of daylight obtained by several configurations of simple models of light pipes installed into a 5 &times, 5 m plant area room. All simulations are carried out in a DAYSIM environment, which allows calculating the annual availability of daylight based on a RADIANCE raytracer backward. Several daylight conditions were analyzed for different light pipe configurations, considering different pipe lengths and a variable number of light pipes. The light pipes are tested also in the horizontal position, for different orientations. The results of all the combinations were compared with the performances of a window with dimensions equal to 1/8 of the internal surface, which was in accordance with the minimum value to be guaranteed by the Italian Regulation (D.M. 5 July 1975 n. 190) for different orientations. The results indicated a difference in daylight distribution, showing a strong correlation between the percentage levels of DA and DAc with the length and number of pipes, during different periods of the year. The simulated model is strongly influenced by the aspect ratio (R = diameter/length). The results show that the illuminance levels decrease drastically, increasing the length.

Buildings built in warm climates are affected by severe overheating problems in summer, which negatively affects people's comfort and health. For these reasons, many users are forced to install cooling systems, leading to an increase in costs, consumption and a meaning impact on the environment. This study gives a valid method to monitor the overheating problems in buildings located in Mediterranean climates, without the use of cooling systems, but just with an accurate design of the envelope. The main challenge is to demonstrate that the hourly monitoring of the internal operative temperature (TOP), in accordance with the UNI EN ISO 52016, is able of defining univocally the performances of the building, taking into consideration the characteristics of the envelope. The optimization of this parameter permits to reach high level of internal comfort in a building, ensuring the designer to identify the best choice of building materials that compose the envelope. The TOP trends, for a whole year, are tested on a single-residential building model located in a warm Mediterranean climate, considering different configurations of the external walls. The results put in evidence that the best solutions are characterized by the presence of the double layer of tuff, with a very massive layer in the internal side and resistive layer outside. At the end, this study demonstrates that once optimized the envelope, it is easier to reach good values of internal operative temperature with the only use of a mechanical ventilation system.

The development of hybrid renewable systems is an economically competitive solution to reach energy decarbonization and reduction of greenhouse gasses. Based on the literature, energy, economic and environmental indicators were rarely simultaneously employed in the optimization of a hybrid renewable system. In addition, there is no procedures or a set of indicators to be applied uniformly in all applications for the shared analysis. The paper presents a novel energy-economic-environmental multi-criteria decision-making in the optimization of a hybrid renewable system, based on a new set of dimensionless indicators, proposed as a standard for future applications. The procedure compares the entire PV-wind-battery system configuration with the PV-wind, PV-battery and wind-battery system sub-configurations. A width parametric and multi-optimization analysis permit the identification of the most proper nominal powers of each system component. The procedure proposed was applied in a Mediterranean residential building, demonstrating that some system configurations allow complying simultaneously with at least two of the three energy objectives proposed, the cost-optimal level and the maximum reduction of emissions, for specific values of the load. The solar source was the most suitable both from energy, environmental and economic point of view, while the use of the wind source leads to a greater system operating time in the nominal power conditions. The study pointed out and quantified that, for specific loads, PV, wind and battery powers, the development of specific incentives for wind systems and of battery systems with a higher lifespan can help to make the hybrid systems more economically competitive.

The convergence behaviour of Genetic Algorithms (GAs) applied to aerodynamic optimisation problems for transonic flows of ideal and dense gases is analyzed using a statistical approach. To this purpose, the concept of GA-hardness, i.e. the capability of converging more or less easily toward the global optimum for a given problem, is introduced, as well as a statistical GA-hardness indicator. For GA-hard problems, reduced convergence rate and high sensitivity to the choice of the starting population are observed. To check the validity of the proposed framework, a reference single-objective optimisation problem, namely, wave drag minimization for a non-lifting transonic flow past a symmetric airfoil is considered. Several optimisations runs are performed at different flow conditions using a GA coupled with a compressible flow solver. The results show that GA-hardness is greater for flow problems characterized by very weak shocks, and is strongly affected by numerical inaccuracies in the evaluation of the objective function. Then, some possible cures to GA-hardness are proposed and numerically verified. An efficient objective-function evaluation procedure based on Richardson extrapolation is introduced, which drastically reduces GA-hardness with a very moderate increase (and sometimes a slight decrease) in computational cost of optimisation runs. Finally, an application of the proposed strategy to a multi-objective optimisation problem is provided, clearly demonstrating the advantages deriving by the use of the proposed technique.

A tensorial-expanded chaos collocation method is developed to take into account uncertainties on thermodynamic properties of complex organic substances. Precisely, we analyse the effect of uncertainties introduced by several thermodynamic models on the numerical results provided by a computational fluid dynamics solver for flows of molecularly complex gases close to saturation condition (dense gas flows). The tensorial-expanded chaos collocation method is used to perform both a priori and a posteriori tests on the output data generated by three popular thermodynamic models for dense gases with uncertain input parameters. A priori tests check the sensitivity of each equation of state to uncertain input data via some reference thermodynamic outputs, such as the saturation curve and the critical isotherm. A posteriori tests investigate how uncertainties propagate to the computed field properties and aerodynamic coefficients for a flow around an airfoil placed into a transonic dense gas stream.