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In this work, we propose to extend an efficient strategy for robust optimization when a large number of uncertainties is considered, in order to include multi-criteria decision making tools. This strategy is based on ANOVA analysis for reducing the stochastic dimension and a massive use of metamodels for predicting the sensitivity indexes in the design variables plan. This approach is applied to the optimization under uncertainty of horizontal ground heat exchangers, used in Ground Source Heat Pumps (GSHPs) for heating and cooling of buildings. System efficiency is maximized taking into account several uncertain parameters, such as the heat conductivity of the ground around the tubes, the velocity inside the tubes and the depth of installation.

International audience; Covariance decomposition of output variance is used in this paper to take account of interactions between non-orthogonal components in anchored ANOVA method. Results show this approach is less sensitive to the anchor reference point than existing method. Covariance-based sensitivity indices (SI) are also used, compared to variance-based SI. Furthermore, we emphasize covariance decomposition can be generalized in a straightforward way to decompose high order moments.

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Solar greenhouses are currently the most energy-intensive agricultural sector. In literature, there is no worldwide mapping of solar greenhouse performance under different climate scenarios. This study analyzes the performance of a Venlo solar greenhouse for 48 localities around the world. Solar greenhouses are mainly made of a transparent envelope and the effect of the direct and diffuse component of solar radiation impacts the internal plant well-being. This study aims to identify the best solution of a transparent envelope on locations with different latitudes and evenly distributed around the globe. The simulations are carried out using TRNsys, considering different thermal phenomena three-dimensional shortwave and longwave radiative exchange, airflow exchanges, presence of lamps with their exact 3D position, ground, plant evapotranspiration, and convective heat transfer coefficients. A total of 336 simulations are performed in the free-floating regime. A new index for the identification of the best glass solutions based on annual average deviation is defined. For all climates, the best glass solutions work better in winter than in summer. The optimal choice of the glass must be combined with effective scheduling of openings for natural ventilation to avoid internal overheating phenomena.

This work presents a new protocol for monitoring rising damp, which is applied to three masonry models made of tuff, carparo, and Lecce stone. First, the physical characteristics of each stone were derived in the laboratory, which included porosity, imbibition, drying index, permeability, capillarity, and sorptivity. In this case, the protocol provided three columns, one for each material, consisting of five blocks. A layer of cotton tissue was interposed between columned blocks to simulate the hygroscopic behavior of a mortar, allowing a quick disassembly and reassembly of the multiblock columns for a quick weighing. The bottoms of the columns were immersed in water to a level of about three centimeters, providing a constant replenishment for the phenomena of evaporation and rising in the stone. The maximum height achieved by the rising damp depends on the characteristics of the building materials, i.e., the amount and size of pores, pore connectivity, etc. Since these materials have different physical characteristics, the objective was to quantify the rising moisture level of the three materials tested, block by block, in a controlled indoor microclimate environment. The three columns were periodically weighed, the quantity of collected water was evaluated, and a thermographic survey was performed. The results show that at the end of the test, the highest level of rising damp is reached by tuff with a height of 43 cm, followed by Lecce stone and carparo with a height of 40 cm and 21 cm, respectively. The innovation of this study is the proposal of a new flexible and easy-to-apply method for monitoring this phenomenon. It gives clear and numerically comparable results. Moreover, it is applicable to any type of stone, allowing the user to evaluate both the existing state and different design solutions.

Thermal modeling of building components plays a crucial role in designing energy efficiency measures, assessing living comfort, and preventing building damages. The accuracy of the modeling process strongly depends on the reliability of the physical models and the correct selection of input parameters, especially for historic buildings where uncertainties on wall composition and material properties are higher. This work evaluates the reliability of building thermal modeling and identifies the input parameters that most affect the simulation results. A monitoring system is applied to a historic building wall to measure the temperature profile. The long-term dataset is compared with the result of a simulation model. A sensitivity analysis is applied for the determination of the influential input parameters. A two-step optimization is performed to calibrate the numerical model: the first optimization step is based on an optimized selection of the database materials, while the second optimization step uses a particle swarm algorithm. The results indicate that the output of the simulation model is largely influenced by the coefficients describing the coupling with the boundary conditions and by the thermal conductivities of the materials. Very good results are obtained already after the first optimization step (RMSE=0.75°C) while the second optimization step improves further the agreement (RMSE=0.48°C). The parameter values reported in the datasheets do not match those found through optimization. Even with extensive optimization using an algorithm, starting with monitoring data is insufficient to identify material parameter values.

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.

Hygrothermal simulations are expected to provide powerful support to the design process in the context of energy retrofit of historic buildings and prevent the moisture-related damages. They can be used to predict the hygrothermal behaviour of the building in detail and exclude the occurrence of moisture related damages, such as mould formation or material degradation. However, these simulations require various input data related to materials and boundary conditions, which are often difficult to find during the design phase. In this article we analyse the potential of hygrothermal simulations in predicting the hygrothermal behaviour of an internally insulated wall, even with limited information on the hygrothermal properties of the materials composing the historical wall. The quality of the simulation's results is evaluated through a comparison with monitored data. The numerical model is calibrated to maximise the agreement with the monitored data. The considered case study is a historical building located nearby Bolzano (Northern Italy). The monitoring system is installed with the aim of analysing temperature and relative humidity profiles within the construction. In addition, the climatic boundary conditions are measured both inside and outside the building, including temperature, relative humidity, driving rain and solar radiation. The numerical simulation of the wall under analysis is performed with the software DELPHIN.

Around the world, expected climate changes can affect indoor comfort conditions in buildings. Analysing the climate in which buildings are located is the first step towards high-efficiency design, and today it is no longer possible to ignore impending climate change. This study has provided a worldwide picture of how comfort conditions inside a building can change as external climatic conditions change. For the first time, a building is tested worldwide over a long-term period, and not just in a specific climate or a small group of climates. Several cities homogeneously distributed around the world were selected, covering all climates of the Koppen-Geiger classification. A hypothetical building was implemented with the Termolog Epix 11 software in order to monitor the operative temperature (TOP) in free-floating mode on an hourly basis and test its temperature variations in the short, medium and long term. The percentage values of the hours when the TOP is in a comfort or discomfort conditions were compared for all configurations. The results showed that the comfort conditions vary with the climate. Climate zone A displayed for most subclimates high TOP values. Climate zone B showed an irregular trend, from 2020 to 2080 the hours when TOPs fall below 20 °C decreased in most locations. Climate zone C included areas where TOPs are mostly in the comfort range. Some sub-climates in zone D show very cold climates, with an average of about 15–20% of the annual hours in the comfort zone in 2020, then increasing slightly by a few percentage points in 2080.

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.

Zero Energy Buildings (ZEBs) are expected to play a significant role in reducing energy consumption and combating climate change. Despite this awareness, there is a lack of approaches and indicators at the regulatory level to quantify the long-term potential of strategies applied to buildings today. This study concerns the dynamic thermal modeling over the years, until 2080, of a multi-residential building located in Lecce, a city in southeastern Italy, characterized by a Mediterranean hot summer climate. Over time, Italian legislation has brought increasingly stringent limits on the design of the building envelope. Although with different regulatory limits, in the different climates across Italy, a growing trend towards a more insulated envelope, characterized by very low transmittances, has been observed over the years. This study shows how, in hot climates, buildings constructed within the legal limits will suffer from overheating over the years, necessarily leading to a disproportionate, and more extensive, use of cooling systems throughout the year. This study proposes a critical analysis of the long-term effectiveness of national strategies applied to the building envelope to date to achieve the ZEB goal, emphasizing that long-term predictive analyses become relevant in current building design and should be considered in regulations.

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.

In questo lavoro è presentata un’analisi energetica ed economica di un sistema ibrido connesso alla rete, costituito da un generatore fotovoltaico, un microgeneratore eolico e un sistema di accumulo elettrico, per la fornitura di energia elettrica ad uso residenziale. Lo studio è stato effettuato in ambiente TRNSYS, attraverso la definizione di un modello e un algoritmo dinamico per la valutazione della potenza elettrica in ingresso e in uscita da ciascun componente del sistema ibrido. In particolare, la potenza prodotta e utilizzata dall’utenza, la potenza accumulata e rilasciata dalla batteria, la potenza in eccesso e la potenza prelevata dalla rete sono state calcolate in relazione all’andamento temporale del carico elettrico dell’utenza residenziale. Gli andamenti temporali delle potenze sono state utilizzate per valutare le prestazioni energetiche annuali del sistema al variare della potenza del generatore fotovoltaico e del generatore eolico, per diversi valori della capacità di accumulo elettrico. L’analisi parametrica ha permesso di identificare le configurazioni del sistema che garantiscono valori elevati di energia prodotta e autoconsumata e valori ridotti di energia in eccesso inviata alla rete. I risultati dell’analisi energetica sono stati utilizzati per sviluppare un’analisi economica impiegando il metodo del Net Present Value (NPV), allo scopo di stimare la fattibilità dell’investimento e di definire la migliore configurazione del sistema.

La European Energy Performance of Buildings Directive (EPBD) recast (EPBD) propone una metodologia comparativa per calcolare i livelli ottimali in termini di costi dei requisiti minimi di rendimento energetico per gli edifici. Questo articolo presenta una metodologia in grado di selezionare il migliore intervento di retrofit per i sistema di illuminazione negli edifici pubblici. In particolare essa si basa su una analisi selettiva delle condizioni di luce diurna nei diversi ambienti e sulla applicazione della cost-optimal analysis. La metodologia è stata applicata a due casi studio presenti in Italia per i quali sono stati scelti diversi scenari. Con l’obiettivo di migliorare le condizioni di comfort visivo e di raggiungere risparmi energetici ed econocmici, gli scenari selezionati propongono due soluzioni di interventi di retrofit: la sostituzione delle lampade esistente con tecnologie più efficienti e l’applicazione di sistemi di controllo. Il risultato della analisi “cost-optimal” suggerisce l’azione o la combinazione di azioni che massimizza il valore attuale netto.

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.

A tool has been developed to integrate electric vehicles into a general systems for the energy management and optimization of energy from renewable sources in the Campus of the University of Salento. The tool is designed to monitor the status of plug-in vehicles and recharging station and manage the recharging on the basis of the prediction of power from the photovoltaic roofs and usage of electricity in three buildings used by the Department of engineering. The tool will allow the surplus of electricity from photovoltaic to be used for the recharge of the plug-in vehicles. In the present investigation, the benefits in terms of CO2 and costs of the scheduled recharge with respect to free recharge are evaluated on the basis of the preliminary data acquired in the first stage of the experimental campaign.