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The Renovation Wave for Europe highlighted the role of the public building stock for which Directive 2012/27/EU has set an annual renewal rate of 3%, which should rise to reach the goal of decarbonization by 2050. In this paper, the energy retrofit of an educational building—at the academic level—in Southern Italy was investigated. The aim was to evaluate the incentive share, which could accelerate the energy efficiency process, to achieve a cost-effective nZEB. The results show that the highest incentive rate is required for interventions on the opaque building envelope, which are also those that allow the least energy savings. An incentive rate of about 45% for the energy efficiency of the transparent envelope is necessary to reduce the payback time by about 7 years. The efficiency of the plants and the installation of a PV system are energetically and economically convenient even without forms of economic incentive. Finally, if the building is brought to high energy standards—a primary energy saving of 46% and energy class A3—an incentive rate of 40% is required to repay the intervention in about 10 years. [ABSTRACT FROM AUTHOR]

• Artifact conservation and occupant comfort in a fourteen-century church. • Design of microclimatic control system in historical buildings. • CFD simulations and BES for the provision of indoor microclimatic conditions. • Experimental and numerical approaches for the evaluation of indoor microclimate. Heritage buildings represent part of a city's identity, and their conservation, as well as the preservation of the works of art they house, is indispensable. This study gives a contribution to the topic of indoor microclimatic analysis and control in building heritage, focusing on the environmental monitoring of an ancient church in the center of Naples (Italy). The measurement campaign, performed during two typical winter and summer periods, was a necessary preliminary step to examine the current indoor microclimate and to calibrate a dynamic energy model of the church. The numerical model was employed for coupled analyses of the church by performing BES (Building Energy Simulations) and CFD (Computational fluid dynamic) simulations. The monitoring revealed the inadequacy of current indoor microclimatic conditions for the conservation of the artistic heritage, and for the comfort of the occupants, therefore a heating and cooling system was designed paying attention to the historical/artistic value of the church. The results of BES and CFD simulations demonstrate an indoor temperature increase of up to 4.4 °C in winter and a decrease of up to 3 °C during the summer, by assuring the preservation of artifacts (e.g., too cold or too hot conditions can induce cracks of wooden materials) and improving occupants' thermal comfort. [ABSTRACT FROM AUTHOR]

[Display omitted] • Accurate building energy simulations need high modeling and computational burden. • ANN-based MPC is performed through a genetic algorithm for a nearly-zero energy building. • Multi-objective optimization of heating cost and thermal comfort is obtained. • Optimal control strategies for HVAC systems are achieved through MPC. • High benefits in terms of both heating cost and thermal comfort are proved. Using a simulation- and optimization-based framework that leverages artificial neural networks for the model predictive control of space heating operation, machine learning techniques are explored to predict the energy performance of a real nearly zero energy building located in Benevento (Southern Italy, Mediterranean climate). The framework's goal is to minimize heating energy costs and thermal discomfort by providing optimal values of setpoint temperatures on a day-ahead planning horizon based on weather forecasts. To achieve this, a Pareto multi-objective approach is applied, which considers thermal comfort via the adaptive theory of ASHRAE 55, assessing a comfort penalty function. The optimization problem is solved using a genetic algorithm in the MATLAB® environment. Objective functions are evaluated using the coupling between MATLAB® and EnergyPlus, which is used as building performance simulation tool. Multi-criteria decision-making is performed to select an optimal solution from the Pareto front while setting a limit to the comfort penalty. To test the framework, EnergyPlus weather data is used to simulate weather forecasts for typical days of the winter season. Two different economic scenarios are simulated in order to be able to analyze both conditions and given the variability of the electricity price. For the different days tested, the best results in terms of savings achieved through the proposed solution are on Feb. 28, corresponding to the coldest day and the highest energy cost, with daily savings of 26% compared to a reference control with a fixed setpoint of 21 °C, while maintaining similar comfort performance. The results suggest that optimized control is a crucial aspect of sustainable building design, and the proposed framework can be virtually implemented or integrated into automation systems for real-time model predictive control. [ABSTRACT FROM AUTHOR]

[Display omitted] • The transition of building districts to sustainable energy communities is addressed. • The case study is set in a real social housing district in Naples, South Italy. • Brute-force optimization is used to drive the transition maximizing sustainability. • Design variables include envelopes, energy systems, renewables, storage, control. • A multi-objective approach is applied to trade-off sustainability and costs. The decarbonization of the energy industry is essential to achieve a future net-zero energy system. To maximize the capacity of citizens to contribute to the clean energy transition, sustainable energy technologies are mandatory. Accordingly, the development of nearly-zero energy districts and communities is up-to-date, and, about it, the net-zero energy goal requires a challenging combination of building design and retrofit, renewable energy sources, energy storage systems. This manuscript investigates several alternative solutions for a shared energy system, to turn a 29-building social housing district in Naples, Southern Italy, in a nearly zero-energy community. The method is quite articulated, based on various numerical approaches, applied by the cycling use of many programs, namely: DesignBuilder® for the building modeling, EnergyPlus as simulation tool, and MATLAB® as optimization engine. A sustainability index based on emissions is introduced. A first optimization is carried out to maximize the sustainability index of the energy community, with a brute-force algorithm used to investigate several design variables, that address building envelopes, energy systems, renewables, electric storage, and operation strategies, resulting in 2,224,044 solutions explored. A second multi-objective optimization is then performed on a limited number of solutions, to evaluate not only the energy-environmental aspects but also the economic ones. The analyzed solutions have a minimum sustainability level equal to 85% and it shows a suitable combination of common buildings retrofit measures. Finally,in order to be able to achieve generalizable results, possible energy and economic targets are outlined: sustainability levels of 85%, 90%, and 95% with an investment budget of up to 150–200 €/m2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simulation- and optimization-based model predictive control is implemented. • A nearly zero energy building in Mediterranean climate is the case study. • Energy cost & discomfort – Fanger & adaptive – are minimized via a Pareto approach. • Cooling setpoints are optimized on a daily horizon based on weather conditions. • Optimal solutions can reduce both cost & discomfort vs a fixed setpoint strategy. The space conditioning of buildings is liable for more than 10 % of World final energy uses and related CO2-eq emissions. Such share must be drastically reduced to pursue sustainability by optimizing both energy design and devices control. In this frame, space cooling is assuming an increasing weight owing to climate change. Accordingly, this study applies a simulation- and optimization-based framework for the model predictive control (MPC) of space cooling systems. The case study is a nearly zero energy building located in Benevento – Southern Italy, Mediterranean climate – featuring an efficient air-source multi-split system for cooling. The framework is envisioned to provide optimal values of setpoint temperatures on a day-ahead planning horizon to minimize energy cost and thermal discomfort, based on weather forecasts. Accordingly, a Pareto multi-objective approach is applied considering different discomfort indicators to compare the Fanger theory with the adaptive one of ASHRAE 55. The optimization problem is solved by running a genetic algorithm – variant of NSGA II – under MATLAB® environment. The objective functions are assessed via the coupling between MATLAB® and EnergyPlus, using a validated building energy model. The multi-criteria decision-making is performed by setting a limit to discomfort to pick an optimal Pareto solution. The framework is tested addressing a typical day of the cooling season and using monitored weather data to simulate weather forecasts. Different optimal solutions are provided to fit different comfort categories. Compared to a reference control at fixed setpoint – 26 °C – the proposed solutions with similar comfort performance ensure cost savings around 28 %. Besides the proposed hypothetical implementation, the framework can be integrated in automation systems for real-time MPC. The novel contributions of this study lie in the methodology to combine MPC with different thermal comfort models as well as in the results, which provide deeps insights about the application of MPC for the space cooling of nearly zero energy buildings in a balanced climate. [ABSTRACT FROM AUTHOR]

• The resilience of a building designed to be nearly zero energy is evaluated in Mediterranean climate. • Weather file defined with monitored data are used for a short-term analysis. • Projections of climate changes are considered in the construction of weather files. • The net primary energy will decrease (–23%) and the in-situ renewable adoption will increase (85%). • Overheating will occur in the intermediate months with the need to turned on the cooling system. The paper is focused on the evaluation of how the climate changes can influence the performance of buildings designed to be nearly zero energy (nZEB) and on the evaluation of the resilience in term of energy balance. A real case study is used; it is named BNZEB, a single-storey dwelling built in Benevento (South Italy, Mediterranean climate). With five-years monitored meteorological data, both a short-term and medium-term analysis is developed; the first one consists in the evaluation of the energy behavior compared to the first operating year. Then, the energy performance is evaluated considering the medium-term climate projections generated using the CCWorldWeatherGen tool. This analysis, with reference to the case study, suggests to designers and researchers that, in a typical Mediterranean climate, the reduction of the heating demand could compensate the increment in the cooling request. In the worst climatic scenario, the net primary energy could change from 25.4 kWh/m2 year (first year of life, 2017) to 19.5 kWh/m2 year (projection to 2050) with a rate of self-consumption of 85% (80% for 2017). However, a critical point is the operating period of the cooling system. Indeed, an indoor overheating problem could occur during the spring with operative temperature higher than 30 °C; this indicates that in future, the occupants will require higher number of operating hours with most frequent switch off. This could change the results of the energy balance, reducing, for instance, the imbalance between production and consumption that currently occurs in the intermediate periods. [ABSTRACT FROM AUTHOR]

Abstract: Thermal bridges are weak areas of the building envelope, determining heat flows higher than those characterizing the common dispersing surfaces (i.e., walls without discontinuities). This phenomenon induces uncontrolled thermal losses and hygiene problems, connected to the possible vapor condensation and mold growth. Presently, the numerical codes for the energy audits, as, for instance, EnergyPlus, carry out zero-dimensional (indoor air) and one-dimensional (conduction heat transfer) analyses, approximately estimating the thermal bridge effects on the seasonal heating demand of buildings. In this paper, results obtained by means of the simplified 1-D models are compared to those obtained by more sophisticated models 2-D or 3-D, in order to point out differences in terms of equivalent conductivity and thermal transmittance. Then, dynamic simulations compare the outcomes in terms of seasonal energy consumption. A typical office building has been considered, analyzing – according to three different approaches – the thermal bridge represented by the roof structure. The outcomes, with reference to several Italian climates, show that a proper modelling is necessary. In particular, an over estimation of the heat losses, determined by an approximate evaluation, induces higher cost of refurbishing, higher cooling energy requests in summer, minor thermal comfort in naturally ventilated buildings. [Copyright &y& Elsevier]

Abstract: The European Energy Efficiency Building Directive 2002/91/CE, as well as other acts and funding programs, strongly promotes the adoption of passive strategies for buildings, in order to achieve indoor thermal comfort conditions above all in summer, so reducing or avoiding the use of air conditioning systems. In this paper, the energy performances achievable using an earth-to-air heat exchanger for an air-conditioned building have been evaluated for both winter and summer. By means of dynamic building energy performance simulation codes, the energy requirements of the systems have been analysed for different Italian climates, as a function of the main boundary conditions (such as the typology of soil, tube material, tube length and depth, velocity of the air crossing the tube, ventilation airflow rates, control modes). The earth-to-air heat exchanger has shown the highest efficiency for cold climates both in winter and summer. The possible coupling of this technology with other passive strategies has been also examined. Then, a technical-economic analysis has been carried out: this technology is economically acceptable (simple payback of 5–9 years) only in the cases of easy and cheap moving earth works; moreover, metallic tubes are not suitable. Finally, considering in summer a not fully air-conditioned building, only provided with diurnal ventilation coupled to an earth-to-air heat exchanger plus night-time ventilation, the possible indoor thermal comfort conditions have been evaluated. [Copyright &y& Elsevier]

• Aim: energy modeling and retrofit optimization of districts/neighborhoods. • Energy consumption and global cost are minimized exploring sundry retrofit levels. • Two opposite perspectives are satisfied: the public one and the private one. • The most sustainable and the cost-optimal solutions are provided. • A part of an existing neighborhood in Naples (Italy) is addressed as case study. Buildings account for about 36% of CO 2 emissions and 40% of energy consumption at EU level. Thus, a deep renovation of the building stock is fundamental to achieve the sustainability targets established worldwide. Accordingly, the study proposes an integrated approach for energy modeling and retrofit planning of districts/neighborhoods of buildings. A Geographic Information System (GIS) tool is coupled with SketchUp® to generate accurate geometrical models, while the thermophysical definition of the building envelopes is performed under DesignBuilder®. Then, EnergyPlus is used as dynamic energy simulator, while MATLAB® is the external post-processing engine. In detail, two phases are identified: 1) development of the energy model; 2) energy retrofit optimization. The approach is relevant to different scale-levels simultaneously, from a single apartment to the whole district/neighborhood as an entity. Furthemore, the use of EnergyPlus ensures high accuracy in energy predictions, while modeling the energy systems directly under MATLAB® environment strongly reduces the computational burden without affecting the results' reliability. As a case study, part of an existing neighborhood located in Naples (Italy) and representative of the Southern Italy building stock is modeled, and its retrofit is optimized. According to the Italian laws, three retrofit levels are investigated to compare their effects on selected energy, financial and environmental indicators. Finally, two optimal solutions are selected: the "nZEB" (nearly Zero-Energy Building) and the "cost-optimal" ones. The former is the one that minimizes the neighborhood's primary energy consumption, which passes from 116.9 kWh/m2a to 72.3 kWh/m2a, while the latter minimizes the global cost, which passes from 184.4 €/m2 to 129.6 €/m2. [ABSTRACT FROM AUTHOR]

• University buildings must be safe, secure and suitable for an "in-presence" education. • Architectural and technological retrofits are necessary to face the COVID-19. • HVAC-related measures anti-contagion need studies in both time and space domains. • A numerical model of a University building, calibrated against measurements, is proposed. • The design of refurbishment is performed by coupled numerical methods, BES and CFD. The proposed investigation is aimed at providing useful suggestions and guidelines for the renovation of educational buildings, in order to do University classrooms safe and sustainable indoor places, with respect to the 2020 SARS-CoV-2 global pandemic. Classrooms and common spaces have to be thought again, for a new "in-presence" life, after the recent worldwide emergency following the spring 2020 pandemic diffusion of COVID-19. In this paper, starting from a real case study, and thus the architectural and technological refurbishment of an Italian University building (Campobasso, South Italy, cold climate), with the aims of improving the classrooms' quality and safety, a comprehensive approach for the retrofit design is proposed. By taking into account the necessary come back to classrooms starting, hopefully, from the next months (Autumn 2020), experimental studies (monitoring and investigations of the current energy performances) are followed by the coupling of different numerical methods of investigations, and thus building performance simulations, under transient conditions of heat transfer, and computational fluid dynamics studies, to evidence criticalities and potentialities to designers involved in the re-thinking of indoor spaces hosting multiple persons, with quite high occupancy patterns. Both energy impacts, in terms of monthly and annual increase of energy demands due to higher mechanical ventilation, and indoor distribution of microclimatic parameters (i.e., temperature, airspeed, age of air) are here investigated, by proposing new scenarios and evidencing the usefulness of HVAC systems, equipment (e.g., sensible heat recovery, without flows' contamination) and suitability of some strategies for the air distribution systems (ceiling squared and linear slot diffusers) compared to traditional ones. [ABSTRACT FROM AUTHOR]

In recent times, the inter-building effect has been deeply investigated because it can highly affect building energy performance. Thus, reliable energy simulations of a single building can require to model the effects of surrounding buildings. This can imply complex models, and consequently high computational burden. The study aims at investigating such phenomena with suitable simplifications by keeping high reliability. Two typical buildings of European cities, located in South Italy, are investigated with building models developed using DesignBuilder® and EnergyPlus. Dynamic energy simulations are performed by using different modeling approaches: detailed modeling, different shading systems, different shading setpoints, no shading, no inter-building effect and the combination no shading and no inter-building effect (simplest model). For each approach different simulation timesteps are considered. The coupling between EnergyPlus and MATLAB® is implemented for a comprehensive comparison of the performance indicators provided by the different approaches. The main goal is to identify the models that ensure the best tradeoff between accuracy and computational burden as well as to verify if these latter can reliably replace the most detailed model. The tradeoff models provide – compared to the most detailed one – mean bias error around 2% and reductions in simulation times around 46%, which can be considered an excellent tradeoff. Finally, the study proposes insights into building modeling to answer the question: Is it fundamental to model the inter-building effect for reliable energy simulations? Image 1 • Accurate building energy simulation can imply complex, time-expensive models. • Different modeling approaches are compared to trade-off accuracy and complexity. • Inter-building effect, shading type and use, simulation time steps are explored. • DesignBuilder®, EnergyPlus and MATLAB® are used as simulation/processing tools. • The approaches ensuring the best tradeoff accuracy-computational burden are found. [ABSTRACT FROM AUTHOR]

• The performance of "Benevento" Nearly Zero Energy Building is discussed. • The dynamic behaviour of the walls and the comfort conditions are measured. • The optimal management of the internal and external shades is evaluated. • The effectiveness of pre-treatment of ventilation air by means of geothermal probes is studied. • The hourly energy balance is analyzed with some new indexes. The paper discusses the results of a monitoring campaign performed during the spring and autumn with the purpose to evaluate the operational energy performance of an existing nearly zero energy building (nZEB). It is located in Benevento, a middle-size city of South Italy with typical Mediterranean climate. A methodology for real-time nZEB performance analysis is proposed by taking into consideration the implications of the continuous interplay between external conditions and indoor occupant requirements as well as between on-site generation and the building loads with the resulting interaction with the energy grid. It takes into account the inertial properties of building envelope and the occupant perception in term of thermo-hygrometric and visual comfort as well as of indoor air quality. Compilation and assessment of appropriate quantitative indicators are proposed basing on data with hourly time step for finding the optimal management of the internal and external shades and the ventilation system. Moreover it is discussed how daily variations can influence the efficiency of the whole building-HVAC system with particular attention to the pre-handling system based on an earth-water heat exchanger. [ABSTRACT FROM AUTHOR]

• According to EU 844/2018, existing buildings must be innovated to nZEB in next years. • Sixties and seventies residential buildings are energy-intensive and require renovations. • For a calibrated multistory building model, feasible energy retrofits are evaluated. • Starting from energy demands of a refurbished building, wrong behaviors are simulated. • Wrong habits (setpoints, vent, light, equip. and shading) can nullify the retrofit benefit. The necessity to predict building energy performance assumes a predominant role today. Present regulations in energy matter introduce pressing objectives for the energy requalification of buildings. Within spring 2020, EU Member States must adopt the European Directive 2018/844, which focuses the attention on present buildings. It establishes new obligations to retrofit the existing building stock. Solutions to improve building energy performance and to achieve economic, energy, and environmental benefits become mandatory, requiring robust and reliable procedures for energy modeling and simulation. The present study will show the importance of considering a non-standard occupant profile in energy performance simulations. The investigated edifice is a typical residential building in Naples (southern part of Italy, Mediterranean climate), built during the sixties and seventies. For the energy retrofit of the building, the most common refurbishment interventions in the Neapolitan building stock will be assessed for energy, economic and emissions savings, and thus new thermal insulation and replacement of windows. Firstly, the results will be analyzed by taking into account a standard-use profile of the occupants. Secondly, the possible wrong behaviors of users will be examined, to compare an "energy-intensive" model with the standard retrofitted model. The impact on building energy demand of the following actions will be analyzed: more energy-intensive use of the electric and lighting systems, the opening of the windows during the activation hours of the heating/cooling systems, the modification of the thermostat setpoint, the deactivation of the shading systems. The study shows a considerable increase in energy demand, following the wrong behavior of the occupants, which affects the economic convenience of the refurbishment investment. The energy retrofit is economically and energetically feasible for a standard building occupation, but sometimes wrong habits can reduce the convenience, if energy-intensive behaviors occur. This work will show that, when the numerical building model of a common building refurbishment is realized and when the cost-benefits analysis is performed, the uncertainty in occupant behavior cannot be neglected. [ABSTRACT FROM AUTHOR]

The present work concerns the energy retrofit of a public educational building at the University of Molise, located in Termoli, South Italy. The study provides a comparison of the results obtained by different dynamic simulations of passive strategies to improve thermal comfort and energy behavior of the building during the summer regime. Firstly, the building model was calibrated against historical consumption data. Then, a subsequent step involves the technical-economic analysis, by means of building performance simulations, of energy upgrading scenarios, specifically, cool roof and green roof technologies for the horizontal opaque envelope and thermal insulation, vented façade, and phase change materials' applications for the vertical opaque envelope. Improving the indoor thermal comfort and reducing the thermal energy demand during summertime through innovative solutions will be the primary objective of the present study. The energy efficiency measures are compared from the energy, emissions, costs, and indoor comfort points of view. Phase Change Materials applied to the inner side of the external walls are analyzed in depth and, by varying their melting temperature, optimization of design is performed too. This innovative material, with a melting temperature of 23 °C and a freezing temperature of 21 °C, determines the reduction of summer energy consumption of 11.7% and the increase of summer indoor comfort of 215 h. Even if consolidated, other solutions, like the cool roof, green roof, thermal insulation, and vented façade induce improvements in terms of summer energy saving, and the percentage difference compared to the basic building is less than 2%. For this case study, a Mediterranean building, with construction characteristics typical of the 1990s, traditional passive technologies are not very efficient in improving the energy performance, so the investigation focused on the adoption of innovative solutions such as PCMs, for reducing summer energy demand and improving indoor thermal comfort. [ABSTRACT FROM AUTHOR]