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Shifting from an individual vision to a community vision, also in the field of buildings, is a great challenge of our times. Notably, the deployment of energy district/community concepts is crucial to enable the energy transition with a view to sustainable urban growth. In this regard, the optimal combination of building design/retrofit, renewables, and energy storage systems, is challenging and crucial to achieve the net-zero energy district (n-ZED) and ZED targets. The latter is more stringent because it means an energy-independent district, without the need of energy from the grid. To understand how to achieve such ambitious targets, this paper addresses a real case study, i.e., a small building stock in Monterusciello (suburb of Naples, coastline, Southern Italy), composed of 29 residential buildings with poor energy performance as concerns both envelopes and systems. A comprehensive optimization approach is implemented to drive the energy transition of the stock to a community to minimize energy consumption and related environmental footprint. Accordingly, sundry scenarios are investigated to provide guidelines about different strategies to reach the n-ZED and ZED targets, including full-roof photovoltaic systems, efficient reversible heat pumps, refurbishment of building envelopes, and energy storage systems, i.e., batteries and compressed air energy storage, considering different size. Energy is shared by the buildings creating a community. The energy retrofit of the district is investigated in order to find different solutions to achieve n-ZED and ZED performance, using EnergyPlus as simulation tool and MATLAB®? as optimization engine. The optimal solutions are compared to a traditional individual vision addressing the retrofit of each single building without shared energy and plants. Results show that sharing energy can be a powerful tool – if combined with optimization – enabling a more significant reduction of building environmental footprint compared to standard retrofit approaches.

The reliable assessment of building energy performance requires significant computational times. The chapter handles this issue by proposing an original methodology that employs artificial neural networks (ANNs) to predict the energy behavior of all buildings of an established category. The ANNs are generated in MATLAB by using EnergyPlus simulations for testing and training purposes. The inputs are properly set by means of a thorough preliminary sensitivity analysis. The final aim is a reliable assessment of the global cost for space conditioning as well as of the potential global cost savings produced by energy retrofit measures for each category’s building. The benefit is a huge reduction of computational times compared to standard reliable simulation tools. Definitely, this can support the diffusion of rigorous approaches for cost-optimal energy retrofits. Beyond the presentation of the methodology, this is applied to the office building stock of South Italy built in the period 1920–1970. The results show a high ANN reliability compared to EnergyPlus simulations, with regression coefficients (R) always higher than 0.98.

This chapter investigates strategies for approaching the energy refurbishment of historic buildings, by proposing, beyond a general methodology aimed at guaranteeing feasibility of the design, its application to two cases studies in the context of South Italy, in a typical Mediterranean climate according to the Köppen classification. According to the latest international guidelines in matter of building energy efficiency and future trends, by 2020, a great effort should be applied to both new constructions and building refurbishments, to achieve goals of nearly zero-energy impacts or very low energy demand. Of course, the energy refurbishment of architectures characterized by historical or artistic values should not determine damage of the valuable peculiarities. In this study, by means of the proposed case studies, and thus an admirable Italian building, examples of an approach toward cost-effective and architecturally compatible actions are proposed, according to the European methodology of cost optimality. Moreover, by comparison with the feasible refurbishment of an existing building, the difference in energy retrofit designs of historical or modern edifices is evidenced. The proposed case studies are an educational ancient palace built beginning in the 12th century and, as an existing building, a railway station located in the same city. In both cases, replacement of components of thermal envelope and active energy systems will be applied, by evidencing that, based on the building peculiarities, technologies, architectural values, and kinds of loads, different boundary conditions imply different cost-optimal energy conservation measures.

Assessing energy performance and retrofit potentials of a whole building stock is an arduous task, especially for complex buildings such as healthcare facilities. This issue is tackled by proposing a new methodology, which extends the outcomes related to a reference building (RB) to all represented buildings. A hospital RB (RBh) is developed by means of an original approach to represent Southern Italy healthcare facilities, and transient energy simulation is used to simulate annual energy performance for different weather data files and types of opaque and transparent envelopes. Hence, for each configuration, indices expressing thermal energy demand (TED) for space heating, cooling and domestic hot water (DHW), per unit of area [kWh/m2a], are calculated. Various indices are provided for different use classifications and are employed to predict the TED of all represented buildings, depending on climatic location, envelope type and extension of each use classification. The HVAC system efficiency is, then, exploited to assess primary energy consumption (PEC) and energy cost. The same approach is used to estimate energy retrofit potentials in order to detect the cost-optimal solution. Compared to real data, an error around 10% is achieved for different case studies.

Today, it is not well-known the impact of cool roofs during heating season in balanced climates. Proposed study tries to quantify the increase of energy demands of buildings characterized by high-reflective and high-emissive coatings of roof, by means of experiments and numerical simulations. Three coatings are investigated with different solar absorptance and thermal emittance. The experiments have been carried out at the living lab of the University of Sannio, a full-scale test-room, provided with a large flexibility in terms of variability of the thermal envelope and air-conditioning system. Moreover, numerical evaluations of heating and annual energy consumptions are presented. (C) 2016 The Authors. Published by Elsevier Ltd.

Dopo aver sinteticamente presentato il quadro normativo attualmente in vigore per l’efficienza energetica in edilizia, la memoria approfondisce le principali problematiche connesse alla progettazione integrata del retrofit energetico di edifici con destinazione d’uso complessa, quali le strutture ospedaliere. Coniugare gli standard di efficienza energetica vigenti, con le norme e le leggi relative alla progettazione delle strutture sanitarie, rappresenta infatti una delle più grandi sfide per il processo di efficientamento energetico del patrimonio edilizio nazionale. Nell’edilizia ospedaliera, in particolare, la progettazione di interventi per il risparmio energetico deve avvenire nell’ottica irrinunciabile della progettazione integrata del sistema edificio-impianti poiché, da un lato, il controllo del microclima deve essere operato sia dall’impianto che dall’involucro, dall’altro, è altresì necessario selezionare i sistemi HVAC in funzione delle loro necessità gestionali e manutentive, principalmente in modo da non interferire con il ciclo di funzionamento continuo dell’edificio. Pertanto, gli impianti devono non solo garantire condizioni di comfort termo-igrometrico e qualità dell’aria per gli occupanti, ma è richiesto che soddisfino anche esigenze di processo legate alle diverse attività mediche previste, considerando che, in molti ambienti, il rispetto di taluni requisiti minimi (efficienza di filtrazione, quantità di ventilazione di aria esterna, condizioni di pressione dell’ambiente) è la condizione necessaria allo svolgimento dell’attività stessa. In questo lavoro, tali aspetti saranno approfonditi attraverso la presentazione di un esempio di diagnosi e riqualificazione energetica di un edificio adibito ad ospedale, presentando come caso studio il lavoro svolto dagli stessi autori per il Day-Hospital del Complesso Ospedaliero “G. Pascale”, situato a Napoli. Per questo edificio, incrociando procedure sperimentali e numeriche, è presentata la caratterizzazione energetica dello stato attuale attraverso la costruzione di un modello numerico e la simulazione del rendimento energetico del sistema edificio-impianto per la valutazione energetica, ambientale ed economica di possibili interventi di retrofit, mediante azione sia sull’involucro edilizio che sugli impianti termotecnici installati. Partendo dai risultati dall’analisi di convenienza tecnico-economica per il caso studio presentato, nella parte conclusiva la memoria suggerisce spunti di riflessione per la selezione di interventi idonei alla riqualificazione di edifici adibiti ad ospedali, nell’ottica di un funzionale ed efficace controllo microclimatico.

La Direttiva Europea 2002/91/CE, così come altri provvedimenti legislativi e programmi di incentivazione, promuove l’utilizzo di soluzioni tecniche passive per gli edifici, con l’obiettivo di ottenere, soprattutto in regime estivo, condizioni di comfort termico, evitando o riducendo il ricorso ad impianti di riscaldamento/raffrescamento. L’adozione, la progettazione e la scelta di tali tecnologie non sono indifferenti alle specifiche condizioni al contorno. La memoria analizza le prestazioni ottenibili mediante l’utilizzo di scambiatori interrati terra-aria, in regime invernale ed estivo, per un edificio provvisto di impianto di riscaldamento/raffrescamento. Mediante simulazioni energetiche dinamiche sono state analizzate le principali caratteristiche di tali scambiatori, modificando le principali condizioni al contorno connesse alle condizioni climatiche, alle tipologie di terreno ed ai parametri costruttivi dello scambiatore, nonché alla velocità dell’aria che li attraversa e alle portate d’aria di ventilazione adottate. Inoltre, sono state considerate diverse modalità di utilizzo, con l’obiettivo di fornire indicazioni ottimali relative a ciascuna condizione climatica. L’energia elettrica richiesta dai ventilatori rappresenta un altro aspetto critico, in quanto bisogna ottenere il massimo scambio termico minimizzando le perdite di carico, per evitare che l’utilizzo di tali scambiatori possa risultare energeticamente non conveniente.

Con l’entrata in vigore dei Decreti Legislativi 192/2005 e 311/2006 l’Italia, recependo i contenuti della Direttiva Europea 2002/91/CE EPBD - Energy Performance of Building Directive -, ha modificato la precedente normativa energetica nazionale, centrata intorno alla legge 10/91, così come attuata attraverso il D.P.R. 412/93 e successivi decreti di modifica ed integrazione. Le misure sopra citate, aventi valore di legge, fondano su un vasto “pacchetto” di norme tecniche, alcune contemporanee alle disposizioni legislative, altre precedenti o successive, altre ancora in fase di emanazione. E’ da sottolineare come, pur facendo esclusivo riferimento ai provvedimenti di legge, l’evoluzione legislativa italiana in materia di energia, a partire dalla legge 373/76, non ha seguito percorsi lineari, creando sovrapposizioni di provvedimenti e frequenti rimandi a futuri decreti attuativi tardivi o mai emanati, la qual cosa ha contribuito sia a creare confusione in tema di regolamentazioni sia a indurre pericolosi vuoti legislativi che, di fatto, hanno indebolito fortemente la qualità energetica del nostro parco edilizio, il quale, negli ultimi 35 anni, con un’applicazione solo lievemente più attenta di quanto invece fatto, sarebbe potuto essere contraddistinto da un livello di efficienza molto maggiore di quella invece misurabile nelle nostre città. Questa memoria, elaborata nell’estate del 2008, proporrà una lettura critica dello stato attuale della normativa, sia in riferimento alle misure legislative emanate negli ultimi anni sia per quanto concerne le norme tecniche cui queste rimandano e fanno riferimento, riscontrando nei testi numerosi ed opportuni elementi di novità, ma anche talune incongruenze ed incertezze che, nuovamente, rischiano di vulnerare l’efficacia delle giuste ed ormai improrogabili disposizioni espresse dai nuovi orientamenti internazionali e nazionali in materia di uso efficiente dell’energia. Lo studio proposto, relativo alle metodologie per la certificazione energetica degli edifici, sviscerata nei suoi aspetti critici con dissertazioni sul metodo e nel merito, si avvarrà dei risultati quantitativi ottenuti mediante analisi numeriche delle prestazioni energetiche del sistema edificio-impianto di climatizzazione, considerando entrambi i regimi di funzionamento invernale ed estivo.

The EPBD, together with other acts and funding programs, strongly promotes the passive strategies in order to achieve, above all in summer, indoor comfort conditions, reducing or avoiding the active air-conditioning. The adoption and the design of these strategies are not indifferent to the specific boundary conditions. In this paper, the performances achievable adopting an earth-to-air heat exchanger for an air-conditioned building are evaluated for winter and summer. The analysis has been carried out on varying the main boundary conditions related to the environmental context, the soil, the tube properties and connected behaviours of the airflow crossing it. Several control strategies have been simulated too, in order to propose the most suitable design criteria for each climate. The fan electrical energy represents a design critical aspect, requiring an accurate evaluation, in order to achieve the maximum thermal exchange and limiting the pressure drops inside the buried pipes. Otherwise, the use of an EAHX can be also penalizing.

L’emanazione della Direttiva Europea 2002/91/CE (Energy Performance of Buildings Directive - EPBD) ha rivitalizzato e dato nuovo impulso alle tematiche proprie dell’efficienza energetica in edilizia, obbligando, in un contesto internazionale vivacizzato dalle problematiche ambientali e legate all’approvvigionamento energetico, gli Stati membri dell’Unione verso nuovi e comuni traguardi da raggiungere relativamente alla riduzione improrogabile della domanda di energia nel settore edilizio. L’obiettivo dell’attività di ricerca riportata in questa Tesi è consistito nello studio di misure di efficienza energetica in diversi ambiti del settore civile, con particolare riferimento all’edilizia residenziale, al settore terziario ed alle architetture adibite a musei. Gli studi di efficienza energetica hanno valutato sia gli aspetti metodologici e procedurali alla luce dei nuovi orientamenti legislativi e normativi scaturiti dalla EPBD, sia le potenzialità di miglioramento delle prestazioni di involucri edilizi ed impianti, per quanto concerne gli usi energetici dovuti ai bisogni di riscaldamento, ventilazione e climatizzazione degli edifici.

This volume reports a year-long advanced studio program carried out in the Master’s degree in Architecture at Federico II in 2018-2019. As an interdisciplinary course, the advanced studio is a challenge for students who have to deal with different forms of knowledge and design skills to deliver a transformation project for a complex context. Castel Volturno, a coastal town on the western shore of Napoli’s urban region, is the target area where the program has been implemented. The context’s main features are a growing migrant community from Africa, established in the area given the large amount of abandoned homes available for letting, a series of major environmental concerns, such as flooding, pollution and unplanned buildings, and a quite extraordinary natural landscape made of wetlands, green and farming areas, and marine environments. The volume presents the students works, with a methodological foreword from the faculty of the program.

A significant part of the housing stock in southern Europe is obsolete and in need of extensive retrofitting to improve its energy performance and thermal comfort. However, before adequate retrofit measures can be proposed for this housing stock, the characterization of current building performance is fundamental. Although the simulation tools frequently used and widely accepted by the scientific community ensure accurate results, these require high computational times. The main aim of this paper is the development of a surrogate model to speed up the thermal comfort prediction for any member of a building category, ensuring high reliability by testing the entire simulation process with real data measured in-situ. To this end, an artificial neural network (ANN) is generated under MATLAB® environment using the data obtained from EnergyPlus simulations for linear-type social housing multi-family buildings in southern Spain, which were constructed in the post-war period. The developed ANN provides a regression coefficient between simulation targets and ANN outputs of 0.96, with a relative error between monitored and simulated data below 9%. A further result is that the building category characterization shows a general lack of suitable indoor thermal comfort conditions, thereby showing the great need for effective retrofit strategies.

Buildings are responsible for about 35-40% of energy demand and greenhouse gas emissions, and it implies that improvements of local and global climate, containment of urban heats islands, saving targets, and environmental goals cannot be achieved without high-efficient new buildings and a deep energy renovation of the existing building stock. This work analyses three possible case studies to fulfill the goals of policies in energy-matter and considers real case studies of new construction and the energy refurbishment of existing buildings. This is only a small part of a wider study that provides an overview of evolution, achieved goals, criticalities, and perspectives of twenty years of policies in the matter of energy performance of buildings. The new construction of a single-story dwelling, the refurbishment of a historical building, and a 70s cement-based building are the three exemplary case studies that will be proposed, as a part of a larger investigation.

The paper proposes a discussion about the operational performance of an existing nearly zero energy building in the Mediterranean climate, during the heating season. The required electric power for variable winter conditions is analyzed and it is compared with design calculation, under stationary conditions. Indeed, the indoor and outdoor conditions, during the real operating mode, could be quite different compared to the ones adopted during the design period, also because of the progressive climate change. Thus, it is important to understand if the building-HVAC system is able to meet the variable conditions that can occur and what is the difference that could happen during the sizing of the systems for the microclimatic control.

The energy retrofit of the building stock is a central issue in the view of reduction of energy consumption and climate change. The energy efficiency measure proposed in this study provides first the application of a double skin facade and the evaluation of the positive and negative effects due to this measure; then, in a second phase, to counteract the possible negative effects, a control logic for opening windows of the double skin facade is defined. These windows respond dynamically to variation of external conditions by allowing an air flow from the cavity to the internal environment in winter period and from the cavity to the external environment in summer period. The building under investigation belongs to the University of Naples Federico II and it is dedicated to offices. The building geometry and the characterization of building envelope and systems installed are realized with the graphical software DesignBuilder®, while EnergyPlus software is used for the dynamic simulation of the building thermal and energy performance. The control logic for the opening of the windows is defined through the module Airflow Network of EnergyPlus. The energy benefit in terms of reduction of primary energy demand for the space heating and cooling reaches values of 44.4% and 8.4%, respectively. Finally, semi-transparent a-Si photovoltaic modules (efficiency of 4 %) are integrated into the facade. When they cover the half area of the external facade, there is a production of 5120 kWh/year and a saving of 11.2% in electricity consumption.

The redevelopment of the existing building stock is essential to reach sustainability goals, worldwide. The energy retrofit measure analyzed in the study is based on the installation of a double skin facade with the integration of transparent photovoltaic on a structural exoskeleton that has the function of providing the building with a higher level of structural and seismic safety. The examined building is an Italian typical building construction of the 60s and 70s, i.e., it represents an archetype building and not a real building. After carefully collecting the input data, the graphical software DesignBuilder® is used to model the building geometry and the HVAC systems, while EnergyPlus software is used for dynamic energy simulation. The model is validated against the energy need for the type of reference buildings. Initially, the effect related to the double skin façade is assessed, and then a gradual inclusion of the transparent photovoltaic is implemented. Therefore, the energy benefit, in terms of primary energy consumption, due to the combined use of the two technologies is evaluated. When PV panels cover the entire area of the external facade, a saving of 55% in primary energy consumption is achieved.

COVID-19 pandemic brought economic crisis, also in the building sector, with an increase of energy consumption in the residential sub-sector due to the more intensive use. The strategic plans put in place by the European Union to face this crisis look to environmental sustainability, by identifying the building as a key sector. In Italy, it has been offered a tax deduction of 110% (divided into 5 annual quotas) aimed at promoting energy efficiency measures for existing buildings, also for fulfilling the new requirements of the Directive EU 844/2018. This investigation aims to analyse - from energy, environmental and economic points of view - this new funding program. It will be shown how it leads to prefer energy efficiency measures characterized by the best energy performance, and not by the best cost/benefit ratio.

The current World situation is particularly complex and heavy, from many points of view, among which energy and socio-economic ones. The COVID-19 pandemic, besides causing a health crisis, has brought out, even more, the need to reduce emissions for a healthier environment. The role played by the existing building stock is fundamental, as it is responsible for 36% of CO2 emissions in Europe. The proposed work aims to define some energy refurbishment interventions, for a residential building in south Italy, regarding the building envelope, the heating and cooling systems, and the addition of systems from renewable energy sources in order to improve its energy labeling. The methodological approach has followed the guidelines for the energy certification of buildings in Italy. It was possible to evaluate the improvement in building energy labels according to the proposed efficiency measures, highlighting those which allow for a tax relief recently introduced by the Government. Finally, the addition of photovoltaic and solar collector systems was evaluated to allow even the fulfillment of nZEB standard.

Facing the climate change is a common priority, due to ethical issues related to general concept of sustainability and livable future for the next generations. Moreover, ethical aims for contrasting energy poverty, heat-related diseases and deaths, availability of food and water, infections and viral-bacteriological risks, meteorological extreme phenomena, such as floods and intense and destructive precipitations, are stringent and pressing targets. All serious and independent investigations reveal future scenarios of an overall global warming that surely make worrying the evolution of quality of life on this earth. Each one has to do his part. In this study, the research is focused on renewable technologies for the passive cooling of buildings. Indeed, the space cooling is a strongly increasing use of energy and induces a vicious circle, being, at the same time, a cause and an effect of the anthropogenic overheating of the planet. The paper mainly reviews techniques for suitably governing the energy interaction between buildings and surrounding environment. The energy efficiency concerns the building envelope design, the use of efficient HVAC systems, adoption of renewable energy on-site. On the other hand, every energy conversion process determines waste heat, so that also a ‘free of operational cost’ solar cooling system however causes dissipation of heat into the ambient. Finally, renewables cannot be the unique solutions for supplying the energy required for the building use. Conversely, strategies for reducing the building cooling are needed, and these are reviewed in this study. In thermodynamics terms, the building is seen as part of the system and not the mere control volume. Greenery of facades and roofs, phase change materials, nocturnal convective cooling, evaporative and ground cooling, solar systems such as chimneys for improving the building ventilation are here discussed, as well as emerging technologies such as breathing walls and dynamic insulation. The reviewed studies, selected on the basis of more recent progresses concerning the investigated technologies, revealed potentialities but also criticalities in the design.

Building activity is the sector that affects for the most part the anthropogenic climate change. Indeed, even if differences can be found among countries, according to the level of development and climates, buildings require about 30–40% of the overall energy demand, with similar share concerning the greenhouse emissions. According to the more recent EU Directives in matter of energy efficiency in energy use, a great attention has to be paid to energy refurbishments of existing buildings. Indeed, the turnover rate of the EU building stock is generally low in fully-developed countries, so that the energy retrofits are also more important compared to new nearly zero-energy buildings. The proposed investigation concerns the demonstrative role of the public hand, whose necessity is underlined by the EU Directives 2010/31/EU and 2012/27/EU, through a multi-step and multi-objective optimization of an educational building of an Italian University. All preliminary investigations aimed at a reliable modelling, the iterative method that combines genetic algorithms and transient energy simulations tailored on calibrated numerical models make the investigation complete and repeatable. All levers of energy efficiency have been pressed, and thus the refurbishment of building envelope, HVAC systems, integration of energy supply by renewables. The multi objective optimisation concerns costs, incentives, indoor comfort, energy demands for heating and cooling and a novel approach is proposed for choosing the best configuration of retrofit. It is resulted that the most profitable energy efficiency measures involve the modernization of energy systems, even if also the retrofit of the building envelope can be profitable under favourable financial conditions. The cost-effective refurbishment reduces the primary energy demand up to a value of 12 kWh/m2a, so that the building can be surely considered as nZEB.

A new comprehensive approach is proposed to support cost-optimal design of building envelope’s thermal characteristics and HVAC (heating, ventilating and air-conditioning) systems in presence of a simulation-based model predictive control (MPC) for heating and cooling operations. The cost-optimal solution is identified through a main mono-objective genetic algorithm (GA) that minimizes global costs for space conditioning. The explored solutions represent building thermal designs integrated with the MPC of HVAC systems. For defining the MPC strategies, the main GA launches two secondary bi-objective GAs that optimize heating and cooling operations, respectively. These secondary GAs perform Pareto optimizations by minimizing operating costs and thermal discomfort. They provide the optimal hourly set point temperatures for heating and cooling operations, with a day-ahead planning horizon, by considering the forecasts of weather conditions and building use. The optimal control strategies are found based on requirements of users, who set a minimum comfort level to be fulfilled. The GAs are implemented by coupling MATLAB ® with EnergyPlus. The methodology is applied to a new multi-zone residential building in Naples (Southern Italy). It yields primary energy savings around 35.4 kW h/m 2 a and global cost savings around 7000 €, ensuring the same satisfying comfort level, compared to a standard design approach.

How to predict building energy performance with low computational times and good reliability? The study answers this question by employing artificial neural networks (ANNs) to assess energy consumption and occupants' thermal comfort for any member of a building category. Two families of ANNs are generated: the first one addresses the existing building stock (as is), the second one addresses the renovated stock in presence of energy retrofit measures (ERMs). The ANNs are generated in MATLAB ® by using the outcomes of EnergyPlus simulations as targets for networks' training and testing. A preliminary ‘Simulation-based Large-scale sensitivity/uncertainty Analysis of Building Energy performance’ (SLABE) is conducted to optimize the ANNs' generation. It allows to identify the networks' inputs and to properly select the ERMs. The developed ANNs can replace standard building performance simulation tools, thereby producing a substantial reduction of computational efforts and times. This can allow a wide diffusion of rigorous approaches for retrofit design, which are currently hampered by the excessive computational burden. As case study, office buildings built in South Italy during 1920–1970 are investigated. Comparing the ANNs' predictions with EnergyPlus targets, the regression coefficient is between 0.960 and 0.995 and the average relative error is between 2.0% and 11%.

Design criteria for a residential nZEB in Mediterranean climate are discussed. The integrated design procedure focuses on the problem of a large number of available building variants concerning the building envelope. The aim is to search the ones that minimize winter and summer energy demand without compromising thermal comfort. The adopted methodological approach combines the use of dynamic energy simulation tool (EnergyPlus), based on a one-dimensional conduction finite difference solution method, and a constrained multi-objective optimization algorithm. For four cities (Madrid, Nice, Naples, Athens), several passive strategies are compared: thermal properties of the building envelope, adoption of phase change materials with different melting temperatures, cool roof solutions, several window/wall ratio values, some external and internal shading systems. The results allow to evidence that it is difficult to understand the best trade-off between summer and winter performance, by assuring high standard of thermal comfort when the aim is to reach NZEB objectives in Mediterranean climate. However, some guidelines are indicated, starting from the discussed results.

Nowadays the study of Net Zero Energy Buildings (NZEBs) is fundamental, because they are the main strategy to reduce the building energy demand and CO2-equivalent emissions. This paper analyses a case study concerning a multipurpose building located in Palermo (Southern Italy), and evaluates the benefits related to the use of an earth-to-air heat exchanger in a NZEB, in terms of energy saving and reduction of CO2-equivalent emissions, for a Mediterranean climate. The chosen building envelope is thermally performing. The HVAC system consists in fan-coil units connected to an air-to-water heat pump, and mechanical ventilation. The energy demand is reduced by an earth-to-air heat exchanger that pre-heats the ventilation outside air in winter and cools it in summer. The optimization of the heat exchange with the ground is a key-element to reduce the primary energy requirements and CO2-equivalent emissions, especially during summer. Moreover, this paper assesses the possibility to obtain a NZEB using only on-site renewable energy (on the roof of the building), with and without the earth-to-air heat exchanger. The energy analysis is carried out by means of a dynamic building simulation engine, namely EnergyPlus. In addition, a thermal performance and an environmental analysis are performed.

Public energy policies must support the deep energy retrofit of buildings in order to fight climate change and energy poverty. Assessing the impact of such policies is extremely important because the supported energy retrofit measures (ERMs) can ensure huge energy, economic and environmental benefits. However, the energy investigation of wide building stocks is very complex. This issue is here tackled by using and enhancing the methodology SLABE ('Simulation-based Large-scale uncertainty/sensitivity Analysis of Building Energy performance'), which conducts reliable analyses of energy retrofitting building categories. SLABE employs Latin hypercube sampling to generate Representative Building Samples (RBSs), which represent the energy behaviour of the explored building stock. Then, post-processing is applied to assess the impact of proper ERMs on energy consumption, polluting emissions and lifecycle costs. Thus, the cost-optimal retrofit solutions are found in absence and presence of financial incentives, respectively. The outcomes are exploited to assess the effectiveness of current energy policies and to propose potential improvements for harmonizing the public and private perspectives. The methodology combines EnergyPlus and MATLAB®. As case study, it is applied to the Italian office building stock. The outcomes show huge potential energy and cost savings as well as polluting emission reductions.

The paper proposes a multi-objective optimization approach to address the energy design of the building envelope. A genetic algorithm (GA) is implemented by means of the coupling between MATLAB® and EnergyPlus to minimize primary energy consumption (PEC), energy-related global cost (GC) and discomfort hours (DH). The design variables concern the set point temperatures, the radiative properties of plasters, the thermo-physical properties of envelope components, the window type, the building orientation. The GA performs a Pareto optimization and finally two optimal solutions are recommended: the nZEB (nearly zero energy building) optimal solution, which minimizes PEC, and the cost-optimal solution, which minimizes GC. These solutions provide the optimal design strategies for the public and private stakeholders, respectively, which represent the main actors involved in building design. The approach is applied for the design of a new typical Italian residential building. Four locations are considered to investigate the typical Italian climates. The outcomes can give precious indications to rebuild the Italian residential stock with a view to energy-efficiency and cost-optimality, given that the optimal solutions provide low values of PEC – between 62.0 and 91.9 kWhp/m2a – and of GC – between 456 and 665 €/m2 – depending on the location.

The comprehensive optimization of building energy design is fundamental to promote sustainability but it is an arduous issue that involves a huge domain of variables and objectives. The proposed investigation addresses this issue through a novel comprehensive framework – Harlequin – that performs a multi-phase and multi-objective design optimization. Three phases are carried out to optimize design variables related to the whole building-plants system, considering different energy, comfort, economic and environmental performance indicators. Phase 1 implements a genetic algorithm to achieve the Pareto optimization of envelope, geometry and space conditioning set points. Phase 2 performs a smart exhaustive sampling of design scenarios to find optimal energy systems. Phase 3 provides the most sustainable, the cost-optimal and the lowest investment (but energy-efficient) design solutions. Among these, the stakeholders can choose the best solution according to their wills and needs. Harlequin uses EnergyPlus (only in phase 1) and MATLAB® and it is so-called because building geometry and envelope are optimized for each exposure, thereby providing “Harlequin buildings”. The novelty and scientific significance consist in ensuring a reliable design optimization by investigating a domain of variables and objectives, as comprehensive as never before. As a case study, Harlequin is applied to design a typical Italian office in Milan. Compared to a reference design, significant reductions of primary energy consumption (PEC), global cost (GC) and CO 2 -eq emissions can be achieved, depending on the chosen solution. The maximum reductions are 43.9 kWh p /m 2 a for PEC, 63.9 €/m 2 for GC (discount rate of 3%) and 12.3 kg/m 2 a for CO 2 -eq. © 2019 Elsevier Ltd

A comprehensive multi-objective optimization framework is proposed to address the energy retrofit of typical villas on Mediterranean coastlines. Primary energy consumption and global cost are minimized using a Pareto approach. Two different construction technologies (i.e., a lightweight house in reinforced concrete and a massive tuff-made villa), in two different climates (i.e., Greek and Italian coasts), are investigated to provide robust optimal retrofit strategies according to two different criteria, i.e., the achievement of the nearly zero energy standard and the cost-optimality, respectively. The optimal energy retrofit strategies are achieved by coupling transient energy simulations and a genetic algorithm. They address all main factors affecting energy performance, i.e., building envelope (thermal insulation, reflectance of coatings, windows and solar shading), active energy systems (space conditioning devices) and renewable energy sources (solar photovoltaics). The investigation findings can provide useful generic guidelines for the retrofit of houses on the Mediterranean coastlines with a view to energy-efficiency and cost-effectiveness. The implementation of the suggested retrofit strategies to the case studies can yield substantial primary energy savings, up to 125 kWh/m2a, and global cost savings, up to 140 €/m2. The most energy-efficient and cost-effective retrofit solutions are the improvement of energy systems’ efficiency, the installation of full-roof photovoltaic systems, the replacement of windows and the roof thermal insulation.