Thermal Engineering and Building Energy Systems

Abstract

This chapter summarizes the research activities and main outcomes of the groups engaged in Thermal Engineering and Building Energy Systems, in the decade 2013–2023. The research topics are typical of the sectors called “Fisica tecnica industriale” and “Fisica tecnica ambientale”.

1 Introduction

Research activities in the field of Thermal Engineering and Building Energy Systems have been carried out at the Università degli Studi di Napoli Federico II throughout the last decades. They concerned all the topics pertaining to Fisica tecnica industriale (FTI) ed Fisica tecnica ambientale (FTA) mentioned in the October 4, 2000, Italian Ministerial Decree, which are resumed as follows.

FTI investigates fundaments and industrial engineering applications of thermodynamics, heat transfer and applied energy, thermodynamics of energy processes and their impact on the environment, conversion and use of renewable and non-renewable energy, energy management, thermo-economy, combined heat transfer mechanisms, refrigeration, thermal plants, thermo-physical properties of materials, thermofluid-dynamics measurements and regulation.

FTA investigates fundaments and building applications of thermodynamics, heat transfer and applied energy, lighting and applied acoustics in industrial and civil buildings as well as in territorial planning and architecture, physics of indoor environment, conditioning plants aimed at comfort and air quality, measurement and processing of ambient data, active and passive conditioning systems, energy and environmental planning, management of energy systems.

In the last decade researches have been focused on the topics described in the following sections: Applied acoustics, Energy efficiency and renewable energy, Heat transfer in civil, industrial and biological systems, Heating, ventilation, air conditioning and energy efficiency of the building-plant system, Indoor environmental quality, Lighting, Experiments and modelling of innovative systems for refrigeration, Refrigeration and heat transfer on systems alternative to vapor compression, Sustainable energy systems.

The above reported topics are also addressed in undergraduated, graduated and Ph.D. courses in Engineering and Architecture at the Università degli Studi di Napoli Federico II; students also attend Ph.D. courses and seminars in other universities in Italy and abroad.

2 Background and Legacy

The research and teaching activities were carried out at the Istituto di Fisica tecnica until the end of the seventies of the last century, then at the Dipartimento di Ingegneria meccanica per l’energetica during the eighties, and at the Dipartimento di Energetica, termofluidodinamica applicata e condizionamenti ambientali up to October 31, 2012, when the Dipartimento di Ingegneria industriale was activated.

Many researchers educated under the Fisica tecnica in the Università Federico II have been serving as professors in several Italian Universities, some of them holding important academic positions.

In the last decades Professors Cesarano, Fucci, Ianniello, Mazzei, Naso, Reale, Vanoli, Vigo retired; Professors Alfano, Berardi, Betta, Cannaviello passed.

3 Main Research Programs

3.1 Applied Acoustics

The research activity of the team is focused on several issues of environmental, industrial and architectural acoustics. It is aimed at the analysis of the interaction between sound waves and porous materials for civil and industrial applications [1,2,3] as well as for the improvement of acoustic insulation and acoustic comfort in rooms [4, 5]. The research team has also developed models, procedures and measurement equipment for the characterization of porous materials to be used in the development of thermo-acoustic devices [6,7,8,9] and for the assessment of the acoustic behaviour of innovative materials, such as metamaterials [10] (Fig. 1).

Fig. 1

Measurement set-up to assess the complex Young’s modulus of porous materials

Experiments are carried out in the acoustics laboratory of the department, equipped with a small semi-anechoic chamber and devices for the determination of the main properties affecting the acoustic behaviour of porous materials and metamaterials as well as for the assessment of the room acoustic quality. Recently, the laboratory has been equipped with two measurement prototypes: one aimed at assessing, at low frequency, the thermal and viscous dissipative effects in porous materials and the other for testing the performance of non-conventional porous materials used in thermo-acoustic devices.

The research team collaborates with several foreign universities, such as the University of Tallinn, the University of Salford, the University of Achen, the Gustave Eiffel University.

The research programmes funded by public institutions have been:

• PRIN 2017: “Thermoacoustic technology for solar and waste heat powered energy conversion systems” in collaboration with University of Naples Parthenope, University of Messina, University of Cagliari and National Research Council.

• Research Agreement DII-CeRICT scrl: “Vibro-acoustic analysis for quality control” in collaboration with P &P Product and Process Development srl.

• Research Agreement DII-MedITech Competence Center: “Measurement of the mechanical characteristics of polyurethane foams and numerical-experimental assessment of the radiation efficiency of EPDM plates combined with polyurethane foams” in collaboration with Adler EVO srl.

3.2 Energy Efficiency and Renewable Energy (EERE)

Research activities are carried out on the development and application of advanced models for the dynamic simulation and optimization of systems. The main SW tools used are TRNSYS, Energy Plus, MATLAB, SIMULINK, EES, Fortran, Aspen plus, ENERGY PLAN, Labview. Researches are focused on the thermodynamic and thermo-economic simulation, analysis and optimisation of systems and technologies for energy saving and renewable energy in buildings, industrial applications and transports. Recently, key enabling technologies for the energy transition, such as thermal and electric energy storage systems and hydrogen-based applications, have been emphasised.

The main research topics are:

• solar energy, including Concentrated Solar Power (CSP), hybrid Photovoltaic-Thermal systems (PVT), Building-Integrated PV (BIPV) and combined PV/Wind systems [11,12,13] (Fig. 2);

• geothermal energy [14];

• renewable district heating and cooling, Combined Heat and Power (CHP), polygeneration and multi-energy systems [13, 15].

Fig. 2

Experimental set-up for hybrid photovoltaic-thermal collectors: (1) PVT collectors; (2) BSV ELBI storage tank; (3) connection pipes; (4) expansion vessel; (5) safety valve; (6) circulation pump

In the last decade, the team has reinforced its international cooperations, which now include Virginia Tech (USA); Colorado School of Mines (USA); A. Alto University (Finland); University of Cyprus; University of Zagreb (Croatia); University of Zaragoza (Spain); Concordia University (Canada); Universidad Carlos III de Madrid (Spain); University of Krakow (Poland).

Research programmes have been funded by public institutions:

• 2010–2013: SAHARA (Solar-Assisted Heating and Refrigeration Appliances), financed by the Italian Ministry of Environment;

• 2012–2015: “RISE—Research and Innovation in the Energy Field”—Work Package: Solar Energy, financed by Regione Campania, PON 2007–2013;

• 2018–2021: “Biofeedstock—Development of Integrated Technological Platforms for the Valorisation of Residual Biomass”, Work Package: biogas and biomethane from organic waste, financed by Italian Ministry of University and Research (MUR), PON R &I 2014–2020 e FSC programmes;

• 2020–2022: “Optimal refurbishment design and management of small energy micro-grids”, funded by the Italian MUR, PRIN 2020.

3.3 Heat Transfer in Civil, Industrial and Biological Systems

The research team, by means of experimental, numerical, and analytical approaches, investigates heat transfer phenomena in several applications of life and science. The activities are described in the following.

Energy efficiency in buildings. The research concerns the environmental impact of the use of energy, from the single material to the whole building, both in the operating phase and the lifecycle. Two main areas and challenges for future years are considered: a sustainable retrofitting of existing buildings and a new paradigm of the energy performance of the new architecture, to match the mandatory sustainability requirements for a low-carbon future.

Heat transfer in buildings and in industries is investigated at different deepening levels, depending on the needs of each program. Heat transfer in industrial applications is investigated from micro- to macro- scale, with both theoretical predictive models and engineering devices. Renewable thermal energy conversion in industrial processes, measurement methods and materials suitable for providing renewable heat most efficiently as well as bioheat transfer for various potential clinical applications are studied.

The research team collaborates with the Universities of Seville, Minho, Split, Athens, Thessaloniki, BBSR in Germany, UPV in Valencia, INSA in Lyon, New South Wales (UNSW) in Australia, Connecticut (UConn) in USA, Purdue University in West Lafayette USA, University of California in USA. Experimental studies at a real-scale, living labs and test rooms—performed with numerical calculation labs, workstations, remote controls, IoT, are carried out in partnership with the Università del Molise and the Università del Sannio. Research activities are also carried out with Italian ENEA, CNR and I.S.A.S.I-CNR.

As far as energy efficiency in the civil sector is concerned, within national and international collaborations, methods and technologies to improve the energy efficiency of the massive and inefficient built environment (buildings with cultural value, health facilities included) are investigated. The research involves primary issues of energy efficiency in the building sector, like materials and technologies of the building envelope, active energy systems for microclimatic control, environmental comfort, and energy supply from renewable energy sources. The main research fields of the research team are:

• EVALUATION METHODS. Methodologies for calculating the energy performance indexes, with reference to both the building envelope and active energy systems, according to the EU EPBD targets and the EPBD cost-optimality. Multi-objective optimization of building energy performances, taking into account investments, indoor comfort, operational energy demands. Model predictive control (a day-ahead planning horizon), to reduce the operating cost of space conditioning and thermal comfort. Research of simplified methodologies for evaluating the energy performance of new and existing buildings, in order to transfer data into Geographic Information Systems (GISs) and develop Urban Energy Maps.

• ENVELOPE TECHNOLOGIES AND ENERGY SYSTEMS. Building components and responsive technologies to mitigate the heat gains and cooling loads (dynamic insulation; airflow in vented walls and double skin facades; cool materials and selective coatings; phase change materials [16]; evapotranspiration in green-based building components). HVAC systems to reduce the operating costs of high-care facilities, cultural heritage, and educational buildings, with reference to both systems for air conditioning and air diffusion equipment. Renewable-based building components and systems, passive and active solar technologies for buildings, and exploitation of the ground source.

• WHOLE BUILDING ENERGY ANALYSES. Evaluation of buildings energy performances through hourly energy simulations, to propose tailored refurbishments. Development and validation of numerical methods, aimed at the integration into hourly energy simulation codes, for the solution of two-and three-dimensional thermal bridges. Integrated optimizations of building energy retrofits, with reference to both energy performances and structural safety, in order to improve the building behaviour by considering the cost-optimality in seismic areas.

• DISTRICTS AND URBAN SCALE. Large-scale energy optimization of the energy retrofit of entire building stocks, by means of either uncertainty and sensitivity analyses or the development of surrogate models, like artificial neural networks [17]. Proposal and testing of mitigation strategies at both building and district scales to improve living conditions in suburbs and massive house for low-income people, paying attention to both energy performance and comfort. Development and Optimization of Smart and Renewable Energy Communities. Digitalization and Artificial intelligence in building energy efficiency, energy sharing, and sustainable management.

Heat transfer in industries. Heat transfer plays a primary role in several sectors, such as electronics, renewables, manufacturing new materials, like metal foams and phase change materials. Heat removal from electronic systems, renewable energy conversion, as well as novel thermal energy storage systems are investigated.

With reference to industrial applications, nowadays new solutions based on innovative materials are required in applications where heat transfer plays a primary role, such as thermal management for heat removing from electronic components or renewable energies requiring more efficient systems. The investigated fields are:

• Metal foams pore-scale analysis, to investigate typical heat transfer parameters, such as effective thermal conductivity, permeability, radiation extinction coefficient, and convection heat transfer coefficient, by using different techniques to generate the metal foam structure [18].

• Macro-scale analysis, using volume-averaged approach, to simulate and optimize engineering devices, like metal foam-based heat sinks and similarly ceramic foam-based volumetric air solar receivers.

• Numerical heat transfer studies on phase change materials, to predict the melting evolution and to improve it by means of metal foams.

• Engineering applications of phase change materials, either to store energy or to be included within heat sinks for electronics, also with metal foams.

Heat transfer in solar-thermal and hybrid collectors. In the context of the global drive towards clean, cost-effective, and sustainable alternatives, solar-based power plants are main actors in renewable thermal energy conversion. This plays a key role in many applications, ranging from the agri-food sector to petrochemical industries. All major components—from collectors to piping—are subjected to heat transfer principles and optimization criteria. Advanced absorbent surfaces and high vacuum insulation are studied, measuring and enhancing the thermal efficiency of high-vacuum solar collectors and power plants.

Several industrial processes, like boiling, steaming, pasteurising, require thermal energy at operating temperatures below $150^{\,\circ }{\text {C}}$. At these temperatures, thermal demand can be satisfied by adopting renewable solutions like solar-thermal and hybrid photovoltaic-thermal flat plate collectors. Methods and materials suitable for providing renewable heat efficiently are studied, focusing on high vacuum insulation technology and deposition and characterization of selective solar absorbers. The following fields are investigated:

• Control, measurement, and simulation of radiative and optical characteristics of materials, lowering the emittance of selective solar absorbers to reduce the radiative losses of the collector; development of low emissive materials mounted on the absorber surface; design and development of new selective solar absorber coatings with optimized optical characteristics attaining higher operating temperatures than commercial absorbers (up to $200^{\,\circ }{\text {C}}$) [19].

• Building up a Mini Test Box with an experimental set up for the measurement of the emittance and the absorptance of selective solar absorbers. Measurements are made with the calorimetric approach, which allows the sample characterization in a wide range of temperatures; building up an under vacuum oven and designing a procedure for aging tests of new absorber samples; defining a new Performance Criterion based on absorber efficiency and forecasting the service lifetime; setting up a new procedure to reconstruct the specific temperature frequency function of absorbers, which accounts for the high thermal efficiency and stagnation temperature and predicts the aging of absorbers employed in mid-temperature applications; deriving new efficiency correlations, for both Non-Evacuated and High-Vacuum Flat Plate collectors (different kind of solar absorbers).

• Modeling through Matlab of Novel Hybrid Flat Plane Photovoltaic-Thermal collectors insulated in high vacuum (HV PV-T), optimized for thermal production. The model is based on the Spectral Splitting concept, the thermal coupling of a high-band gap PV cell and a Solar absorber, the adoption of low emissive transparent conductive oxides, and high vacuum insulation.

• Modelling, testing and optimization of several auxiliary technologies for solar thermal power plants; CFD simulation of Sensible Stratified Thermal Energy Storages (SSTES), with the generation and validation of data-based models; experimental and numerical optimization of control logics and functional parameters; data-driven model predictive control applied to thermal energy storage systems and solar thermal power plants; design and thermal test of high-vacuum insulator for heat delivery pipes as well as proposal of a novel high vacuum-based solution; optimization of indirect and direct solar-generated low and middle pressure steam production systems.

Heat transfer in biomedics. Understanding the mechanisms ruling biological processes within the human body is an old-fashioned problem, crucial to propose new potential clinical solutions. Heat transfer—especially when it is relevant in clinical applications—plays a significant role in treating cancer, cardiovascular diseases, and so on. Research is carried out in order to optimize existing medical treatments and to find new ones.

The biomedical industry includes high temperature applications, where heat transfer is of primary importance. They include tumors ablation via radiofrequencies or microwaves, hyperthermia to treat heart arrhythmias, as well as hyperthermia that might affect low-density lipoproteins deposition. The heat transfer team is carrying out the following research activities in the bio heat transfer sector, employing both numerical and analytical approaches:

• Cancer treatment via radiofrequencies or microwave ablation, in order to improve existing predictive models and therapies [20].

• Arrhythmia treatments, like atrial fibrillation, via radiofrequency-induced cardiac ablation, with the aim of improving existing predictive models.

• Low-density lipoprotein deposition in arterial walls, to mark temperature effects on molecules transport and atherosclerotic plaque growth.

3.4 Heating, Ventilation and Air Conditioning (HVAC) and Energy Efficiency of the Building-Plant System

The research team investigates the optimization of the building-plant system, mainly with reference to Heating, Ventilation and Air Conditioning (HVAC) systems.

The main research topics are innovative HVAC systems; energy efficiency of the building-plant system, like Net Zero Energy Buildings (NZEBs); hygrothermal characteristics of the building envelope.

The Earth-to-Air Heat Exchanger and its applications in civil buildings were analysed in [21, 22] by coupling it with an air handling unit, to obtain high energy saving and reduction in CO$_2$ emissions for the HVAC system. The efficiency of this innovative system has been proven for several worldwide climatic conditions.

A simulation research activity refers to NZEBs, particularly to the integration of a geothermal heat pump and its energy comparison with that of an air-to-water heat pump. The research activity was based on a simulative approach; a multi-objective optimization was also employed [23].

An experimental research activity on the desiccant wheel [24] was performed with the Università del Sannio. This innovative typology of air dehumidification was compared to the traditional mechanical dehumidification, and significant energy saving has been obtained.

The energy performance of a historic building (Palaeontology Museum of the Università degli Studi di Napoli Federico II) was analysed by dynamic energy simulation [25].

Research was carried out on building envelopes, by predicting how a high insulation thickness could increase energy consumption in summer [26], and by evaluating, through experimental laboratory tests, the thermal decay of external thermal insulation of a NZEB [27].

The research team collaborates with the Università di Salerno, Università del Sannio, University of Zagreb (Croatia), Pennsylvania State University (USA), as well as with other departments of the Università Federico II. The researchers in the team have been Guest editors of special issues for the international journal “Energies”.

3.5 Indoor Environmental Quality

Since its birth the research team has dealt with the indoor built environment, occupational hygiene and historical building preservation issues.

Research programs cover three main areas: Indoor environmental quality (IEQ) and indoor built environment, historical buildings, occupational health issues. They were financed mainly by national (PON, PRIN, PNRR) and local (FRA, FARB) programs.

The criticalities in the subjective and objective assessment of thermal comfort conditions [28], consistently with energy-saving requirements, were investigated [29]. The studies also dealt with the synergies among the four components of the IEQ [30] and the measurement of physical quantities [31,32,33] (ISO 7726). More recent studies focused on the role of ventilation in public transport environments to predict contagion [34].

Special protocols for the control of microclimatic conditions in historical buildings [35] and the diagnosis of moisture in buildings affected by rising damp [36] were developed. Further studies also dealt with energy issues.

The criticalities of the metrics for the evaluation of heat and cold stress conditions at workplaces were investigated [37]. Results have been included in the revisions of ISO Standards 7243, 7730, 7933 and 11079.

Collaborations were established with the Università degli Studi di Cassino e del Lazio Meridionale, Università degli Studi di Salerno, Technical University of Denmark, Université Catholique de Louvain, Standardization bodies (UNI, CEN,’ISO), technical associations in the field of air conditioning (AiCARR) and scientific societies (AISI).

The team members are leading or joining important research institutions, technical committees and editorial boards of journals.

3.6 Lighting

The research team started research in lighting focusing on the evaluation of indoor daylight availability, the characterization of sky models, and the measurement of indoor and outdoor luminance distribution. A small laboratory was set up, where some main photometric characteristics were measured.

Almost coinciding with the transition to the DII, the world of lighting was revolutionized thanks to various technological and scientific developments: the spread of LEDs, the progress on automatic controls, the discovery of light effects on circadian rhythms. Therefore, the research perspectives expanded as the research activities of the team too. The laboratory was upgraded with several new instruments for spectral measurements, crucial for the evaluation of non-visual effects of light. A test-room was equipped with a false ceiling in which different LED sources are installed. The sources are managed by a controller, setting different scenarios. Moreover, two twin test-rooms have been set up equipped with different LED sources. Both the test-room and the twin rooms are used for the experimental studies evaluating visual and non-visual effects of light on people.

The team carries out numerical and experimental research activities on daylight and its impact on people’s well-being and on the reduction in electricity consumption [38, 39], the integration between daylight and electric lighting through automatic controls [40], the “non-visual” effects of light, such as the impact of lighting on performance, mood, attention, and circadian rhythms [41]. The characterization of the quality of the luminous environments and the lighting applied to cultural heritage [42, 43] are also investigated.

The research team collaborates with national and international partners. Moreover, it actively participates in the associations promoting lighting culture both in Italy and around the word. A member of the team is President of the Associazione Italiana di Illuminazione (AIDI) in the period 2023–2025 and Governing Board Member of the Commission Internationale de l’Eclairage (CIE) in the period 2023–2027, another member is vice-coordinator of the CIE National Committee—Division 3: Interior Environment and Lighting Design.

Research activity was mainly funded within the PON SMART CASE 2013–2016, PRIN 2015, PNRR PE PE5 CHANGES PE00000020 and FRA 2020 Linea B programs.

3.7 Experiments and Modelling of Innovative Systems for Refrigeration

The research topics of the team are related to experimental activities, modelling and simulation of refrigeration systems and their devices, with a special focus on advanced two-phase heat transfer systems.

Fig. 3

Prototype of a multi-ejector carbon dioxide heat pump tested in cooperation with ENEA

The performance of heat pumps and refrigerating plants, using new refrigerants able to reduce their contribution to global warming, has been investigated. As a part of a six-year project funded by the Italian Ministero dello sviluppo economico through ENEA, an experimental and parametric analysis was carried-out on carbon dioxide heat pumps with multi-ejectors expansion devices (Fig. 3). New applications of heat pumps working with natural fluids, within an FP7 European project, their potential use and risks were investigated [44]. Within the SMART-CASE project, the optimal design of heat pumps for residential use, employing several refrigerants with a multi-objective approach including total costs of ownership and environmental impact during life cycle, was investigated [45]. Recently, the integration of heat pumps with energy storage systems and air, sun, ground as heat sources, has been studied in projects with companies and in cooperation with the University of Huelva (ES) [46]. Also, as a part of a project financed by the Italian Ministero dello sviluppo economico through ENEA, the effects of multiple faults on the performance degradation of heat pumps have been assessed and the possibility to find such faults based on direct and cheap measurements has been demonstrated [47]. A national project on this topic is also funded by MUR in the frame of PRIN2022 and is coordinated by the group. Several studies related to special applications for the commercial and transport refrigeration have been performed, also with funding from private companies. A special attention is paid to the study of two-phase heat transfer and pressure drop in flow boiling of new refrigerants and spray systems. The main objective is to provide experimental data for the design of innovative heat exchangers and heat sinks to the industry. The research team, one of the leading worldwide concerned on this topic, produced with continuity a large database of accurate experiments for the academy and the industry, also in cooperation with other labs, like LTCM at EPFL(CH) [48, 49].

The research team runs the Refrigeration laboratory at the Università degli Studi Federico II in Napoli and has established several and durable research cooperations with national and international Universities, research centres and private companies, such as CEMAFROID (FR), CNR (IT), ENEA (IT), EPFL (CH), INSA Lyon (FR), University of Byalistok (PL), Università del Molise (IT), Università di Padova (IT), Università del Sannio (IT), Università di Salerno (IT), University of Huelva (ES), University Pol. of Valencia (ES). Also, the group is affiliated and contributes to scientific and technical activities of relevant associations for the sector (like IIR, IEA and AICARR), covering several representative roles in working groups, scientific and technical committes and boards.

3.8 Refrigeration and Heat Transfer on Systems Alternative to Vapor Compression

The research activities are mainly focused on finding new viable alternative systems to vapor compression in refrigeration, air conditioning and heat pumps systems. Vapor compression refrigerants are mostly synthetic (CFC, HCHC, HFC, HFO) or natural (CO$_2$, NH$_3$, hydrocarbons). In the past, synthetic refrigerants have been responsible of the ozone layer thinning and have been replaced on the basis of regulations by non-zero Ozone Depletion Potential (ODP). Substitute fluids HydroFluoroCarbons (HFCs), however, are characterized by a significant direct contribution to global warming since they have high Global Warming Potential (GWP). The need, therefore, arises to develop further alternative refrigeration techniques. Among these, there are those based on solid-state refrigerants which aren’t harmful to the environment (zero ODP and GWP) and are based on the caloric effect proper of solid materials through a temperature change because of an adiabatic variation of an external field.

Technologies based on the caloric effects are a feature topic. Magnetocaloric was the first caloric effect investigated by the team. The research concerned the realization of 8Mag, the first experimental prototype of an Italian rotating magnetocaloric refrigeration, and test campaigns on it as well as the modelling of magnetocaloric devices for numerical investigation [50, 51]. Electrocaloric, elastocaloric, barocaloric were also investigated numerically in order to identify the most promising caloric refrigerants [52, 53]. Elastocaloric technology based on elastocaloric effect, which is a physical phenomenon where a Shape Memory alloy forced through a mechanical stress varies its reticular structure and, consequently, its temperature. Thanks to the project SUSTAINABLE the first Italian heat pump based on solid-state refrigerants showing an elastocaloric effect is being built at the DII Heat Transfer Lab [54]. Within the CHECK TEMPERATURE project, the first elastocaloric device in the world for electronic circuits cooling was designed [55]. Studies on vapor compression about substitutive refrigerants due to high GWP, e.g., the replacement of HFC134a with HFOs, continued [56]. The heat transfer and energy performance of renewable energy source systems, such as Earth-to-Air Heat Exchanger, were evaluated numerically [22].

3.9 Sustainable Energy Systems (SES)

The research team is involved in studies on various cutting edge energy systems. Skill and expertise are modelling, simulation and optimization of systems, especially coupled to renewable energy-based technologies. Energy, economic and environmental performances of systems are assessed through a dynamic analysis by developing in-house simulation models. Renewable energy sources, new energy saving plants and innovative HVAC systems for civil and industrial applications are studied for achieving energy efficiency/flexibility and sustainability in the next generation of buildings, communities, transportation systems (ships, trains, e-cars, etc.) and related infrastructures (ports, stations, etc.) towards the zero-energy goal. Innovative energy saving technologies and materials for systems envelopes are also analysed. Experimental analyses are also employed [57,58,59,60,61,62,63].

Scientific activities are carried out in collaboration with international partners through suitable academic Memorandum of Understanding (MoUs): Cyprus University of Technology; Ulster University, UK; Universitat de Lleida, Spain; Concordia University, Canada; University of Colorado Boulder, USA; Imperial College London, UK; Rovira i Virgili Universitat de Tarrragona, Spain; University of Patras, Greece. Joint collaborations are/were also conducted with: Ben Gurion University of the Negev, Israel; Lawrence Berkeley National Laboratory, USA; Fraunhofer Institute for Solar Energy (ISE), Germany; Dublin Institute of Technology, Ireland; University of Cyprus; Eurac (European Academy), Italy; ENEA, Italy.

Research has been also funded by many projects, awarded by members of the team, that received several M€ in grants and public/private funding. The research team is promoter or responsible of the research projects HEMOS—Ship Heat Energy Management System by the Aid of Dynamic Optimization Algorithms, funded by HORIZON Europe; LOVE 4 PIPENET, funded by Italian Territorial Cohesion Agency; Energy sustainability, air quality and indoor comfort in modern ships for the development of architectures and technologies that enable significant optimization of energy consumption in the naval field, funded by Fincantieri; SuShi—Sustainable Ships, funded by Fincantieri; Strengthening and critical analysis of the Regione Campania School Building Registry (energy aspects), funded by Regione Campania; Comparison of new calculation methodologies with those provided by current regulations, funded by MISE; Smart and sustainable industry, energy and environment: technologies for renewable sources based on innovative solar thermal collectors, funded by the Italian Ministero per l’Istruzione, l’università e la ricerca (MIUR); FC SMART GEN—Fuel Cells and Hybrid Polygeneration Platforms from fossil and renewable sources, PON01 02864 funded by MIUR; NEXT.COM—Towards the NEXT generation of multiphysics and multidomain environmental COMfort models: theory elaboration and validation experiment, PRIN 2017 funded by the Italian Ministero per l’Università e la ricerca (MUR); GREENROAD—GRowing Energy Efficiency through National ROundtables Addresses, funded by Horizon 2020; HERA—Holistic Energy Recovery Agent tool for sustainable urban clusters, PRIN 2022 funded by MUR; DiAGreen—Digital twin of Agricultural Greenhouses: a multi-domain tool for energy efficiency, decarbonization, enhanced production and cost reduction of intensive greenhouse cropping; Nest—Network 4 Energy Sustainable Transition, Spoke 6 (thermal storage) funded by MUR. Adolfo Palombo is national scientific responsible of the project PRIN 2022 funded by the Ministero per l’Università e la ricerca (MUR), ATOL—Advanced Thermal energy storages On Large ships.

Research activities are also carried out either with or funded by industrial companies (CETENA SpA, Fincantieri SpA, Hitachi Rail STS SpA, GESAC SpA, Carrier) and important national research institutions (ENEA, EURAC and the Azienda Universitaria Ospedaliera (AOU) Federico II).

A patent was released by European Patent Office/Register in 2022 (n. 4046834A1) “Electric or hybrid traction vehicle equipped with an air conditioning system, with heat recovery from cooling of electrical and/or electronic components”.

In collaboration and co-ownership with Hitachi Rail STS SpA, researchers of the team are members of the International Scientific Committee of the International Center for Sustainable Development of Energy, Water and Environment Systems (SDEWES). They are also permanent members of the editorial board of several Q1 Journals (Elsevier’s Renewable energy, Energy conversion and management, and others), also serving as associate and senior editors for the Elsevier Journal Energy reports. Researchers of the team were members of the Management Committee of the Action TU1205 Building Integration of Solar Thermal Systems, BISTS of the European COST (Cooperation in Science and Technology), Transport and Urban Development (TUD) funded by Horizon 2020. Additional present and past memberships: member of the Management Committee of the Blue Italian Growth National Technology Cluster (BIG); member of the Board of Expert of Italian Energy and Environmental Services (IEES); member of the Management Committee of IBPSA-Italy; member of the Board of Experts at the Permanent Observatory on Energy, Water and District Heating Regulation of ARERA; member of the Board of Verification Activities of Italian Energy Services Manager (GSE).

4 Future

The future research activities of the Applied Acoustic team will be focused on the use of auralization techniques to be applied in the insulation of both airborne and structure-born sound, in the construction of binaural room impulse responses and in the assessment of the industrial products sound quality, especially in the automotive field. The use of ultrasound techniques to detect failures in concentrating solar power plants will also be investigated.

In the next future, the Energy Efficiency and Renewable Energy (EERE) team will be involved in two major experimental research programs, in the framework of the National Plan for Recovery and Resilience—Next Generation EU program:

• 2021–2024: NEST—Network 4 Energy Sustainable Transition, Spoke 7 (Smart sector integration) and 8 (Final use optimization, sustainability & resilience in energy supply chain), funded by the Italian Ministero dell’università e della ricerca (MUR).

• 2022–2024: GRETHA—a novel GReen Energy Technology based on fuel cells, hydrogen and renewables, funded by the Italian Ministero della Transizione Ecologica.

In the Heat transfer in civil, industrial and biological systems field, a strong strengthening of the national and international collaborations to share methods, approaches, and results is expected in the next years. Besides key concepts of nearly, net and zero-energy buildings, the target of the research team is a wider horizon, that looks at the whole community. “Living spaces” should be transformed into “liveable spaces” to contrast the energy poverty and to guarantee the human, universal, and European rights of the well-being and pleasant life, compatible with the right and responsible use of energy, emissions, and environmental impacts. Within the industrial applications, new techniques to improve the capability of managing heat at higher power densities will be proposed and optimized, to be sure that the electronics industry will be able to design better performing devices. On the renewable energy conversion, high vacuum flat plate collectors, equipped with the projected optimized absorbers, will first be designed numerically and then prototypes will be tested by means of real scale experiments. A novel measurement chain will be developed to evaluate the effective thermal energy exploitable with high-vacuum hybrid collectors. Moreover, new thermal energy storage devices will be proposed to improve the overall efficiency of renewable energy-based systems. Finally, new techniques for cancer treatment and other similar diseases will be investigated.

Future research in Heating, Ventilation and Air Conditioning (HVAC) and energy efficiency of the building-plant system will concern high-efficiency air conditioning systems and their influence on Zero Carbon Buildings, through simulation, experiments and multicriteria optimization approaches.

The research on Indoor environmental quality will enlarge its horizon consistently with the challenge imposed by the energy transition, climatic change, and cultural heritage preservation. Advanced thermal comfort models, such as adaptive and thermo-physiological for possible applications in naturally ventilated buildings, vehicles, workplaces and not uniform environments (e.g., industrial sites) will be investigated. To balance IEQ levels and energy consumption, specific studies on the mutual interaction among the four facets of the IEQ are in the program. A significant part of the activity will include new integrated monitoring strategies for IEQ parameters, aiming at designing and optimizing the sensors for assessing and controlling indoor environmental conditions, even in historical buildings, where fruition should be compliant with preservation.

Future research in Lighting will aim at deepening the non-visual effects of light and the potentiality offered by dynamic lighting control systems. They will be carried out within the scopes of the Subtask B of the IEA Task 70—Low Carbon, High Comfort Integrated Lighting. The activity concerning the effects of light on cultural heritage will continue, also funded by the PNRR.

The research team on Experiments and modelling of innovative systems for refrigeration will investigate new high temperature heat pumps for heating and industrial processes and the related technological challenges will be investigated experimentally and numerically. Also, the assessment of the potential advantages for the control, the energy performance improvement and the fault detection entailed by the use of artificial intelligence in the refrigeration sector will be investigated.

In the field of Refrigeration and heat transfer on systems alternative to vapor compression numerical and experimental studies will be carried out on the development of new devices based on solid-state cooling. Specifically, a new prototype based on the elastocaloric effect close to commercialization will be designed and constructed. Further investigations will be focused on multicaloric effects, i.e., the simultaneous combination of two caloric effects.

Future research in the Sustainable Energy Systems (SES) field will concern energy efficiency and environmental sustainability of innovative systems, including storage systems and renewable-based devices, to be implemented, along with novel energy management strategies, in buildings, communities, transportation systems, and associated infrastructures for flexibility and energy savings aims.

5 Awards

Many awards have been gained in relevant international conferences as well as many papers were rewarded as highly cited paper in Web of Knowledge database.

Fabrizio Ascione, Nicola Bianco, Annamaria Buonomano, Francesco Calise and Massimo Dentice D’Accadia are in the list of the top researchers of Università degli studi Federico II, ranked into the best scientists according to the standardized citation metrics of University of Stanford.

Fabrizio Ascione was awarded as author of the best paper published in (Solar Energy—Elsevier, 2017).

Diana D’Agostino won a national research award sponsored by the Associazione Nazionale Poliuretano Espanso rigido (ANPE).

Annamaria Buonomano has been an Affiliate Professor at the Department of Building, Civil and Environmental Engineering, Concordia University (Montreal, Canada), since 2017. With this university, several cotutelle Ph.D. programs were also activated.

Best Paper Awards

Best Paper Awards received by researchers of the Sustainable Energy Systems (SES) team at International Conferences are:

• Modelling the thermal response of the human body for thermal comfort assessment in indoor spaces: an experimental validation at METROLIVE 2022.

• Air-based photovoltaic thermal collectors: theoretical and experimental analysis of a novel low-cost prototype at SDEWES 2018.

• Solar Heating and Cooling Systems for Residential Applications: a Comparison among Different System Layouts and Technologies at SDEWES 2016.

• Comparison of the Electrical and Thermal Performance of Double Skin Facade and Insulating Glazing Unit integrating Semi–Transparent Photovoltaics at EU PVSEC 2018.

• Analysis of residential hybrid ventilation performance in U.S. climates at AIVC 2009.

Best Poster Awards

• Buonomano et al., “Solar Heating and Cooling Systems for Residential Applications: a Comparison among Different System Layouts and Technologies”, SDEWES 2016.

• Calise et al., “Dynamic Numerical Model for a Geothermal Well”, SMART-GREENS 2023.