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Ceramic tile manufacturing is a highly energy-intensive process. Concerns about carbon emissions and energy costs make energy management crucial for this sector, which holds a leading role in Italian industry. The paper discusses the energetic and environmental performance of cogeneration (CHP) in the ceramic industry, where prime mover exhaust heat is supplied to a spray-dryer system, contributing to the satisfaction of the thermal demand and decreasing natural gas consumption. A thermodynamic model of a dryer unit, validated against real data, has been set-up to provide a detailed representation of the thermal fluxes involved in the process. Then, the thermal integration with two types of CHP prime movers of similar electric size (4 MW) is investigated. Energetic results show that the gas turbine can contribute up to 81% of dryer thermal consumption, whilst internal combustion engine contribution is limited to 26%. A methodology was ad-hoc defined for the environmental assessment of CHP, accounting for global (CO2) and local (CO and NOX) emissions. Results confirm that CHP units guarantee reduction of CO2 and NOX compared to separate generation, with maximum values equal to 81 g/kWhth and 173 mg/kWhth, respectively; CO emission is decreased only in the case of gas turbine operation, with savings equal to 185 mg/kWhth.

Green roofs are components of the building envelope that have become increasingly popular in urban contexts because other than providing numerous environmental benefits they are also capable of reducing building energy consumption, especially in summer. However, despite all these advantages, green roofs are still affected by some limitations. Specifically, there are some gaps affecting the energy modelling consisting in the absence of a proper database, information (growth stage, leaf area index, and coverage ratio) relative to the different green roof plant species, which technicians could use in case of lack of actual field data to perform energy analysis of buildings equipped with green roofs. These gaps concern also environmental and economic assessments of such technology. In fact, the currently available green roof LCA and LCC studies seem to underestimate the role of the substrate on the overall environmental impact and the role of the disposal phase on the life cycle cost of the green roof. In this chapter, all these aspects are addressed, and contributions to their solution, which arose from both experimental and modelling research, carried out by the authors are presented.

Ceramic tile production is an industrial process where energy efficiency management is crucial, given the high amount of energy (electrical and thermal) required by the production cycle. This study presents the preliminary results of a research project aimed at defining the benefits of using combined heat and power (CHP) systems in the ceramic sector. Data collected from ten CHP installations allowed us to outline the average characteristics of prime movers, and to quantify the contribution of CHP thermal energy supporting the dryer process. The electric size of the installed CHP units resulted in being between 3.4 MW and 4.9 MW, with an average value of 4 MW. Data revealed that when the goal is to maximize the generation of electricity for self-consumption, internal combustion engines are the preferred choice due to higher conversion efficiency. In contrast, gas turbines allowed us to minimize the consumption of natural gas input to the spray dryer. Indeed, the fraction of the dryer thermal demand (between 600–950 kcal/kgH2O), covered by CHP discharged heat, is strictly dependent on the type of prime mover installed: lower values, in the range of 30–45%, are characteristic of combustion engines, whereas the use of gas turbines can contribute up to 77% of the process’s total consumption.

This paper investigates air-to-air (AAHX) and earth-to-air (EAHX) heat exchangers, to reduce the energy requirements of air conditioning systems for office buildings. The AAHX considered is of static type with a partition wall and allows recovering both sensible and latent heat. The EAHX technology exploits the capability of the ground as energy storage, through a system of earthed air ducts laid horizontally. In summer, the ground usually presents temperatures lower than outside ventilation air temperatures, while in winter it could have, in some hours/days, a temperature higher than the outside air. Three European cities are considered: Palermo (southern Italy), with mild winters and very hot summers; Milan (northern Italy), with cold winters and hot summers; Berlin (Germany), with very cold winters and quite hot summers. The analysis is performed by means of EnergyPlus, a dynamic building energy simulation software, with reference to the same, newly designed office building, with or without heat recovery systems. The air conditioning system is based on fan-coils and primary air, and the EAHX (or the AAHX) is inserted in the first part of the primary air-handling unit. The research shows that in winter the use of the AAHX reduces the energy requirement much more than the EAHX, while in summer the EAHX is preferable. Moreover, the annual analysis shows that the use of the EAHX is more convenient in hot climates. The case of coupled heat exchangers (AAHX + EAHX) is also investigated. The evaluated discounted payback is about 6–9 years for the EAHX (3–5 years if an incentive of 20% is considered) and 1–3 years for the AAHX (less than 1 year with the incentive).

Although the 2019 global pandemic slowed the growing trend of CO2 concentrations in the atmosphere, it has since resumed its rise, prompting world leaders to accelerate the generation of electricity from renewable sources. The study presented in this paper is focused on the evaluation of the energy and environmental benefits corresponding to the hypothesis of hybridizing a dish-Stirling plant installed on the university campus of Palermo (Italy). These analyses were carried out by means of dynamic simulations based on an accurate energy model validated with the experimental data collected during the measurement campaign that occurred during the period of operation of the reference plant. Assuming different scenarios for managing the production period and different fuels, including renewable fuels, it was found that the annual electricity production of the dish-Stirling system operating in solar mode can be increased by between 47% and 78% when hybridized. This would correspond to an increase in generation efficiency ranging from 4% to 16%. Finally, assuming that the dish-Stirling system is hybridized with renewable combustible gases, this would result in avoided CO2 emissions of between approximately 1594 and 3953 tons over the 25-year lifetime of the examined plant.

The purpose of this study is investigating the grid parity (GP) time and the levelized cost of energy (LCOE) of grid-connected photovoltaic (PV) systems installed in densely urbanized contexts. The analysis, which was elaborated for three Italian cities, considered the effects of the promoting policies enacted by the Italian government from June 2010 to May 2016. An appropriate methodology was applied with the aim of realistically defining the energy produced by PV systems installed on buildings with different roof types and number of floors. The calculus of the disbursements considered the operating, maintenance and insurance costs and the wear of PV panels and inverters. The results showed that, depending on the type of the initial investment (with or without a bank loan), the site latitude and the solar shading caused by possible obstacles, the calculated values of LCOE vary from 0.219 €/kWh to 0.485 €/kWh. The time to reach the grid parity resulted shorter than 20 years for the cities in Southern and Central Italy, even considering a reduction of 10% of the solar radiation caused by the surrounding obstacles; less favourable values were obtained in the north of Italy.

This work analyses experimentally the possibility of using the reduced GWP refrigerant R-407H (HFC family, GWP = 1378) as drop-in substitute of R-404A (HFC family, GWP = 3945) in low temperature centralized direct expansion refrigeration system. The experimental plant and the test methodology are described. It covered top up or partial drop-in and energy consumption tests at −20 °C of product temperature and 25, 35 and 45 °C of condensing temperature using a small-scale supermarket under laboratory conditions. It has been measured that the use of R-407H instead of R-404A is favourable from the point of view of energy efficiency. Reductions in the energy consumption of up to 7.7% (compressor) and 4.0% (whole system) have been measured. However, there is an increment in the compressor's discharge temperature of up to 13.8 K. In addition, the operation of the system with both refrigerants was correct. The authors gratefully acknowledge the Ministerio de Economía y Competitividad – Spain (project ENE2014-53760-R.7, grant FPI BES-2015-073612) for financing this research work.

In this study the discounted pay-back (DPB) period of rooftop photovoltaic (PV) systems installed in urban contexts was investigated during the course of time with the aim of evaluating the effects of the different supporting policies enacted by the Italian government. The profitability of the investment in three Italian cities was observed from June 2010 to May 2016 by means of an exhaustive economic analysis based on the study of the variation of the costs and benefits during the lifetime of the investment. The analysis considered the disbursements for the PV system devices, maintenance and management, insurance, and wear of PV panels and inverters. Other significant parameters, such as the degradation rate in the efficiency of the PV panels, the discount rate, the inflation rates and the revenues from the sale of the energy exported to the grid and the reduced electricity bills were also taken into account. Compared to the feed-in tariff (FIT) and premiums mechanism in force in Italy until July 2013, the current tax credit program has determined shorter values of DPB periods, which, depending on the site latitude, range from 7.44 to 12.78 years at the end of 2015.

In recent years, the interest of the scientific community towards building energy performance has become more evident in order to meet the National and European Directives. In this context, retrofits that result in improved building energy performance are widely investigated. The paper presents a comparative analysis of two different and complementary strategies to enhance the energy performance of an existing tertiary building located in Bologna, Italy. The first retrofit action is to reduce the heat transfer by transmission (i.e. use of low-emissivity glass) and the second one is to decrease the ventilation losses (i.e. installation of a heat recovery system). Then a third case has been investigated: it contemplates simultaneously both the solutions of windows replacement and installing a ventilation recovery system. Potential energy savings were calculated by means of dynamic simulation assisted by Trnsys energy simulation tool. Finally, an evaluation of the simple payback time and the net present value was performed in order to investigate global cost assessment. The window replacement option in the analyzed building office proved to be absolutely unprofitable, even if it would appear as the first and simplest action to be performed. On the contrary, the installation of a total energy recovery system resulted in sensible reduction of energy consumption and at the same time generated good values of NPV with reference to all the three different analyzed variation of the cost of energy.

This chapter discusses hydrogen-methane blends for use in the transportation industry. The use of fossil fuels in hydrogen production may limit the advantages of this technology. However, a more sustainable approach is being developed in the use of renewable sources to supply energy for electrolysis. An energetic and environmental assessment of hydro-methane is necessary to determine its sustainability, and the information collected must be used to drive technological choices. © 2014 Woodhead Publishing Limited All rights reserved.

The aim of this research is to evaluate energy efficiency of organic horticultural farms in Italy at both surface (GJ/GJ ha-1 year -1) and product (kgMJ-1) level. The methods used is the Output/Input balance at farm level using energy equivalents of the three phases: production, transformation/conservation and marketing. The methodology have been applied to 8 case studies of the organic horticultural Italian sector. The results show that the energy input is low but also the energy efficiency is not high especially if compared to other study of the arable sector. However they show very positive aspects in the commercial phase.

HVAC systems in supermarkets must assure both thermal comfort for occupants and suitable climatic conditions for refrigerated cases, which operate better with low ambient relative humidity (40-45%). Since open display cases substantially reduce sensible load and moderately reduce latent load, ambient sensible/total heat load ratio is less than usual. Thus, if dehumidification is carried out with a traditional cooling coil, over-sizing of the coil and re-heating of the treated air are necessary, with energy and economic waste. To offset these disadvantages, hybrid HVAC systems with chemical dehumidification may be employed. In this paper a case study is presented in which a traditional HVAC system is compared to hybrid systems with chemical dehumidification. Dynamic simulation codes (DOE and DesiCalcTM) and Test Reference Year data (TRY), opportunely elaborated, have been used. Annual operating costs have been estimated and large savings have been obtained with hybrid systems. Considerable reduction of electric energy demand as well as better control of thermal-hygrometric conditions were noted. A simple payback of about 1 year has been obtained. Finally, a virtual retrofitting operation on 30% of the existing HVAC systems in Italian supermarkets has shown significant operating cost savings.

HVAC systems with desiccant wheel (DW) are energy efficient, with a low ambient impact, and can be profitable if compared to traditional systems. They also allow a better indoor air quality. In this paper the summer operating costs of both the desiccant and traditional systems are obtained using three software codes. Two are based on DOE calculation engine (PowerDOE and DesiCalc™), one (DTPE) is an autonomously developed code, based on a subdivision of the psychrometric chart in zones, each one corresponding to a different air handling. DOE and DTPE take into account the most recent DW performance values. Calculation assumes hourly weather data extracted from the European file named “Test Reference Year” (TRY) and appropriately processed. With reference to operating costs of the desiccant systems in summer Italian conditions, for a retail store application, interesting savings (up to 35%) are obtained, as well as reduction in thermal cooling power (up to 52%). Starting costs of the desiccant system are generally greater with respect to the traditional system; considering the present costs of the Italian market, a simple payback of about 5–7 years is obtained. If slightly de-rated DWs are considered, the payback attains lower values, near to 3–4 years.

Especially in the last decade, efforts have been made in developing the sustainable building assessment tools, which are usually performed based on fundamentals of the First Law of Thermodynamics. However, this approach does not provide a faithful thermodynamic evaluation of the overall energy conversion processes that occur in buildings, and a more robust approach should be followed. The relevance of Second Law analysis has been here highlighted: in addition to the calculation of energy balances, the concept of exergy is used to evaluate the quality of energy sources, resulting in a higher flexibility of strategies to optimize a building design. Reviews of the progress being made with the constructal law show that diverse phenomena can be considered manifestations of the tendency towards optimization captured by the constructal law. The studies based on First and Second Principle of Thermodynamics results to be affected by the extreme generality of the two laws, which is consequent of the fact that in thermodynamics the “any system” is a black box with no information about design, organization and evolution. In this context, an exploratory analysis on the potentiality of constructal theory, that can be considered a law of thermodynamics, has been finally outlined in order to assess the energy performance in building design.