Economic and Human Features for Energy and Environmental Indicators: A Tool to Assess Countries’ Progress towards Sustainability

: Energy and environmental data represent fundamental information for the analysis of sustainable development. On the other hand, these aspects should be associated with economic and human dimensions in order to obtain a more holistic vision. From this perspective, some indicators are discussed and analyzed in this paper in order to assess the performance of a country. As regards the energetic aspects, the data of total primary energy supply and exergy losses were considered. The environmental aspects were taken into account by considering the greenhouse gas emissions and the particulate matter emissions. These energy and environmental data were put in relation to the GDP (gross domestic product) and HDI (human development index, a multidimensional index proposed by United Nations), respectively. So, two sets of indicators were introduced—the set E for economic properties and the set H for human aspects. A case study was conducted by analyzing a group of countries that meet two criteria: the same macro-geographical area and comparable numbers of citizens. The European area—in particular, its six most populous countries—was chosen. From the results obtained, it is possible to point out that some countries present different rankings depending on whether set E or set H is considered. Another important aspect discussed is the temporal evolution of the indicators (the interval from 1990 to 2017 was considered). Political decision-makers can be supported by the use of the indicators of set H in order to evaluate well-being related to their choices on actions related to the energy and environment. These indicators can be used both to analyze the trends of a country and to compare them with the performance of some other similar countries.


Introduction
Indicators are quantitative or a qualitative measurements [1], and they represent the main tool usually adopted: • To monitor the performance of a country in a certain time interval; • To determine priorities and choices for policy-making in relation to available data.
Nowadays, moving towards sustainability is becoming a continuous and compulsory requirement [2] to assure human well-being for the present and future generations. Sustainability indicators are needed in order to capture quantitative and qualitative information about the underlying asset base, which must be sustained [3]. Despite the fact that the debate on the proper definition of sustainable development still remains alive [4,5], every facet of this complex topic has its roots in long-term human well-being. Indeed, sustainability has to be focused not only on maintaining every key environmental function, but also, in a more general socioeconomic view, on maintaining the ability to provide a non-declining well-being over time [6].

Efforts for Going towards Sustainable Development-History in Brief
The concept of sustainable development was initially promoted at the beginning of 1970s in order to achieve suitable environmental conditions during the development of societies and technologies [7]. The work "The Limits to Growth" [8] is considered a precursor of this topic [9,10], putting the spotlight on the finite capacity of the biosphere of being able to meet human needs at that rate of exploitation. In "The Limits to Growth" is presented a dynamic model of prediction ("World3"), which considers the interactions between humans and Earth in relation to the exponential growth of five main interacting variables [11][12][13]: • Food production, related to economic, demographic, and environmental conditions; • Industrialization, considering the related economic growth, which is affected by other factors, such as demographic growth; • Non-renewable resources, represented by the availability of natural resources required to produce goods and services; • Pollution, considering the outputs due to industrial, agricultural, and service production that could affect the ecosystem, including agricultural systems and human health; • Population, considering the demographic effects of social, economic, and environmental aspects that affect human birth and death rates.
The results of this model indicate that the exploitation of natural resources at the current rate, without any change in human activities and social behavior, would result in a "death time" for resources themselves, as well as, finally, for humans. Therefore, just fifty years ago, the failure of integrating conservation with development was noticed, and, consequently, the recognition of the need to act urgently for a more sustainable management of the use of the Earth's limited resources emerged.
In 1980, the term "sustainable development" was first introduced in the World Conservation Strategy Report with the subtitle "Living Resource Conservation for Sustainable Development" [14]; indeed, a global approach was pointed out to be required for the administration of resources, which human life and development depend on. Two main issues were examined: • The conservation of global ecosystems; • The interrelations between actions on the local and global levels, highlighting the ramifications of those on the local level for the global one, as well as the awareness of human actions.
The most often cited definition of sustainable development [15], indicating development "that meets the needs of the present without compromising the ability of future generations to meet their own needs" [16], was introduced in the Brundtland Report in 1987 by the World Commission on Environment and Development (WCED). After the publication of this report, the attention on sustainable development and on its implications grew in the international policy framework, too [17], and in scientific literature [18]. The Brundtland Report put the spotlight on the need to integrate economic growth with social (focused on equity) and environmental issues, which has been translated into sustainable development [18].
In 1992, the United Nations Conference on Environment and Development (UNCED), commonly known as the "Rio Earth Summit", was held in Rio de Janeiro, and it represented the largest meeting of world's leaders ever organized [9], with the aim of beginning an international partnership in order to achieve the target of sustainable development for all of Earth's inhabitants [19]. During this conference, five main documents were produced, suggesting a new viewpoint for approaching sustainability and human activities: • The Rio Declaration of Principles, which contains a list of 27 principles with the aim of establishing a "new and equitable global partnership" [20], moving in the direction of international agreements, safeguarding the integrity of both environmental and developmental systems, and integrating legislative instruments to pursue environmental issues in each country.

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The United Nations Framework Convention on Climate Change (UNFCC) [21], which is an international treaty on environment, with the aim of fixing the amount of greenhouse gases concentrations in the atmosphere to the 1990 levels, preventing a human interference with natural climate system.

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The Convention on Biological Diversity (CBD) [22], an international treaty with three main aims: "the conservation of biological diversity, the sustainable use of its components and the fair and equitable sharing of the benefits arising out of the utilization of genetic resources", highlighting the finite amount of natural resources and the need for all to preserve them.

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The Statement on Forest Principle [23], a document which contains principles to manage and preserve the forests reserves, using them in a sustainable way. • Agenda 21 [24], which represents a global action plan (both analyses and recommendations [19]) with the aim to integrate issues related to environment and development, in order to improve living standards and to guarantee a better future for all the people with a particular attention to the ecosystem. All these issues are considered the challenges of XXI Century and is highlighted the central role of multiscalar cooperation from an international level to a local one [25]. Indeed, the need to bring the Agenda at a local level within each Nation has led to a program called Local Agenda 21 (LA21) in which local communities are recognized as the core for the implementation and control of the planning for actions towards sustainable development.
Substantially, in Agenda 21, the use of indicators was proposed as the main tool to monitor and address the proper measures and actions towards sustainable development.
After the "Rio Earth Summit", the Commission to Sustainable Development (CSD) was created in order to follow-up the progresses of Agenda 21 and, in 2000, the United Nations Millennium Development Goals (MDGs) were introduced in order to implement its targets up to 2015. In particular, MDGs have put the spotlight on a powerful approach, to achieve social priorities worldwide [26], including crucial topics such as energy, health, poverty, gender inequality, schooling and environmental degradation. The eight MDGs main targets were focused specially on poor countries, while the richer countries had to support them, by finance and technology. The main criticism related to the MDGs has been the difficulty of their objective measurement, due to the low amount of data [27], which can be collected only in some regions of the globe, and not worldwide [28]. Moreover, MDGs have been also highlighted to have promoted a decision making system about equitable well-being and social issues, based on an economistic perspective of development [29].
In 2012, the "UN Rio + 20 Summit"was held in Brazil, with the aim to create a new set of goals, in order to carry forward the targets of MDGs until 2030 [30]. A new ambitious UN plan for action, called 2030 Agenda for Sustainable Development, has been presented in 2015. Thus, the 17 Sustainable Development Goals (SDGs), and their 169 related targets, were introduced as a global challenge, in order to achieve them until 2030. In this context, the nexus approach has been introduced [31] in order to highlight the lever effect of the economic activities in order to achieve the SDGs, and to evaluate the related difficulties in assessments. The goals have been set to stimulate universal action, for human well-being on the following interlinked main areas: People, Planet, Prosperity, Peace, Partnership.
The achievement of SDGs implies a well defined government decision-making process, which had to be understood by means of introducing proper tools, such as the indicators.

Indicators of Sustainable Development
The present days are characterised by some issues-such as the biodiversity loss, the global change, etc.-that depend on human behaviours, so much that the Anthropocene (human-dominated geological epoch) has been introduced in order to describe the period in which we are living [32][33][34]. This issues (and all those derived from them) highlight how the transition to sustainability must occur [35]. In order to monitor and to assess the performance of sustainability policies, indicators are needed [36], as reported in Agenda 21 'indicators of sustainable development need to be developed to provide solid bases for decision-making at all levels and to contribute to a self-regulating sustainability of integrated environment and development systems' [24]. Moreover, Meadows [37] has also highlighted that 'what is needed to inform sustainable development is not just indicators, but a coherent information system from which indicators can be derived'.
Therefore, to support decision-making towards sustainable development, organizations and researchers have proposed indexes and indicators for sustainable development. In 1989, Cobb [38] introduced the Index of Sustainable Economic Welfare (ISEW) as an alternative to the Gross Domestic Product (GDP); ISEW has subsequently been modified by the same author [39] in order to give a more reliable monetary indicator of welfare and sustainability. It has been criticised for the ambitious attempt to enclose too many different information into a single index [40].
Another sustainability indicator proposed in the 1990s was the ecological footprint (EF) [41], which considers the area of biologically productive land required to support a given population [42] at its current level of consumption [43]. Recently, this indicator has been used to build assessments of performances on environmental sustainability [44][45][46][47][48]. Its widespread has been promoted by its clear calculation and its intuitive definition, which represent also the bases of any criticisms against it [49].
The Genuine Savings Indicator (GS) has been presented as a measure of the change of the annual total capital stock of a country [50], including the wealth accounting [51], and, recently, some improvements have been introduced [52].
The Environmental Sustainability Index (ESI) is a composite index to assess sustainability, by using environmental and socio-economic indicators. This index encloses twenty different indicators, which are combined with two to eight variables [53]. Then, this composite index has been modified, by adding some indicators regarding human health and environmental issues, designing the Environmental Performance Index (EPI). The latter identifies economic and social driving forces, and environmental pressures, assesses the impacts on human health, and on the environment [54].
Since 1990, the United Nations Development Programme (UNDP) has proposed the Human Development Index (HDI) [55,56] as a multidimensional index to measure the development of a country from a socio-economic viewpoint, with a specific focus on the human well-being. This index has been introduced to switch the focus from a pure economic development viewpoint to a more human-centred one, considering some crucial parameters of social development [56,57]. This indicator combines three dimensions together: the long and healthy life (life expectancy of birth), the knowledge (years of school) and a decent standard of living (the gross national income per capita). Since 2010, HDI has been improved in relation to the new needs emerged in relation to sustainability, as deeply analysed in Refs. [57][58][59].
In Table 1, the indicators considered in this Section, are summarised in relation to their chronological introduction.

This Study
From the Brundtland definition of sustainability emerges the achievement of a balance between human requirements and environmental integrity [35], considering intraand inter-generational equity. Social and economic development are needed in order to make sustainability really effective. However, these developments are mutually interconnected with the environment in which occur (nature). Thus, the sustainability can be described as three inter-related dimensions [5,61]: Economy.
These pillars can be analytically expressed by changing the only financial and economical quantities into socio-economic ones, considering that all human actions entail an interaction with the environment, as a consequence there is always irreversible footprint. The fundamental problem is to identify the proper quantities. A great number of models have been proposed, but each of them presents limits of application in obtaining a comprehensive description of sustainability.
In order to try to respond to this problem, in this paper, we develop some considerations on the different results obtained by using a more economic versus a more human oriented approach. To do so, we have built two different sets of indicators: • An economic set, based on Gross Domestic Product, as usually done in all economic assessment in literature; • A more human-centred set, which has been related to the UN's Human Development Index, in order to take into account human well-being.
Therefore, the aim of this paper is to develop some considerations on the current state of sustainability, by introducing an analysis that points out the needs of the human being, in order to show the difficulty of find a unique way to respond quantitatively to a fundamental open problem: does the actual technical and economical state agree with the human equality? This question is crucial, because just human equality is one of the fundamental milestones of the sustainability concept itself. In this paper, we will develop the analysis of two sets of indicators in order to highlight that each approach allows us to obtain different considerations of the current state of development in relation to sustainability. Consequently, we can highlight that it could be better consider integration between different approaches rather than mutual exclusion of them.

Materials and Methods
In this section, we develop an analysis of the current state of the art, related to the socio-economic development, in order to introduce some considerations on the human well-being.
In order to do so, we analyse two different sets of indicators, which present different reference indicators: • Economic indicators, usually used for decision-making; • Human indicators, introduced for the assessment of the human well-being.
To do so, we consider four different sets of data for each country: 1.
The Total Primary Energy Supply (TPES), which is the total amount of energy available for a country; 2.
The Exergy Losses (W λ ) in the energy chain; 3.
The amount of particulate matter (PM) emitted.
The first parameter has been chosen because the access to energy and its availability represent a key quantity for human well-being, and are essential for human development.
The exergy losses, here considered, are the ones directly involved in the country energetic chain, and they are directly related to the technological development [62].
The amount of greenhouse gases represents an environmental issue at global scale, contributing to the greenhouse effect, and the related increase of Earth's mean temperature. Moreover, the particulate matter is a useful parameter to assess environmental pollution, directly related to air quality, which can have negative effects on human health [63].
So, all these data have been put in relation respectively with two main indicators used to assess performances of a country: • The Gross Domestic Product (GDP) [$] [64]: where I health is the normalized Life Expectancy Index, which is the life expectancy at birth [yr], I education is the normalized Education Index which considers two different indicators equally weighted (by their mean arithmetic value): the mean years of schooling and the expected years of schooling [yr] and, I income is the normalized Gross National Income per capita at purchasing power parties GN I pc,PPP [$ per capita]. The GNI per capita 'is the sum of value added by all resident producers in the economy plus any product taxes (less subsidies), not included in the valuation of output plus net receipts of primary income (compensation of employees and property income) from abroad, divided by midyear population. Value added is the net output of an industry after adding up all outputs and subtracting intermediate inputs' [58]. All the values of indicators that appear in Equation (2) are normalized ones by using their minimum and maximum values in the following way: where I actual is the actual value of the indicator, I min is its minimum value and, I max is the maximum value of the indicator. In the case of the GN I pc,PPP the natural logarithms are applied to the normalization formula (Equation (3)) in order to consider that higher incomes have a declining contribution to human development [60]. In Table 2, the values used for the normalization-since 2010-have been reported. The aim of the normalization is to obtain a non dimensional value in the range between 0 and 1. These indicators allow us to compare the results obtained from two different viewpoints: • The classical economic approach; • A more social-related one.
Therefore, we have considered the two following different sets of indicators. The first set has been named set E , which is characterised by considering as a reference quantity a purely economic one: the gross domestic product per capita, GDP pc (at purchaser's prices in constant 2011 US$ [66]).
The set E is represented by the following equations (Equations (4)- (7)): where TEPS pc = TEPS/pop is the total primary energy supply per capita, which is calculated as the amount of energy, TEPS [toe], available for a country, divided by the considered country population (pop). This indicator provides the total amount of primary energy that a country has at their disposal in relation to its gross domestic product; where W λ, pc = (TEPS − AFC)/pop are the exergetic losses related to the energy chain of the country considered per capita, calculated as the difference between the total primary energy supply, TEPS, and the energy available for energy consumption, AFC [toe]. This indicator provides the total amount of the exergetic losses related to the energy chain that occur in each country, in relation to its gross domestic product; E3 = CO 2,eq pc GDP pc (6) where CO 2,eq pc = CO 2,eq /pop is the amount of carbon dioxide equivalent [ton] per capita emitted in the atmosphere, due to the anthropic activities. This indicator provides the total amount of carbon dioxide equivalent emissions of a country, in relation to its gross domestic product; where PM pc = PM/pop is the amount of particulate matter emissions [ton] per capita emitted in the atmosphere, due to the anthropic activities. This indicator provides the total amount of particulate matter emissions of a country, in relation to its gross domestic product; The second set of indicators has been named set H. It is analogous to the previously introduced set E, with the difference that, all the variables above considered-the total primary energy supply (TEPS), the exergetic losses due to the energetic chain (W λ, pc ), the greenhouse gases emissions (CO 2,eq pc ) and the particulate matter emissions (PM pc )-have been divided by the Human Development Index, HDI. In this way, the reference indicator (HDI) is directly related to human well-being and is not a purely economic reference indicator. Thus, the set H can be written as follows: In relation to this two sets of indicators, we wish to stress that they represent two different viewpoints for the same quantities. Here, we wish to show how two different approaches for the same quantity bring to two different results: one in relation only to the economic approach, while the other results more social-need oriented. In Figure 1, are summarised the indicators and the relative quantities involved in the two sets of indicators considered in this paper to develop our study, in relation to the economic and human-oriented approach. In relation to our previous considerations on sustainability, the indicators H represent the quantity which allow us to express analytically the pillars of sustainability. Therefore, we wish to suggest that the set H proposed allows us to develop an analysis towards the requirement of sustainability.
Starting from this hypothesis we wish to highlight: • E1 and H1 allow us to evaluate the country energy consumption, • E2 and H2 allow us to evaluate country technological level, • E3 and H3 allow us to evaluate country GHGs emissions, • E4 and H4 allow us to evaluate country PM emissions, respectively in relation to the economic and human viewpoint, obtaining a way to point out if the policy makers can achieve sustainable decisions by using only economic approaches, or if a change in the standpoint is required. In relation to the different requirement of decision, depending on the social and human conditions of the country considered, it could emerge the unsuitability of the GDP, just related to sustainability; if it is the case a new approach [67], which links economics to engineering, is required.

Results
In this paper, we have introduced two sets of indicators, in order to show two different approaches: a more economic-centred one, and a more human well-being centred one. Indeed, the parameters considered are always the same, but the reference quantities are different for any set of indicators.
In particular, we have focused our first analysis by choosing a group of countries that meet the following criteria: • Countries which belong to the same macro geographical area; • Countries with comparable number of inhabitants.
Therefore, we have considered the overall data of the European Union and the six more populated European countries in 2017 [68]: It has to be highlighted that, the United Kingdom left the European Union on 31 January 2020, however the UK was still a member during the period of time analysed.
We have compared the trends of the two indicators, evaluated between 1990 and 2017. The demographic behaviour is represented in Figure 2; we can highlight that in this period of time there has been a population growth of:  In Figure 3, the trends of the four main parameters involved in the analysis are shown for the selected countries (including the overall EU values) from 1990 to 2017 and, in Figure 4, are represented their relative variations, comparing their values in 1990 with those of 2017. We can point out the following considerations:

•
The Total Primary Energy Supply per capita TPES pc (Figure 3a) presents different trends among the European countries. Spain and Italy have shown a relevant increase in TPES pc until 2005, followed by a reduction in the subsequent years, while, as regards the UK and Germany, their decreasing trend in TPES pc can be highlighted. On the contrary, for France and Poland, a stable trend in TPES pc can be noticed. The overall variation from 1990 to 2017, presented in Figure 4, highlights that: the UK, Germany and France have reduced their total Primary Energy Supply, compared with the 1990's values, respectively of 26%, 15% and 3%, while, for Italy and Poland, this quantity has remained almost constant and, an increase of 21% has occurred in Spain. As concerns the overall TPES pc of EU during the same reference time, it has shown a reduction of 8%; • The Exergy Losses related to the energy chain per capita (Figure 3b) present similar shapes if compared with the TPES pc ones, with an overall reduction (Figure 4) of 21% for Poland, 27% for Germany, 42% for the UK, while an increment for France, Italy and Spain relatively of 4%, 4% and 31% can be identified. For the European Union an overall reduction trend of 15% in W λ,pc has been verified; • The Greenhouse Gases emissions per capita (Figure 3c) have been reduced in the UK of 46%, in Germany of 30%, in France of 26%, in Italy of 23% and in Poland of 10%. On the contrary, in Spain an increase of 1% of the greenhouse emissions has been shown. The overall European Union GHGs emissions reduction has been of 28%; • The Particulate Matter emissions per capita (Figure 3d) present a decreasing trend for all the countries involved in the analysis. Their reduction between 1990 and 2017 ( Figure 4) has been: of 61% in the UK, of 60% in France, of 44% in Germany, of 37% in Italy, of 35% in Spain and of 22% in Poland. Moreover, the overall reduction of the European Union has been relevant (48%).  In Figure 5a,b the trends, between 1990 and 2017, of the GDP pc and of the HDI have been plotted. As concerns the GDP pc , for all countries, it can be shown an increase until 2008, whereupon, due to the important global financial crisis, a subsequent reduction of the GDP pc in the European Union can be noticed. It can be observed that some countries (Italy and Spain) have suffered the crisis more than others, with consequent reductions during the subsequent years. As concerns the HDI, it can be observed an overall growth of this indicator during the period between 1990 and 2017.
It can be noticed that the ranking of countries with respect to the GDP pc is, in some cases, different from that of the HDI. For example, in 1990 the ranking of the top three countries for GDP pc was: France, Germany and Italy, while for the HDI it was: Germany, France and the UK. While, in 2017, the top three countries in the ranking were: Germany, UK and France for GDP pc , and Germany, UK and Spain for HDI. In Figure 5c, the percentage variations, both of GDP pc and HDI, between 1990 and 2017, are shown for the six countries examined (including also the overall EU data): positive variations are observed in all cases. A very high improvement on GDP pc can be observed for Poland, although the increase of HDI has not noticed a similar value. Italy results the country that has had the smallest improvement in terms of both GDP pc and HDI. In particular, the GDP pc variation noticed in Poland has been of ∼166%, while Italy is the country that had the lowest increase. In relation to HDI, we can highlight that its value has grown for all countries, and its range is ∼14-22%. It can be also be observed that the European Union has shown relevant improvements both in GDP pc and HDI, respectively of 48% and 14%.
The proposed indicators have been built as reported in Equations (4)- (11), and their comparison is represented in Figure 6, where the attention has been focused on the two extreme years of the analysed period: 1990 and 2017.
As regards indicator E1 (Figure 6a), in 2017 the UK was the best performing country (while in 1990 Italy presented the best value); all the countries considered have improved this indicator. Although Poland is the country with the worst value in both years analysed, it has however narrowed the gap with respect to other countries, in fact during the time interval analysed, the indicator has shown a significantly reduction (−62%) and, this is due to the strong growth of its GDP pc , while its energy consumption has been stable. Italy is the country that has had the lowest improvement (−12%), essentially due to a modest increase in the GDP pc . Considering the overall EU data, it can be observed a good improvement on the E1 indicator, equal to −38%.
As regards indicator H1 (Figure 6b), in 2017 also for this indicator the UK was the country with the best performances, having undergone a significant reduction compared to 1990 (−38%). It should be noted that Spain, which had the best value in 1990, did not undergo significant changes in 2017 because the improvement in HDI was offset by an increase in energy consumption. Germany and France, on the other hand, were the countries that had a worse value both in 1990 and in 2017. The overall EU value of H1 has shown a reduction (−20%) due both to a TPES pc reduction and to a HDI increase.
As concerns indicator E2 (Figure 6c) the best performing countries in 2017 were Italy and the UK, but while Italy had a modest improvement compared to 1990 (−9%), the United Kingdom had a significant improvement (−62%). The worst value is that of Poland, although compared to 1990 it has made a significant step forward. The overall EU value has shown a relevant improvement, equal to −43%. As concerns indicator H2 (Figure 6d), Italy maintains the best value of the indicator in both years, France in 2017 presented the worst value. It should be noted that Spain is the only country where this indicator worsened between 1990 and 2017 (+10%). As concerns the overall EU data, an improvement of −23% can be noticed.
For indicator E3 (Figure 6e), France is confirmed as the country that has the best value in both years, in particular thanks to the fact that it has both low emissions and high GDP pc . This indicator for Poland is still far from that of the other countries, but it achieved a significant reduction (−66%) between 1990 and 2017, mainly thanks to the growth of GDP pc . The overall EU value has shown an important reduction (−51%).
For indicator H3 (Figure 6f), in 2017 France had the best value, followed by the United Kingdom which obtained a high reduction between 1990 and 2017 (−55%) while the worst values are those of Poland and Germany, due to their high GHG emissions. For the EU, the H3 indicator improvement has been equal to −36%.
For indicators E4 and H4 (Figure 6g,h), Germany shows the best value in both periods followed by the UK. Also for these two indicators, Poland had the worst values. A significant improvement can be observed for all countries, both for E4 (from −45% to −74%) and for H4 (from −36% to −67%). For the EU the E4 and H4 indicators have shown a relevant reduction: −65% and −54% respectively. All these results can be also directly linked to the generalized reduction of PM emissions between 1990 and 2017.

Discussion
The requirement to dispose of information and data availability, regarding the conditions of each single Country, is set in Chapter 40 of Agenda 21. This has led to the requirement of defining indicators of sustainability, in order to "provide solid bases for decision-making at all levels and to contribute to a self-regulating sustainability of integrated environment and development systems" [24].
A first set of 134 sustainable development indicators, and their relative methodologies, were provided in 1995 by the CSD [72]. Those were grouped into four main domains: 1. Social; 2. Economic; 3. Environmental; 4. Institutional.
In order to classify them, the CSD initially used the "Pressure-State-Response"framework [73] which was already been introduced by OECD [74] for Environmental Indicators. But, this approach was not suitable at all for social and economic aspects. So, it was modified into "Driving force-State-Response"and, after its test, it was further changed into "Policy issues", collecting them into main themes and sub-themes [75].
In this paper, in order to assess the sustainability of a macro system such as a country, the energy and environmental dimensions were preliminarily examined through four indicators: the total primary energy supply, the exergetic losses, the greenhouse gases emitted and the particulate matter emitted (al values adopted are per capita ones).
The choice of this four main parameters has been taken due to their direct link to sustainability, because they cover and represent the crucial domains of sustainable development, useful to build a concise set of indicators, that means providing a general overview of the behaviour of the system [76].
Indeed, a fundamental requirement to enable human well-being is energy: human development and access to energy have always gone hand in hand and, this clearly emerges specially in the history of the two last centuries, from the industrial era up to now [77]. The exergy losses (or the dissipated available energy) are proportional to the entropy generation [78,79], and can be linked to the technological development [80] that is another fundamental dimension in sustainability. The primary driver for climate change are the greenhouse gases emissions: from 1990 to 2018, the global carbon dioxide emissions have registered an increase of about 65%, passing from 22.18 × 10 6 t to 36.57 × 10 6 t [81], and achieve their rapid reduction is crucial, as highlighted in The Paris Agreement [82]. Conversely, the particulate matter emissions are directly linked to human wealth [83].
Then, an economic dimension has been introduced through the GDP per capita, and from the combination of energetic, environmental and economic aspects, a set of indicators, called set E was generated: Equations (4)- (7). Among these indicators, E1, E3 and E4 (Equations (4), (6) and (7)) have usually been adopted in literature, while E2 (Equation (5)) is less used but, it gives the dissipated energy associated to the GDP and, it can be an useful sustainability indicator.
Since purely economic aspects are considered to be too limited, a more holistic set of indicators has been proposed. It is based on the index introduced by the United Nations, called Human Development Index, which tries to quantify human well-being in a multidimensional way. Indeed, this index was introduced in order to consider that the ultimate criteria to assess development must reflect human well-being and not the economic growth alone. From a thermoeconomic point of view, GDP can be seen as a flow (financial flow), while HDI is analogous to a state variable, describing the state of the system at a certain time. Consequently, these two indicators represent the analytical expression of two different approaches, and, we argue, possible complementary. Therefore, the second set of indicators has been defined as set H (Equations (8)-(11)), taking into account human well-being. The case study discussed in this paper has been focused on European area and on its six more populated countries. As can be observed in Figure 5, the GDP pc and HDI trends are quite different and, these trends have an impact in the respective sets of indicators. Indeed, some countries present a different ranking depending on whether considering set E or set H. For example, in the comparison of dissipation indicator (E2 and H2), it can be observed that, while for E2 is the UK that leads the ranking, for H2 Italy presents the first value in this ranking. Even the last position in the two rankings is different: for E2 the last position is covered by Poland, while for H2 is covered by France.
Another important aspect is how an indicator has evolved over time and how much it has improved over a significant period of time considered in this work: between 1990 and 2017. For example, Poland is the country which presents the worst values for all four indicators of set E and for two of the indicators of set H. However, it emerges that Poland has made significant improvements: in 1990 it had a large gap compared other countries, while in 2017 the gap was often reduced.
It is believed that political decision makers can find in the indicators of set H a help to understand if the choices made are bringing benefits. These indicators can be used both to analyse the trends of the country that they are governing, and to compare that country with the performance of similar countries.

Conclusions
In this paper, we have developed an analysis of two different approaches to sustainable development: one more economic-oriented and the other one, more human-oriented. We have developed this study to show the difficulty to find a unique response to one of the pillars of sustainability: the human equity.
At one glance, everyone could be induced to prefer a human-oriented indicator, just for the way used to build it. After a deeper consideration of the analysis developed, it emerges that the choice of the indicator must be related to the target and the aim of the decision to be made. Consequently, the conclusion we have achieved is that an integration of the two approaches is more useful for sustainability than a mutual exclusion of them.
Last, it is possible to argue that these two approaches do not consider the technological level of the system used in power and industrial sectors. Consequently, a possible new choice is to develop a more thermo-economic approach to sustainability, because this field of investigation allow us to link economics and optimization methods for systems, but it requires the introduction of human-oriented quantities in thermodynamic indicators. So, we conclude that this paper suggests new frontiers of research, based on an interdisciplinary approach. Thus, further analysis may be carry out in the following directions: • The two sets of indicators proposed could be applied to other countries with different population dimensions both in Europe and in other aggregated macro-regions (such as: America, Asia, Africa, etc.); • Many other alternatives to HDI have been proposed, in order to measure the development of a country from a socio-economic viewpoint, therefore new sets of indicators could be introduced, analysed and compared; • Although two important pollutants were chosen in this work (one with global impact and the other with local impact) it would be interesting to introduce other environmental indicators that could be useful to policy makers. Funding: This research received no external funding.

Conflicts of Interest:
The authors declare no conflict of interest.

Abbreviations
The following abbreviations are used in this manuscript: