**1. Introduction**

The effects of climate change are global. For many years now, polar ice caps and glaciers have been melting, sea levels are rising, and storms and floods are destroying people's habitats. Therefore, it is particularly important to reduce anthropogenic greenhouse gas (GHG) emissions through energy efficiency (EE) [1].

Energy efficiency [2] is gaining more and more attention in the society. The term energy efficiency means using less energy to guarantee the same benefits of output [3].

The reasons for the increasing interest in energy efficiency are the persistent climate change, depletion of fossil fuels, and rising energy prices. The production as well as the use of energy based on fossil fuels is one of the biggest drivers of climate change. The sustainable use of energy or "green energy" is playing an increasingly important role in various decision-making processes for companies and other organizations [4].

The application and implementation of energy efficiency is often the cheapest way to reduce fuel costs and carbon dioxide (CO2). Of course, the needs of the present are to be satisfied, but future generations should not be disadvantaged. The most important sectors in terms of energy efficiency include industry, buildings, and transport. Year after year, countless institutes and corporations are researching new technologies to ensure that energy efficiency can be continuously optimized, alongside decarbonization [4, 5].

The European Union (EU) has adjusted its policy framework based on annual CO2 emissions. In 2005, the EU introduced an emissions trading system for all member states to reduce CO2 emissions (for details, see **Figure 2**, purchase and sale of emission certificates) [6–9]. This chapter deals with the current state of the art of freight trains and cargo aircraft.

Energy efficiency means using less energy to provide the same level of utility. It is therefore one method to reduce anthropogenic (human) greenhouse gas emissions [3].

EE is a universally applicable concept relevant for consumers and industry alike that can be achieved by a more efficient technology, an improved process, or a change of individual behavior. Energy efficiency can, according to the International Energy Agency's (IEA) World Energy Outlook (IEA WEO), "close the competitiveness gap caused by differences in regional energy prices" [10].

In November 1974, the International Energy Agency, an autonomous agency, was founded. Its main mission is to promote energy security among its 29 member countries.

Energy efficiency is the key to ensure a safe, reliable, affordable, and sustainable energy system for the future. It is the one energy resource that every country possesses in abundance and is the quickest and least costly way of addressing energy security and environmental and economic challenges. While energy efficiency policies are becoming a key part of the global energy market, there remains vast untapped-into potential [11].

Energy efficiency means using the same amount of energy to achieve the same utility level. The term energy efficiency itself is therefore very clear and selfexplanatory [12].

"Energy intensity" looks at how much energy was needed to get a certain result. The units of energy intensity used are usually given by the primary energy consumption per inhabitant or by the primary consumption per unit of gross domestic product (GDP). Measuring energy efficiency as an energy intensity is basically possible at the macroeconomic level [4]. As an indicator of energy efficiency, the energy intensity of a country is often used for the assessment. This is because at a high level it is a proxy measure of energy needed to provide the used energy service (the energy intensity measures the energy needed to provide units of economic value). Moreover, it is very readily available as an indicator, and it is easier to rate or compare countries. If a country has a low energy intensity, it does not necessarily mean that the energy efficiency of that country is also high. Conversely, it should be noted that lower-intensity trends are not necessarily due to efficiency improvements. Energy efficiency contributes to

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*Energy Efficiency Management: State of the Art and Improvement Potential Analysis…*

rooms was the largest emitting end use (see **Figure 1** for 2013 data) [13].

The European Union has adopted a wide range of legal instruments to improve energy efficiency. For EU directives, it is up to the member states how they transpose the directives into national law. In the official journal of the European Union, directive 2009/28/EG promoting the use of energy from renewable sources and amending and subsequently repealing directives 2001/77/EG and 2003/30/EG are binding and non-binding guidelines for an efficient energy use in the EU. All member states have to give their best to implement those improvement measures [6]. The main targets of the directive 2009/28/EG are the so-called 20-20-20 targets. This means that, as target, renewable energies account for 20% of the final energy consumption across the EU, the greenhouse gas emissions have to be reduced by 20%, and the energy efficiency should be increased by 20% in the EU referring to 1990 as base year. Furthermore, the directive 2009/28/EG stipulates that biofuels

There are also some long-term objectives of the EU. The proportion of renewable energies in energy consumption and the energy efficiency should increase to at least 27% by 2030. In 2020, the goals should be reviewed to see whether an increase of 30% is possible. In 2030 the greenhouse gas emissions must be reduced by almost

The European Union Emissions Trading System was introduced in 2005 for the regulation of greenhouse gas emissions in energy-intensive industries. The relevant system operators concerned must have a certificate for each tonne of CO2 emitted and submit it to the regulatory authority. The system enables trading in carbon certificates under a defined overall framework for all participants—a so-called "cap-and-trade" system. These allowances are freely tradable, which means that participants who emit more greenhouse gases can purchase emission certificates from other participants with lower greenhouse gas emission needs. In order to reduce overall emissions, the proportion of allowances is reduced by 1.74% per year

The principle of the "cap-and-trade" system is easy to recognize in **Figure 2**. In this example, issuer A generates more emissions than issuer B, thus exceeding the authorized amount of CO2. In order to solve the problem, issuer A can purchase the unused

certificates from issuer B (which has very low CO2 emissions in this example).

**2. Political framework operations in the EU**

must account for 10% of total fuel consumption by 2020 [7].

**2.1 European emissions trading system (EU ETS)**

by 2020 [9]. **Figure 2** illustrates the EU ETS scheme.

40% (base year 1990) [8].

the definition of intensities and trends. However, other factors play a major role, e.g., the structure of the economy, the presence of large energy-consuming industries, the passenger car density, and the specific housing sector. Globally, passenger cars, together with road haulage vehicles, account for about one-third of energy-related CO2 emissions and consume approximately as much energy as the entire housing sector [13]. Canada, the USA, Australia, and New Zealand are among the regions in which transport is currently the highest consumption sector. The manufacturing sector has the largest share of energy in Japan and Korea. In particular, the subsectors' ferrous metals and chemicals have a high energy demand. The residential sector is the highest in most European countries. This stems very much from the consumption for space heating and heaters. For the IEA countries, emissions for residential heating were higher for household appliances as well as for each subsector of the manufacturing sector. Especially in countries such as the UK and Germany, the heating of the

*DOI: http://dx.doi.org/10.5772/intechopen.86552*

**Figure 1.**

*Top six CO2-emitting end uses in IEA countries in 2013. Reproduced with permission from [13].*

*Energy Efficiency Management: State of the Art and Improvement Potential Analysis… DOI: http://dx.doi.org/10.5772/intechopen.86552*

the definition of intensities and trends. However, other factors play a major role, e.g., the structure of the economy, the presence of large energy-consuming industries, the passenger car density, and the specific housing sector. Globally, passenger cars, together with road haulage vehicles, account for about one-third of energy-related CO2 emissions and consume approximately as much energy as the entire housing sector [13]. Canada, the USA, Australia, and New Zealand are among the regions in which transport is currently the highest consumption sector. The manufacturing sector has the largest share of energy in Japan and Korea. In particular, the subsectors' ferrous metals and chemicals have a high energy demand. The residential sector is the highest in most European countries. This stems very much from the consumption for space heating and heaters. For the IEA countries, emissions for residential heating were higher for household appliances as well as for each subsector of the manufacturing sector. Especially in countries such as the UK and Germany, the heating of the rooms was the largest emitting end use (see **Figure 1** for 2013 data) [13].
