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Embodied energy is the sum of all the
energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of ...
required to produce any goods or services, considered as if that energy was incorporated or 'embodied' in the product itself. The concept can be useful in determining the effectiveness of energy-producing or
energy saving Energy conservation is the effort to reduce wasteful energy consumption by using fewer energy services. This can be done by using energy more effectively (using less energy for continuous service) or changing one's behavior to use less service (f ...
devices, or the "real" replacement cost of a building, and, because energy-inputs usually entail
greenhouse gas emissions Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and ...
, in deciding whether a product contributes to or mitigates
global warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
. One fundamental purpose for measuring this quantity is to compare the amount of energy produced or saved by the product in question to the amount of energy consumed in producing it. Embodied energy is an accounting method which aims to find the sum total of the energy necessary for an entire product lifecycle. Determining what constitutes this lifecycle includes assessing the relevance and extent of energy into raw material extraction,
transport Transport (in British English), or transportation (in American English), is the intentional movement of humans, animals, and goods from one location to another. Modes of transport include air, land ( rail and road), water, cable, pipelin ...
,
manufacture Manufacturing is the creation or Production (economics), production of goods with the help of equipment, Work (human activity), labor, machines, tools, and chemical or biological processing or formulation. It is the essence of secondary secto ...
, assembly, installation, disassembly, deconstruction and/or
decomposition Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and ...
as well as human and secondary resources.


History

The history of constructing a system of accounts which records the energy flows through an environment can be traced back to the origins of
accounting Accounting, also known as accountancy, is the measurement, processing, and communication of financial and non financial information about economic entities such as businesses and corporations. Accounting, which has been called the "languag ...
itself. As a distinct method, it is often associated with the
Physiocrat Physiocracy (; from the Greek for "government of nature") is an economic theory developed by a group of 18th-century Age of Enlightenment French economists who believed that the wealth of nations derived solely from the value of "land agricult ...
's "substance" theory of value, and later the agricultural energetics of Sergei Podolinsky, a Russian physician, and the ecological energetics of Vladmir Stanchinsky. The main methods of embodied energy accounting as they are used today grew out of Wassily Leontief's
input-output model In computing, input/output (I/O, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, possibly a human or another information processing system. Inputs are the signal ...
and are called ''Input-Output Embodied Energy analysis''. Leontief's input-output model was in turn an adaptation of the neo-classical theory of
general equilibrium In economics, general equilibrium theory attempts to explain the behavior of supply, demand, and prices in a whole economy with several or many interacting markets, by seeking to prove that the interaction of demand and supply will result in an o ...
with application to "the empirical study of the quantitative interdependence between interrelated economic activities". According to Tennenbaum Leontief's Input-Output method was adapted to embodied energy analysis by Hannon to describe ecosystem energy flows. Hannon's adaptation tabulated the total direct and indirect energy requirements (the ''energy intensity'') for each output made by the system. The total amount of energies, direct and indirect, for the entire amount of production was called the ''embodied energy''.


Methodologies

Embodied energy analysis is interested in what energy goes to supporting a
consumer A consumer is a person or a group who intends to order, or uses purchased goods, products, or services primarily for personal, social, family, household and similar needs, who is not directly related to entrepreneurial or business activities. ...
, and so all energy depreciation is assigned to the final demand of consumer. Different methodologies use different scales of data to calculate energy embodied in products and services of nature and human
civilization A civilization (or civilisation) is any complex society characterized by the development of a state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system). ...
. International consensus on the appropriateness of data scales and methodologies is pending. This difficulty can give a wide range in embodied energy values for any given material. In the absence of a comprehensive global embodied energy public dynamic database, embodied energy calculations may omit important data on, for example, the rural road/highway construction and maintenance needed to move a product,
marketing Marketing is the process of exploring, creating, and delivering value to meet the needs of a target market in terms of goods and services; potentially including selection of a target audience; selection of certain attributes or themes to emph ...
, advertising, catering services, non-human services and the like. Such omissions can be a source of significant methodological error in embodied energy estimations. Without an estimation and declaration of the embodied energy error, it is difficult to calibrate the sustainability index, and so the
value Value or values may refer to: Ethics and social * Value (ethics) wherein said concept may be construed as treating actions themselves as abstract objects, associating value to them ** Values (Western philosophy) expands the notion of value beyo ...
of any given material, process or service to environmental and economic processes.


Standards

The SBTool, UK
Code for Sustainable Homes The Code for Sustainable Homes was an environmental assessment method for rating and certifying the performance of new homes in United Kingdom. First introduced in 2006, it is a national standard for use in the design and construction of new homes w ...
was, and USA LEED still is, a method in which the embodied energy of a product or material is rated, along with other factors, to assess a building's
environmental impact Environmental issues are effects of human activity on the biophysical environment, most often of which are harmful effects that cause environmental degradation. Environmental protection is the practice of protecting the natural environment on t ...
. Embodied energy is a concept for which scientists have not yet agreed absolute universal values because there are many variables to take into account, but most agree that products can be compared to each other to see which has more and which has less embodied energy. Comparative lists (for an example, see the University of Bath ''Embodied Energy & Carbon Material Inventory''G.P.Hammond and C.I.Jones (2006)
Embodied energy
and
carbon footprint A carbon footprint is the total greenhouse gas (GHG) emissions caused by an individual, event, organization, service, place or product, expressed as carbon dioxide equivalent (CO2e). Greenhouse gases, including the carbon-containing gases carbo ...
database'', Department of Mechanical Engineering, University of Bath, United Kingdom
) contain average absolute values, and explain the factors which have been taken into account when compiling the lists. Typical embodied energy units used are MJ/kg (mega joules of energy needed to make a kilogram of product), t (tonnes of
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...
created by the energy needed to make a kilogram of product). Converting MJ to t is not straightforward because different types of energy (oil, wind, solar, nuclear and so on) emit different amounts of carbon dioxide, so the actual amount of carbon dioxide emitted when a product is made will be dependent on the type of energy used in the manufacturing process. For example, the Australian Government gives a global average of 0.098 t = 1 GJ. This is the same as 1 MJ = 0.098 kg = 98 g or 1 kg = 10.204 MJ.


Related methodologies

In the 2000s drought conditions in
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
have generated interest in the application of embodied energy analysis methods to water. This has led to use of the concept of embodied water.


Data

A range of databases exist for quantifying the embodied energy of goods and services, including materials and products. These are based on a range of different data sources, with variations in geographic and temporal relevance and system boundary completeness. One such database is th
Environmental Performance in Construction (EPiC) Database
developed at The University of Melbourne, which includes embodied energy data for over 250 mainly construction materials. This database also includes values for embodied water and greenhouse gas emissions. The main reason for differences in embodied energy data between databases is due to the source of data and methodology used in their compilation. Bottom-up 'process' data is typically sourced from product manufacturers and suppliers. While this data is generally more reliable and specific to particular products, the methodology used to collect process data typically results in much of the embodied energy of a product being excluded, mainly due to the time, costs and complexity of data collection. Top-down environmentally-extended input-output (EEIO) data, based on national statistics can be used to fill these data gaps. While EEIO analysis of products can be useful on its own for initial scoping of embodied energy, it is generally much less reliable than process data and rarely relevant for a specific product or material. Hence, hybrid methods for quantifying embodied energy have been developed, using available process data and filling any data gaps with EEIO data. Databases that rely on this hybrid approach, such as The University of Melbourne'
EPiC Database
provide a more comprehensive assessment of the embodied energy of products and materials.


In common materials

Selected data from the Inventory of Carbon and Energy ('ICE') prepared by the University of Bath (UK)


In transportation

Theoretically, embodied energy stands for the energy used to extract materials from mines, to manufacture vehicles, assemble, transport, maintain, transform them and to transport energy, and ultimately to recycle these vehicles. Besides, the energy needed to build and maintain transport networks, whether road or rail, should be taken into account as well. The process to be implemented is so complex that no one dares to put forward a figure. According to the :fr:Institut du développement durable et des relations internationales, in the field of transportation, "it is striking to note that we consume more embodied energy in our transportation expenditures than direct energy .. Put in other words, we consume less energy to move around in our personal vehicles than we consume the energy we need to produce, sell and transport the cars, trains or buses we use ".
Jean-Marc Jancovici Jean-Marc Jancovici (born 1962) is a French engineering consultant, energy and climate expert, professor, conference speaker, writer, and independent columnist. He is co-founder and associate at the Carbone 4 consultancy firm, and the founding p ...
advocates a carbon footprint analysis of any transportation infrastructure project, prior to its construction.


In automobiles


Manufacturing

According to
Volkswagen Volkswagen (),English: , . abbreviated as VW (), is a German Automotive industry, motor vehicle manufacturer headquartered in Wolfsburg, Lower Saxony, Germany. Founded in 1937 by the German Labour Front under the Nazi Party and revived into a ...
, the embodied energy contents of a Golf A3 with a
petrol engine A petrol engine (gasoline engine in American English) is an internal combustion engine designed to run on petrol (gasoline). Petrol engines can often be adapted to also run on fuels such as liquefied petroleum gas and ethanol blends (such as ' ...
amounts to 18 000 kWh (i.e. 12% of 545 GJ as shown in the report(de
Volkswagen environmental report 2001/2002
see page 27
). A Golf A4 (equipped with a
turbocharged direct injection TDI (Turbocharged Direct Injection) is Volkswagen Group's term for its current common rail direct injection turbodiesel engine range that have an intercooler in addition to the turbo compressor. TDI engines are used in motor vehicles sold by th ...
) will show an embodied energy amounting to 22 000 kWh (i.e. 15% of 545 GJ as shown in the report). According to the French energy and environment agency ADEME a motor car has an embodied energy contents of 20 800 kWh whereas an
electric vehicle An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. It can be powered by a collector system, with electricity from extravehicular sources, or it can be powered autonomously by a battery (sometimes ch ...
shows an embodied energy contents amounting to 34 700 kWh. An electric car has a higher embodied energy than a combustion engine one, owing to the battery and electronics. According to Science & Vie, the embodied energy of batteries is so high that rechargeable hybrid cars constitute the most appropriate solution, with their batteries smaller than those of an all-electric car.


Fuel

As regards energy itself, the factor energy returned on energy invested (EROEI) of fuel can be estimated at 8, which means that to some amount of useful energy provided by fuel should be added 1/7 of that amount in embodied energy of the fuel. In other words, the fuel consumption should be augmented by 14.3% due to the fuel EROEI. According to some authors, to produce 6 liters of petrol requires 42 kWh of embodied energy (which corresponds to approximately 4.2 liters of diesel in terms of energy content).


Road construction

We have to work here with figures, which prove still more difficult to obtain. In the case of road construction, the embodied energy would amount to 1/18 of the fuel consumption (i.e. 6%).


Other figures available

Treloar, ''et al.'' have estimated the embodied energy in an average automobile in Australia as 0.27 terajoules (i.e. 75 000 kWh) as one component in an overall analysis of the energy involved in road transportation.


In buildings

Although most of the focus for improving energy efficiency in buildings has been on their operational emissions, it is estimated that about 30% of all energy consumed throughout the lifetime of a building can be in its embodied energy (this percentage varies based on factors such as age of building, climate, and materials). In the past, this percentage was much lower, but as much focus has been placed on reducing operational emissions (such as efficiency improvements in heating and cooling systems), the embodied energy contribution has come much more into play. Examples of embodied energy include: the energy used to extract raw resources, process materials, assemble product components, transport between each step, construction, maintenance and repair, deconstruction and disposal. As such, it is important to employ a whole-life carbon accounting framework in analyzing the carbon emissions in buildings.


In the energy field


EROEI

EROEI (Energy Returned On Energy Invested) provides a basis for evaluating the embodied energy due to energy. Final energy has to be multiplied by \frac in order to get the embodied energy. Given an EROEI amounting to eight e.g., a seventh of the final energy corresponds to the embodied energy. Not only that, for really obtaining overall embodied energy, embodied energy due to the construction and maintenance of power plants should be taken into account, too. Here, figures are badly needed.


Electricity

In the BP ''Statistical Review of World Energy June 2018'', toe are converted into
kWh A kilowatt-hour (unit symbol: kW⋅h or kW h; commonly written as kWh) is a unit of energy: one kilowatt of power for one hour. In terms of SI derived units with special names, it equals 3.6 megajoules (MJ). Kilowatt-hours are a common bill ...
"on the basis of thermal equivalence assuming 38% conversion efficiency in a modern thermal power station". In
France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
, by convention, the ratio between primary energy and final energy in electricity amounts to 2.58, corresponding to an efficiency of 38.8%. In
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...
, on the contrary, because of the swift development of the renewable energies, the ratio between primary energy and final energy in electricity amounts to only 1.8, corresponding to an efficiency of 55.5%. According to ''EcoPassenger'', overall electricity efficiency would amount to 34% in the UK, 36% in Germany and 29% in France.


Data processing

According to association négaWatt, embodied energy related to digital services amounted to 3.5 TWh/a for networks and 10.0 TWh/a for data centres (half for the servers per se, i. e. 5 TWh/a, and the other half for the buildings in which they are housed, i. e. 5 TWh/a), figures valid in France, in 2015. The organization is optimistic about the evolution of the energy consumption in the digital field, underlining the technical progress being made. '' The Shift Project'', chaired by
Jean-Marc Jancovici Jean-Marc Jancovici (born 1962) is a French engineering consultant, energy and climate expert, professor, conference speaker, writer, and independent columnist. He is co-founder and associate at the Carbone 4 consultancy firm, and the founding p ...
, contradicts the optimistic vision of the association négaWatt, and notes that the digital energy footprint is growing at 9% per year.(fr
Lean ITC
website theshiftproject.org; see page 4.


See also

* Biophysical economics * Ecological economics * Embodied emissions * Energy accounting * Energy cannibalism *
Energy economics Energy economics is a broad scientific subject area which includes topics related to supply and use of energy in societies. Considering the cost of energy services and associated value gives economic meaning to the efficiency at which energ ...
* Environmental accounting * Life cycle assessment *
Systems ecology Systems ecology is an interdisciplinary field of ecology, a subset of Earth system science, that takes a holistic approach to the study of ecological systems, especially ecosystems. Systems ecology can be seen as an application of general syst ...


References


Bibliography

* * * * * * * * * *{{cite journal , first1=G.J. , last1=Treloar , first2=P.E.D. , last2=Love , first3=G.D. , last3=Holt , title=Using national input-output data for embodied energy analysis of individual residential buildings , journal=Construction Management and Economics , volume=19 , issue=1 , pages=49–61 , year=2001 , doi=10.1080/014461901452076 , s2cid=110124981


External links


Embodied energy data and research at The University of MelbourneResearch on embodied energy at the University of Sydney, AustraliaAustralian Greenhouse Office, Department of the Environment and Heritage
Energy development Systems ecology Ecological economics Russian inventions