Embodied energy
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This article is incomplete. (September 2011) |
Embodied Energy is the sum of all the energy required to produce 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 devices (does the device produce or save more energy that it took to make it?), of buildings, and, because energy-inputs usually entail greenhouse gas emissions, in deciding whether a product contributes to or mitigates global warming.
Embodied energy is an accounting method which aims to find the sum total of the energy necessary for an entire product life-cycle. Determining what constitutes this life-cycle includes assessing the relevance and extent of energy into raw material extraction, transport, manufacture, assembly, installation, dis-assembly, deconstruction and/or decomposition as well as human and secondary resources. Different methodologies produce different understandings of the scale and scope of application and the type of energy embodied.
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History [edit]
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 itself. As a distinct method, it is often associated with the Physiocrat's "substance" theory of value,[1] and later the agricultural energetics of Sergei Podolinsky, a Ukrainian physician,[2] and the ecological energetics of Vladmir Stanchinsky [3]
The main methods of embodied energy accounting as they are used today grew out of Wassily Leontief's input-output model 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 with application to "the empirical study of the quantitative interdependence between interrelated economic activities".[4] According to Tennenbaum[5] Leontief's Input-Output method was adapted to embodied energy analysis by Hannon[6] 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.
Embodied energy methodologies [edit]
Embodied energy analysis is interested in what energy goes to supporting a consumer, 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. 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, human marketing, advertising, catering services, non-human services and the like. Such omissions can be a source of significant methodological error in embodied energy estimations.[7] Without an estimation and declaration of the embodied energy error, it is difficult to calibrate the sustainability index, and so the value of any given material, process or service to environmental and human economic processes.
Standards [edit]
The SBTool, UK Code for Sustainable Homes and USA LEED are methods in which the embodied energy of a product or material is rated, along with other factors, to assess a building's environmental impact. 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[8]) 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 (megajoules of energy needed to make a kilogram of product), tCO2 (tonnes of carbon dioxide created by the energy needed to make a kilogram of product). Converting MJ to tCO2 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[9] gives a global average of 0.098 tCO2 = 1 GJ. This is the same as 1 MJ = 0.098 kgCO2 = 98 gCO2 or 1 kgCO2 = 10.204 MJ.
Related methodologies [edit]
In the 2000s drought conditions in Australia have generated interest in the application of embodied energy analysis methods to water. This has led to use of the concept of embodied water.
Embodied energy in common materials [edit]
Selected data from the Inventory of Carbon and Energy ('ICE') prepared by the University of Bath (UK), and available at http://perigordvacance.typepad.com/files/inventoryofcarbonandenergy.pdf
| Material | Energy MJ per kg | Carbon kg CO2 per kg | Density kg /m3 |
|---|---|---|---|
| Aggregate | 0.083 | 0.0048 | 2240 |
| Concrete (1:1.5:3) | 1.11 | 0.159 | 2400 |
| Bricks (common) | 3 | 0.24 | 1700 |
| Concrete block (Medium density) | 0.67 | 0.073 | 1450 |
| Aerated block | 3.5 | 0.3 | 750 |
| Limestone block | 0.85 | 2180 | |
| Marble | 2 | 0.116 | 2500 |
| Cement mortar (1:3) | 1.33 | 0.208 | |
| Steel (general, av. recycled content) | 20.1 | 1.37 | 7800 |
| Stainless steel | 56.7 | 6.15 | 7850 |
| Timber (general, excludes sequestration) | 10 | 0.72 | 480 - 720 |
| Glue laminated timber | 12 | 0.87 | |
| Cellulose insulation (loose fill) | 0.94 – 3.3 | 43 | |
| Cork insulation | 26.00* | 160 | |
| Glass fibre insulation (glass wool) | 28 | 1.35 | 12 |
| Flax insulation | 39.5 | 1.7 | 30 |
| Rockwool (slab) | 16.8 | 1.05 | 24 |
| Expanded Polystyrene insulation | 88.6 | 2.55 | 15 – 30 |
| Polyurethane insulation (rigid foam) | 101.5 | 3.48 | 30 |
| Wool (recycled) insulation | 20.9 | 25 | |
| Straw bale | 0.91 | 100 – 110 | |
| Mineral fibre roofing tile | 37 | 2.7 | 1850 |
| Slate | 0.1 – 1.0 | 0.006 – 0.058 | 1600 |
| Clay tile | 6.5 | 0.45 | 1900 |
| Aluminium (general & incl 33% recycled) | 155 | 8.24 | 2700 |
| Bitumen (general) | 51 | 0.38 - 0.43 | |
| Medium-density fibreboard | 11 | 0.72 | 680 – 760 |
| Plywood | 15 | 1.07 | 540 - 700 |
| Plasterboard | 6.75 | 0.38 | 800 |
| Gypsum plaster | 1.8 | 0.12 | 1120 |
| Glass | 15 | 0.85 | 2500 |
| PVC (general) | 77.2 | 2.41 | 1380 |
| Vinyl flooring | 65.64 | 2.92 | 1200 |
| Terrazzo tiles | 1.4 | 0.12 | 1750 |
| Ceramic tiles | 12 | 0.74 | 2000 |
| Wool carpet | 106 | 5.53 | |
| Wallpaper | 36.4 | 1.93 | |
| Vitrified clay pipe (DN 500) | 7.9 | 0.52 | |
| Iron (general) | 25 | 1.91 | 7870 |
| Copper (average incl. 37% recycled) | 42 | 2.6 | 8600 |
| Lead (incl 61% recycled) | 25.21 | 1.57 | 11340 |
| Ceramic sanitary ware | 29 | 1.51 | |
| Paint - Water-borne | 59 | 2.12 | |
| Paint - Solvent-borne | 97 | 3.13 |
| Photovoltaic (PV) Cells Type | Energy MJ per m2 | Carbon kg CO2 per m2 |
| Monocrystalline (average) | 4750 | 242 |
| Polycrystalline (average) | 4070 | 208 |
| Thin film (average) | 1305 | 67 |
Embodied energy in automobiles [edit]
Treloar, et al. have estimated the embodied energy in an average automobile in Australia as 0.27 terajoules as one component in an overall analysis of the energy involved in road transportation.[10]
Embodied energy in Telecommunication [edit]
Recently the embodied energy is going to used also in other sectors as ICT and telecommnication [11]. The ICT energy consumption, in the USA and worldwide, has been estimated respectively at 9.4 % and 5.3 % of the total electricity produced [12]. The Embodied Energy concept can help to evaluate the impact of devices and networks.
See also [edit]
References [edit]
- ^ P. Mirowski (1999) More Heat than Light: Economics as Social Physics, Physics as Nature's Economics, Historical Perspectives on Modern Economics, Cambridge University Press, Cambridge; pp. 154–163
- ^ J. Martinez-Alier (1990) Ecological Economics: Energy Environment and Society, Basil Blackwell Ltd, Oxford.
- ^ D.R. Weiner (2000) Models of Nature: Ecology, Conservation and Cultural Revolution in Soviet Russia, University of Pittsburgh Press, United States of America; pp. 70–71, 78–82.
- ^ W. Leontief (1966) Input-Output Economics, Oxford University Press, New York; p. 134
- ^ S.E. Tennenbaum (1988) Network Energy Expenditures for Subsystem Production, MS Thesis. Gainesville, FL: University of FL, 131 pp. (CFW-88-08)
- ^ B. Hannon (1973) "The Structure of ecosystems", Journal of Theoretical Biology, 41, pp. 535–546.
- ^ Lenzen, 2001
- ^ G.P.Hammond and C.I.Jones (2006) Inventory of (Embodied) Carbon & Energy (ICE), Department of Mechanical Engineering, University of Bath, United Kingdom
- ^ CSIRO on embodied energy: Australia's foremost scientific institution
- ^ Treloar, Graham J.; Love, Peter E. D.; Crawford, Robert H. (January/February 2004). "Hybrid Life-Cycle Inventory for Road Construction and Use". Journal of Construction Engineering and Management 130 (1): 43–49. doi:10.1061/(ASCE)0733-9364(2004)130:1(43). Retrieved 2010-06-29.
- ^ Puglia, Virgilio (January 2013). "Energy indices for environmental sustainability". International Journal of Technology Marketing 8 (1/2013).
- ^ {url=http://www.itu.int/ITU-D/cyb/app/docs/itu-icts-for-e-environment.pdf}
Bibliography [edit]
- D.H. Clark, G.J. Treloar and R. Blair (2003) 'Estimating the increasing cost of commercial buildings in Australia due to greenhouse emissions trading, in J. Yang, P.S. Brandon and A.C. Sidwell, Proceedings of The CIB 2003 International Conference on Smart and Sustainable Built Environment, Brisbane, Australia.
- R. Costanza (1979) "Embodied Energy Basis for Economic-Ecologic Systems." PhD Dissertation. Gainesville, FL: Univ. of FL. 254 pp. (CFW-79-02)
- R.H. Crawford (2005) "Validation of the Use of Input-Output Data for Embodied Energy Analysis of the Australian Construction Industry", Journal of Construction Research, Vol. 6, No. 1, pp. 71–90.
- M. Lenzen (2001) "Errors in conventional and input-output-based life-cycle inventories", "Journal of Industrial Ecology", 4(4), pp. 127–148.
- M. Lenzen and G.J.Treloar (2002) 'Embodied energy in buildings: wood versus concrete-reply to Börjesson and Gustavsson, Energy Policy, Vol 30, pp. 249–244.
- G.J. Treloar (1997) Extracting Embodied Energy Paths from Input-Output Tables: Towards an Input-Output-based Hybrid Energy Analysis Method, Economic Systems Research, Vol. 9, No. 4, pp. 375– 391.
- G.J. Treloar (1998) A comprehensive embodied energy analysis framework, Ph.D. thesis, Deakin University, Australia.
- G.J. Treloar, C. Owen and R. Fay (2001) 'Environmental assessment of rammed earth construction systems', Structural survey, Vol. 19, No. 2, pp. 99–105.
- G.J.Treloar, P.E.D.Love, G.D.Holt (2001) Using national input-output data for embodied energy analysis of individual residential buildings, Construction Management and Economics, Vol. 19, pp. 49–61.
External links [edit]
- Research on embodied energy at the University of Sydney, Australia
- Australian Greenhouse Office, Department of the Environment and Heritage
- University of Bath (UK), Embodied Energy & Carbon Material Inventory
- eTool LTD, Embodied Energy Calculations within Life Cycle Analysis of Residential Buildings
- Embodied Carbon of Steel Construction
