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What is the EIOLCA model used on this web site?

The Economic Input Output-Life Cycle Assessment software traces out the various economic transactions, resource requirements and environmental emissions require for a particular product or service. The model captures all the various manufacturing, transportation, mining and related requirements to produce a product or service. For example, you might wish to trace out the implications of purchasing $ 46,000 of reinforcing steel and $ 104,000 of concrete for a kilometer of roadway pavement. Environmental implications of these purchases can be estimated using EIO-LCA. The current (1997) model is based upon the Department of Commerce's 491 sector industry input-output model of the US economy.

What are the data sources for the eiolca.net software?

The data in eiolca.net is developed from a variety of public datasets and assembled for various commodity sectors. For the most part, the data is self-reported and is subject to measurement error and reporting requirement gaps. For example, automotive repair shops do not have to report to the Toxics Release Inventory. The major data sources include:

  • Input/Output Matrix: 1992: commodity/commodity input-output (IO) matrix of the US economy as developed by the US Department of Commerce. The matrix includes 485 commodity sectors. 1997: industry by industry IO matrix (491 sectors)
  • Economic Impacts are computed from the IO matrix and the user input change in final demand. Economic Impacts are reported in 1992 $ millions.
  • Electricity use includes manufacturing and mining sectors developed from the 1992 Census of Manufacturers. Service sector electricity use is estimated using the detailed IO workfiles and average electricity prices for these sectors.
  • Fuel and ore use is calculated from commodity purchases (contained in the IO workfiles) and average 1992 prices.
  • Energy use is calculated by converting fuel use per sector and 31% of electricity use into Terrajoules (31% is the amount of electricity produced in 1992 from non-fossil fuel sources).
  • Revision: Fuel, Electricity, and Energy use have been revised. Please refer to this report.
  • Fertilizer use is calculated from commodity purchases (contained in the IO workfiles) and average 1992 prices.
  • Conventional Pollutant emissions are from the U.S. EPA AIRS web site, using a concordance to the input-output sectors.
  • Greenhouse Gas Emissions calculated by emissions factors from fuel use using U.S. EPA AP-42 emissions factors for CO2 and Methane. N2O emissions estimated to be 10% of NOx emissions. Global Warming Potential (GWP) values converted into CO2 equivalents using the Adriaanse report. Adriaanse, A., "Environmental Policy Performance Indicators - A Study on the Development of Indicators for Environmental Policy in the Netherlands," Sdu Uitgeverij Koninginnegracht, May 1993.
  • Toxics Releases are derived from the US EPA's 1995 toxics release inventory (TRI) and 1995 value of shipments from the 1995 Annual Survey of Manufacturers.
  • CMU-ET is a weighting scheme for toxic emissions to account for their relative hazard. It is computed from occupational exposure standards (called threshold limit values). The gross amount of toxic emissions is converted into metric tons of sulfuric acid emissions equivalent. More information is available here.
  • RCRA (Resource Conservation and Recovery Act) Subtitle C hazardous waste generation, management and shipment was derived from the 1993 biannual US EPA report.
  • External costs are calculated from conventional air pollutant emissions and estimates of pollution damage taken from the economics literature. Detailed information on these values are available from the following source: H. Scott Matthews and Lester B. Lave, "Applications of Environmental Valuation for Determining Externality Costs," Environmental Science and Technology, Vol. 34, No.8, 2000.
  • Water data from U.S. Department of Commerce, "Water Use in Manufacturing," 1982 Census of Manufactures, Subject Series, Washington, DC: U.S. Department of Commerce, Economics and Statistics Administration, Bureau of the Census, MC82-S-6, March 1986.
  • OSHA Safety Data from the following sources:
    • U.S. BLS (Bureau of Labor Statistics). 1994. Survey of Occupational Injuries and Illnesses 1992. Washington, D.C.:U.S. Department of Labor.
    • U.S. Department of Labor, Bureau of Labor Statistics, Census of Fatal Occupational Injuries, 1992 - 1998.
  • Employment data from the following sources (by use):
    • 1997 Economic Census: Comparative Statistics for United States 1987 SIC Basis
    • U.S. BLS 1997. Industry Illness and Injury Data 1997
    • Statistical Abstract of the United States (1998-200)
    • National Marine Fisheries Service. 2000. Employment, Craft, and Plants (Table) Processors and Wholesalers 1999
    • Bureau of Transportation Statistics. Employment in For-Hire Transporation and Selected Transportation-Related Industries http://www.bts.gov/btsprod/nts/Ch3_web/3-19.htm
    • USDA. Agricultural Exports and the Rural Economy in the 1990's http://www.ers.usda.gov/publications/rct71/rct71f.pdf


What is a supply chain?

We often say that a particular car is made by a company such as General Motors or at a particular plant. However, in any product such as an automobile, there are a large number of other companies involved as suppliers. For the automobile, there are paint suppliers, metal fabricators, steel producers, and iron ore mining companies involved, among many others. Even identifying the companies that General Motors purchases components from does not reveal all the second and third level suppliers for an automobile. In the eiolca.net software, all the various goods and services involved in producing a product such as an automobile are identified over the entire supply chain. In most cases, a purchase from one sector will involve supplies from several hundred of the other sectors in the economy as can be seen in the eiolca.net software.

What is life cycle assessment?

Life cycle assessment involves the evaluation of the relevant environmental, economic and technological implications of an object or process throughout its lifetime from creation to waste. A full life cycle assessment involves identification of environmental impacts, assessment of any hazards and improvement. The eiolca.net software is only one approach to help life cycle assessment. A second common approach is to detail the most important processes associated with a product over its entire supply chain and life, but this approach requires considerable attention and time.

What is an economic input/output model?

Wassily Leontief developed economic input/output models over fifty years ago. The model divides an entire economy into distinct sectors. For the eiolca.net software, roughly 500 sectors are used. The model can be visualized as a set of large tables (or, in mathematical terms, a matrix) with 500 rows and 500 columns, with one row and one column for each sector. The tables can represent total sales from one sector to others, purchases from one sector, or the amount of purchases from one sector to produce a dollar of output for the sector. Most countries in the world routinely produce such input/output models, although very few are as large as the 500-sector model used in eiolca.net. The economic input/output model is linear, so that the effects of a $ 1,000 purchase from a sector will be ten times greater than the effects of a $ 100 purchase from the same sector.

How do I use the eiolca.net software to do a life cycle assessment?

The eiolca.net software will identify the economic and environmental impacts of a purchase from a particular sector. The entire supply chain for producing this purchase is represented. However, any impacts from the use of the purchase are not included. Thus, suppose you are interested in assessing the life time impact of a motor home. You could use the eiolca.net software to assess the environmental effects of producing $ 1 million of motor homes. If your motor home cost $ 50,000, then the environmental effects of the single motor home would be $ 50,000/$ 1,000,000 = 0.05 or five percent of the $ 1,000,000 eiolca.net impacts. To this total, you should add the environmental impacts of producing the petroleum and maintenance items that would be used by the motor home over its lifetime. Each of these items can be assessed with the eiolca.net software. Finally, you need to estimate the direct air emissions from the motor home (as provided by the manufacturer and summarized in consumer magazines) plus any disposal impacts.

Can you show me an example of an eiolca.net application?

Suppose you wish to compare the environmental implications of two pavements with the same expected lifetimes but made out of different materials: asphalt versus steel reinforced concrete (SRCP) pavements. First, you would have to establish the designs and costs of the two pavement sections made of different materials. In this case, the asphalt pavement would be thicker than the SRCP pavement design. The final demands are the costs of the pavement materials: $145,500 for the asphalt pavement, and $106,700 for the concrete and $23,400 for the steel content in the SRCP. Then, the eiolca.net software can be used to calculate the environmental burdens of both materials in the manufacturing stages. Both pavement types were estimated in this analysis by commodities in the 500 x 500 input-output matrix. For the asphalt pavement, the sector "asphalt paving mixtures and blocks" (Standard Industrial Classification, SIC, code 2951) was used. For the concrete content of the pavement, the sector "ready-mixed concrete" (SIC code 3273), and for the steel reinforcement, the sector "blast furnaces and steel mills" (SIC code 3312) was used. The total economic transactions in the supply chain for the two pavements were similar: $349,000 for asphalt, and $289,000 for steel-reinforced concrete. This total demand indicates that as a result of the final demand in the asphalt and the concrete and steel industries, there was additional demand for products and services in the entire national economy for $203,500 in the case of asphalt, and for $158,900 in the case of CRCP. After this, the relevant environmental impacts can be estimated with the eiolca.net software.

Why does $ 1million of purchases result in more than $ 1 million in economic activity?

The eiolca.net software reflects the entire supply chain of transactions to produce a good or service. For example, purchase of an automobile will require purchase of steel, paint, plastics and many other goods. The eiolca.net software estimates the total set of such transactions. Note that purchase of $ 1 million of one good often results in more than $ 1 million of output for this sector because many sectors may use the good themselves in their production.

Who made this site?

A team of researchers within the Green Design Initiative at Carnegie Mellon University developed this site. Elisa Cobas-Flores, Chris Hendrickson, Arpad Horvath, Satish Joshi, Lester Lave, H. Scott Matthews and Francis McMichael developed the eiolca.net model. The eiolca.net software was developed by Chris Hendrickson, Arpad Horvath, Octavio Juarez, and H. Scott Matthews.

Where can I go to read more?

Further information about the analysis procedures used appears in Hendrickson, C., A. Horvath, S. Joshi and L.B. Lave, "Economic Input-Output Models for Environmental Life Cycle Analysis," Environmental Science & Technology, April, 1998, and in other Green Design Publications.


Where can I find price information for goods and services?

With the growth of eCommerce, price information for most commodities is available by searching on the World Wide Web. Current prices should be converted to $ 1992 by the use of an appropriate economic index. A good source of price indices is the Statistical Abstract of the United States, available online. For example, the conversion from 1997 prices to 1992 prices using the consumer price index is accomplished by finding the 1997 CPI value (160.5) and dividing it by the 1992 value (140.3), equal to 0.87. Thus 1992 prices can be found by multiplying 1997 prices by 0.87.

What is the uncertainty in the eiolca.net software results?

There are numerous sources of uncertainty in the eiolca.net software. Some of the more important include:

  1. Old data: The latest economic input/output table developed by the Department of Commerce varies from 2 to 7 years old. Similarly, there is a lag in receiving environmental data. Of course, some data may be fairly stable, such as the economic input/output coefficients for relatively stable industries. Other factors may be changing more rapidly, such as air emissions from vehicles.
  2. Incomplete data: While the eiolca.net strives to include comprehensive data, some sources are incomplete. For example, the toxics release inventory only is required for some industrial sectors and only for plants above administratively defined threshold sizes. As a result, the toxics emissions are likely to be underestimated.
  3. Missing data: The eiolca.net software does not include all environmental effects. For example, habitat destruction for manufacturing plants is not included. Similarly, the external costs of production are limited to health effects of conventional air emissions due to lack of data on the valuation of other effects.
  4. Aggregation: Even with 500 sectors, we would like to have more detailed information on particular products or processes. For example, we might like to examine different types of batteries that are all aggregated in the rechargeable battery sector. Similarly, the eiolca.net software represents typical US production within each sector. Users might wish to make corrections for specific plants or product mixes. One approach to this problem is to combine process models and the eiolca.net software.

How can I combine process models with the eiolca.net software?

Due to the aggregation issues noted earlier, it is often useful to develop specific models of particular products or processes to supplement the eiolca.net software. For example, the eiolca.net software might be used to assess the electricity input to a plant, while the plant may itself might be modeled separately. Alternatively, the economic input-output sectors might be disaggregated to represent particular companies, plants or products. However, the eiolca.net site does not permit this type of disaggregation.

Which input/output table is being used in eiolca.net?

The default (and recommended) model is the 1997 benchmark industry-by-industry economic input-output model as developed by the US Department of Commerce's Bureau of Economic Analysis (available here). The advanced page of the website allows access to other, including older, models of the economy.

How does eiolca.net account for imports?

Imports are implicitly assumed to have the same production characteristics as comparable products made in the United States. Thus, if a truck is imported and used by a US company, the environmental effect of the truck is expected to be comparable to those made in the US. To the extent that overseas production is regarded as more or less of an environmental concern, then the impacts developed from eiolca.net software should be modified by adding additional transportation and logistics (e.g., for overseas delivery) as well as possibly adjustment for different production processes..