Frequently asked questions

What is this?

A web tool for economic input-output life cycle assessment. You choose one of 411 U.S. commodity sectors and an amount of money, and it reports the resource use and emissions of producing that amount, including the whole supply chain. It runs on the U.S. EPA's USEEIO v2.0.1 model, in your browser, from files served by this site.

Why does the course host its own copy?

For about twenty years the course used Carnegie Mellon's eiolca.net for the input-output half of Assignment 3. That site went offline in January 2023 and came back in September 2026, restored by one of its original developers under a private consultancy. It now serves the same USEEIO v2.0.1 model as this site, with greenhouse-gas and economic results only, beside the older 1992–2007 U.S. models and several national models. EPA itself publishes the model as data files and code, not as a tool for students. A copy hosted by the course, pinned to one model version, means the numbers you cite in week three are the same in week ten, the tool is there during assignment week, and the air-emission flows, the price conversion and the citation block the assignments rely on are all in one place. Use eiolca.net for the older models and as a cross-check: for the same sector and dollars, its greenhouse-gas totals match this tool's.

When should I use it?

For the input-output values in the assignments, and for the parts of your term-project LCA for which you cannot find a specific value in SimaPro.

• Lecture 3 and Assignment 3. The tool is the full-size version of the ten-sector model you build by hand: the same mathematics with 411 sectors. The IO tables view shows the direct requirements you reconstruct.
• Term projects. When a process step in your system has no process data, map it to the closest sector, query the impacts for the dollars involved, and record in your data-quality discussion that the step was estimated with sector-average input-output data. This is the hybrid method from the design module.

Is this a replacement for SimaPro?

No. SimaPro is the course's process-LCA tool: unit processes, the foreground system you model yourself, characterization methods, and the process side of Assignment 3. It stays where it is.

This tool gives sector averages for the 2012 U.S. economy, in dollars. That is the right instrument for screening, for background processes and for gaps, and the wrong one for product-level claims, for comparing two designs within one sector, or for anything the project brief asks you to model as a process. Estimating a whole product from its sale price is a screening estimate, not an LCA.

What are the numbers, exactly?

Impact per dollar of final demand in the chosen sector, multiplied by your dollars after conversion to 2012 producer prices. Totals include the supply chain. Definitions that differ from older tools, in particular NOx, PM10 and energy, are listed in Documentation.

Will the numbers change during the quarter?

No. The model version is pinned and named on every page and in every copied result. Changes happen between quarters, together with the assignment materials.

Does it store anything about me?

No. There are no accounts, no uploads and no server-side code.

Who made the data and the software?

The model is EPA's. The three data views are EPA's useeio-widgets. The tool page, the documentation and this FAQ are by the course. Licenses and the citation format are on Usage and Copyright.

Who maintains it?

The CEE 226 teaching team. Bring questions about a number that looks wrong to class, with the model version and your inputs.