Differentiating steel sourcing in LCA

Hello folks -

Does anyone know how to differentiate sustainable steel sources (e.g. steel manufactured using an EAF in a renewable grid, or Responsible Steel certified facility, or Econiq) within an LCA study that starts out in Tally?

This question is analogous to the ongoing XPS dilemma - how to differentiate HFO-blown XPS products in a Tally study that doesn’t carry data for HFO-blown products.

Has anyone run into the need to get really granular with steel definitions in your LCA studies?

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We tend to use Tally as a way of getting the overall weight assumption of the steel, and then manually adjusting the data using EPD data. We typically use the AISC industry-average steel EPD for hot rolled steel (baseline) and a plant specific steel replacement. Both have a functional unit of 1 ton of steel, which is why we’re using Tally for the weight assumption - some epds we replace are better served by volume or area. Then we poke around in the raw tally data side to replace the A1-A3 stage data to match the EPD impacts. B-stage usually is zero for structural steel, and we leave C and D stages as we assume that end of life is typical for steel, regardless of initial procurement. It’s clunky, but it gives us an estimate.

We’ve had our way of teasing out the data on this tab, but something i just heard of is that interesting things happen if you close out the excel file while it’s being created in the tally report…

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One more thing we’ve noticed: the AISC baseline uses Gabi and some steel EPDs (Gerdau, for instance) use ecoinvent for the underlying LCI data. While this doesn’t impact GWP significantly, it does impact eutrophication and some other attributes significantly.

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I haven’t gotten this far into the weeds yet in Tally but it’s my understanding that the region you are in defines renewable grid content and so the implication in your question is you are trying to source a specific manufacturer in a region heavy with renewable generation.

What is your plan to rectify the potential increase in transportation based carbon and (eventually though hopefully not too long) specifying EV heavy vehicle transport to counteract that increase?

I realize you are likely looking for an immediate answer so forgive me if my question is not entirely relevant to current needs.

I agree with Justin, the best way to account for this is with EPDs for the mills and specific products where you get your steel from. This is unfortunately a post-processing step if starting from Tally and you will definitely run into issues finding EPDs that are this specific at this time. Kjell’s point about significant misalignments in non-GWP categories is also true. We need to move towards better-aligned background data and a better understanding of the absolute scale of some of these other impact categories.

To Patrick’s point, Tally does not regionalize any material impact data. The location of a project does not affect the embodied impacts of the selected materials (in Tally’s assessments).


Hello, we are building a carbon declarative language and looking for a “steel taxonomy” i.e. descriptors used. Documents – Carbon-ML any tips or pointers appreciated. The goal is making it easy to pass CO2e messages and declarations using shared contexts across systems and actors.

i think the best thing you can do is ensure they are EAF manufactured in the country you are located in. You can ensure that by 1) making sure the invoice from the mill says “EAF from ____, USA” and b) when the product arrives on site it will come with mill certs which will reconfirm which mill the steel came from

Are you asking about passing digital information or something else? If digital, Building Transparency has something that might be useful: 1) EC3 has EPD data in a standard format, accessible via API, and includes material-specific descriptors (search for “Steel” in the API link). 2) we are working on an openEPD format and API which will include material-specific extensions along the lines of what EC3 already does, but could include additional things like the type of mill etc. Try EC3 out and see the steel categories and various descriptors we track there.

One can argue that a product that depends purely on purely sustainable/renewable energy sources cannot actually be sustainable/renewable, at least not as long as non sustainable/renewable energy is used anywhere else in the economic/social system. If opportunity cost of the embodied carbon and sunk capital that are required for the renewable energy are considered then we are left with an efficient allocation model problem for the available renewable energy. We face many illusions.