Unfabricated vs. fabricated steel EPDs

We are looking to incorporate in our specifications/generals notes GWP limits on steel products. Buy Clean California gives limits for “unfabricated” steel, but many EPDs that are available are for fabricated sections. While the unfabricated value can be “back calculated” from the fabricated it does not seem very straight forward nor efficient to do so.

How have you tackled this given the variety of values in the EPDs and whether it’s fabricated or unfabricated? Do you recommend we list both values? Or perhaps only list unfabricated so it is in line with BCCA for California projects, and then fabricated for all other project locations?

This seems to be a problem with ‘Buy Clean’ legislation in general - the final laws are not consistent with actual practice. Our Colorado Buy Clean law requires “For any solicitation for a contract for the design of an eligible project, an agency of government shall require the designer who is awarded the contract to include, in project specifications when final construction documents are released, a current environmental product declaration, type III…” [Colo. Rev. Stat. § 24-92-117]. This means designers would have to include an EPD from a specific manufacturer in the construction documents (?!!), but the law does not appear to require that this product be used.

I have not read the California law, but it seems that they are assuming EPDs break down stage A3 into pre and post fabrication, which is not often (never?) the case. My thought would be to write your specs and notes to limit GWP to fabricated sections - after all that is what you will be using.

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I recently spoke with AISC on this topic and my understanding is that the industry standard is to use fabricated EPDs. Fabricated sections, after all, are what are actually used in construction projects. CA is the only known jurisdiction requiring unfabricated steel EPDs. Suppliers will have to report both unfabricated and fabricated GWP within the EPD to comply (as far as I understand but others can confirm). The unfabricated GWP does not simply equate to A1 of the fabricated GWP, because the fabricated GWP will include scrap.

I would recommend fabricated steel GWP limits in all specifications across all jurisdictions as a base performance requirement, with the introduction of unfabricated steel GWP limits for projects where Buy Clean CA applies.

And I’ll note here that Buy Clean CA is facility specific EPDs, not supply-chain specific EPDs (as proposed in Buy Clean language from other states). So the spec language should be tied to Type III product specific EPDs for now, but need to be mindful as other Buy Clean Acts are passed that the type of EPD required in the specification may have to change depending on jurisdictional requirements.


I’ve been doing a lot “deep-dives” into structural steel/steel construction data myself, and came across this same issue. After discussions with AISC’s team, I think I can resolve your question.

When structural steel is delivered to a site, it typically does NOT come directly from a steel mill. Rather, it gets fabricated at a fabrication shop using other structural elements (plate for example) to meet the drawing requirements. This is great from a construction standpoint, but a nightmare in terms of carbon counting as EPDs for the final fabricated member do not exist. However, in the scope of A1-A3, A1 would be the impacts for the steel mill (aka unfabricated, but then you also need to account for waste steel generated during fabrication), A2 would be the impacts from transportation to a fabrication shop, and A3 would be the impacts at the fabrication shop (excluding any coatings applied). Due to the relatively few steel mills compared to fabrication shops, what’s happened is that the steel mill companies have generated product specific EPDs with mill specific GWP values showing the mills impacts under A1, and then industry average fabrication values for A2 and A3. In some instances, the larger steel mill companies have begun to acquire fabrication shops, in which case they may end up using their own fabrication shops’ A2 and A3.

As you can see, the largest “unknown” is in what YOUR fabrication shops’ A2 and A3 is (your being the shop who is conducting the fabrication for any given project). If I had to guess, this is why BCCA listed both unfabricated and fabricated product specific GWP values. It is also important to note that even though there is uncertainty behind A2 and A3, all of the product-specific EPDs are third-party verified against ISO 14025 and 14044.

In order to accomplish your goal of incorporating GWP limits on steel products, what you would need to do is the following:

  1. Isolate the specific steel products you are looking for - the GWP varies greatly between product (product meaning…HSS, Plate, Hot-Rolled, Rebar, etc).
  2. Determine where your steel products are currently being sourced from - if it’s from within the US or North America, than using the AISC Industry Average values, or other steel product’s industry average would be relevant since it’s tied to the “local” (relative to the world) steel market.
  3. Use the Industry Average steel product EPD GWP value for A1-A3 (which would include fabrication) + a degree of uncertainty if you do not know which specific mills you are commonly sourced from. If you do know which steel mills your sourcing from, you can tailor your value to better suit what you actually receive. Or, you could come to release that adopting the BCCA limits for fabricated steel products would not be a challenge/reach for you/your firm.
  4. Rinse and repeat for EACH steel product.

On the implementation side, the best way to go about it would be to stay on top of the tonnage purchased per steel product per mill before it is fabricated. It can be a heavy data lift, but tracking the “as purchased” steel product tonnage is the best approach from my standpoint since you can then tie it back to a product specific EPD that lists the mill specific GWP values.