Steel and Aluminium Embodied Carbon
Two engineers specify the same beam. One reports it at 0.7 kg CO₂e per kg, the other at 3.0. Neither made an arithmetic error — they chose different production routes, different recycled-content rules, and different module boundaries.
For structural metals, the embodied-carbon answer is decided by methodology, not by the factor you look up.
Steel and aluminium embodied carbon is material mass × an EN 15804 module factor, summed across the declared modules. The result is dominated by production route — EAF versus blast furnace, smelter electricity — and by recycled-content allocation.
Put this into practice with the Embodied Carbon — Steel & Aluminium Calculator, which implements the method described on this page.
Structural steel and aluminium are the two highest-intensity mainstream construction metals, and they share a methodological structure: both are reported per unit mass against EN 15804 life-cycle modules, both carry a primary-versus-recycled split that swings the result several-fold, and both expose the single hardest decision in materials accounting — how to allocate the carbon benefit of recycling between the producer who supplies scrap and the producer who consumes it. This methodology covers the boundary system, the factor hierarchy, the route- and electricity-dependence that make generic factors dangerous, the allocation rules that govern recycled content, and a fully reconciled worked example.
What Embodied Carbon Means for Steel and Aluminium
Embodied carbon is the greenhouse-gas emission associated with producing, transporting, installing, maintaining and disposing of a material — everything except the operational energy the finished building or product consumes in use. For steel and aluminium the dominant share sits in the “cradle-to-gate” stage (EN 15804 modules A1–A3): mining or scrap collection, smelting or steelmaking, and fabrication. This is fundamentally different from the Scope 1 process emissions a steelmaker reports for its own furnaces, or the Scope 1 PFC emissions a smelter reports for anode effects. Those are the producer’s direct emissions; embodied carbon is the purchaser’s view of the same physical process, accounted as a supply-chain factor.
Why these two metals are reported together
Steel and aluminium are grouped because they share an accounting skeleton that differs from concrete, timber or masonry. Both are priced and specified by mass, both have a mature primary/secondary production split, both are highly recyclable without loss of structural function, and both have embodied factors that are governed more by energy source than by chemistry. Where concrete embodied carbon is driven by clinker content (covered in the concrete and cement embodied methodology), metal embodied carbon is driven by the electricity and reductant used to win the metal from ore or to remelt scrap.
Where embodied metal sits in the GHG inventory
For an organisation buying steel or aluminium, embodied carbon is a Scope 3 figure. Materials bought into a product or building bought for resale or use fall under Scope 3 Category 1 (purchased goods and services); metals embodied in capital equipment, plant or owned buildings fall under Category 2 (capital goods). In the MasterBrain, ÖKOBAUDAT embodied rows carry the capital-goods scope tag by default, and the CBAM default rows carry the purchased-goods tag — but the scope assignment is a property of your use of the material, not of the factor. Classify by what the metal becomes in your organisation, then apply the factor.
An embodied-carbon factor and a producer’s process-emission factor describe the same physics but answer different questions. The 1.46 t CO₂/t crude steel a blast-furnace operator reports as Scope 1 is not the number a building owner enters for embodied carbon — the owner needs a cradle-to-gate EN 15804 factor that also captures upstream ore, alloying, rolling and fabrication, expressed per kilogram of the finished product, not per tonne of crude metal.
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The EN 15978 / EN 15804 Module Framework
Embodied carbon is not a single number; it is a sum over declared life-cycle stages. The BS EN 15978 assessment framework and the EN 15804 product-EPD standard divide the life cycle into modules. Every Environmental Product Declaration states which modules it covers, and an embodied-carbon total is only comparable across products when the module boundary is the same.
| Module | Life-cycle stage | What it captures for metals | Typically declared? |
|---|---|---|---|
| A1–A3 | Product (cradle-to-gate) | Ore extraction or scrap supply, smelting/steelmaking, alloying, casting, rolling, fabrication | Always — the mandatory core |
| A4 | Transport to site | Mill or stockholder to construction site | Project-specific |
| A5 | Construction / installation | Cutting waste, welding energy, fixings | Project-specific |
| B1–B7 | Use stage | Maintenance, repainting of steel, coating renewal | Rare for bare metal |
| C1–C4 | End of life | Demolition, processing of recovered metal, disposal of residues | Increasingly required |
| D | Benefits beyond the boundary | Net credit/load from recycling or reuse of the recovered metal | Reported separately — never netted into A–C |
Module D is the methodological flashpoint for metals. It carries the recycling credit for scrap recovered at end of life, and under EN 15804 it is reported as a separate figure that is never silently merged into the A1–C total. A headline “X kg CO₂e/kg” that already has the Module D credit subtracted is not comparable to one that reports modules A–C and D separately — and mistaking one for the other is the most common cause of overstated savings claims in metal substitution studies.
Never compare two embodied factors without confirming they cover identical modules. An A1–A3 cradle-to-gate factor and an A1–A3 + C + D “net” factor can differ by more than the recycled-content gap they are trying to illustrate. Module mismatch is silent — both numbers look like “embodied carbon” and both carry the same unit.
Factor Sourcing Hierarchy
Embodied factors come from four tiers of data quality. Use the highest tier you can substantiate, and document the tier in your assessment so a reviewer can trace every figure to its source. The hierarchy mirrors the PCAF-style data-quality logic applied to embodied carbon: product-specific evidence first, generic averages as a fallback, regulatory or spend-based proxies last.
Tier 1 — Manufacturer EPD
A product-specific, third-party-verified EN 15804 EPD from the actual supplying mill. Highest quality. Captures the real production route and grid mix of the specific plant. Required for credible low-carbon procurement claims.
Tier 2 — Generic EPD / database average
An industry-average EPD from ÖKOBAUDAT, the ICE Database, or a national dataset. Route- and region-representative but not plant-specific. The MasterBrain ÖKOBAUDAT rows sit here.
Tier 3 — CBAM default value
The EU CBAM default emission factor for the product. A regulatory reporting value with a different boundary from an LCA factor — use it for CBAM declarations, not for whole-life carbon assessment.
Tier 4 — Spend-based proxy
An economic-input-output factor (kg CO₂e per unit currency). Lowest resolution; only acceptable as a screening estimate where no mass-based or product data exists. Flag for replacement.
The CBAM default and the LCA embodied factor for the “same” product are not interchangeable. CBAM defaults capture direct (and, for some goods, indirect) emissions at the producing installation under a regulatory boundary; an EN 15804 A1–A3 factor captures the full cradle-to-gate supply chain under an LCA boundary. They serve different filings and routinely differ in magnitude. Keep them in separate columns.
Steel: Production-Route Dependence
Steel’s embodied carbon is decided first by production route. Two routes dominate global output, and they differ by roughly an order of magnitude in direct intensity:
| Route | Feedstock | Reductant / energy | Direct process intensity | Embodied implication |
|---|---|---|---|---|
| Blast furnace – basic oxygen furnace (BF-BOF) | Iron ore + ~20–30% scrap | Metallurgical coke (coal) | ~1.46 t CO₂/t crude steel | High embodied carbon; coal-reductant dominated |
| Electric arc furnace (EAF) | Up to ~100% recycled scrap | Grid electricity | ~0.08 t CO₂/t crude steel (process) | Low direct process emissions; embodied carbon tracks the grid mix powering the furnace |
The two route intensities above are the IPCC process factors a steelmaker would use for its own Scope 1 inventory — reproduced here only to show the scale of route-dependence. They are not the embodied factors a purchaser enters; a cradle-to-gate EN 15804 factor for finished steel sits higher than the bare process figure because it also carries upstream ore, alloying, rolling and the grid electricity behind an EAF. The lesson for embodied accounting: a “world-average steel” factor blends BF-BOF and EAF output and will misstate a route-specific procurement by a wide margin. Where the supplying route is known, use a route-specific or plant-specific EPD.
Reinforcement, sections, plate, galvanised and stainless
Within steel, the product form changes the factor. Reinforcing bar (rebar) is predominantly EAF and carries a lower embodied factor than hot-rolled structural sections; galvanising adds a zinc-coating burden; stainless steel carries a substantial alloying burden (chromium, nickel) that lifts its embodied carbon well above carbon steel. The MasterBrain surfaces these as ÖKOBAUDAT rows, rendered live below. Where a specific grade row is still being verified against the live dataset, it renders from the canonical keypath at page load rather than from a frozen figure.
| Steel product (ÖKOBAUDAT) | Module A1–A3 (live) | Unit (live) | Notes |
|---|---|---|---|
| Reinforcement (rebar) | 0.47398 | kg CO2e per kg | Predominantly EAF; recycled-content sensitive |
| Structural sections | 0.56029 | kg CO2e per kg | Hot-rolled; route-dependent |
| Galvanised steel | 2.48 | kg CO2e per kg | Carbon steel plus zinc-coating burden |
| Stainless steel fasteners (screws) | 6.883 | kg CO2e per kg | Alloying burden (Cr, Ni) lifts factor above carbon steel; the only stainless dataset is for fasteners, so treat it as indicative |
ÖKOBAUDAT 2024 EN 15804 EPDs, surfaced via the GreenCalculus MasterBrain. Values resolve live at render; an em-dash indicates a keypath still being verified.
The recycled-content problem for steel
Because EAF steel is made largely from scrap, its embodied carbon depends heavily on how the recycling benefit is allocated — and on whether the scrap input is treated as burden-free (cut-off) or carries an upstream load. A high recycled-content figure does not automatically mean low embodied carbon: an EAF running on a coal-heavy grid can exceed a BF-BOF plant on green hydrogen. Recycled content is a proxy, not a guarantee. The allocation rules in the next-but-one section are what actually determine the number.
Aluminium: Electricity Dependence
Aluminium’s embodied carbon is decided first by electricity. Primary aluminium is won from alumina by electrolysis (the Hall-Héroult process), which consumes roughly 13–15 MWh of electricity per tonne of metal. The carbon intensity of that electricity — hydro at one extreme, coal at the other — dominates the embodied factor far more than any process improvement. A primary smelter on hydropower and one on a coal grid can differ by a factor of three or more for the same metal.
Secondary (recycled) aluminium avoids the electrolysis step entirely — it is remelted, not reduced — so its embodied carbon is a small fraction of primary. The MasterBrain ÖKOBAUDAT averages make the gap explicit:
Bar widths illustrate relative composition across the three ÖKOBAUDAT average rows; recycled-secondary remelt carries far less load than primary reduction. Figures resolve live from the MasterBrain.
Primary vs secondary aluminium
The primary/secondary distinction is the aluminium analogue of steel’s route question, but sharper. Steel’s two routes differ by an order of magnitude in direct process emissions but converge somewhat once upstream and finishing are added; aluminium’s primary and secondary routes differ structurally because one requires electrolytic reduction and the other does not. The practical consequence: for aluminium, recycled content is a much stronger lever on embodied carbon than it is for steel, provided the secondary metal genuinely displaces primary rather than supplementing it.
Why grid mix at the smelter dominates
Two primary ingots with identical chemistry can carry very different embodied factors purely because of where they were smelted. This is why a generic “primary aluminium” factor is a blunt instrument: it averages a global smelter fleet that ranges from near-zero-carbon hydropower to coal. Where the smelter or its electricity contract is known, a plant-specific EPD captures the real intensity; where it is not, the ÖKOBAUDAT average is the defensible fallback — but its uncertainty band is wide and should be disclosed.
Aluminium primary smelting also generates perfluorocarbons (PFCs) during anode effects — CF₄ and C₂F₆, gases with extreme global warming potentials (PFC-CF₄ GWP-100 = 7,380 [GreenCalculus gwp.PFC_CF4.ar6_100 · IPCC AR6 WGI Ch 7 Table 7.SM.7 (2021) — AR6 GWP-100]). In a cradle-to-gate EPD these are already embedded in the A1–A3 figure. They are reported separately only when the smelter accounts for its own Scope 1 PFC emissions — do not add them again on top of an embodied factor that already includes them.
Recycled Content and End-of-Life Allocation
This is the section that determines the answer. For recyclable metals, the carbon benefit of recycling can be attributed in more than one place, and the chosen allocation method can move the reported figure by a large margin. Three approaches are in use, and EN 15804 prescribes how they map onto the modules.
Cut-off (recycled-content) approach
Recycled input enters the system burden-free; the producer using scrap claims the benefit. End-of-life recycling of the product generates no credit for this producer (the next user claims it). Simple, avoids double-counting, but ignores the value of the scrap the product will become.
End-of-life recycling (avoided burden / Module D)
The product carries its full primary burden, but a credit is given for the scrap recovered at end of life, calculated as the primary production it avoids. EN 15804 places this credit in Module D, reported separately from A–C. Rewards recyclability of the output.
Closed-loop / 50:50 hybrids
Various national and sector rules split the benefit between supplier and user of scrap, or apply a closed-loop assumption where the metal returns to the same application. Used to avoid the extremes of the two pure methods.
The decision is not cosmetic. The same beam can be reported at its full primary burden with a separate Module D credit, or at a low recycled-content figure with no end-of-life credit, and both are “correct” under their respective conventions. What is not permitted is mixing them — claiming a low recycled-content A1–A3 figure and a Module D end-of-life credit for the same metal double-counts the recycling benefit.
Double-counting the recycling benefit is the defining error of metal embodied-carbon accounting. If your A1–A3 factor already reflects recycled content (cut-off), you cannot also subtract a Module D recycling credit — the benefit is being counted twice. Pick one convention per assessment, state it explicitly, and apply it to every material in the comparison.
EN 15978 whole-building assessments and RICS Whole Life Carbon Assessment both require Module D to be reported separately and never netted into the headline A1–C total precisely to keep this distinction visible. When you compare materials, compare A1–C against A1–C, and compare D against D — never A1–C of one against “net of D” of the other.
Calculating Embodied Carbon Module by Module
The core calculation is mass times factor, summed across declared modules. For a single material in a single module:
ECmodule = m × EFmodule
where m = material mass (kg) and EFmodule = the EN 15804 module factor (kg CO₂e/kg) for that product and module. The whole-life embodied total is the sum over the declared modules, with Module D reported alongside but not added into the A1–C subtotal:
ECA1–C = Σ (m × EFmodule) for modules A1–C | ECD reported separately
Three rules make the arithmetic defensible:
- Mass, not volume. Metals are accounted per kilogram. Convert any sectional or volumetric quantity to mass using the product density before applying the factor — getting density wrong is a silent multiplier on the whole result.
- Match the module to the question. A cradle-to-gate procurement decision uses A1–A3. A whole-life building assessment uses A–C with D separate. Do not pad a cradle-to-gate factor with a guessed end-of-life term.
- One allocation convention throughout. Whatever recycled-content or Module D convention you choose, apply it to every material in the assessment so the comparison is like-for-like.
For CO₂e, embodied factors already aggregate the relevant gases at their GWP-100 weighting. Corporate and whole-life reporting use AR6 GWP-100 by default; CO₂ has a GWP of 1 [GreenCalculus gwp.CO2.ar6_100 · IPCC AR6 WGI Ch 7 Table 7.SM.7 (2021) — AR6 GWP-100] and the metal-relevant PFCs sit at the high end (PFC-CF₄ at 7,380 [GreenCalculus gwp.PFC_CF4.ar6_100]). You do not re-weight an EPD factor — it arrives pre-aggregated as CO₂e.
Worked Example: Structural Frame Material Comparison
A worked example computed end-to-end. All figures here are fixed as an audit record at the snapshot date of this methodology revision — they reconcile to their stated inputs and do not move when the live dataset updates.
Comparing two framing options for an identical structural demand: a primary-aluminium option (2,000 kg) against a recycled-secondary-aluminium option (2,000 kg). Aluminium factors snapshot at ÖKOBAUDAT 2024 averages: primary ingot 1.896 kg CO₂e/kg; recycled secondary 1.383 kg CO₂e/kg. Module A1–A3 (cradle-to-gate) only. Single allocation convention: cut-off recycled content, no Module D credit applied on either side.
| Step | Primary aluminium option | Recycled-secondary option |
|---|---|---|
| Mass (kg) | 2,000 | 2,000 |
| Module A1–A3 factor (kg CO₂e/kg) | 1.896 | 1.383 |
| A1–A3 embodied carbon (kg CO₂e) | 2,000 × 1.896 = 3,792.0 | 2,000 × 1.383 = 2,766.0 |
| Expressed in tonnes CO₂e | 3.792 tCO₂e | 2.766 tCO₂e |
| Saving vs primary | — | 1,026.0 kg CO₂e (−27.06%) |
The recycled-secondary option saves 1,026.0 kg CO₂e — a 27.06% cradle-to-gate reduction — purely from avoiding electrolytic reduction. The saving is real only because both options are accounted under the same module boundary (A1–A3) and the same allocation convention (cut-off, no Module D). Switch the recycled option to “primary burden plus Module D credit,” and the headline A1–A3 figure would rise to the primary value with the benefit appearing separately in Module D — a different presentation of the same physics, and not comparable to the primary option’s A1–A3 figure unless the primary option’s Module D is shown too.
The factors above are frozen at the values the dataset returned on the day this methodology was last reviewed. A verifier checking the arithmetic a year from now must see the same inputs and the same result. Live references elsewhere on this page use the [gc_factor] shortcode and will track the dataset; this worked example does not, by design.
Governance, Standards and Disclosure
These element-level factors roll up into the building-scale whole-building LCA methodology and the RICS whole life carbon methodology; for design-option comparisons, see the material-substitution methodology.
Four standards govern how steel and aluminium embodied carbon is measured, declared and disclosed. They nest: a product standard generates the factor, an assessment standard sums it across a building, a professional standard sets the reporting discipline, and a regulatory regime sets the import-declaration boundary.
| Standard | Role | What it governs for metals |
|---|---|---|
| EN 15804 | Product EPD rules | How a steel or aluminium EPD is structured — module definitions, declared unit, allocation rules for recycled content and Module D |
| BS EN 15978 | Building assessment | How module factors are summed across a whole building; the requirement to report Module D separately |
| RICS WLCA | Professional methodology | Reporting discipline, data-quality tiers, mandatory separation of embodied and Module D for UK practice |
| EU CBAM | Import regulation | Default emission factors for imported iron, steel and aluminium under a regulatory boundary — a declaration value, not an LCA factor |
The CBAM defaults illustrate why boundary discipline matters. The MasterBrain CBAM default for crude steel ingot is 8.21 kg CO₂e per kg [GreenCalculus materials.cbam.iron_steel.crude_steel_ingot · CBAM 2026] of good, and for unwrought aluminium 3.198 kg CO₂e per kg [GreenCalculus materials.cbam.aluminium.unwrought · CBAM 2026] of good. These are regulatory declaration values — they are not the cradle-to-gate LCA factors used in a whole-life building assessment, and they should never be substituted into an EN 15978 model. Use them for CBAM quarterly reporting; use EN 15804 EPDs for embodied-carbon assessment.
A single project can legitimately carry two different “embodied” numbers for the same steel: a CBAM default for the import declaration and an EN 15804 EPD figure for the whole-life carbon assessment. They are not in conflict — they answer different regulatory questions under different boundaries. The error is using one where the other is required, or averaging them. Keep each in its own filing and document which boundary applies.
Error Traps with Calculable Magnitudes
Each error below produces a specific, quantifiable distortion. Magnitudes are shown against the worked-example aluminium options where applicable.
| Error | What happens | Magnitude | How to avoid |
|---|---|---|---|
| Double-counting the recycling benefit | A cut-off recycled-content A1–A3 factor is used and a Module D credit is subtracted for the same metal | Benefit counted twice — can overstate savings by the full Module D credit | One allocation convention per assessment; if A1–A3 reflects recycled content, claim no separate D credit |
| Comparing mismatched modules | An A1–A3 factor for one material is compared against an A1–C+D “net” factor for another | Distortion can exceed the recycled-content gap being illustrated | Compare A1–C to A1–C, D to D; confirm module coverage on every EPD |
| World-average steel for a known route | A blended global factor is applied to steel known to be EAF or BF-BOF | Route intensities differ several-fold (≈1.46 vs ≈0.08 t CO₂/t at the process level) | Use route-specific or plant-specific EPDs where the route is known |
| Generic primary aluminium for a hydro smelter | A global-average primary factor is applied to metal from a low-carbon-electricity smelter (or vice versa) | Smelter grid mix can swing the factor by 3× or more | Use a plant- or contract-specific EPD; disclose the uncertainty band on generic averages |
| Volume instead of mass | A sectional or volumetric quantity is multiplied by a per-kg factor without density conversion | Silent multiplier — error scales with the density mistake | Convert to mass with the correct product density before applying the factor |
| Adding PFCs on top of an EPD | Smelter PFC emissions are added to an aluminium A1–A3 factor that already includes them | Double-count of a very high-GWP term (PFC-CF₄ = 7,380) | A cradle-to-gate EPD already embeds A1–A3 PFCs; only the smelter’s own Scope 1 inventory reports them separately |
| Substituting a CBAM default into an LCA model | A CBAM regulatory default is entered into an EN 15978 whole-life assessment | Boundary mismatch — different scope and purpose | CBAM defaults for CBAM filings; EN 15804 EPDs for embodied-carbon assessment |
Data Sources and EPD Databases
Five sources cover most steel and aluminium embodied needs. Use them in the data-quality hierarchy: manufacturer EPD > national/database average > CBAM default > spend-based proxy.
- Manufacturer EN 15804 EPDs — product- and plant-specific, third-party verified. The only tier that captures the actual route and grid mix of the supplying mill. Required for credible low-carbon procurement claims.
- ÖKOBAUDAT 2024 — the German national LCA database; route- and region-representative EN 15804 EPDs. The MasterBrain embodied rows for aluminium and steel are sourced here.
- ICE Database — the Inventory of Carbon and Energy; widely used generic embodied factors, useful for early-stage screening and cross-checking.
- EU CBAM default values — regulatory declaration factors for imported iron, steel, aluminium and other goods. Distinct boundary from LCA; use only for CBAM reporting.
- Spend-based proxies — economic-input-output factors as a last-resort screening estimate where no mass-based data exists. Flag every spend-based line for replacement with product data.
What the Calculator Handles vs What You Decide
The embodied-carbon calculators automate the mechanical arithmetic. This methodology covers the upstream decisions the calculator cannot make for you.
The calculator handles automatically
- Mass × module-factor arithmetic across A1–C
- Module D reported separately from the A1–C subtotal
- Primary-vs-recycled factor selection from the dataset
- Unit conversion (kg, tonnes) with an audit trail
- CO₂e aggregation at the EPD’s GWP basis
- Side-by-side material comparison at a matched boundary
You must decide before using it
- Allocation convention — cut-off vs Module D vs closed-loop, applied consistently
- Module boundary — cradle-to-gate vs whole-life, matched across materials
- Data tier — manufacturer EPD, database average, or proxy
- Production route / smelter — route-specific where known, generic where not, with uncertainty disclosed
- Scope classification — Category 1 vs Category 2 by what the metal becomes in your organisation
Frequently Asked Questions
Three variables move the figure independently of any error: production route (EAF vs BF-BOF), the recycled-content or Module D allocation convention, and the EN 15804 module boundary the factor covers. A world-average factor blends routes; a cut-off factor and a Module D “net” factor present the recycling benefit differently; an A1–A3 factor and an A1–C factor cover different stages. To compare two figures meaningfully, confirm all three match before reading the numbers.
In cradle-to-gate terms, recycled (secondary) aluminium is structurally lower because it skips electrolytic reduction — it is remelted, not won from ore. The ÖKOBAUDAT averages put primary ingot at 1.896 kg CO₂e/kg against recycled secondary at 1.383 kg CO₂e/kg. The caveat is that the benefit is only real if the secondary metal genuinely displaces primary production rather than supplementing it, and the comparison must hold the module boundary and allocation convention constant on both sides.
No. CBAM default values are regulatory declaration factors under a regulatory boundary — they capture direct (and for some goods indirect) emissions at the producing installation, not the full cradle-to-gate LCA supply chain that an EN 15804 EPD covers. The CBAM crude steel ingot default and an EN 15804 cradle-to-gate steel factor answer different questions. Use CBAM defaults for CBAM quarterly filings and EN 15804 EPDs for whole-life carbon assessment; never substitute one for the other or average them.
Module D captures the net benefit or load beyond the system boundary — principally the recycling or reuse credit for metal recovered at end of life, valued as the primary production it avoids. EN 15804 and EN 15978 require it to be reported as a separate figure rather than netted into the A1–C total, because doing so keeps the recycling benefit visible and prevents it from masking the in-boundary embodied carbon. Compare A1–C against A1–C and D against D — never one material’s A1–C against another’s net-of-D figure.
Choose one allocation convention per assessment and apply it to every material. If your A1–A3 factor already reflects recycled content under the cut-off method, you cannot also subtract a Module D end-of-life credit for the same metal — the benefit would be counted twice. Either use cut-off recycled content with no separate D credit, or use a full primary burden with the recycling benefit shown separately in Module D. State which convention you used so a reviewer can trace it.
Yes — a cradle-to-gate EN 15804 A1–A3 factor for aluminium already embeds the smelter’s perfluorocarbon emissions (CF₄, C₂F₆) and all other process gases, aggregated to CO₂e at the EPD’s GWP basis. You do not add them again. PFCs appear as a separate line only in a smelter’s own Scope 1 process inventory, where they are accounted directly rather than embodied in a purchased-material factor. Adding them on top of an EPD double-counts a very high-GWP term.
Corporate and whole-life carbon reporting uses IPCC AR6 GWP-100 by default, consistent with the GHG Protocol and CSRD. EPD factors arrive pre-aggregated as CO₂e, so you do not re-weight them — but when reading or reconciling underlying gas data, the metal-relevant terms are CO₂ at 1 and PFC-CF₄ at 7,380 [GreenCalculus gwp.PFC_CF4.ar6_100]. Never mix AR5 and AR6 bases within a single assessment.