Structural Materials Embodied Carbon
A concrete mix, a steel section and a glulam beam all carry an embodied carbon figure you can look up in minutes. What none of those figures tell you on their own is which life-cycle module they cover, which database year they came from, or whether the material family even declares the modules you are about to add them to.
The number is the easy part; the boundary attached to it is where structural estimates go wrong.
Structural embodied carbon covers concrete, steel and aluminium, timber, and masonry and finishes. Each is estimated per material unit against EN 15804 modules — and module coverage differs by material, so totals are only comparable within a stated boundary.
These calculators read ÖKOBAUDAT 2024 EPDs, European Aluminium 2024 and the MPA FS18 2025 binder set — three sources with three vintages, versioned in the GreenCalculus MasterBrain. See how the numbers are built for which source backs which material.
Structural embodied carbon tools and guides
Concrete & Cement Calculator
You have a mix design or a volume of ready-mix and need kg CO₂e per m³ by C-grade.
Steel & Aluminium Calculator
You have a tonnage of sections, rebar, plate or extrusion and need it per kg.
Timber & Bio-Materials Calculator
You are specifying CLT, glulam, sawn timber or a bio-based product and need the biogenic carbon handled properly.
Masonry & Finishes Calculator
You have brick, block, tile, plasterboard or paint quantities to account for.
Material Substitution Savings Calculator
You have a baseline specification and want to test a swap against it before committing.
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Which calculator do I need?
Structural materials divide by what you are counting and the unit you are counting it in. Concrete arrives as volume, steel and aluminium as mass, tile as area. Pick by the quantity you actually hold — a bill of materials, not a building.
| Calculator | What it estimates | Unit | When it is enough | Methodology | Next step |
|---|---|---|---|---|---|
| Concrete & Cement | Ready-mix by C-grade, cement and binder constituents | kg CO₂e / m³ (binders per kg) | You know the grade and the volume | Concrete & cement methodology | Test a lower grade or an SCM against the baseline |
| Steel & Aluminium | Sections, rebar, plate, ingot and extrusion | kg CO₂e / kg | You know the product form and the mass | Steel & aluminium methodology | Check recycled content and the module boundary |
| Timber & Bio-Materials | Engineered and sawn timber, bio-based products | kg CO₂e / m³ | You know the product and the volume | Timber & bio-materials methodology | Read A1–A3 and C3 together, never separately |
| Masonry & Finishes | Brick, block, tile, plasterboard, paint | Varies — per m², per kg, per unit | You know quantities by product type | Masonry & finishes methodology | Carry the module set through to the build-up |
| Material Substitution Savings | A specified swap against a stated baseline | Delta, in the baseline’s unit | You have a baseline and a candidate | Material substitution methodology | Take the delta into the whole-building model |
Why the module you cite changes the answer
Every figure here is an EN 15804 module, and the module is half the number. EN 15804 splits a product’s life into stages: A1–A3 is cradle-to-gate — extraction, transport, manufacture. B1 is the use stage, which for cementitious materials means carbonation, the slow reabsorption of CO₂ into the surface. C1 to C4 cover deconstruction through disposal. D sits outside the system boundary as a reuse or recovery credit, and ISO 21930 is explicit that it is always reported separately rather than netted off.
The practical consequence is that two correctly-sourced figures for two materials may not be addable. A1–A3 is the only module every material declares. Everything past it depends on what the EPD published — and that varies by family, not by your preference. The module coverage matrix below is the thing to check before you sum anything.
Where this stops and whole-building LCA starts
This slice ends at the material. The moment materials are assembled into a build-up — a wall, a roof, an envelope — you are one scale up, and the question changes from “what does this material cost per unit?” to “what does this assembly cost across a 60-year study period, including replacement and operational energy?” That is EN 15978 territory, and it needs scenario parameters this slice does not carry: transport distances, wastage rates, component service lives. If you are modelling a building rather than specifying a material, start at Whole-Building & Life-Cycle Carbon instead — the building envelope calculator lives there, because an envelope is an assembly.
What each calculator covers
Concrete and cement
Concrete’s footprint is driven almost entirely by cement content, which is why it tracks structural grade so closely. Ready-mix runs from 112 kg CO₂e/m³ [GreenCalculus materials.concrete.ready_mix.c8_10.module_a1_a3 · OEKOBAUDAT 2024 · v2026.284]; at C8/10 to 286 [GreenCalculus materials.concrete.ready_mix.c55_67.module_a1_a3 · OEKOBAUDAT 2024] at C55/67 — roughly two and a half times across the range, for the same cubic metre of material. C30/37, the standard structural grade, sits at 196 [GreenCalculus materials.concrete.ready_mix.c30_37.module_a1_a3 · OEKOBAUDAT 2024].
| Grade | kg CO₂e / m³ (A1–A3) | Grade | kg CO₂e / m³ (A1–A3) |
|---|---|---|---|
| C8/10 | 112 | C30/37 | 196 |
| C12/15 | 129 | C35/45 | 220 |
| C16/20 | 150 | C45/55 | 273 |
| C20/25 | 157 | C50/60 | 275 |
| C25/30 | 181 | C55/67 | 286 |
ÖKOBAUDAT 2024, module A1–A3, market-average ready-mix.
The design lever this exposes is specification discipline: grade is frequently set by habit or by a single governing element, and dropping an over-specified pour from C30/37 to C25/30 removes about 8% of its cradle-to-gate carbon at no material cost. Concrete is also one of only three families declaring module B1 — carbonation reabsorbs roughly 14 kg CO₂e/m³ over the use stage, a genuine negative, and small enough that it does not rescue an over-specified mix.
Ready-mix, cement, binders: three sources in one section
This section mixes vintages, and the calculator is explicit about which is which because they are not interchangeable. Ready-mix and cement are ÖKOBAUDAT 2024 EPDs. Binders and supplementary cementitious materials — GGBS at 0.155 kg CO₂e/kg [GreenCalculus materials.concrete.scm.ggbs.module_a1_a3 · MPA FS18 2025] and fly ash at 0.022 [GreenCalculus materials.concrete.scm.fly_ash.module_a1_a3 · MPA FS18 2025], against CEM I Portland at 0.84 [GreenCalculus materials.concrete.binder.cem_i_portland_uk.module_a1_a3 · MPA FS18 2025] — come from MPA FS18 2025, a UK-specific dataset. Constituents trace to ICE v2.0, published 2011 and now the oldest data on this page.
Mixing a 2011 constituent figure into a 2024 EPD total is defensible only if you say so. Full method: concrete and cement embodied methodology.
Steel and aluminium
These two sit in one calculator and behave differently. Steel’s footprint turns on production route — recycled-content electric-arc against primary blast-furnace — and the ÖKOBAUDAT 2024 set covers 29 product forms across sections, rebar, plate and sheet. Aluminium is more carbon-intense per kg by a wide margin: primary ingot at 10.1 kg CO₂e/kg [GreenCalculus materials.aluminium.ingot_primary.module_a1_a3 · EUROPEAN 2024] and extrusion at 10.48 [GreenCalculus materials.aluminium.extrusion.module_a1_a3 · EUROPEAN 2024], backed by the European Aluminium Environmental Profile Report 2024 for the primary rows.
Aluminium is also the most awkward material in this slice for boundary reasons. It declares A1–A3, C3 and C4 only — no C1, no C2, no D. There is no deconstruction figure, no transport-to-end-of-life figure, and no recovery credit, despite aluminium being among the most recycled construction metals in practice. That absence is a data gap in the published EPDs, not a statement that the impacts are zero, and it means an aluminium line and a steel line cannot be summed across a full life cycle without saying which modules each contributed. Full method: steel and aluminium embodied methodology.
Timber and bio-materials
Timber is where structural embodied carbon is most often misreported, and the mechanism is worth being precise about.
Why timber’s A1–A3 is negative and why that isn’t a sink
Engineered and sawn timber carry negative A1–A3 figures — biogenic carbon fixed during growth and still stored in the product at the factory gate. CLT is around −660 kg CO₂e/m³, glulam −608, sawn hardwood −1,019. Every structural timber product in the set is negative at that module.
The reversal is at end of life. CLT’s C3 is roughly +753 kg CO₂e/m³ — waste processing releases what production stored, and then some. Quote A1–A3 alone and you have published a carbon sink that the rest of the life cycle undoes. The defensible statement is that timber defers and stores, that the storage is real for the service life, and that the balance depends on what happens at the end — which is a design decision about disassembly and reuse, not a property of the material.
The second trap is assuming the sign follows the family. It does not. Among bio-based products, hemp (58.26) and flax (64.07) are positive, while cellulose (−72.72), cork (−85.08), straw (−98.03) and wood fibre (−253.4) are negative — processing energy, not biological origin, decides it. Full method: timber and bio-materials embodied methodology.
Masonry and finishes
The quiet strength of this member is completeness. Brick is the only family in this slice declaring every module — A1–A3 through D, including B1 carbonation and a D recovery credit — which makes it the one material where a genuine cradle-to-grave figure is available without caveats. Tile declares everything except C4. Plasterboard and paint declare the full C-range but no B1.
The calculator covers clay solid and perforated brick, aerated concrete block, sand-lime, ceramic and roof tile, plasterboard and emulsion paint, across mixed units — per m² for tile, per kg for paint. That heterogeneity is why quantities need care before they are combined. Full method: masonry and finishes embodied methodology.
Material substitution savings
This is the decision tool for everything above it. It reads the same rows as the other four members — ready-mix at C25/30 and C30/37, the brick set, aluminium extrusion, and the glass products — and tests a specified swap against a stated baseline rather than producing a standalone number.
Two things about its scope. It compares like-for-like products, so the answer is only as good as the functional equivalence you assert: a lower grade is a saving only if it meets the structural requirement. And it does not currently model binder substitution — swapping GGBS for Portland within a mix is a concrete-section question, not something this calculator does today. Use it when you have a baseline specification and a candidate. Full method: material substitution methodology.
How the numbers are built
Every calculator in this slice reads EPD-derived rows from the same versioned factor set as the rest of GreenCalculus — no member carries private numbers.
Where each factor comes from
| Factor set | Source | Vintage |
|---|---|---|
| Ready-mix concrete, cement | ÖKOBAUDAT | 2024 |
| Binders and SCMs (GGBS, fly ash, limestone fines, calcined clay) | MPA FS18 | 2025 |
| Concrete constituents | ICE v2.0 | 2011 |
| Steel (29 product forms) | ÖKOBAUDAT | 2024 |
| Aluminium — primary rows | European Aluminium EPR | 2024 |
| Aluminium — remaining rows | ÖKOBAUDAT | 2024 |
| Timber, brick, tile, plasterboard, paint | ÖKOBAUDAT | 2024 |
Module definitions follow EN 15804 with core EPD rules from ISO 21930 and declaration rules from ISO 14025. The ÖKOBAUDAT database and the ICE Database are the underlying EPD sources. Values are versioned in the MasterBrain and update when the source databases publish.
Module coverage is ragged, and absence is not zero
This is the table to check before adding anything to anything else. A dot means the EPD does not declare that module for that family.
| Family | A1–A3 | B1 | C1 | C2 | C3 | C4 | D |
|---|---|---|---|---|---|---|---|
| Concrete | Y | Y | Y | Y | Y | · | Y |
| Steel | Y | · | Y | Y | Y | Y | Y |
| Aluminium | Y | · | · | · | Y | Y | · |
| Timber | Y | · | Y | Y | Y | Y | Y |
| Brick | Y | Y | Y | Y | Y | Y | Y |
| Tile | Y | Y | Y | Y | Y | · | Y |
| Plasterboard | Y | · | Y | Y | Y | Y | Y |
| Paint | Y | · | Y | Y | Y | Y | Y |
ÖKOBAUDAT 2024 declared-module coverage. Aluminium is the ragged case — no C1, C2 or D. Brick is the only complete family.
A missing module means the EPD did not publish one — not that the impact is nil. Do not fill a gap with zero and do not sum across families to a single “total” without stating which modules each contributed. An aluminium figure with no D credit and a steel figure with one are not comparable, and a cradle-to-grave claim covering both is not supportable from this data.
What an EPD average can and cannot support
These are database averages, not your supply chain. A market-average ready-mix figure describes typical production for that grade, not the plant pouring your slab, whose actual mix design and transport distance may move it materially. For a project requiring verified figures, use these to specify, compare and prioritise — then obtain product-specific EPDs from the suppliers you actually appoint. The gap between a category average and a manufacturer EPD is often larger than the saving you are trying to demonstrate.
Zoom out: from materials to the whole building
Two levels sit around this one. If you are working across the full category — including product footprints, purchased goods and capital goods under Scope 3 — the Materials & Embodied Carbon hub covers all of it, including materials this slice deliberately leaves out. If you have moved past individual materials and need a building assessed across its life — assemblies, replacement cycles, a 60-year study period, benchmarks against RICS whole-life carbon or PAS 2080 — go to Whole-Building & Life-Cycle Carbon. Material figures are an input to that model, not a substitute for it.
Next step
Most structural assessments start with concrete, because it is usually the largest single line and the easiest quantity to obtain. Steel follows. Once you have a baseline, the substitution calculator is where the specification decisions actually get tested — and where a stated boundary matters most, because a saving measured across different modules is not a saving.
Start with the material carrying the most volume.
Frequently asked questions
Multiply your volume in cubic metres by the A1–A3 factor for the specified grade. C30/37, the standard structural grade, is 196 kg CO₂e/m³ [GreenCalculus materials.concrete.ready_mix.c30_37.module_a1_a3]; on ÖKOBAUDAT 2024 market-average data. Grade drives the number almost linearly through cement content, so the specified grade matters more than any other single input. The Concrete & Cement Calculator covers the full C-grade range plus cement and binders.
A1–A3 is cradle-to-gate: raw material supply, transport to the factory, and manufacturing. It is the only module every material declares, which is why it is quoted most and misread most — it excludes transport to site, installation, use-stage effects, end of life, and any recovery credit. Modules B, C and D are declared per material where the EPD publishes them, and coverage is uneven; see the coverage matrix above before combining figures.
At A1–A3, yes — CLT is around −660 kg CO₂e/m³ because biogenic carbon fixed during growth is still stored in the product at the factory gate. Across the full life cycle, no: CLT’s C3 waste-processing module is roughly +753 kg CO₂e/m³, releasing what was stored. Timber defers and stores carbon for its service life, which is real and worth having, but quoting A1–A3 alone overstates it. Whether the balance holds depends on end-of-life reuse.
The gap is large at the constituent level: GGBS is 0.155 kg CO₂e/kg [GreenCalculus materials.concrete.scm.ggbs.module_a1_a3] and fly ash 0.022 [GreenCalculus materials.concrete.scm.fly_ash.module_a1_a3], against CEM I Portland at 0.84 [GreenCalculus materials.concrete.binder.cem_i_portland_uk.module_a1_a3]. What that means for a mix depends on replacement level and the performance you still need to hit, and the binder set is UK-specific MPA FS18 2025 data rather than the ÖKOBAUDAT ready-mix rows. For steel, the equivalent lever is production route rather than an additive.
The question is not answerable in the units the two are sold in — concrete is per m³, steel per kg — and it should not be answered per material at all. What matters is carbon per unit of structural performance in a specific frame, which depends on spans, loads and the quantity each option actually requires. Compare designs, not materials, and check the module boundary is the same on both sides before you do.
It depends on what the material becomes. Materials bought as inputs to something you produce or sell are Category 1, purchased goods and services. Materials forming an asset you capitalise — a building you own and will use — are Category 2, capital goods. The same tonne of steel lands in different categories depending on the accounting treatment of what it goes into, and both routes are covered from the parent Materials & Embodied Carbon hub.