Embodied Carbon Calculator
Calculate A1-A3 embodied carbon (kgCO2e) for your building's structural and envelope materials — concrete, steel, timber, masonry, glass, and insulation.
About this calculator
Total Embodied Carbon (kgCO2e) sums six independent material tallies -- concrete, structural steel, mass timber, masonry, glazing, and insulation -- each converted from your entered quantity to a mass in kilograms (using standard densities: ~150 lb/ft3 for concrete, a US short ton at 907.185 kg for steel, and so on), then multiplied by a fixed embodied- carbon coefficient in kgCO2e per kg of material. Those per-material coefficients are drawn from the Inventory of Carbon and Energy (ICE) Database, the widely-used embodied-carbon reference originated at the University of Bath and now maintained and published by Circular Ecology, cross-checked against published Environmental Product Declaration (EPD) averages. At default entries, Concrete Volume (cubic yards) contributes the single largest share of Total Embodied Carbon of any material here, both because concrete typically appears in the largest quantity on a project and because its coefficient, while modest per kilogram (0.12 kgCO2e/kg), applies to a very large mass.
Mass Timber gets unique treatment: unlike every other material, timber carries a Biogenic Carbon Stored credit (1.8 kgCO2e per kg of wood, versus its own emission factor of only 0.40 kgCO2e/kg) that is SUBTRACTED separately to produce Net Carbon -- so adding mass timber to a design raises Total Embodied Carbon slightly (the 0.40 factor) but lowers Net Carbon by more (because 1.8 exceeds 0.40), the calculation's way of reflecting that wood keeps carbon it absorbed while growing. Insulation Type is a coded selector (XPS, EPS, mineral wool, or cellulose) rather than a continuous quantity -- each option carries its own density and emission-factor pair, with cellulose the lowest-carbon and XPS the highest of the four at the same coverage area.
Inputs
Results
Total Embodied Carbon (kgCO2e)
61,462
Figures current as of 2026. Source: Circular Ecology, Inventory of Carbon and Energy (ICE) Database — originated at the University of Bath by Dr. Craig Jones and Prof. Geoff Hammond, now maintained and published by Circular Ecology
How to Use This Calculator
- Enter quantities of primary structural materials: Concrete Volume in cubic yards, Structural Steel in tons.
- Enter Mass Timber volume in board feet, Masonry Wall Area, Glazing Area, and Insulation Area.
- Select the Insulation Type (XPS, EPS, mineral wool, or cellulose) — cellulose has the lowest carbon.
- Review Total Embodied Carbon in kgCO2e and metric tons for the A1–A3 life-cycle stages.
- Check Biogenic Carbon Stored (timber credit) and Net Carbon to assess the overall material carbon footprint.
How the result changes with Concrete Volume (cubic yards)
| Concrete Volume (cubic yards) | Total Embodied Carbon (kgCO2e) |
|---|---|
| 75 | 44,929 |
| 113 | 53,306 |
| 225 | 77,996 |
| 375 | 111,064 |
What each input means
- Concrete Volume (cubic yards)
- Total volume of ready-mix concrete (foundations, slabs, columns, walls).
- Structural Steel (tons)
- Total weight of structural steel in short tons (beams, columns, deck, rebar).
- Mass Timber (board feet)
- Volume of CLT, glulam, or other mass timber in board feet.
- Masonry Wall Area (sq ft)
- Total area of 8-inch CMU walls in square feet.
- Glazing Area (sq ft)
- Total insulated glass unit (IGU) area.
- Insulation Area (sq ft)
- Total area of insulation coverage (at ~4 inches thick).
- Insulation Type (0-3)
- 0 = XPS (highest carbon), 1 = EPS, 2 = Mineral Wool, 3 = Cellulose (lowest carbon).
What each result means
- Total Embodied Carbon (kgCO2e)
- Sum of A1-A3 embodied carbon for all specified materials.
- Total (metric tons CO2e)
- Embodied carbon expressed in metric tons.
- Biogenic Carbon Stored (kgCO2e)
- CO2 permanently stored in timber products (negative emissions).
- Net Carbon (kgCO2e)
- Embodied carbon minus biogenic storage credit.
- Carbon Intensity (kgCO2e/kg)
- Average embodied carbon per kg of material used.
- Tree Offset Equivalent
- Number of trees needed to absorb this carbon over a 40-year lifespan.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersConcrete Volume (cubic yards) = 150, Structural Steel (tons) = 20, Mass Timber (board feet) = 0, Masonry Wall Area (sq ft) = 0 = 7 input(s) provided
- Calculate Total Embodied CarbonTotal Embodied Carbon = concreteCarbon + steelCarbon + timberCarbon + masonryCarbon + glassCarbon + i...61462 = 61462
- Calculate TotalTotal = totalEmbodiedCarbon / 100061.5 = 61.5
- Calculate Biogenic Carbon StoredBiogenic Carbon Stored = timberMassKg * 1.80 = 0
Figures and sources
- Embodied-carbon coefficients (kgCO2e/kg) for structural and envelope materials (2026) — Circular Ecology, Inventory of Carbon and Energy (ICE) Database — originated at the University of Bath by Dr. Craig Jones and Prof. Geoff Hammond, now maintained and published by Circular Ecology
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why does Concrete Volume move Total Embodied Carbon more than Structural Steel at the default entries?
Concrete's per-kilogram emission factor (0.12 kgCO2e/kg) is much lower than steel's (1.37 kgCO2e/kg) -- steel is far more carbon-intensive by weight. But at this calculator's default quantities (150 cubic yards of concrete versus 20 tons of steel), concrete's much larger total mass still produces the larger absolute carbon contribution, so it moves Total Embodied Carbon more for the same percentage change in quantity. Both coefficients come from the Inventory of Carbon and Energy (ICE) Database, the reference embodied-carbon dataset originated at the University of Bath and maintained today by Circular Ecology.
Why does adding Mass Timber (board feet) raise Total Embodied Carbon but lower Net Carbon?
These are two different totals. Total Embodied Carbon only sums the emission side (timber's own factor is 0.40 kgCO2e/kg, so more timber does add a little to that total). Net Carbon then subtracts Biogenic Carbon Stored -- carbon the wood physically holds from growing, credited at 1.8 kgCO2e/kg -- which is more than four times timber's own emission factor. So swapping in more mass timber raises the embodied total slightly while lowering the net figure by more, the calculation's way of crediting wood's carbon storage.
How does Insulation Type change the result if I keep Insulation Area the same?
Each of the four Insulation Type options (XPS, EPS, mineral wool, cellulose) carries its own density and carbon coefficient, so switching the type at a fixed area changes the insulation contribution to Total Embodied Carbon even though nothing else changed. Cellulose has by far the lowest coefficient (0.12 kgCO2e/kg) of the four, while XPS has the highest (3.8 kgCO2e/kg) -- switching from XPS to cellulose at the same coverage area can cut the insulation share of your total dramatically.
Why does Tree Offset Equivalent not shrink when I add more Mass Timber?
Tree Offset Equivalent is derived from Total Embodied Carbon (the emissions total, not the net figure), divided by roughly 880 kgCO2e per tree over a 40-year lifespan. Since adding mass timber raises Total Embodied Carbon slightly rather than lowering it (see above), Tree Offset Equivalent moves up slightly too, even though the same timber lowers Net Carbon once its biogenic storage credit is applied separately.
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