Design better. Count everything.
Standard EPD accounting stops counting at the edge of a tree. This calculator adds the three carbon liabilities that current standards exclude. Toggle between standard and full-boundary accounting. Adjust for disassembly and recyclability. See what better design choices do to the number.
Building inputs
Full-boundary accounting (DRL)
Adds soil organic carbon efflux, end-of-life methane, and foregone sequestration — the three liabilities standard EPDs exclude.
Standard
Full boundary
Standard EPD boundary
—
tCO₂e · EN 15804 / ISO 21930
Full boundary (DRL)
—
tCO₂e · SOC + EOL CH₄ + OCP
Breakdown
A1–A5 embodied carbon (disclosed)—
Biogenic storage credit (EPD −1/+1 convention)—
Module D recovery credit—
Soil organic carbon efflux at harvest—
End-of-life methane (landfill fraction, adjusted for recovery)—
Foregone sequestration — opportunity carbon penalty—
Full-boundary total—
The asymmetry, made visible
Steel, concrete, and aluminium carry no biogenic liabilities. Their full-boundary figures are identical to their standard figures. Timber is the only structural material whose carbon accounting changes under full-boundary rules — and the only one designed for single use at end of life.
Mass timber (CLT)
NZ Radiata pine · 3,000 m² · 8 storeys
3 DRL liabilities
~5% recyclable
Standard EPD−510 t
+ SOC efflux+680 t
+ EOL methane+290 t
+ Foregone seq.+840 t
Full-boundary total+1,300 t
End-of-life circularity
Recovery rate~5%
Landfill fraction65%
Module D creditNone
Mass timber — designed for disassembly
NZ Radiata pine · 3,000 m² · 8 storeys · 70% recovery
3 DRL liabilities
70% recovery
Standard EPD−510 t
+ SOC efflux+680 t
+ EOL methane (reduced)+88 t
+ Foregone seq.+840 t
Full-boundary total+1,098 t
End-of-life circularity
Recovery rate70%
Landfill fraction~20%
Module D creditPartial (reuse)
Concrete (reinforced)
Standard mix · 3,000 m² · 8 storeys
No biogenic liabilities
~25% recyclable
Standard EPD+1,260 t
SOC / EOL CH₄ / foregone— not applicable —
Full-boundary total+1,260 t
End-of-life circularity
Recovery rate~25%
Landfill fraction~40%
Module D creditMinimal
Steel (structural)
30% recycled content · 3,000 m² · 8 storeys
No biogenic liabilities
~85% recyclable
Standard EPD+2,040 t
SOC / EOL CH₄ / foregone— not applicable —
Full-boundary total+2,040 t
End-of-life circularity
Recovery rate~85%
Landfill fraction~5%
Module D creditSignificant
Aluminium (structural)
Recycled content · modular · 3,000 m² · 8 storeys
No biogenic liabilities
~95% recyclable
Standard EPD (A1–A5)+1,640 t
SOC / EOL CH₄ / foregone— not applicable —
Module D recovery credit−580 t
Full-boundary + Module D+1,060 t
End-of-life circularity
Recovery rate~95%
Landfill fraction<2%
Module D credit−580 t (improves with grid)
| Material | Permanence | Full-boundary accounting | Circularity | Verdict |
|---|---|---|---|---|
| Mass timber (standard) | Degrades · burns | Fails — 3 liabilities hidden | ~5% recyclable | Fails all three |
| Mass timber (disassembly design) | Degrades · burns | Fails — SOC and OCP remain | 70–90% recoverable | Improving — EOL methane reduced |
| Concrete | Durable | Passes — no biogenic liabilities | ~25% recyclable | Passes 2 of 3 |
| Steel | Durable | Passes — no biogenic liabilities | ~85% recyclable | Passes all three |
| Aluminium (modular) | Durable · disassemblable | Passes — no biogenic liabilities | ~95% recyclable | Passes all three + Module D improves over time |
All figures are illustrative estimates for a 3,000 m² 8-storey reference building using published-literature emission factors. Standard EPD figures follow EN 15804 / ISO 21930 including the biogenic carbon storage credit for timber. Full-boundary figures add: soil organic carbon efflux (Manaaki Whenua S-Map; Scion Long-Term Site Productivity trials; k = 0.048 yr⁻¹ first-decade decay); end-of-life methane (EPA WARM v15; NZ GHG Inventory HWP parameters; GWP₁₀₀ = 28; adjusted for recovery rate); foregone sequestration (Stephenson et al. Nature 507, 2014; Luyssaert et al. 2008; SCC $190/t NPV-discounted). Aluminium Module D credit based on secondary smelting energy intensity; improves with grid decarbonisation and low-carbon primary smelting (ELYSIS inert-anode process). Recyclability rates: WORLDSTEEL (2023) for steel; European Aluminium (2023) for aluminium; EN 15804 Module C defaults for timber and concrete. The disassembly recovery rate slider affects EOL methane only — SOC efflux and foregone sequestration are harvest-point liabilities unaffected by end-of-life design. Reproduction sheets for Brock Commons (UBC, 2017) and T3 Minneapolis (Hines, 2016) with full source citations are available at the Corrected Ledger. Full methodology in the DRL Thesis Codex v4.3.3.