Embodied Carbon Calculator — Structural Steel

Estimate the embodied carbon (kgCO₂e) of a steel structure during fabrication and construction (lifecycle stages A1–A3). Enter member lengths, unit masses, and select a material carbon coefficient. Results update live with a per-member breakdown.

What is Embodied Carbon?

Embodied carbon refers to the greenhouse gas emissions associated with the extraction, manufacture, and transportation of building materials — before the structure is even occupied. For steel structures, fabrication and rolling typically dominates. Embodied carbon is typically measured in kgCO₂e (kilograms of CO₂ equivalent).

Lifecycle Stages

Embodied carbon is categorised by the RICS/EN 15978 lifecycle framework:

A1–A3 is the most commonly reported scope and is required by LETI, RIBA 2030 Challenge, and most client sustainability briefs. Full whole-life carbon (A–C) requires project-specific data not available at preliminary design stage.

How the Calculation Works

For each member:

The unit mass (kg/m) is found in section tables — for example, a 610UB125 has a unit mass of 125 kg/m. Total carbon is the sum across all members.

Carbon Coefficients

The carbon coefficient (also called an emission factor) varies by steel product type, supply chain, and country. Values in this calculator are A1–A3 cradle-to-gate figures from the Circular Ecology ICE Database v3.0 and publicly available EPD data:

For detailed project reporting, request manufacturer-specific Environmental Product Declarations (EPDs), which may be significantly lower than generic database values, particularly for electric arc furnace (EAF) steelmakers.

Industry Targets

Several frameworks set embodied carbon targets for structural systems:

• LETI 2030 target — ≤ 300 kgCO₂e/m² (GIA) whole building, structural target typically ≤ 100 kgCO₂e/m²
• RIBA 2030 Challenge — Aligned with LETI, recommends reduction from baseline (approx. 400–600 kgCO₂e/m²)
• SCORS (UK) — Structural Carbon Rating Scheme, A–G ratings for structural systems
• SE 2050 — Net-zero embodied carbon for structural engineering, commitments from major firms

Reducing Embodied Carbon in Steel Structures

• Specify low-carbon steel grades with EPDs from EAF producers
• Use structural optimisation to reduce steel tonnage — more efficient sections, longer spans with less material
• Prefer UK/EU CARES-certified products where possible (1.13 vs 1.55 kgCO₂e/kg)
• Consider hollow sections only where structurally justified — they carry a higher coefficient than open sections
• Design for deconstruction and reuse — bolted connections instead of welded, documented for future occupants

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