Embodied Carbon Calculator — Structural Members

Estimate product-stage A1–A3 embodied carbon from member lengths, unit masses, and generic or project-specific emission factors. This is a cradle-to-gate material estimate, not a whole-life carbon assessment.

What is Embodied Carbon?

Embodied carbon covers greenhouse-gas emissions associated with materials and construction across defined lifecycle modules. This page includes only product stages A1–A3: raw-material supply, transport to manufacturing, and manufacturing. Results are measured in kgCO₂e (kilograms of carbon-dioxide equivalent).

Lifecycle Stages

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

A1–A3 is a common product-stage reporting slice, but many whole-life methods and client briefs require additional modules. State the assessment boundary with every result; A1–A3 must not be compared directly with an A1–A5 or whole-life target.

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 product type, supply chain, and country. Values below are indicative A1–A3 cradle-to-gate factors from the Institution of Structural Engineers' How to Calculate Embodied Carbon (2nd edition, 2022), Table 2.3, which draws on published EPDs, Worldsteel and MPA data. They include regional defaults, product values, and an explicitly labelled typical lower bound; use a factor that matches the actual product and supply scenario. They are for preliminary estimating only; use project-specific EPDs for formal reporting:

IStructE published a third edition in 2025. The built-in values remain transparently tied to the verified 2022 table and must not be treated as current defaults; check the current IStructE guidance and current product data before relying on them.

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.

Comparing with Project Targets

This calculator returns an A1–A3 member subtotal in kgCO₂e. It does not know gross internal floor area, substructure and non-frame quantities, construction impacts, replacement, end-of-life scenarios, or the assessment rules behind a project target. Normalize and compare results only after matching the target's lifecycle modules, element scope, area basis, geography, and current framework version.

Reducing Embodied Carbon in Steel Structures

• Use current, product-specific EPDs where available and compare equivalent declared units and lifecycle scope
• Use structural optimisation to remove unnecessary material, spans, transfers, and cantilevers while meeting robustness and serviceability needs
• Compare viable supply routes and products using like-for-like EPD data; a generic factor does not establish the impact of a particular mill or manufacturing route
• Compare open, hollow, concrete, timber, and hybrid solutions at whole-system level rather than selecting on a material factor alone
• Design for deconstruction and reuse with a documented reuse plan, accessible connections, traceable materials, and realistic future scenarios

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