Build a quick A1–A3 embodied carbon estimate by adding material lines.
Default factors are generic placeholders. Always replace with EPD / product data for final reporting.
Optional A4 transport uses either a flat % uplift or per-line mass × distance × mode (DESNZ/DEFRA GHG conversion factors 2023); per-line A4 applies only to mass-bearing kg and m³ lines (m² lines have no mass basis). Excludes A5, B-stage use, and C-stage end-of-life. For design guidance only. Always verify with a qualified engineer.
About this embodied carbon calculator
This free embodied carbon quick estimator builds an indicative A1–A3 product-stage carbon estimate by adding material lines, concrete, steel, timber, insulation, ductwork, pipework and more. For each line you set a quantity, a unit (kg, m³ or m²) and an emission factor, and the tool totals the result in tonnes of CO₂e. It is built for UK building-services engineers and contractors who need a fast tender- or design-stage figure. The built-in factors are generic placeholders blended from ICE v3 (Bath, 2019) and typical UK EPDs. Always replace them with product-specific EPD data for final reporting.
How the estimate is calculated
The A1–A3 total is the sum of each line’s quantity multiplied by its emission factor, Σ(qty · factor), following the RICS Whole Life Carbon Assessment for the Built Environment (2nd edition, 2023) module structure. An optional A4 transport uplift can be added two ways: a flat percentage on the total, or per line as mass(t) × distance(km) × a mode factor, road HGV, rail or sea freight, drawn from the UK Government (DESNZ/DEFRA) GHG Conversion Factors for Company Reporting 2023. Per-line A4 applies only to mass-bearing kg and m³ lines; m² lines carry no mass basis. The estimate excludes module A5 (construction), B-stage in-use and C-stage end-of-life carbon, and is for design guidance only.
Frequently asked questions
Which life-cycle stages does it cover?
Only the product stage, modules A1–A3, with an optional A4 transport uplift. It deliberately excludes A5 construction, B-stage operational and use carbon, and C-stage end-of-life, so it is a partial, not a whole-life, assessment.
Can I use the default emission factors for reporting?
No. The defaults are generic placeholders blended from ICE v3 and typical EPDs to get you started. For any formal reporting, replace each factor with project-specific EPD or manufacturer data and verify with a qualified engineer.
How is the kgCO₂e/m² benchmark worked out?
If you enter a gross internal area (GIA), the tool divides the grand total carbon by that area to give a kgCO₂e/m² intensity for comparison against LETI/RIBA benchmarks. Leave GIA blank and only the absolute totals are shown.