Embodied Carbon Calculator
The upfront embodied carbon of a building from its material quantities and carbon factors — per square metre against the benchmarks the profession now uses, and which material dominates.
Embodied carbon is each material's quantity times its carbon factor, summed.
How the embodied carbon calculator works
Embodied carbon is each material's quantity times its carbon factor, summed. Concrete and steel usually dominate, not because their factors are highest but because there is so much of them.
The per-square-metre figure is what benchmarks use: under 500 kg CO₂e/m² is good practice for a new building in most current guidance; 800 or more is business as usual. The factors are inputs because they vary by supplier, grid and year.
Formula: embodied carbon = Σ (quantity × factor); intensity = total / GFA
Worked examples
| Inputs | Embodied carbon per m² (kg CO₂e) | Note |
|---|---|---|
| A concrete-framed building | 202.2 | about 470 kg/m² |
| A timber frame | 6.2 | well below benchmark |
| Steel-heavy | 299.8 | steel dominates |
FAQFrequently asked questions
What is embodied carbon?
The emissions from making, transporting and installing a building's materials — the carbon spent before anyone moves in. It is now a third to a half of a new building's lifetime total.
What is a good figure per square metre?
Current guidance puts good practice under 500 kg CO₂e/m² for upfront carbon and business-as-usual at 800 or more. Targets are tightening every year.
Where do the carbon factors come from?
Environmental product declarations and national databases. They vary by supplier and by the grid the factory runs on, which is why they are inputs.
Why is timber negative?
Because the tree absorbed carbon as it grew and the timber stores it. Accounting rules differ on whether to count that; the default here does.
How do I reduce it?
Use less concrete and steel — smaller sections, lower-carbon mixes — and more timber where it works. Reusing an existing structure beats all of them.
Where these figures come from
- Sabine (1922) — Collected Papers on Acoustics — the reverberation-time equation
- CIBSE Guide A — Environmental design — daylight, comfort and ventilation criteria
- Neufert — Architects' Data — the standard reference for space and dimension
- International Code Council — International Building Code — occupant load and egress factors
- Building Regulations — Approved Documents — the UK building regulations
Last checked: September 2026. Formulas are the standard building-science and code relationships; default thresholds are common international values and should be replaced with the ones in your code.