How to calculate embodied carbon emissions

Embodied carbon is in essence the carbon footprint of a material, or cumulatively, a building. To calculate these emissions, multiply the quantity of the material (e.g. steel or concrete) by its carbon factor – the amount of carbon released in the creation/production of the material up to this point.

Reference: What is embodied carbon (and what can we do about it)?

1. Aluminium — Highest Embodied Carbon

Typical Embodied Carbon: 8–18 kg CO₂e/kg (Primary Aluminium)

Primary aluminium consistently ranks as the most carbon-intensive mainstream construction material because of its energy-intensive electrolysis process.

Key Findings

• Extremely high electricity demand during smelting.
• Carbon footprint varies significantly depending on electricity source.
• Hydropower-based production can reduce emissions substantially.
• Recycled aluminium lowers embodied carbon by nearly 90–95%.

Best Applications

• Curtain walls
• Window framing
• Architectural facades

References

• https://circularecology.com/embodied-carbon-footprint-database.html
• https://www.buildingtransparency.org/tools/ec3/
• https://carbonleadershipforum.org/ec3-tool/

2. Stainless Steel

Typical Embodied Carbon: 5–7 kg CO₂e/kg

Stainless steel contains chromium and nickel, both requiring energy-intensive extraction and processing.

Key Findings

• Higher emissions than carbon steel.
• Recycling significantly lowers impacts.
• Long service life offsets replacement emissions in many applications.

3. Carbon Steel

Typical Embodied Carbon: 1.7–2.8 kg CO₂e/kg

Steel remains one of the largest contributors to embodied carbon because of the enormous quantities used in buildings.

Key Findings

• Blast furnace production has the highest emissions.
• Electric Arc Furnace (EAF) steel using recycled scrap dramatically reduces carbon footprint.
• Responsible for a significant proportion of structural embodied carbon.

4. Cement (Ordinary Portland Cement)

Typical Embodied Carbon: 0.75–0.95 kg CO₂e/kg

Cement production accounts for approximately 7–8% of global CO₂ emissions due to limestone calcination and kiln fuel consumption.

Key Findings

• Cement is considerably more carbon-intensive than concrete on a per-kilogram basis.
• Supplementary Cementitious Materials (SCMs) such as fly ash and GGBS substantially reduce emissions.
• Low-clinker cement technologies continue to improve carbon performance.

5. Plastics & Polymer-Based Construction Products

Typical Embodied Carbon: 2–6 kg CO₂e/kg

Plastic products originate primarily from petrochemical feedstocks.

Key Findings

• High manufacturing energy demand.
• Difficult end-of-life management.
• Carbon footprint varies considerably by polymer type.

Examples include:

• PVC
• HDPE
• Polycarbonate
• Acrylic panels

6. Glass

Typical Embodied Carbon: 0.8–1.5 kg CO₂e/kg

Glass manufacturing requires continuous high-temperature furnaces.

Key Findings

• Float glass production is energy intensive.
• Triple glazing improves operational efficiency but increases embodied carbon.
• Recycled cullet reduces production emissions.

7. Fired Clay Bricks

Typical Embodied Carbon: 0.20–0.45 kg CO₂e/kg

Kiln firing dominates brick emissions.

Key Findings

• Manufacturing fuel determines carbon intensity.
• Local sourcing reduces transportation impacts.
• Fly ash bricks generally outperform fired clay bricks.

8. Concrete

Typical Embodied Carbon: 0.08–0.20 kg CO₂e/kg

Although concrete has relatively low emissions per kilogram, it is the world’s most widely consumed construction material, making its total climate impact extremely significant.

Key Findings

• Cement content determines overall embodied carbon.
• SCM substitution offers immediate reductions.
• Carbon-cured concrete technologies are emerging rapidly.

9. Gypsum Board (Drywall)

Typical Embodied Carbon: 0.20–0.35 kg CO₂e/kg

Key Findings

• Moderate manufacturing emissions.
• Increasing recycled gypsum content lowers impacts.
• Lightweight products reduce transport emissions.

10. Natural Stone

Typical Embodied Carbon: 0.05–0.20 kg CO₂e/kg

Key Findings

• Quarrying dominates emissions.
• Minimal processing compared with manufactured materials.
• Local stone generally offers lower embodied carbon than imported alternatives.

11. Engineered Timber (CLT, Glulam)

Typical Embodied Carbon: 0.05–0.15 kg CO₂e/kg

Engineered timber is among the lowest-carbon structural materials currently available.

Key Findings

• Stores atmospheric carbon during tree growth.
• Requires significantly less manufacturing energy than steel or concrete.
• Sustainable forestry certification is essential for long-term environmental performance.

12. Solid Timber — Lowest Embodied Carbon

Typical Embodied Carbon: 0.02–0.10 kg CO₂e/kg

Solid timber consistently ranks among the lowest embodied carbon construction materials.

Key Findings

• Renewable resource.
• Minimal processing energy.
• Excellent carbon storage potential.
• Particularly suitable for low-rise residential and hybrid structures.

See also:

Embodied Carbon: Its Impact on Global Construction

Top 10 ways to reduce embodied carbon through built environment