Structural Steel.
Steel has a high CO₂ footprint per kg, but is strong and recyclable. Always specify recycled content — it makes a significant difference to the carbon accounting. Read the numbers together with function, lifespan, detailing and the specific building element.
- Carbon Footprint (GWP)
- 1.46 kg CO₂-eq/kg
- Source: ECO Platform EPD average (primary steel)
- Density
- 7850 kg/m³
- Expected Lifespan
- 100+ years
How to use this assessment
The assessment of structural steel is a first decision basis. Carbon numbers, density and lifespan give a point of comparison, but the material must always be read together with structure, moisture, fire requirements, detailing, maintenance and the condition of the existing building. A good material choice is therefore both a data question and an architectural judgement. The useful next step is to clarify which questions should be examined further before the material is specified in a project.
What is structural steel?
Structural steel is one of the most commonly used materials for load-bearing structures. It's strong, precise, and can be recycled almost indefinitely. Carbon footprint varies significantly depending on production method — electric arc furnace steel (from recycled scrap) has a markedly lower footprint than primary blast furnace steel.
Carbon Footprint Compared
Negative carbon footprint (green) indicates carbon storage. Data based on EPD averages from ECO Platform and estimates per EN 15804.
Typical Applications
- check_circle Load-bearing columns and beams
- check_circle Roof structures
- check_circle Bridges and large structures
- check_circle Facade elements
- check_circle Stairs
In Renovation
Steel is used in renovation for reinforcing existing structures, extensions, and roof structures. Prefabricated steel systems provide rapid installation with minimal disruption to existing construction.
Questions about structural steel
What's the difference between primary and recycled steel?
Primary steel (from blast furnace) has a GWP of approximately 2.0–2.5 kg CO₂/kg. Electric arc furnace steel from recycled scrap has approximately 0.4–0.8 kg CO₂/kg — up to 5 times lower. This is a significant difference that should be reflected in material selection.
Can steel be recycled?
Steel is one of the world's most recycled materials. Over 85% of steel in buildings ends up as recycled scrap. In practice, recycled content percentage should always be specified in climate calculations.
Is steel better than concrete climatically?
It depends on context. Steel has higher GWP per kg, but you typically use much less steel than concrete in a structure (steel is stronger). Total climate impact per structural unit can be comparable.
When do you choose steel over concrete?
Steel is ideal for large spans (halls, industry, bridges), complex geometries, prefabrication, and tight timelines. It's easier to disassemble than concrete, enabling element reuse at demolition.
Related Materials
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