Service D · continued

## Life cycle thinking

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Fig. 13.1 · Whole-building life cycle stages, EN 15978 module structure
A1–A5
Product and construction stages, where most embodied carbon is fixed
B1–B7
Use stage, covering maintenance, repair and replacement
C1–C4
End of life, covering demolition, transport and disposal

A life cycle assessment is only useful if it changes a decision. We run it at the point where the structural system, the façade build-up and the primary materials are still open, and we present the result as a comparison between options, not as a single number.

Where the decisions are made

Concept | Structural system, grid, massing, basement extent. The largest single influence on embodied carbon.
Scheme | Façade build-up, glazing ratio, structural efficiency, material family selection.
Detail | Concrete mix design, cement replacement, steel recycled content, finishes.
Procurement | Supplier EPDs, transport distance, local sourcing, substitution control.

Environmental and financial together

LCA quantifies the environmental impact of a specification. LCC, overleaf, quantifies its financial impact. OKELIS runs both from the same model, so that the two results can be read against each other rather than argued separately.

Deliverables

- Whole building LCA report
- Embodied carbon baseline

- Hotspot analysis
- Material option comparison

- EPD review & register
- Reduction recommendations

- Certification credit evidence
- Procurement guidance note

D · Life Cycle Assessment & EPD 13