Carbon LCA — design & construction monitoring
From the design study to controlling what is actually delivered
The RE2020 carbon Life Cycle Assessment (indicators Ic_construction and Ic_energy) plays out in two stages. At design, the study calculates the project's theoretical footprint and validates compliance with the 2025, 2028 and 2031 thresholds. During construction, material substitutions, supplier changes and technical adjustments can move the as-built LCA away from the design LCA — exposing the client to non-compliance at handover. ARKEMEP supports both stages: a robust design LCA study, then construction monitoring with control of the EPDs actually installed, substitution trade-offs and gap management.
A risk few clients anticipate
The design LCA is not the as-built LCA — the gap can tip compliance.
RE2020 controls a building's carbon performance through two indicators:
- Ic_construction — carbon footprint of the envelope components and systems, measured in kg CO₂e/m² of floor area over 50 years.
- Ic_energy — carbon footprint of in-use energy consumption over 50 years.
At design, both indicators are calculated from the specified EPDs (Environmental Product Declarations, French FDES) and the planned systems. Thresholds tighten over time: 2022, 2025, 2028, 2031.
The problem: during construction, materials change. An insulation swap for supply reasons, an HVAC unit replaced by an equivalent model, a variant traded off during execution — each substitution can move the as-built LCA away from the design LCA. If the EPDs actually installed are not the ones specified, the as-built LCA can exceed the thresholds — with direct consequences: non-compliance, administrative blockage, rework, litigation.
Construction-phase LCA monitoring is not a strict regulatory obligation — but it is contractual reassurance for the client, answering a growing expectation from buyers, lenders, ESG investors and CSRD auditors.
Phase 1 — Design
An RE2020-compliant LCA study with a safety margin.
Ic_construction measurement
Carbon footprint of components: structure, envelope, joinery, systems, external works. EPD data from the INIES database. Broken down by work package to identify the dominant contributors.
Compliance margin
The design LCA is calibrated below the applicable threshold to absorb the inevitable construction-phase variations — rather than landing exactly on the limit and risking non-compliance at delivery.
Phase 2 — Construction
Controlling the as-built LCA.
EPD control
Verification that the EPDs actually installed match those specified — and recalculation of the impact of every substitution.
Substitution trade-offs
When a material must change, ARKEMEP evaluates the carbon-equivalent alternatives so the as-built LCA stays within the threshold.
As-built LCA at handover
A final LCA reflecting what was actually installed — the defensible evidence for buyers, lenders and CSRD reporting.
FAQ
Frequently asked questions
Scope a carbon LCA assignment
Robust design LCA, then construction-phase monitoring with control of the EPDs actually installed — to secure RE2020 compliance at delivery.
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