Whole-life carbon assessments at Cudd Bentley — New build or refurbishment?

“You can’t predict the carbon impact by looking at drawings. You need to prepare the model, do the math, and let the data show you the right solution.”

- Ahmed Tawheed, Senior Sustainability Consultant at Cudd Bentley Consulting

What is a whole-life carbon assessment?

A whole-life carbon assessment (WLCA) is a standardized method for evaluating greenhouse gas emissions associated with all life-cycle stages of a building or infrastructure asset. It builds on life-cycle assessment (LCA) methodology, but applies construction-specific standards such as EN 15978 (buildings) and EN 15804+A2 (environmental product declarations).

The assessment covers four main modules:

• Product and construction (A1–A5): raw material extraction, transport, manufacturing, site processes.
  
  
• Use stage (B1–B7): operation, maintenance, repair, replacement, water, and energy use.
  
  
• End-of-life (C1–C4): demolition, transport, waste processing, and disposal.
  
  
• Beyond the building (D): credits for reuse, recycling, or energy recovery.

This whole-life scope is critical because focusing only on operational energy (B6) risks overlooking high-impact decisions — such as whether to retain or demolish existing structures.

WLCA versus embodied carbon assessments

While embodied carbon assessments look at emissions from construction materials and processes (Modules A1–A5, B1–B5, C1–C4), WLCAs include both embodied and operational emissions.

• Embodied carbon = “carbon locked in” materials and systems
• Whole life carbon = embodied + operational + end-of-life.

This distinction matters because many net-zero building claims risk overstating performance if they exclude embodied carbon. A building with excellent operational efficiency but carbon-intensive construction materials may still exceed climate targets.

Why timing matters: conducting WLCA early

Early-stage WLCA allows project teams to:

• Compare design options before they are fixed.
• Evaluate refurbishment versus new build.
• Model the effect of retaining structural elements.
• Test alternative mechanical, engineering and plumbing (MEP) systems.
• Benchmark against frameworks such as LETI, RIBA 2030, UK Net Zero Carbon Building Standard, or GLA policies.

Once a design is finalised, only marginal reductions are possible.

“The ideal time is when the design is ongoing. If you wait until it’s complete, it’s too late,” 

- Vibhuti Bhambri, Sustainability Consultant at Cudd Bentley Consulting

Case study: new build versus refurbishment

Cudd Bentley Consulting, using One Click LCA software, modeled two scenarios for an industrial facility:

Findings:

• Refurbishment: 417 kg CO₂e/m²
  
• New build: 511 kg CO₂e/m²
  
• Difference: ~100 kg CO₂e/m² avoided
• Total emissions avoided: 800 tonnes CO₂e

This outcome reflects the carbon intensity of steel and concrete — reusing substructures and frames avoids substantial emissions.

“When we reuse the substructure and frame, we can avoid between 100 and 200 kg CO₂e/m². At scale, that’s enormous.”

- Ahmed Tawheed, Senior Carbon Consultant at Cudd Bentley

Global regulatory context

WLCAs are becoming mandatory across Europe and beyond:

Outside Europe, uptake is uneven, but WLCA is emerging in public procurement and green building certifications globally.

Benefits of WLCA for different stakeholders

For architects and designers

• Conduct early-stage comparisons with tools like Carbon Designer 3D.
• Visualize trade-offs between aesthetic, functional, and carbon outcomes.
  

For structural engineers

• Test design alternatives for structural systems (steel, concrete, timber).
• Quantify benefits of reusing or strengthening existing structures.

• Assess carbon intensity of systems using TM54 (operational energy) and TM65 (embodied carbon in MEP).
• Select low-carbon HVAC, electrification, and refrigerant systems.

For contractors

• Demonstrate compliance with city and national regulations.
• Secure additional BREEAM/LEED credits by evidencing WLCA.
• Reduce demolition and waste management costs.
  

• Support ESG disclosures and investor requirements.
• Future-proof assets against brown discounts.
• Lower carbon offset costs by reducing embodied emissions at source.

• Provide verified EPDs to secure market access and specification.
• Position products in procurement databases used by designers and contractors.
• Prepare for Digital Product Passports, which will become mandatory in the EU.

Tools and data for credible assessments

Accurate WLCA depends on access to robust datasets:

• Environmental product declarations (EPDs): standardized, third-party-verified data under EN 15804 or ISO 21930.
• One Click LCA software: integrates global EPDs, national databases, and compliance modules for 80+ standards.
• Carbon Designer 3D: allows pre-design scenario modeling without detailed BIM inputs.
• MEP carbon tool: incorporates refrigerants, service lives, and TM65 methodology for accurate modeling.

“Without robust data, it’s impossible to make credible claims. One Click LCA’s database helps us prepare accurate models and avoid greenwashing.”

- Ahmed Tawheed, Senior Carbon Consultant at Cudd Bentley

Practical outcomes of WLCA

“Refurbishment versus new build is one of the biggest decisions for carbon. WLCA ensures that that decision is made with facts, not assumptions.”

- Ahmed Tawheed, Senior Carbon Consultant at Cudd Bentley

Frequently asked questions about whole-life carbon assessment

1. What is the purpose of WLCA in construction?

To evaluate and reduce carbon emissions across a project’s full life cycle, ensuring compliance and alignment with net-zero targets.

2. How does WLCA differ from embodied carbon analysis?

Embodied carbon analysis looks only at materials and construction. WLCA adds operational and end-of-life stages.

3. When should WLCA be conducted?

At concept design, with updates at detailed design and post-construction. Early assessment is critical to influence outcomes.

4. Which standards guide WLCA?

EN 15978, EN 15804+A2, ISO 14040/44, ISO 21930, ISO 14067, plus national frameworks like RICS, UKGBC, and GLA.

5. Do WLCAs always show refurbishment is lower carbon?

No — some buildings are unsafe or inefficient to retain. WLCA provides the evidence to decide case by case.

6. How reliable is early-stage WLCA?

While approximate, it gives directionally accurate results when using databases and benchmarks. It is far more reliable than assumptions.

7. What role do EPDs play?

They provide verified carbon data for materials. EPDs are increasingly mandatory under EU CPR and ESPR.

8. Can WLCA reduce project costs?

Yes. Refurbishment avoids demolition, reduces landfill costs, and minimizes offsetting requirements.

9. Is WLCA only relevant in Europe?

No. While regulations are most advanced in the EU, WLCA is increasingly recognized in procurement, ESG reporting, and certifications worldwide.

10. How do WLCAs support net-zero claims?

They ensure both operational and embodied carbon are addressed. A building cannot be credibly “net-zero” without WLCA.

Conclusion: WLCA as standard practice

Whole-life carbon assessment is rapidly becoming a non-negotiable requirement in construction. It allows project teams to balance carbon, cost, and compliance while ensuring credible net-zero pathways.

For project teams, investors, and manufacturers alike, WLCA is not just a compliance exercise — it is a pathway to resilient, future-proofed assets.