Arcadis turns carbon hotspots into design decisions across two Cadogan buildings

A portfolio built on refurbishment, under London's own carbon rules

Cadogan Estates owns and manages a mix of residential, retail, and commercial property concentrated around Sloane Square, Sloane Street, and the King's Road in Chelsea.¹ Its net zero 2030 strategy counts developments and refurbishments as part of its Scope 3 emissions, but the portfolio is overwhelmingly refurbishment led, which meant Arcadis was working within constrained design windows, existing assets, planning restrictions, and multiple stakeholders on every project.

Greater London adds a further layer most refurbishment portfolios outside the capital don't face: Policy SI 2 of the London Plan already requires developments referable to the Mayor to calculate and reduce whole life-cycle carbon, using a methodology built on the first edition of the RICS whole life carbon standard. RICS has since moved the wider industry on to a second edition, RICS V2, but the GLA's own guidance and assessment template haven't been updated to follow it, so a referable London scheme today is still assessed against the earlier version.

Arcadis was brought in at Stage 3, later than ideal, and built baseline carbon models in One Click LCA for the pilot projects that would form Cadogan's standard operating procedure for the wider refurbishment programme. From each baseline, hotspot analysis identified the elements driving whole life carbon, and design workshops with contractors, project managers and other stakeholders used those hotspots to focus the conversation on decisions rather than reporting.

Knowsley House: Retention over replacement

At Knowsley House, an office refurbishment, 68% of life cycle module emissions came from A1 to A3 product-stage impacts, with a further 24% from A5 construction and installation, driven by the scale of the façade design. Top hotspots included:

• Structural steel: 68 tCO2e
• Electrical cabling and fixtures: 37 tCO2e
• HVAC systems: 35 tCO2e
• Aluminium façade: 30 tCO2e
• Windows and insulation

The façade itself had to meet local planning standards for the street it sits on, which limited how far the design could move. The workshop moved quickly from identifying hotspots to testing what could realistically change given those constraints: reusing existing wiring routes and containment, validating and retaining drainage and rainwater pipework nearing end of life, and retaining the structural frame and floor slabs, the single largest saving on the project. The façade veil's fold depth was cut by 80mm, slimming the frame and designing the veil for future disassembly and reuse.

"This is where LCA becomes a design conversation, not just an accounting exercise."
— Amelia Mills, Principal Consultant, Arcadis

Oakley House: Benchmarking sharpens the decision

Oakley House, a hotel refurbishment, told a different story. A Stage 4 model put the project at 479 kgCO2e/m², above both Cadogan's own KPI of 425 kgCO2e/m² (based on LETI's 2030 design targets) and the 475 kgCO2e/m² UK Net Zero Carbon Buildings Standard retail benchmark. That comparison, rather than the model alone, created the urgency for a focused route into target optioneering.

The hotspots sat mainly in external works and substructure. A timber frame for the external car port would have delivered the largest benefit, but wasn't possible given planning constraints on the site, so the team looked instead at locally sourced recycled structural steel. Further down the hotspot list:

• Screed for levelling: 29 tCO2e
• Car port steel: 23 tCO2e
• Aggregates: 21 tCO2e (switched to local recycled content)
• Concrete foundations and substructure (C25/30): 18 tCO2e (cement replacement considered, including GGBS, fly ash, or limestone)
• Asphalt: 7 tCO2e (warm mix and recycled asphalt considered)

Some items, such as the screed specification, were fixed by planning requirements and couldn't be moved. Others, like aggregates, were a straightforward swap once flagged.

From model to procurement

Across both buildings, the pattern held: outputs were deliberately framed so they could carry into design, procurement, and programme-level reporting, rather than sitting in a report that nobody owned. Arcadis has since formalised this into a broader governance loop that it applies across projects, covered in more depth in the "A five-step way to move carbon hotspots into procurement", so that a hotspot identified in a model has an owner, a decision record, and a route into a specification or contract, not just a mention in an appendix.

Looking ahead

Knowsley House and Oakley House were run as pilots for a standard operating procedure Cadogan can repeat across its wider refurbishment portfolio, extending the same baseline-workshop-optioneering-commitment sequence to future projects rather than starting from scratch each time. Arcadis has separately used One Click LCA to achieve a 30% carbon reduction on a UK motorway infrastructure project, suggesting the same early-model, hotspot-led approach travels across sectors.