How we are building a luxury resort sustainably and cost effectively

04/05/2026 360 Insights

Three structural decisions on a remote island project that are reducing both embodied carbon and CAPEX

Across the development industry, cost is the primary concern. Budgets are tight, programmes are fixed, and every line item is scrutinised. When the question of sustainability is raised, it tends to be viewed as an additional expense. And in many cases, that assumption comes from how sustainability is presented. Sustainability is often tied to certifications, specialised systems, or imported solutions that sit on top of the project and that approach can increase cost.

But if you look at where both cost and carbon actually sit in a building, the picture changes. Buildings and construction account for 37% of global emissions, and a large share of that comes from materials. Cement alone contributes about 7% of global emissions, while steel contributes roughly 7% to 9% (source). Studies of commercial buildings consistently show these two materials representing over 60% of a structure’s total embodied carbon — and in concrete-dominant buildings, often significantly more. Reduce the carbon in those materials, and you reduce cost. They are the same decision.

As project managers, this is how we need to position sustainability. Not as an add-on or a way to reduce OpEx in the future, but as a way to build more efficiently.

We’re seeing this on Sofitel La Corniche -Moroni, a luxury resort sitting on a remote archipelago hundreds of kms away from the African mainland. Constrained logistics. A world-class hospitality brand with standards to match. Zero room for error. Our structural analysis shows steel and concrete together contributing approximately 70% of the project’s embodied carbon. So we are focusing there, and only there.

Here are three decisions we made to make the project sustainable. No design compromises. No programme changes. Lower carbon and lower cost.

Decision 1: Post-tensioned concrete instead of conventional RC

PT structures reduce slab thickness, extend column spans, and cut total material demand. On a remote island where every shipment crosses open ocean, less material is a direct budget saving as much as a carbon one. Our structural study for Sofitel La Corniche is showing the following project-specific results versus a conventional reinforced concrete design:

Around 40% lower steel usage compared to conventional RC
Around 16% lower concrete volumes
Approximately 9% lower structural cost

This is a clear example of where sustainability is not a premium decision. Using less material reduces both embodied carbon and direct construction cost. It also improves buildability and reduces logistics pressure on site. Additionally, the architect gained column-free flexibility. The client got a leaner, cheaper, lower-carbon structure from a single early-stage decision.

Decision 2: Choosing CEM III/A over CEM I

Traditional Portland cement is one of the most carbon-intensive materials used in construction. Representative data shows emissions of over 913 kg of CO2 per tonne of cement produced. By comparison, blended cements using GGBS can reduce this significantly, often by 30% to 50% depending on the mix and the source.

The structural engineer gave us two valid options: CEM I 52.5 or CEM III/A with 45% GGBS. Both meet the structural requirements. We are specifying CEM III/A. The reason is simple: replacing 45% of Portland cement with GGBS (a by-product of steel production) cuts the cement’s embodied carbon by around 40%. CEM III/A also outperforms CEM I in marine and coastal environments, offering better resistance to sulphate and chloride attack which means a more durable asset.

A sustainability-driven decision that reduced carbon by ~40%—with a more adapted structural outcome and no cost impact.

Decision 3: Sourcing the lowest carbon steel available

Not all steel carries the same carbon footprint. Production methods and environmental impact can vary significantly. Rather than accepting whatever was closest or cheapest, we went through available suppliers and selected the one with the lowest independently verified carbon output for the steel going into this structure. That supplier also happened to offer one of the most competitive prices on the market.

Lower carbon and lower cost from the same decision without a trade-off.

That process starts before design with a clear sustainability strategy that defines material and carbon targets upfront. By the time tender comes, those requirements are already embedded in the specification. Suppliers either meet them or they don’t. On Sofitel La Corniche, it is one of the reasons we can say with confidence that the carbon numbers we are reporting are real, not estimates.

~40% less steel vs conventional RC*
~16% less concrete volume*
~45% lower cement carbon (CEM III/A vs CEM I)
~50% lower steel carbon

* Project-specific figures based on our structural study for Sofitel La Corniche – Moroni.

Cost and performance drove every call with a major emphasis on achieving better carbon outcomes. When sustainability is embedded at the structural and procurement level from day one, it stops being a trade-off and starts being a discipline.

That’s the version of sustainability that works in practice built into how you specify and procure from the start. It applies whether you are delivering a luxury resort, a commercial tower, or a mixed-use development. The materials are the same. The opportunity is the same.

Use less material. Use more sustainable material. Make those decisions early.

Sofitel La Corniche is under construction in Moroni, Comoros, with a structure that is costing less and emitting less than a conventional approach would have delivered.