Embodied carbon targets are now front and centre for developers and Tier 1 contractors working on large commercial schemes. The UK Net Zero Carbon Buildings Standard has set upfront embodied‑carbon benchmarks in the range of 500–800 kgCO₂e/m² for projects designed in 2025, depending on building type, with increased demonstration of measurable reductions in carbon across the building’s life cycle.
With growing consideration of embodied carbon, material selection is also being examined in detail throughout the building life cycle. While structural systems typically account for the largest share of embodied carbon, secondary elements such as riser systems are gaining traction due to their repetition across floors and service zones.
Embodied carbon and its effects
Embodied carbon refers to the greenhouse gas emissions associated with a product or material before a building becomes operational (Modules A1–A5 in EN 15978 terminology) and is estimated to contribute around 11% of annual global CO₂ emissions from buildings and construction. This includes emissions from:
- Raw material extraction and manufacturing
- Transportation to the site
- Installation and maintenance
- End‑of‑life treatment
According to the UK Green Building Council, embodied carbon from construction and refurbishment makes up around 20% of built environment emissions nationally, and is projected to represent over half of built‑environment emissions by 2035 as operational carbon falls away through grid decarbonisation. In contrast to operational carbon, embodied carbon is largely fixed once materials are specified and installed. This makes early design and specification decisions particularly impactful, specifically on projects where carbon performance is being actively assessed.
Materials with higher COâ‚‚ contribution
When reviewing embodied‑carbon breakdowns for typical commercial buildings, certain materials consistently dominate the totals.
Concrete and cement sit at the top, with cement production being responsible for around 8% of global COâ‚‚ emissions on its own.
Steel follows close behind in many structures, with average embodied‑carbon factors commonly reported in the region of 1.7–2.8 tCO₂e per tonne for primary production and significantly lower for high‑recycled, electric‑arc‑furnace routes. Even with higher recycled content, steel still represents a substantial share of upfront embodied carbon in many superstructures.
These form the structural core, but secondary components contribute too, riser floor systems being one component where different material choices can make a measurable difference to upfront embodied carbon.
How GRP compares to steel in riser floor systems
Glass-reinforced polymer (GRP) comes with specific advantages over steel when it comes to riser floor systems, particularly in high‑rise developments where risers manage vertical services.
In riser systems and their applications, the differences against steel are notable in the following aspects:
- Weight: GRP is typically reported as being up to around 75% lighter than equivalent steel solutions, requiring fewer lorry movements and often allowing installation without heavy lifting equipment such as cranes.
- Maintenance: Steel requires protective coatings and re-coatings over time, with each intervention adding material, labour, and carbon over the building’s life cycle. On the other hand, GRP is corrosion-resistant and typically does not need protective treatment even in humid, saline, or chemically aggressive environments.
- Longevity: Due to its non‑corrosive characteristics, GRP can offer service lives of 50+ years in suitable applications, reducing maintenance interventions and associated whole‑life costs.
EPDs: a look into verified declarations
As the industry accelerates its focus on embodied carbon, the credibility of environmental declarations becomes critical. Independently verified environmental product declarations (EPDs) provide trust and transparency, and give project teams confidence when using products in whole‑life‑carbon assessments.
At Comtec, we have commissioned a full third‑party accredited life-cycle assessment to produce EPDs for AlphaRiser and WallBeam, with both assessed by independent verifiers for final sign‑off. Our initial data shows embodied‑carbon savings of around 45% compared with published EPDs for comparable steel riser products, indicating a significant reduction potential at component level.[
For project teams reporting under BREEAM or responding to investor ESG requirements, the distinction of third‑party scrutiny is increasingly important as it provides robust evidence for whole‑life‑carbon reporting and sustainable finance disclosures.
Where is this heading?
Specification decisions made at the concept and early design stage are likely to sit with a building for decades. Riser floor systems are one area where those decisions can shift the numbers meaningfully without compromising on performance or buildability. Material comparisons have moved from being purely technical and cost‑driven to including quantified carbon and circularity considerations. Choosing materials that align with project‑level sustainability goals is now a strategic decision that can deliver measurable, portfolio‑scale embodied‑carbon reductions while maintaining safety and constructability.
For designers, contractors, and investors targeting the UK Net Zero Carbon Buildings Standard or similar frameworks, GRP‑based riser systems such as Comtec’s AlphaRiser and WallBeam provide a practical way to lock in lower embodied carbon early in the design without adding programme or installation risk.
