VIEWPOINT
CUT CARBON, NOT QUALITY
James Mead, R&D and Quality Director at Saint-Gobain Weber
CONSTRUCTION FACES A clear challenge: how to reduce embodied carbon without compromising on building product quality and durability, and with minimal disruption to site. Low carbon technologies can and must change the face of building products, delivering both quality and less embodied carbon than their traditional counterparts. For products like render – where performance, finish and reliability are non-negotiable – cutting embodied carbon requires a rethink of materials, processes and production, from source to site. It’s a shift that affects every link in the supply chain, including builders’ merchants, who are increasingly expected to stock and advise on sustainable alternatives that still meet practical site needs and can withstand the test of time. Innovation in this space is growing fast. Manufacturers are under pressure from regulators, clients and their own environmental, social and governance (ESG) ambitions to transform products that have traditionally relied on high-carbon components like cement. The transition isn’t just about new materials – it’s also about ensuring these alternatives fit seamlessly into existing specifications, workflows and distribution networks.
At Saint-Gobain Weber, this was the conundrum to address in developing a new type of render with lower embodied carbon. The result was the new weberpral E monocouche render, resulting in a 22%* reduction in carbon emissions from fossil fuels and by 10% overall compared to its current monocouche. Many significant challenges across R&D, production and logistics had to be overcome to get there.
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A rethink of cement- based materials With cement responsible for around 9% of the UK’s production emissions, finding new ways to cut carbon intensive processes is vital. However, the practicalities of finding cement replacements – particularly in products like monocouche render – are complex. There’s no single drop-in alternative, and performance must remain consistent for both hand and machine application. That’s why a team of chemists and technical leads at Weber took a different approach. Rather than using traditional cement substitutes like GGBS (ground granulated blastfurnace slag) – a by-product that’s increasingly limited due to changes in steel production – the team worked to source an alternative, more sustainable supplementary cementitious material (SCM) for the long-term.
Production hurdles The challenge was not only about finding a replacement, it was about maintaining ease of use and application – factors that customers had come to associate with the company’s existing render products.
Early trials of the new SCM highlighted a major issue: the render didn’t flow properly through mechanical spray equipment, which could severely disrupt site application.
Dr Sarah Lowe, R&D Team Leader, explained that the formulation had to be completely re-engineered: “We needed to ensure it would work reliably for applicators without losing the high- quality finish that’s expected.” What this meant was refining the particle size distribution, adjusting the setting profile and balancing
Low carbon technologies can and must change the face of building products, delivering both quality and less embodied carbon than their traditional counterparts.
additives to ensure strength, workability and rheology (the way the material flows and behaves under force).
Over the course of the project, the team identified around 40 major technical and operational barriers to hurdle. From adapting manufacturing equipment and redesigning silo systems, to ensuring logistics and storage could support the new product at scale, every stage of the product lifecycle was reviewed and adjusted.
Savings that count The end result, weberpral E monocouche render, not only achieves carbon emission savings, it uses 28%* less water in the raw material supply too. Crucially, these savings are embedded in the product — not dependent on carbon offsetting or external schemes.
What is more, with many renders requiring 20mm thickness in locations classed as ‘severe exposure’ to combat high levels of wind-driven rain and frost, weberpral E has reduced water absorption so can be applied at just 15mm thickness for the same performance. This means around 25% less material is needed For merchants and their customers, it’s increasingly important that environmental claims are backed by transparent data and built into the material itself. It also means that applicators
can use a more sustainable render without needing to change how they work or compromise on finish quality.
What it means For builders’ merchants, the shift to low-carbon products offers both opportunity and challenge. Stocking sustainable alternatives is increasingly part of client procurement requirements, especially on public or commercial projects. But those products must be practical, proven and deliverable at scale.
The development of a lower- carbon render that fits these criteria shows what’s possible when manufacturers invest in technical innovation, rather than just marketing claims. It’s a model that other product categories are likely to follow and merchants will play a key role in connecting customers with the right solutions. Achieving real carbon reductions in construction isn’t easy, especially when it means tackling the materials we’ve relied on for 200 years. But examples like weberpral E monocouche render show that with persistence, investment, and research, it’s possible to combine low-carbon performance with on- site practicality.
For merchants, keeping an eye on products that truly deliver – not just promise – will be key to staying ahead of changing demand. BMJ
www.buildersmerchantsjournal.net September 2025
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