James Parker speaks to Luke Osborne at Senior Architectural Systems, about why greater transparency in Environmental Product Declarations (EPDs) is essential to help architects make informed specification decisions.

Why does the fenestration industry need a more transparent, evidence based approach?

From my perspective, architects are being asked to make increasingly complex sustainability decisions, and they can only do that well if the information they’re given is clear and grounded in real data. Too often, environmental information is presented in ways that make it hard to compare like for like and when figures aren’t explained properly, it becomes difficult for specifiers to understand the true impact of a fenestration system. A more transparent, evidence based approach simply means giving people the full picture so they can make confident choices. It’s about removing ambiguity and making sure the environmental story behind a product is honest, consistent and easy to interpret.

Why is interrogating EPDs important to avoid artificially lowered figures?

EPDs are incredibly useful, but they only work if the boundaries and assumptions behind them are clear. If certain stages of the lifecycle are left out, or if data is averaged in a way that hides variation, the carbon figures can look lower than they really are. That’s why interrogating an EPD matters. It’s not about catching anyone out but raising awareness and standards and ensuring that the numbers reflect the actual manufacturing processes. When architects dig into what’s included, they can spot where figures might be unintentionally optimistic or generalised, and make decisions based on the real environmental impact rather than a simplified version of it.

We believe fenestration system EPDs should cover the full system – not just the raw aluminium billet. That means accounting for thermal breaks, gaskets, fixings, fabrication and delivery to site, along with the energy-intensive extrusion process. This level of detail is often missing from standard EPDs, which typically report carbon figures for 1 kg of aluminium and exclude key stages of the product’s journey.

Is glazing being included in EPDs creating misinformation?

It can, yes. Most aluminium system manufacturers don’t supply glazing, yet sometimes glass is included within a system’s environmental data. If glazing is included, it can skew results when converted into a carbon figure reported per kilogram of material. The heavy weight of glass, combined with its relatively low carbon per kg figure, makes the overall figures for the aluminium system look lower than they really are.

Because glass has its own manufacturing processes and carbon profile, combining it with the frame can distort the information and means architects might think they’re comparing two systems fairly when, in reality, one includes glazing and the other doesn’t. This becomes even more challenging when glazing specifications vary widely between projects, as different coatings, treatments or performance requirements can significantly change the carbon impact. Keeping glazing separate avoids this confusion and supports more accurate, like-for-like comparisons.

Why should glazing have its own EPD, and what challenges exist for suppliers?

Glazing deserves its own EPD because it’s a completely different material with its own energy intensive processes, coatings and treatments. When it’s included in a system EPD, it blurs the true impact of the frame and makes it harder for architects to understand what they’re actually specifying. The challenge for suppliers is that producing an EPD requires detailed data from every stage of production, and not all glass suppliers have the resources or systems in place to gather that information. It’s a technical and administrative commitment, but it ultimately leads to clearer, more accurate environmental reporting for everyone.

Does separating EPDs create challenges for specifiers – or are they easily managed?

Separating EPDs does add an extra step, but it’s not a major hurdle. Architects already combine information from multiple materials when assessing a building’s carbon impact, so adding glazing as a separate data point is simply part of that process. The benefit is that the final picture is far more accurate. Instead of relying on blended figures, specifiers can see exactly where carbon is coming from and make more informed choices. With consistent formats and clear documentation, the extra effort is small compared to the value of having reliable, transparent data.

Why must manufacturers provide transparent data on aluminium extrusion processes?

The environmental impact of aluminium is shaped long before it becomes a finished profile. The source of the metal, the energy used in extrusion, and the recycled content all influence the final carbon figure. If manufacturers only share the number attached to the finished product, architects miss the context that explains how that number was reached. Transparent data on extrusion helps specifiers understand the real footprint of the material and compare systems fairly. It’s about showing the full journey of the aluminium rather than just the end result.

Are specifiers aware of these issues – and do SMEs have time to interrogate claims?

Awareness is improving, but many specifiers, especially smaller practices, are stretched for time. They want to make responsible choices, but they can’t always dig into every technical detail. That’s why clear, accessible environmental data is so important. If manufacturers present information in a straightforward, consistent way, architects don’t need to become carbon experts to make good decisions. The responsibility shouldn’t sit entirely with SMEs as the industry needs to make transparency the norm so that specifiers can trust the information without having to unpick it line by line.

Are any bodies looking at mandating greater transparency?

Across the construction sector, there is a clear shift toward more rigorous environmental reporting. Frameworks such as the UK Net Zero Carbon Buildings Standard, the growing use of whole life carbon assessments, and increasing scrutiny from green finance, planning and public sector procurement are all driving demand for more transparent data. Green finance requirements are also beginning to place greater emphasis on evidencing what has actually been installed on site, with auditors increasingly being used to verify environmental claims against completed works. While not all requirements are formally mandated, EPDs must already follow the EN 15804 framework, and the direction of travel is clear: environmental information is expected to be transparent, consistent and independently verified. Ultimately, sustainability claims will need to be backed by robust evidence rather than broad statements.

How has Senior approached its EPDs, and have they been externally vetted?

We have deliberately taken a different route with our EPDs. Instead of relying on generic industry datasets, we’ve focused on publishing documents that reflect how our systems are actually made. The process itself isn’t complicated as it’s simply about being open with the data and showing the full picture.

All of our EPDs are independently verified and that is really important as third-party assessments give architects and specifiers confidence that the information has been reviewed by competent people and have not simply been produced behind closed doors.

Our priority has been to make the information clear and easy to use so we have prioritised straightforward data, consistent presentation, and no unnecessary complexity. By pairing real manufacturing inputs with independent verification, we’re aiming to set a higher bar for aluminium systems and encourage a more open approach to sustainability reporting.

What is the future risk if specifiers don’t obtain true carbon data?

If architects don’t have access to accurate carbon data, there’s a real risk that buildings will be designed on assumptions that don’t hold up to scrutiny or real-life applications. That can lead to higher embodied carbon than expected, missed sustainability targets and potential compliance issues as regulations continue to evolve and tighten. It also undermines trust in the fenestration and wider building products sector as, when environmental claims aren’t backed by solid data, it becomes harder for specifiers to make responsible choices. Reliable carbon information is essential for delivering buildings that genuinely meet environmental ambitions rather than just appearing to on paper. Not making sure EPDs provide accurate, transparent and easy to access environmental data also reduces them to a marketing tool that misses the point completely and has the potential to do real harm.

Luke Osborne is UK sustainability lead at Senior Architectural Systems