Reyan Clarey of CA Group discusses the challenge facing the industry of balancing embodied carbon targets against design quality in the race to net zero.

Decision makers are looking for a simple metric by which to measure products’ sustainability credentials. ‘Embodied carbon’ of new construction materials and products is now under scrutiny, with the perception that components manufactured with lower embodied carbon being automatically more sustainable. Yet a better understanding of the picture is essential when identifying and specifying products.

‘Net zero’ continues to be the buzz word throughout the industry, and Scope 3 Emissions offers many challenges to achieving sustainability goals. The rise in EAF (Electric Arc Furnace) steel is an essential evolution for metal cladding solutions, and has seen a slight increase in the availability of construction products with lower embodied carbon content at the ‘Module A’ product stage. However, availability remains limited, and the benefit should not mask environmental concerns that construction products may be exposed to later down the line.

We are finding that many designers and Principal Contractors are requesting significant improvements and reductions be made towards achieving net zero, including striving for lower embodied carbon products. The risk of this leading to a compromise on quality, guarantees, standards or specifications is real if these aspects are not also prioritised.

There is a risk of a deterioration in such performance aspects, where robust products and materials are at risk of being replaced by alternative materials purely on the basis of ‘embodied carbon’ alone, and where little to no consideration is given to the full life cycle assessment of the product. This includes its guaranteed performance, remediation or maintenance requirements, certification and classification in regard to fire, long term durability or the end of life benefits when it comes to deconstruction, recovery and recycling.

Ironically, scrutiny is often directed to the recycled content within new construction materials, with little focus on how these products are then fed back into the recycling stream at the end of their operational life. Selecting products with ‘face value’ lower embodied but with reduced guarantees and serviceable life, and limited recycling options, actually creates a far worse ‘whole life picture.’

The market is looking for its next quick win, a ‘silver bullet’ to differentiate products, and for architects and specifiers to emphasise their commitment to the environmental agenda with easy to communicate metrics. Construction of buildings in the UK has become so complex, with ever changing requirements for fire, sustainability, use of renewable energy solutions and long term financial viability underwritten by guarantees, the prospect of balancing all of these intertwined considerations means that considering just one aspect of performance in isolation is likely to lead to significant unintended detrimental consequences.

In the short term, the UK construction industry cannot be solely focusing on the carbon emissions associated with one specific area of a product’s Environmental Product Declaration (i.e. manufacture alone, ignoring installation, maintenance or end of life), with the risk that environmental benefits of primary material production are outweighed by the burdens of a product’s unsuitability for reuse or recycling processes in later life. These aspects are key elements of circularity, with the 2022 updates to EN 15804+A2 – focusing on mandatory reporting of end of life (Module C) and benefits beyond the life cycle (Module D) for this reason.       

For example, if the use of currently available EAF steel leads to a reduction in guarantee (and therefore reduces the effective product life), this factor needs to be considered in the overall assessment of that product. If a building needs major refurbishment after 35 years compared to 40 years, this is a significant uplift in the life cycle carbon emissions. If a guarantee is compromised or its period reduced by the inclusion of rooftop solar PV modules, this must be considered.

In summary, simply comparing ‘cradle to gate’ embodied carbon is insufficient, and could yield incorrect conclusions when selecting products or solutions. It is essential to consider whole life factors, including using materials with established recycling routes to reclaim the embodied carbon at their end of life. Everyone has to contribute if we as an industry are going to achieve truly sustainable construction solutions. How to measure our achievements is a critical element. Being taken in by marketing slogans does not yield genuine results, therefore don’t just consider embodied carbon up until Module A (product manufacture).

Consider the whole life cycle and look at the big picture. The evolution of cladding systems is underway, but it requires intelligent application of the solutions.

Reyan Clarey is sustainability officer at CA Group