Environmental Product Declarations (EPDs) are now routinely used to compare products and inform whole-life carbon assessments. But how much confidence can we place in the carbon figures they present?  After all, a product might appear to be a green triumph on paper, but is it too good to be true? 

Imagine reviewing an EPD for a building product that boasts exceptionally low carbon emissions, with the manufacturer attributing this performance to the use of renewable energy, biomass or biomethane. However, if you dig a little deeper, a different reality emerges. The factory has no on-site renewables and remains firmly plugged into the national grid. The dramatic drop in emissions didn’t happen within the factory itself, it happened on a spreadsheet. Through the purchase of energy certificates and other contractual environmental attributes, the manufacturer may be able to report significantly lower emissions associated with its energy consumption.

This practice is often referred to as the "book and claim" system, where companies can purchase the environmental attributes associated with renewable energy produced elsewhere, independently of its physical delivery.  

In the UK, Renewable Energy Guarantees of Origin (REGOs) are used to certify renewable electricity, while Guarantees of Origin (GoOs) operate across European markets. Biomethane has its own certification mechanisms, including Renewable Gas Guarantees of Origin (RGGOs). These systems allow the environmental attributes of energy production to be traded separately from the physical energy itself, enabling manufacturers to make renewable energy claims through their carbon reporting. 

Critics argue that this system represents a form of paper-based greenwashing that obscures the reality of the manufacturing process. For defenders, it is said to be the only practical way to funnel corporate investment into the growing renewable energy sector. There is tension between the green paperwork and the physical reality of energy consumption, raising an important question: can the industry buy its way to a sustainable future? 

Utilising these certificates makes the job of an architect or specifier increasingly difficult. Through qualifying renewable electricity procurement, manufacturers may be able to apply a significantly lower, potentially near-zero, market-based emission factors to their electricity consumption.  

Similar accounting mechanisms exist for renewable gas, where certified biomethane can be used to support claims of lower-carbon fuel consumption. This can have a substantial impact on the reported manufacturing emissions within an EPD, particularly for energy-intensive production processes. However, the reported results may not make the distinction between physical energy consumption and contractual renewable energy procurement sufficiently visible to the person using the EPD.  

When the product's EPD is subsequently integrated into a carbon assessment, its declared emissions are incorporated into the results. The specifier may therefore assume that the product was manufactured using genuinely lower-carbon energy, without understanding the contractual arrangements behind the reported figures or the extent to which the factory remains reliant on a fossil-fuel-dependent energy supply. 

The certificate system is viewed by some as a potentially misleading form of carbon accounting, where reported reductions do not necessarily reflect changes in the physical manufacturing process. If an industrial furnace burns natural gas, the resulting emissions enter the atmosphere regardless of whether the manufacturer has purchased renewable energy certificates. Purchasing a certificate does not directly eliminate those emissions or change the fuel being used.  

Where these certificates are incorporated into product-level EPDs without sufficient transparency, an illusion can be created, leading consumers to believe they are purchasing a significantly lower-carbon product when the physical manufacturing processes may have remained largely unchanged. In effect, they could be purchasing the same product, produced using the same energy-intensive processes, but accompanied by a different set of environmental certificates.

Conversely, many argue that the book and claim system is an important mechanism in supporting the transition towards renewable energy. Heavy industrial sites are often constrained by existing infrastructure, geographical location and the practical challenges of transitioning to alternative energy sources. Installing sufficient on-site renewable generation or directly accessing renewable energy is not always feasible for existing manufacturing facilities. Purchasing renewable energy certificates can therefore provide an additional revenue stream for renewable energy generators and help create market demand for cleaner energy.  

However, the extent to which these purchases contribute to additional renewable energy generation is dependent on the circumstances. Purchasing a certificate does not necessarily mean that new renewable capacity has been created or that the purchase has directly funded a new renewable energy project. Certificates must be appropriately cancelled or redeemed against the relevant renewable energy claim to prevent the same environmental attributes being claimed more than once.