Do Green Guide ratings still have a role to play in assessing environmental impact?
Rob Firman has the answer.

GREEN Guide ratings have been around since 2008, and many people in the construction industry continue to use them as a shorthand for communicating the environmental impact of construction products.

‘The Green Guide’ is how the BRE’s ‘Green Guide to Specification’ is usually referred to, and it was created to support BREEAM assessments. It assigned relative ratings to a range of materials and components, across multiple environmental impacts, as well as giving a summary rating.

The ratings were based on lifecycle assessment (LCA). At the time of the Green Guide’s inception, the understanding of LCA and the availability of tools to accurately measure it were not what they are now.

Today, more detailed environmental impact reporting is available in the form of environmental product declarations (EPDs). Decisions on sustainability can be made with more information than a simple summary rating can communicate. For that reason, recent versions of BREEAM have phased out the use of the Green Guide and its ratings.

What’s the biggest difference between Green Guide ratings and EPDs?
A significant difference between the two approaches to communicating environmental impact is that a Green Guide rating doesn’t get into the detail of a product’s lifecycle stages.

LCA makes assumptions about environmental impact at different stages of a product’s lifecycle: construction process, use, end-of-life, and the circular economy. While Green Guide ratings were derived from LCA, an EPD is deliberately structured around reporting the conclusions of the LCA at the different stages.

With more detailed reporting, designers, specifiers, and other construction professionals can make more informed decisions. Choices are more likely to be made based on specific environmental goals, so EPDs allow environmental impact and sustainability to be at the fore of specifying products.

For example, one specifier might seek to reduce the upfront carbon on a project, and therefore focus on the earlier lifecycle stages. Another specifier might be more interested in longer term carbon reductions and the circular economy, so be willing to accept slightly higher upfront impact in order to limit the impacts later in the project.

All this illustrates perfectly why it’s not possible to say whether a product is ‘sustainable’ or not.
EPDs are a tool that allow the environmental impact of products to be compared, so that choices can be made in support of a project’s sustainability goals. Green Guide ratings were designed to do the same thing but, by assigning a summary rating that effectively acted as a ‘ranking’, it arguably made it too easy for people to feel like they were making ‘sustainable choices’ without looking at the detail.

What are the potential issues when continuing to rely on Green Guide ratings?
Taking that to be the case, it’s perhaps unsurprising the ratings continue to be relied upon within the construction industry. We were recently asked about whether one of our products has an A+ rating, even though we have EPDs available offering more detail.

When BREEAM 2018 was launched, environmental impact evidence was changed from Green Guide ratings to EPDs. Four years on, there are likely to be few projects still being assessed under BREEAM 2014 and, therefore, using Green Guide ratings.

Green Guide ratings might still appear in a specification because an older, outdated specification has been copied and pasted. That is a practice that needs to be tackled in the industry generally, but there are other reasons why basing a specification decision on a summary rating is not appropriate.
Not all variants of different products and components were given Green Guide ratings, so historical ratings may not have applied to a particular product at any point. Lack of specificity is an issue when assessing environmental impact generally, as generic ratings and data don’t necessarily reflect the performance and impact of a specific product from a specific manufacturer.

Furthermore, like assuming that a product with an EPD is automatically ‘sustainable’, having a ‘good’ or ‘bad’ Green Guide summary rating doesn’t necessarily mean a product is a ‘good’ or ‘bad’ environmental choice. What environmental impacts are you looking to mitigate, and how did the Green Guide rate the product in that specific area?

Similarly, a ‘bad’ rating would not necessarily communicate some of the potential benefits that a product could offer in terms of whole building performance. Intentional, deliberate product choices are based on various factors a Green Guide rating perhaps couldn’t communicate, even at the time they were more relevant.

Understanding of environmental impact and lifecycle assessment has come on a long way in a short space of time, and specifications should be updated to reflect that better understanding. Green Guide summary ratings may have been useful for specifiers looking to make quick comparisons, but the construction industry is making a definitive shift towards EPDs that is being reflected in certification schemes.
www.polyfoamxps.co.uk
Rob Firman is technical & specification manager at Polyfoam XPS