Claims and counterclaims of the environmental virtues of various materials have dominated competitive posturing in the building products sector. But after two years of delay, the BRE’s updated Green Guide to Specification represents an attempt to slice through the greenwash and give specifiers and designers a simple overview of the environmental impact of building materials.
More than 1,400 generic building products are assessed in the new version, up from 200 in the previous issue published in 1999. It covers materials commonly used in commercial and residential properties.
Products are assessed against 13 environmental factors including its ‘global warming potential’ over 100 years, pollution, resource consumption and waste disposal over a 60-year period. These are obtained from life-cycle assessment data gathered from some 40 trade associations and material industry supply representatives and verified by BRE.
As with previous issues of the guide, for every product each environmental factor has been ranked on an A+ to E scale, where A+ represents the best environmental performance and E the least. This is presented alongside an overall ranking to summarise the total impact.
In recent years the guide’s significance has grown. Its ratings form the basis of the "ecopoint" scores allotted to different materials by the government’s Code for Sustainable Homes, which allows the use of sustainable materials to account for more than 7% of a development’s total score.
The guide plays a similar role in BRE’s Environmental Assessment Method (BREEAM), the environmental rating scheme for buildings. Over 100,000 buildings are now certified to the standard and over 500,000 are seeking certification under the scheme.
One of the key challenges for BRE is to keep the guide up to date. Many specifiers and firms that had improved their product manufacturing processes or had introduced new products were frustrated with the delay in publishing an updated version of the guide.
"The Green Guide is really the only authoritative source out there and we refer our procurement and design teams to it as one of the best places to go to when looking at materials," said Paul Toyne, head of sustainability at Bovis Lend Lease. "But it needs to be kept up to date. New products are coming to market all the time and changes are being made to existing materials. It’s a big job but we need a guide that is kept up to date using the most relevant, scientifically sound and useful information."
The online version should help. BRE says in the future the guide will be amended and updated on an ongoing basis. "Having the guide online gives us the flexibility to add new materials when they are new to the market and we have the data or to regrade materials when industry makes improvements," said Jane Anderson, technical leader of BRE’s environment materials team.
From August BRE plans to include specific product brands with certified environmental profiles in the guide to help specifiers find suppliers of materials and products that are best in class as well as the generic data for material or product types. Some 48 manufacturers have filed environmental profiles, some for several products.
BRE is working with the Construction Products Association to devise a way of explaining to manufacturers how life cycle analysis data is used to produce guide ratings. It hopes this information will help product suppliers explore eco-design at a time when there is a surge of demand for greener construction products as procurers adopt more sustainable procurement policies. Designers and specifers will also soon be able to delve deeper into the data and integrate the information into design tools.
Controversy remains over the methodology that is used in ratings. While it considers maintenance and replacement impacts through a product’s life, it does not consider their contribution to a building’s thermal efficiency. However, this area is now considered to be where most of the climate-related impacts associated with property are generated - a factor that has angered manufacturers in the cement industry as it is here that its products perform well.
But it is unlikely that ‘in-use’ thermal savings will be incorporated into BRE’s methodology soon. "We need to make sure products are compared on a like-for-like basis, so for now the methodology will stand. Only high level developments are now likely to trigger a review," said Ms Anderson.
However, more information on thermal mass is expected to be included in the online guide over time. Later this year, the BRE guide will also include products’ embodied greenhouse gas emissions.