As well as getting A and A+ ratings in BRE’s new Online Green Guide, wood windows get top marks for having the least effect on Climate Change.
The BRE Green Guide online provides specifiers with easy-to-use guidance on how to make the best environmental choices when selecting construction materials and components. Items shown in the guide are assessed in terms of their environmental impact across their entire life cycle from ‘cradle to grave’ within comparable product specifications.
Typical products and building elements manufactured from different materials are given an overall assessment on a scale of A+ to E, where A+ is the lowest environmental impact and E is the highest. This overall score is achieved by assessing 13 impact categories such as climate change, mineral source depletion, ecotoxicity, etc. which in turn are rated on a similar basis.
The BRE Green Guide online is an environmental performance tool developed to help specifiers compare window specifications. Other criteria such as the responsible sourcing of the material used, the energy, security and weather performance of the window in addition to service life should also be taken into consideration.
How wood windows score
Generic, or typical* wood windows have the highest overall ratings for window materials for both domestic and commercial applications in the guide scoring A+ or A.
They also score A+ or A in over 50% of the 13 other impact categories.
One of the most important of these is the impact on climate change – the potential to bring about global warming by the emission of carbon dioxide, and is a measure of the embodied carbon in the product or material.
Wood windows achieve an A rating for climate change, compared with far lower ratings for all other materials, demonstrating wood’s advantage and ability to reduce CO2 as a tree grows and to continue to store carbon during the lifetime of the product.
*Typical windows are those that meet the minimum requirements of BS644 (shown in the guide as non-TWAS). These are windows which do not comply with the additional performance criteria required by British Woodworking Federation’s Timber Window Accreditation Scheme (shown as TWAS in the guide).
Windows manufactured by members of the Wood Window Alliance are also required to meet the TWA Scheme criteria in performance specifications, service life expectations and responsible sourcing of timber.