Pulling together the sustainable specification

These two frameworks, taken together, provide a good basis for assessing a product’s sustainable credentials. LCC and LCA models also enable a quantitative comparison to be made. As always, the validity of these comparisons will depend on the rigour of the analysis. The international standards ISO14040 – 14043 provide frameworks for LCA analysis and it is always important to check that any analysis is carried out to these standards. The LCA analysis carried out was independently verified to the ISO standards.

To provide an independent view of the sustainable credentials of a broad range of construction materials and techniques, the Building Research Establishment (BRE) produce "The Green Guide To Specification". Available from Blackwell Publishing Ltd, this provides a rating for different materials, including pre-finished steel used in wall and roof cladding, based on a number of sustainability criteria.

The Green Guide rates environmental performance against a range of criteria, combining these to give an overall rating of A, B or C, where A has the least environmental impact. Within a category such as external walls, there is an even spread through the three ratings, so these provide a fair comparison of one system against another in a particular application.

For pre-finished steel, the Green Guide:-

• Demonstrates how pre-finished steel can be used in a wide spectrum of applications in combination with a wide variety of other materials.
• Shows that for all specifications within the ‘traditional shed’ category, an ‘A’ summary rating is achievable. This demonstrates that conventional pre-finished steel-based cladding systems, both composite panel and built-up, have a low environmental impact when compared with other materials.
• Highlights that for both roof and wall applications, systems using pre-finished steel perform well when compared with other materials.