This report provides a review of how metals have been assessed within the current edition of The Green Guide to Specification, including the application of the Environmental Profiles Methodology that underlies The Green Guide. This report aims to provide manufacturers and specifiers with a general understanding of the approach and decisions that have been made when applying the Environmental Profiles Methodology to metals. The key impacts of metals over their whole life cycle are discussed and opportunities for improvements within the sector are identified. This report has been produced as part of a series providing background information on the production of The Green Guide to Specification. Many of the other reports in the series that focus on specific materials may also be of use when considering the environmental impact of construction products.