This report provides a review of how insulation materials have been assessed within The Green Guide to Specification, including the application of the Environmental Profiles methodology which underlies it. The way in which insulation is addressed within building level environmental assessment schemes such as BREEAM and the Code for Sustainable Homes is also explained. The report will give manufacturers and specifiers an understanding of the impacts of their insulation products over their life cycle and to identify opportunities for improvements to their environmental performance. It is part of a series that provides comparable information on cladding, floor finishes, windows, metals, timber, masonry and concrete. These will be of value when considering the environmental impact of specific construction materials.