Conceived as a critical assessment instead of as a catalog or technical guide, the book presents a range of approaches to intervene on Modern steel frame glazed assemblies. It evaluates each case study in terms of how the intervention helped to preserve culturally significant features and how it adhered to current understanding of building science, Modern heritage conservation and contemporary requirements for building envelope design for energy conservation and optimum environmental performance. This is the first publication to present a wide range of international case studies with the purpose of delineating much-needed best-practices for intervening on culturally-significant Modern exterior glazed enclosures.