This article examines how the critical history and theory of sustainability intersect with the theory and practice of architectural heritage conservation. It focuses on the outcomes of the course ‘Architecture and a Critical History of Ecology’ which interrogates how the emergence of environmental consciousness since the mid-twentieth century influenced architecture and its social, technological, and design experimentations. This historically minded course taught at the Department of Architecture at the University of Cyprus (Course code ARH 511) has been designed from scratch to provide an alternative perspective and also an important companion to more technically oriented courses on environmental technologies in architectural design. It enhances student’s theoretical knowledge and criticality by cultivating an understanding of the socio-political implications of recent concepts around ‘sustainability,’ ‘green’ and ‘climate’ that shape contemporary architectural theory and practice.