The mid-twentieth century was a period of architectural idealism and rapid technological innovation paired with unprecedented growth in construction and built square footage. As design movements became global and mechanical systems evolved to provide ready access to heating and cooling, buildings became less climate responsive and more energy intensive to operate. Architecture of this time also celebrated structural innovation and novel materials, which led to frequent integration of structure, envelope, and systems. These characteristics resulted in a building stock with typically poor energy efficiency and new material challenges for conservation. Rather than a justification to tear down these buildings and replace them, their vast numbers and significant contributions to global greenhouse gas emissions are reasons why mid-century buildings must be effectively repurposed to meet climate goals while respecting their history. With the imperative to limit global warming to less than 2 degrees Celsius, reusing and upgrading these buildings provides a critical near-term carbon reduction strategy. This paper presents two case studies involving the reuse of undergraduate residence halls of this era. The first illustrates the substantial total carbon savings from restoration and reuse. The second proposes an analysis-based methodology for designing retrofits that optimize carbon payback of targeted interventions.
