Fritz Haller (1924-2012) developed building systems Maxi (industrial halls), Midi (offices), and Mini (private homes) in the mid 1960’s with USM (current Haller-designed furniture manufacturer). Rejecting the individuality of most architectural projects, Hallerbau’s interchangeable parts, rigid grid, and post/beam/curtain wall construction accommodates transformation in industry. As the energy crisis changed building techniques, industrialization waned, and postmodernists criticised systems for their ubiquity, Hallerbau fell out of fashion. However, existing buildings' ongoing use is testament to the continuing relevance of the idea that standardisation provides flexibility through time. Re-Facing Modernism, the accompanying énoncé, examines the post-war building practice of the curtain wall, exploring renovation strategies through case studies in relation to user comfort, historic preservation, and energy performance. The value matrix developed provides a framework for approaching curtain wall restorations. The project Hallerbau in the age of reuse seeks to define the continuing value and possible futures of these buildings/system in a case study in Geneva’s PAV, a former industrial zone being transformed to residential quartier. USM now primarily reconfigures existing USM furniture to fulfil owners’ current needs; this PDM imagines an architect in much the same role at building scale, exploring the possibilities embodied in a system designed for evolution.