Deep renovation methodology for 20th-century masterpieces: the case of Palazzo Affari by Carlo Mollino

This paper proposes a methodological approach to energy renovation in valuable buildings, encompassing architectural, historical, and energy analyses. The research tests its application on a case study: a retrofit proposal for Palazzo Affari in Turin, an office building designed by Carlo Mollino for the Chamber of Commerce (1964–1974). The building, still in use, has never been thermally renovated yet. Palazzo Affari gathers structural, technological, and spatial experimentation worth to be preserved. The core of Mollino's design is a versatile plan, clear from any structural encumbrances, which was made possible thanks to an innovative structural technique. Façades are cladded with finely designed concrete prefabricated panels. As a 20th-century masterpiece, it must be recognized as culturally valuable but also shows enormous energy improvement potential, as many buildings of its age. Based on a deep understanding of the building, the paper proposes a combination of traditional and innovative ad hoc solutions for its renovation, mediated by the need for material and iconic preservation. Both the substitution of the façade panels and the insulation from the outside are excluded. The opaque parts of the façade are insulated from the inside using high-performance Vacuum-Insulation-Panels, and cladded by a new counter-facade conceived to be produced in panels through digital fabrication. On the other hand, windows are fully replaced by choosing glass which is both high-performing and respectful of the original chromaticity and transparency. The new window frames with thermal break are specially designed to respect the original external thickness. The design is configured as an add-in intervention, coherent with the pre-existence. Substitutions are carefully weighted and respect the original architectural features. FEM analysis demonstrates the reduction of the thermal flux through the opaque walls by 80% and through the windows by 65%. The solar factor is reduced by 35%, thus improving the summer internal thermal comfort.