3D Concrete Printing for Façade Retrofitting: A Parametric Approach to Thermal and Indoor Acoustic Performance in a Residential Unit

A large share of the existing residential stock, particularly in countries that adopted mandatory thermal insulation codes relatively late, exhibits simultaneously poor thermal and acoustic performance. Although 3D Concrete Printing (3DCP) technology has been independently studied for thermal and acoustic applications, the potential to combine these two applications in a facade system constitutes a research gap. This study presents a case-study application of prefabricated 3DCP cladding panels, featuring a ribbed, geometrically complex surface texture, to the facade of a 50 m² precast Reinforced Concrete (RC) residential unit in Ankara, Türkiye, without major structural intervention. The facade panels are manufactured from geopolymer material based on Construction and Demolition Waste (CDW). A parametric workflow integrating Autodesk Revit with Dynamo-based Sabine acoustic analysis and an ISO 6946 DesignBuilder thermal simulation pipeline is employed to quantify pre- and post-retrofit performance. The 3DCP cladding reduces the composite wall U-value from 0.714 to 0.346 W/m²K (−51.5%) and lowers the mid-frequency reverberation time (RT60) from 1.54 s to 0.88 s (−42.9%), while the existing single-glazed windows are retained as a fixed boundary condition. A diagnostic sub-analysis isolates the acoustic contribution of the unchanged glazing, confirming that the 3DCP surface texture is the dominant driver of absorption improvement. The results demonstrate that 3DCP facade panels constitute a viable, multi-functional retrofit layer that simultaneously enhances thermal performance, interior acoustics, and architectural expression through a single intervention, offering a replicable methodology for performance-driven envelope renewal in the existing building stock.