Dynamic heat flow control in building envelopes via thin recycled polymer-modified renderings

ABSTRACT: Optimizing habitability in temperate environments requires replacing the static approach of conventional insulation with dynamic solutions that regulate the envelope's thermal storage and transfer. This study investigates the thermophysical performance of five lightweight cementitious mortars (2 to 8 MPa) for thin renderings, developed with recycled polymers (EVA foam, EPS, and pellets) under circular economy principles to strengthen thermal resilience at low cost in vulnerable contexts. Critical transient regime properties—thermal conductivity (λ), diffusivity (α), effusivity (b), and characteristic response time (τ)—were experimentally evaluated at a 3 cm thickness. Results demonstrate that the EVA mix increases response time by 107% compared to traditional mortar, while EPS reduces thermal effusivity by 56%, optimizing indoor tactile comfort. In conclusion, these functional renderings effectively induce thermal time lag, offering a low-environmental-impact solution for the climate adaptation of buildings.