Envelope Retrofitting by Building-Integrated Agricultural Greenhouses: A Multi-Objective Form Optimisation Procedure

Building-integrated agriculture can enhance urban food resilience when a greenhouse allows production during the cold season, especially in facade greenhouse retrofits on existing buildings, which should balance solar access, solar gains, and indoor comfort. This study presents a parametric workflow to generate and compare facade-integrated agricultural devices for a mid-20th-century social-housing block in South-East Milan, combining geometric reconstruction, regulatory constraints, and performance-driven form finding. The work presents a procedure that includes multi- and single-objective optimisation targeting winter solar access, summer overheating control, and sun-hours availability, and identifies the best option through greenhouse indoor climate simulation. The Pareto front was used to filter candidate solutions, and ANOVA and Tukey HSD tests were then used to compare them. Correlation analysis was used to assess the consistency of shape-driven effects across seasonal conditions. Under uniform operational assumptions (high operable glazing fraction and dynamic interior shading activated by facade irradiance), the choices were then evaluated in an indoor energy model. According to the comparison, several optimised geometries perform about the same across goals. The process allows for a clear, repeatable selection of retrofit envelope options that meet energy, thermal comfort, and agricultural production aspects.