Proportional Design and Restorative Environments: A Post-Occupancy Evaluation of the Cubico Office, Milan

Introduction

This paper presents the post-occupancy evaluation of “Cubico Office”, a 500 m² workplace in Milan, designed for Cubico Sustainable Investments Italy S.r.l. using the Progettazione Aurea (PA) method: a generative design system grounded in the golden ratio (φ = 1.618…) as an organizational principle observed in natural systems. Drawing on biophilic principles, proportional spatial organization, and natural materials, PA aims to bring built environments closer to conditions of naturalness that psychophysiological and behavioral research increasingly recognizes as supportive of occupant wellbeing and conducive to sustainability-oriented behavior.

Methods

The evaluation mobilizes two independent assessment instruments: (1) the Biophilic Quality Index (BQI; Berto & Barbiero, 2017), a peer-reviewed quantitative tool measuring the restorative quality of built environments, and (2) a building-biological survey (Bio OK protocol; Zanella, 2026) measuring electromagnetic field exposure and environmental quality across 37 spatial points.

Results

The BQI assessment returned a score of 86%, placing the office in the highest restorative category. The assessor identified among the project’s distinguishing characteristics the presence of what she described as “organized geometry on Nature”: a spatial organization perceived as supporting environmental preference, perceived restoration, and positive emotional response through the formal logic of the design itself. Electromagnetic measurements confirmed values consistently within the lowest anomaly band of the SBM 2000/IBN standard, a noteworthy result for a densely equipped open-plan office located in central Milan.

Conclusions

The convergence of positive outcomes across independent assessment frameworks suggests that the design strategies implemented in this PA-based workplace are associated with favorable restorative and environmental outcomes in this case study. The findings provide preliminary evidence supporting further empirical investigation into the PA method as a potential contributor to occupant wellbeing and sustainable workplace design. The formalisation of PA as a transferable nature-based design methodology is also discussed.