Most existing and new buildings adapt poorly to variable occupancy, in part due to technical constraints and common operational practice. Although building automation systems and advanced control strategies aim to address this issue by improving adaptability to partial occupancy, no holistic metrics exist to quantify this aspect of building performance. To this end, we present a technology-independent approach to define adaptability as a building performance attribute and introduce metrics to quantify it. These metrics can be used to evaluate how different building technologies and control strategies influence building operations’ adaptability to variable occupancy or estimate their associated energy savings. To demonstrate these metrics, a case study based on simulating a single-story office building was used to compare several control strategies with regards to their effect on improving adaptability. Results showed how the proposed metrics highlighted the additional benefits of these control strategies, especially under low-occupancy scenarios. Performance-based compliance with building energy codes and standards typically assumes full or near full occupancy, which may underestimate the benefits of adaptable building technologies or controls. Therefore, incorporating adaptability metrics in energy codes and operational guidelines would quantify the benefits of adaptable systems, especially under variable occupancy.