<p>Achieving carbon mitigation while enhancing indoor environment quality presents a dual challenge for building sector. The occupant-centric part-time-local-space (PTLS) environmental control strategy offers a promising approach by conditioning only occupied subzones during use. Its effective implementation requires fine-grained understanding of spatiotemporal occupancy patterns beyond the room scale. However, existing individual-scale studies often overlook co-occupancy behavior in multi-occupant scenarios, leading to unclear environmental control demands considering all occupants. To address this gap, this study develops a spatiotemporal occupancy analysis approach using high-resolution positioning data from multiple occupants. This approach quantifies localized occupancy characteristics and overlaps between occupants to identify typical environmental demand scenarios (specifying timing, spatial scope, and involved occupants), thereby guiding the design of flexible, demand-responsive conditioning systems. On this basis, an empirical analysis of four representative households was conducted. Results reveal distinct spatiotemporal co-occupancy patterns across functional zones. Specifically, for the measured cases, the dining subzone demonstrated peak concurrence during mealtimes with average occupancy duration increased by 26.3% despite low spatial overlap. In contrast, the sofa subzone exhibited pronounced nighttime occupancy with significant spatial overlap, expanding required conditioning space by 1.4–2.9 times and prolonging occupancy duration by 50%. These findings demonstrate the fine-grained spatiotemporal analysis gives insights to the design of localized environmental control systems aligned with actual household occupancy patterns, thereby enhancing the energy-saving potential of PTLS operation.</p>