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.

The widespread application of 4G and the rapid development of 5G technologies dramatically increase the energy consumption of telecommunication base station (TBS). Remarkably, the air conditioning system accounts for a significant part of energy consumption in TBS. In this work, passive radiative sky cooling technology has been studied to explore its application potential for TBS. We built a simulation model in DeST to investigate the effect of various envelope thermophysical properties on TBS energy saving. The main influencing factors of the radiative sky cooling on TBS energy saving have been concluded and guidance has been raised for further application. An optimized envelope design combining radiative sky cooling with appropriate heat transfer coefficients has been proposed. The energy-saving and economic analysis of the optimized envelope design at different areas shows that, except for the low heat density TBS in severe cold areas, the annual energy-saving rate is 6.77%–64.29%, and the annual total energy saving is 21.94 kWh/m²–52.74 kWh/m². The payback period is 1.55–4.67 years, and the maximum acceptable cost limited to a 5-year payback period is ＄3.21/m²–＄9.67/m².

To achieve required indoor air quality, fresh air supply in buildings should meet relevant standards and regulations. However, the handling of fresh air introduced a cooling load that takes up a large portion of building energy consumption, especially in tropical and subtropical areas. A proper way should be employed to reduce the cooling load of fresh air. Radiative sky cooling, which is the process that an object cools itself by emitting thermal radiation to outer space without any energy input, is a cost-effective and eco-friendly technology. In this work, a fresh air pre-cooling system using radiative sky cooling is proposed to reduce fresh air cooling load. The system, consisting of filters, a radiative air-cooling system, an air handling unit (AHU), fans, etc., is installed on the rooftop of the modeled building. Six cities in low-latitude areas are selected and investigated. Results show that with the radiative air-cooling system installed, annual cooling energy consumption of the modeled building can be reduced by around 10% in most cities. For arid areas, e.g., Abu Dhabi, the system has even better performance with 19.34% annual cooling energy saving.