Spatial and Temporal Variation of Indoor Environmental Quality and Occupancy across a Five-Node Office Sensor Network
DOI:
https://doi.org/10.33003/fjs-2026-1011-5339Keywords:
Indoor environmental quality, Occupancy, Sensor network, Smart Buildings, Spatial VariabilityAbstract
Indoor environmental quality (IEQ) and occupancy are usually characterized for a single room, yet real buildings comprise many zones that may differ substantially, with direct consequences for zoned heating, ventilation and air-conditioning control. This study quantified the spatial and temporal variation of IEQ and occupancy across a five-node, low-cost sensor network deployed in five offices. Each node logged temperature, humidity, illuminance, motion and a fused occupancy state every minute, yielding 56,173 validated records over 8 days, from which the apparent temperature (heat index) and thermal-comfort compliance were derived. Differences between offices were tested with one-way analysis of variance, the non-parametric Kruskal–Wallis test and Tukey honestly-significant-difference post-hoc comparisons, and the offices were grouped by Ward hierarchical clustering. All four variables differed significantly between offices (p < 0.001). Temperature differed in 10 of 10 pairwise comparisons, mean temperature spanned 30.5–31.1 °C and occupancy ranged from 54% to 75% of the time. Temperature and humidity were strongly anti-correlated (r = -0.78). No office met the conventional comfort envelope for an appreciable share of the time, and the heat index exceeded the caution threshold almost throughout. Clustering separated one low-occupancy office from the rest. The results show that single-zone assumptions are unsafe and that spatially resolved monitoring is required for effective, zone-aware building management.
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Copyright (c) 2026 Ahmed Mohammed, Mustapha Ismail, Abdulhamid Ibrahim Nafada, Muhammad Dawaki, Mohammed Ajuji
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