Relationships between objective environmental parameters and worker satisfaction with thermal and air environments: Surveys of 22 offices in Japan during summer and winter

Thermal and air environments affect workers’ well-being, health, and productivity. Interactions between thermal and air environments have been reported in laboratory experiments; however, evidence from field surveys in actual offices across seasons remains limited. This study aimed to clarify the relationships between objective environmental parameters and worker satisfaction with thermal and air environments in summer and winter. Questionnaire surveys and environmental measurements were conducted involving 738 workers during summer (July–August 2023) and 672 workers during winter (January–February 2024) across 22 offices in Japan. Overall mean values of the measurements were 26.4°C in summer vs. 24.4°C in winter for air temperature, 50.1% vs. 34.6% for relative humidity, 698 ppm vs. 696 ppm for CO 2 concentration, and 2.7 µg/m 3 vs. 9.8 µg/m 3 for PM 2.5 concentration. The proportions of workers reporting dissatisfied ratings were 29.9% in summer vs. 30.5% in winter for the thermal environment and 12.3% vs. 15.0% for the air environment. Multilevel linear regression analyses showed that higher mean air temperatures were correlated with lower thermal satisfaction in summer, whereas greater temporal fluctuations in air temperature were correlated with lower thermal satisfaction in winter. Mean air temperatures were not correlated with satisfaction with the air environment in either season; in contrast, lower mean relative humidity levels were correlated in winter. These findings provide exploratory field-based evidence of interactions between thermal and air environments in actual offices across seasons and suggest the importance of considering interactions for a better understanding of the relationships between objective environmental parameters and worker satisfaction.