Interaction effects of indoor environmental quality on stress among young adults: An experimental study

Background: Indoor environmental quality (IEQ) significantly influences occupant stress in office settings, yet the combined effects of multiple environmental stressors, moderated by personal characteristics, remain underexplored. Objective: This study examines the interaction effects of air temperature, lighting correlated colour temperature (CCT), and background noise on stress responses among office workers, with attention to individual differences in gender and body mass index (BMI). Methods: A mixed-design controlled experiment was conducted with 52 young adults in an open-plan office within a North American Mediterranean climate, varying temperature (20 °C vs. 25 °C), CCT (2700 K vs. 6500 K), and noise level (50 dB vs. 65 dB). Stress was assessed using physiological and psychological indicators. Key Results: Stress responses were shaped not by individual environmental attributes in isolation, but through complex interactions among temperature, CCT, and noise, further moderated by BMI and gender. Individuals with overweight/obese BMI showed heightened sensitivity to warm temperatures, cool CCT, and high noise, while males exhibited greater sympathetic activation under warm and noisy conditions compared to females. Implications: These findings underscore that a one-size-fits-all approach to office environmental design is insufficient. Accounting for occupant heterogeneity, particularly BMI and gender, is essential for developing personalized IEQ strategies that promote workplace well-being.