Personal air purifier fans as adaptive cooling in Qatari offices: Insights from a mixed-methods field study

In hot-climate regions like Qatar, overcooling in centrally air-conditioned offices often leads to occupant discomfort and increased energy use. This study explores the effectiveness of personal air purifier fans (Dyson TP-09) as an adaptive cooling strategy in seven office buildings in Doha across autumn, winter, and spring. Using a mixed-methods longitudinal design, we collected 24,373 environmental data points and 411 occupant survey responses. Fans were used adaptively, with a behavioral threshold around 25°C. Logistic regression confirmed a strong temperature-dependent fan use pattern, while moderate speed settings were preferred due to concerns about noise and draft. Fan usage improved perceived thermal comfort, particularly in counteracting overcooling, though usage was limited (34.6% of observations). Subjective thermal sensation was generally neutral to slightly cool, with many preferring slightly warmer conditions. Air quality remained within healthy limits; VOCs were the most common pollutant, and sensor data from fans closely aligned with independent loggers. Classification tree analysis showed that thermal preference, adaptive behaviors, and air quality perceptions were stronger predictors of overall comfort than fan-specific variables. The findings support the use of personal fans as a low-energy, occupant-centric solution to improve comfort and indoor air quality in hot-climate office environments.