Evaluating the Impact of Fan Design and Air Speed on User and Nearby Occupants’ Thermal Comfort in a Shared Office

Abstract

Personal Comfort Systems (PCS) are increasingly recognized for their potential to improve individual thermal comfort and reduce building energy demand. ASHRAE Standard 55 defines PCS as a device, under the control of the occupant, intended to heat and/or cool individual occupants without affecting the thermal environment of other occupants. Desk fans are common PCS cooling devices, but their use in shared workspaces raises questions about the differential impact on the primary user and nearby occupants. Limited empirical evidence exists on how local air speed and fan technology jointly influence thermal, airflow, and acoustic domains among occupants. To address these gaps, a human-subject experiment involving 40 participants was conducted, paired into 20 pairs: P1 as the fan primary user and P2 as a nearby occupant. Two desk fan designs (conventional-blade and bladeless) were tested at high and low-speed settings. Participants provided repeated comfort assessments at each fan speed condition. The results indicate that both fan technology and operating speed significantly affect the alignment or divergence of comfort between P1 and P2. At low speed, both fan types produced strong convergence, with both occupants reporting neutral thermal sensation, slight satisfaction, and a shared perception of air movement as “just right.” In contrast, at high speed, the bladed fan resulted in divergence: P1 perceived the airflow as “too breezy” and preferred less air movement, while P2 reported no change despite experiencing breezy conditions. Conversely, the bladeless design reduced this asymmetry. At all speeds, both P1 and P2 reported neutral thermal sensation and consistent satisfaction. For primary users, both fan types enhanced thermal comfort at both speeds. The bladed fan was effective only at low speed, as high speed produced a “too breezy” sensation, whereas both speeds were acceptable for the bladeless fan. Despite these advantages, the bladeless fan introduced acoustic disturbance to the environment. High-speed bladeless was perceived as more annoying than the bladed fan, with the P2 group reporting higher annoyance (85%) than the P1 group (65%). This suggests that the high-frequency profile of the air multiplier technology is intrusive, especially for nearby occupants in shared environments. For shared workspaces with mechanical cooling, a low-speed fan setting is recommended. This configuration minimizes acoustic annoyance for both fan technologies (0-5% annoyance) while maintaining high thermal satisfaction for primary users and minimal intrusion into the environment of nearby occupants.