Managing occupants' expectations with fans
How to deal with occupant expectations when fans are introduced in a space?
Last updated
How to deal with occupant expectations when fans are introduced in a space?
Last updated
Fans can be added to an existing AC system to save energy and increase comfort. Besides the aspect related to the system's design, it is also important to consider how the new fans are introduced in the space and how the temperature setpoints are increased.
Occupants take time to adapt to the fan-integrated AC system at warmer temperatures and higher air speed environments. Depending on the site conditions and culture, a grace period for occupant adaptation may take up to 3 months. Any change in temperature cooling setpoint should be small, gradual, and follow occupants’ comfort feedback. Despite studies showing occupants can be comfortable at a higher temperature condition with increased air speed, in practice, they may perceive thermal dissatisfaction with a sharp change in room temperature setpoint (e.g., from 23 °C to 27 °C [73 °F to 81 °F]) without providing a grace period for adaptation. This is particularly important in building retrofits.
For a practical implementation of a fan-integrated system, building facility managers are suggested to go slow and have patience and perseverance with the progressive transformation process. For example, if the thermal comfort analyses indicate it is possible to increase the air temperature cooling setpoint from 25 to 27 °C [from 77 to 81 °F] at higher air speed conditions with fans, in practice, the temperature setpoint shall be first increased to 26 °C [79 °F] and maintained for at least two weeks for occupant adaptation before further increasing it to 27 °C [81 °F]. In addition, occupants’ feedback on the indoor environment shall be continuously monitored during the transformation period. If a lot of thermal dissatisfaction votes have been received, a slightly lower air temperature setpoint should be used. For example, the temperature should be brought down to 25.5 °C [78 °F] to be maintained for two weeks, then raised up to 26 °C [79 °F] again, and advice and training to the occupants about the use of fans should be provided.
Several studies have suggested that occupants can have a higher tolerance to thermal discomfort when provided with control of their micro-environment. Regardless of specific building functions or design intents, allowance for personal control of the fan systems is recommended.
A key indicator of a successful fan-integrated system is ensuring occupants understand the purpose and use of the fans. Figure T13 shows an example of an information plaque informing the fan usage priority – Fan cooling first approach – when occupants feel too warm.
