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.
The benefits of higher temperature cooling with elevated air speed, in terms of energy saving and higher occupant comfort level, have been verified in multiple studies (see "Benefit of Elevated Air Speed"). However, occupants are used to a conventional cooling strategy with only air-conditioning at lower setpoint temperatures.
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 subjects can be comfortable at a higher temperature condition with increased air speed, in practice, occupants 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.
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 many 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.
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 suggested.
A key part of the success of any fan installation is ensuring that occupants understand the purpose and use of the fans given that, in some context is a novel solution. Presenting the changes clearly to the occupants is very important, so they can be informed on how to use the new equipment and why modifications are being proposed. In cases with regular occupants (as opposed to spaces with transient occupants such as lobbies or event spaces) who do not have direct control over the fan operation, occupants should be informed about the purpose and operation of the ceiling fans. Ideally, spaces where occupants do not have direct control over fan operation, should also allow for flexibility so that occupants may find a location within the space that best suits their comfort preferences. In applications where occupants have access to fan controls, it is also helpful to post information or instructions encouraging occupants to adjust ceiling fan settings when they are too warm rather than resorting to reducing thermostat setpoints. Figure 56 shows an example of an information plaque with basic recommendations for user control.
