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Open Access Publications from the University of California

Air movement as an energy efficient means toward occupant comfort


Fans provide a major opportunity for buildings in that they enhance both energy efficiency and occupant comfort. Very low-wattage fans (3 watts) producing 1 m/s (2 mph) air movement near each occupant are capable of offsetting a 6ºF (3K) increase in indoor air temperature, while improving the comfort perceived by the occupants. Increasing the indoor temperature reduces a building’s total HVAC energy about 5% per degree F, or 10% per degree C, and even more in some climate zones if the higher indoor temperature permits natural ventilation or evaporative cooling systems to be used instead of compressor-based cooling.

The opportunities for new design approaches and new fan products are considerable. Room fans have many applications in both new and retrofit designs since they do not involve other HVAC systems, can be easily turned on and off (as with occupancy sensors or wireless controls), yet they can provide an instantaneous cooling effect for the occupant. They strengthen the effectiveness of other energy-efficient measures which may be inherently slow-acting or unpredictable, such as radiant ceilings/floors, and buildings designed to rely on natural ventilation. The technologies involved are especially applicable in California climates.

The overall goal of this study is to encourage the broader adoption of room fans, especially ceiling-integrated fans, in commercial building design. The project addresses a wide range of topics ranging from fundamental human subject studies to new product design and the removal of barriers to implementation in comfort and energy performance standards. 11 subprojects were accomplished.

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