Center for the Built Environment

Moving air cools human body.  In warm environments, fans can provide comfort using less energy than air-conditioning. The savings in HVAC energy is substantial, and greater if fans enable buildings to be successfully conditioned by natural ventilation or evaporative cooling systems, instead of chillers. Although there are many laboratory studies for desk fans and personalized fans, the tests for ceiling fans are rare, mainly from early studies in 1980s.  The purpose of this study is to examine cooling effect of an integrated low-wattage ceiling fan on people in warm environments when air comes from different directions with different speeds.  We conducted 96 human subject tests in an environmental chamber.  Sixteen college students each experienced 6 air movement conditions: two different air speeds and three different air directions from the fan toward the subject-from front, side, or right above the head. The difference in thermal comfort and thermal sensation generated by fixed and oscillating fans was also investigated. The temperature and humidity conditions for the tests were 28 °C and 50% RH. The two air velocities were selected based on previous experiments conducted with human subjects in our environmental chamber. The two hour test schedule included two five minute breaks when subjects were asked to be away from the fans, simulating conditions in real offices when people are away from fans. 

Subjective responses about thermal sensation, comfort, temperature satisfaction, perceived air quality, and preferred air movement were obtained periodically during the test, including the break periods. The results show that the ceiling fan is capable of providing thermal comfort under the tested warm condition.