Ceiling fans are a good low energy means to reduce warm discomfort in buildings. Two automatic ceiling fan systems are described that regulate air speed to maintain comfort in changing conditions. The simpler system, based on the ASHRAE comfort standard, responds only to temperature . The other uses the PMV comfort model to regulate the air speed. In comfort test at 29C and 50% RH both automatic systems provided the same level of comfort at steady state conditions as manual control. However the automatic systems were faster in bringing the subjects to comfort. The comfort performance of the two automatic systems were also compared during a temperature down drift from 29 C to 25C and the PMV system was compared to manual control during humidity changes.