Case Study: Thermal Comfort in a Water Mist on Hot Summer Days

In a case study on outdoor mist cooling, 141 people attending an open campus event were surveyed over 2 hot summer days. Nozzles mounted on an oscillating fan sprayed about 18L/h of mist with average droplet diameter of 25μm. Subjects stood in the misting area where they wished. Time spent in the misting area was recorded. Skin temperature of the forearm and face were taken with IR surface thermometers before entering and after leaving the misted area. Each participant was surveyed for “thermal sensation” on a 9-level scale, and “general comfort” and “feeling of wettedness” on 7-level scales. “Feeling of wettedness” included an additional qualitative parameter of “unpleasant”, “pleasant” or “neither”. Misting will increase wettedness, but it can feel pleasant. On average, thermal sensation dropped from +2.7 (very hot) to -1.4 (slightly cool) and comfort increased from -1.4 to +1.8. Though wettedness increased from +0.8 to +1.6, the qualitative wettedness parameter changed from 75% unpleasant to 75% pleasant. Skin temperatures dropped an average of 1.1˚C on the forearm, and 1.0˚C on the face.