PERFORMANCE EVALUATION OF MISTING FANS IN THE OUTDOORS

Abstract

Misting fans are seen extensively used in the natural environment around Singapore. As more operators resort to the use of misting fans to convert hot and unused spaces into profit generating patios, the effect of misting fans to provide thermal comfort for occupants should be examined closely to actualize its cooling function, especially in the outdoors. Objective measurements and subjective measurements were conducted at an experimental setup to evaluate the thermal conditions and thermal sensations effectuated by misting fans in the outdoors and semi-outdoors. Analysis of objective and subjective data showed that the misting fans were only able to reduced dry-bulb temperature and thermal sensation votes to a limited extent at the outdoors compared with misting fans used in the semi-outdoors. This is coherent where regression analysis showed that with misting fans in the semi-outdoors environment, thermal neutrality can be obtained at a higher outdoor ET* (effective temperature). Despite this, respondents had similar percentage of thermal comfort acceptability at both outdoors and semi-outdoors settings. This proved that acclimatisation has caused most people to be adapted and accustomed to the hot and humid environment of Singapore. Furthermore, the relationship between thermal comfort and the amount of mist generated by misting fans were found not to have a strong positive correlation. An increase in the amount of mist in an environment does not necessary brought about better thermal comfort as shown in an experimental setup at NUS. Excessive production of mist does not lower dry-bulb temperature substantially and relative humidity that was built up caused a reduction in thermal comfort.