EFFECTS OF CEILING FANS ON THE THERMAL COMFORT OF STUDENTS IN LEARNING ENVIRONMENTS OF BAYERO UNIVERSITY, KANO, NIGERIA

Abstract

It is well known that thermal comfort is influenced by major physical parameters; air and radianttemperatures, humidity, and air speed in combination with personal attributes; clothing insulationand activity level. Although temperature is conventionally considered in adaptive thermalcomfort model, as the most important physical parameter where cooling is involved, moderateair speed can enhance thermal comfort during higher temperatures. Through convective andevaporative cooling, ceiling fans cool people by causing sweat from the occupant’s body toevaporate. The northern part of Nigeria, being in the tropics, is known for higher temperatureregimes for most part of the year. The use of air conditioning to achieve thermal comfort is notsustainable, for economic reasons and the lack of stable electrical energy. Therefore, a majorityof naturally ventilated spaces could be kept thermally comfortable with the control of ceilingfans and operable windows. As part of a research work on learning environments in a NorthernNigerian university, this study reports on the effects of ceiling fans on the thermal comfortperception of the students in two lecture theatres. In addition to the measurements of air speed,air and radiant temperatures, relative humidity, a comfort survey was also undertaken in thespaces, from which activity levels and clothing insulations were obtained. Adaptive thermalcomfort standards, ASHRAE 55 and EN 15251, state that thermal comfort can be maintained asair temperature rises with the use of ceiling fans operating at moderate speed. The results fromthis study show that reductions of 31% and 22% in overheating from the two lecture theatreswere realised, as a result of ceiling fans usage, measured by the degree hour’s exceedanceindicator. These results were further corroborated by the students’ acceptance of thermalconditions of the lecture theatres at temperatures above Tmax.Keywords: Ceiling fans, thermal comfort, overheating, Bayero University, Kano