Predicted percentage dissatisfied (PPD) model evaluation of evaporative cooling potentials of some selected cities in Nigeria
In some developing nations like Nigeria, poverty and epileptic power supply are the twin problems impeding people from the use of refrigeration - based air conditioning systems to achieve thermal comfort. Direct evaporative cooling is a viable option of achi eving thermal comfort especially in hot and dry climates. Direct evaporative coolers, apart from their low power requirements, are relatively cheap and are environment friendly. This paper attempts to estimate the direct evaporative cooling potential of so me selected cities in Nigeria using the predicted percentage dissatisfied (PPD) model. The model stipulates that a conditioned space is thermally comfortable if not more than 20% of the occupants are thermally unsatisfied. These selected cities are Enugu, Kano, Jos, Maiduguri and Mubi - South. The computed PPD for the months of January through December for the selected cities were determined. The computed PPD of these cities reveal the suitability of using evaporative coolers in the months of January and Dece mber for Enugu; all the twelve months for Kano; January, February, March, April, May, September, October, November and December for Jos; January, February, March, April, May, June, October, November and December for Maiduguri and, all the twelve months for Mubi - South, because their computed PPD in these months are less than 20%. This, however, shows that there is high potential of using direct evaporative coolers in Kano, Jos, Maiduguri and Mubi - South which can be attributed to the relative high outdoor tem peratures and low relative humidity. Apart from Enugu, direct evaporative coolers are recommended in these areas and in areas with similar climatic characteristics.
Keywords: Predicted percentage dissatisfied, Evaporative cooling, Thermal comfort, Predic ted mean vote