COMPARISON OF THERMAL COMFORT INDICES ACROSS CLIMATIC ZONES OF NIGERIA

Abstract

The study investigates the thermal comfort conditions across climatic zones of Nigeria. Heat index describes the combined effect of temperature and relative humidity on the body. The aim of this research is to compare the Thermal Comfort Index of selected stations in Nigeria using three (3) different indices and compare the results with standard values. The data for this study were obtained from the Nigerian Meteorological Agency (NIMET), Oshodi Lagos, Nigeria. The monthly temperature and relative humidity data spanned from 1985 to 2010. The stations used were (eighteen) 18 in numbers from the Northern and Southern part of Nigeria and chosen in order to represent all climatic zones (Sahel, Sudan and Guinea Savannah as well as Rain forest and Swamp forest) with at least 2 or more states from each region. Three Thermal Comfort indices were applied in this study, namely; Relative Strain Index (RSI), Apparent Temperature Index (ATI) and Effective Temperature Index (ETI). Temperature and Relative Humidity are essential parameters for computation of the (three) 3 indices. The spatio-temporal variability of the heat indices across climatic zones of Nigeria was assessed, and compared. Results from the study revealed monthly variation in the temperature and relative humidity. From the spatial variation, the Northern regions were observed to have lower ATI and ETI values than the other regions in the dry season, particularly January and December. The ETI, ATI and RSI provided contrasting result of thermal comfort for Nigeria, because of its varied climate. The trend of heat indices showed a decreasing trend of Apparent Temperature Index across all the stations, while some stations had increasing trend for Effective Temperature Index and Relative Strain Index. It was observed that thermal stress has increased in Nigeria