Choice of a thermal index for architectural design with climate in Nigeria

Thermal indices are used to measure the degree and nature of thermal stress. Dozens of these have been developed, but the various ranges of application and accuracy in the Nigerian climate complicate choice of the most appropriate index. This study compares various thermal indices to determine which one is most reliable in the prediction of thermal stress. The thermal indices compared are the Mahoney scale, the Evans scale, the Bioclimatic chart, TSENS and the effective temperature. The study uses a mental assessment test to record thermal stress for 203 cases and then predicts the thermal stress for the same conditions using the selected thermal indices. The indices were then ordered by ranking them according to their ability to predict thermal stress using frequency analyses, ordinal- and interval-level data analyses. The little-known Evans scale was shown to be generally more accurate. The conclusion is however limited by the very nature of thermal comfort and the scope and duration of the study.