The purpose of this paper is to elucidate the correct specification of the analytical CTTC model for predicting the urban canopy layer (UCL) air-temperature. Improvement in the model specification was proposed by Elnahas-Williamson by incorporating in the prediction process diurnal information from a site's representative meteorological station. The paper demonstrates that the proposed improvement causes a serious error in the diurnal predictions, the effect of which may reflect on the indoor energy savings policy. (C) 2004 Elsevier B.V. All rights reserved.