The present study estimates the temporal variability of the anthropogenic heat flux density (Q(F)) for three common land use types found in Singapore between October 2008 and March 2009. Q(F) is estimated by separately considering the major sources of waste heat in urban environments, which are heat release from vehicular traffic, buildings and human metabolism, respectively. The individual components of Q(F) are calculated by using a combination of top-down and bottom-up modelling approaches of energy consumption applied to the local context. Results show that over a 24-h period, magnitudes of mean hourly Q(F) reach maximum values of 113 W m(-2) in the commercial, 17 W m(-2) in the high-density public housing and 13 W m(-2) in the low-density residential areas, respectively. Buildings are found to be the major source of anthropogenic heat (primarily related to space cooling) in each study area, contributing to between 49-82% of Q(F) on weekdays and 46-81% on weekends. The spatial and temporal variations of Q(F) are attributed to differences in traffic volume, building energy consumption and population density. This is one of the first anthropogenic heat studies carried out in a tropical city and the results show that Q(F) can be substantial and of the same order of magnitude as calculated for city centres in mid-latitude cities during winter time. (C) 2011 Elsevier Ltd. All rights reserved.