The anthropogenic heat emissions generated by human activities in London are analysed in detail for 20052008 and considered in context of long-term past and future trends (19702025). Emissions from buildings, road traffic and human metabolism are finely resolved in space (30 min) and time (200 x 200 m2). Software to compute and visualize the results is provided. The annual mean anthropogenic heat flux for Greater London is 10.9 W m-2 for 20052008, with the highest peaks in the central activities zone (CAZ) associated with extensive service industry activities. Towards the outskirts of the city, emissions from the domestic sector and road traffic dominate. Anthropogenic heat is mostly emitted as sensible heat, with a latent heat fraction of 7.3% and a heat-to-wastewater fraction of 12%; the implications related to the use of evaporative cooling towers are briefly addressed. Projections indicate a further increase of heat emissions within the CAZ in the next two decades related to further intensification of activities within this area. Copyright (c) 2011 Royal Meteorological Society