The significance of the anthropogenic heat emissions of Londonʹs buildings: A comparison against captured shortwave solar radiation

This study addresses the anthropogenic heat emissions from buildings in London, i.e. the total energy delivered to buildings, all of which will ultimately end up as heat energy. The study was undertaken in an attempt to understand the significance of these emissions with regards to the impact on the local climate in London. In order to place the emission of this anthropogenic heat in context, it was thus compared against the net short wave solar radiation captured within the urban environment. This study provides a preliminary analysis of the spatial and temporal anthropogenic heat emissions from buildings across London as part of the urban climate modelling element of the LUCID (‘The Development of a Local Urban Climate Model and its Application to the Intelligent Design of cities’) project. Four urban environment models, representative of the range of urban density found in central London, were developed for the comparison of the anthropogenic heat emissions and the net shortwave solar radiation. It was found that the annual average anthropogenic heat emission from the built environment across London was approximately 9 W/m2 (ground area). However, this average value conceals a significant spatial and temporal range. In those urban areas with deep canyons and high densities, the anthropogenic heat constitutes a significant portion of the total energy input. A comparison indicates that the total heat emission from buildings during a winter day ranges between 3 and 25 times greater than the incident solar radiation, and during a summer day between 0.04 and 0.4 times, depending on built form density.