The sensitivity of predicted energy use to urban geometrical factors in various climates

Urban morphology, including building typology and layout, has a significant influence on the built environment’s access to the sun, which impacts its energy exchange with the environment. This energy exchange is a strong factor in determining the comfort levels of occupants in buildings and the energy consumed to reach comfort. The influence of urban form has been quantified in previous studies for certain building typologies and programs for specific climates (i.e. location-specific case studies). We are interested in taking this further to assess the variation, due to climate, of the influence of different urban forms on the urban energy balance. This is part of a larger project to study the interaction between form and climate vis-à-vis energy and comfort in buildings. In this paper, we explore this issue through simulation, in various climates, of 3D neighbourhood models. These models consist of a series of parametrically generated variations on building typologies like block, L-shaped, and courtyard block. Each neighbourhood alternative is described through a set of geometrical parameters including the form factor, window-to-floor and plot ratio. We used an extensive database of heating and cooling uses generated by simulating each variant in a representative set of climates to assess the sensitivity of energy use to the geometrical descriptors and climate types. This is done using a regression equation whose input parameters are easily calculable, e.g. form factor, and whose output is an estimate of simulated energy use. The aim of exploring this relationship is to use it to assess the suitability of different urban forms in a given climatic context. Moreover, it provides a promising route to avoid the necessity of detailed energy simulations in comparing the performance of different early urban design alternatives.