Introduction to Constructal Law Analysis for a Simplified Hourly Energy Balance Model of Residential Buildings at District Scale

The energy consumption of buildings is related to multiple factors, such as construction and geometric characteristics, occupancy, climate and microclimate conditions, solar exposure, and urban morphology. Therefore, the interaction between buildings and their surroundings should be taken into consideration. The aim of this work is to create a bottom-up model at urban scale to evaluate the energy balance of residential buildings starting from their hourly consumption data. The model of hourly energy consumption presents some simplifications to be applied on an urban scale and introduces some variables at block of buildings scale (e.g. sky view factor and canyon height to width ratio). A Geographical Information System was used to localize the data and to provide information on how the shape of the city affects buildings consumption. The new model was verified on about 50 residential buildings for two consecutive heating seasons in the city of Turin (Italy). The results show that a simplified model can be powerful in evaluation of the energy demand and supply of buildings at urban scale. Moreover, the analogy between buildings and cooling fins allows to point out that the buildings shape is fundamental in the heat exchanges.