Introducing a hybrid energy-use model at the urban scale: the case study of Turin (IT)

As in the past, the urban morphology plays an important role for the liveability of the city and for both outdoor and indoor human comfort. Nowadays, the relationship between the urban form and energy consumption has been estimated by many researchers, showing how the morphological aspects influence the energy consumption of the buildings, the thermal comfort of the urban spaces and the district air quality. Conversely, in recent urban planning processes, these morphological aspects are undervalued or no more considered. To reinforce their importance, this paper presents an optimization of a previous statistical model made by the complementary use of bottom-up and top-down models to evaluate the energy-use for residential buildings. The average intensity of energy-use data for residential buildings with different age, shape and heated volume has been corrected using the urban energy modelling tool CitySim Pro. This hybrid approach describes how the urban form, the solar exposure of buildings, the outdoor spaces and the material characteristics of urban surfaces impact on the energy performance of buildings. This research analyzed a case-study in the city of Turin (Italy) to quantify the space heating energy-use of residential buildings. To estimate the buildings heating energy-use, the urban energy simulation tool CitySim Pro was used, and the building information model of Turin was validated with the real consumptions data using two years of monitoring data. The results of this research show a direct correlation between the buildings energy-use and the following five urban variables: Building Coverage Ratio, Aspect ratio, Main Orientation of the Streets, Solar factor and albedo coefficients of outdoor surfaces. The building density and the urban canyon phenomenon play an important role, reducing the heating energy-demand in medium density urban contexts. Furthermore, the solar exposure strongly influences energy demands, especially for high buildings density contexts, as well as the presence of green surfaces.The proposed methodology, based on a multi-variate compensative approach, can support urban planning to improve the energy sustainability of the cities.