From Building Energy Models (BEM) to Urban Building Energy Models (UBEM): input data and modelling approaches

The past 15 years have seen a strong development of advanced new Urban Building Energy Model (UBEM) tools that have been generated with existing (e.g., EnergyPlus) or new calculation engines. Due to the high computational time and the huge level of uncertainty in UBEMs, the introduction of some model simplifications and assumptions becomes unavoidable. The present contribution addresses the differences between Building Energy Model (BEM) and UBEM for the categories that characterise the input data and the calculation models. General considerations, independent of specific energy performance simulation programs, are made. The analysis of the theoretical differences between the two calculation models provides useful support both to beginners and expert UBEM developers. A preliminary analysis of the mutual energy interactions between buildings in UBEMs is performed. Specifically, shortwave and longwave radiation exchanges between a building and the urban context are analysed and discussed, by comparing a single-building energy model and an urban building energy model. The analysis has been applied to a real neighbourhood, composed of eleven apartment blocks, sited in the northwest of Italy (Turin).