Building Efficiency Models and the Optimization of the District Heating Network for Low-Carbon Transition Cities

Nowadays, greenhouse gas emissions continue to increase with the consequent climate changes. Energy consumption of buildings strongly affects atmospheric pollution, therefore for a sustainable development it is necessary to adopt energy efficiency policies combined with low-carbon technologies. In particular, the use of district heating (DH) has environmental and economic advantages in energy production and distribution for space heating consumption. In this paper, the combined effect of DH expansion with different buildings retrofit scenarios using a GIS-based model is proposed for a more sustainable city. This methodology is applied to the DH network of the city of Torino and, energy savings hypotheses were analyzed, evaluating different energy saving trends starting from the current one with existing policies. A GIS-based methodology has been developed with bottom-up and top-down approaches; then two future energy savings scenarios have been hypothesized. Energy retrofit measures have been applied to the most critical areas with low potential of heat distribution; in a second phase, to the whole area connected to the DH network. The results showed that intervening in the critical areas only +5% of potential buildings can be connected to the existing DH network (standard retrofit) while this percentage could grow up to +25% with advanced buildings retrofit. On the other hand, intervening on the whole city, there is a considerable reduction of consumptions and the connectable quota of buildings to the DH network reaches +42% with standard retrofit and +82% with advanced retrofit scenario with an optimization of energy distribution as well.