Abstract
The urban territory is responsible for a high percentage of natural resources depletion and waste generation. Population increases and cities expand, and thus energy demand climbs. Consequently, an efficient use of energy is becoming more and more crucial in order to promote both local and global sustainability. To achieve such a goal, the reduction of energy demand, the optimization of energy supply sources, and the increase of renewable energy share can facilitate the transition of urban areas into highly efficient and sustainable districts. In this framework, this study assesses to what extent typical building retrofit interventions can reduce energy consumption, enabling a transition towards a nearly Zero Energy District (nZED). A state-of-the-art urban simulation was developed with CitySim for part of the city of Bolzano, Italy, to evaluate the annual district energy uses and define possible efficiency measures (e.g., façade and roof insulation and substitution of windows). Achievable energy savings are analyzed and the most significant factors affecting the overall performance identified.