**2. Study Areas and Data Used**

The considered case studies have been two different cities, Bristol (UK) (Figure 2a) and Barcelona (Spain) (Figure 2b). Both cities are very different in almost every possible feature to consider, in the city design as house grouping, drainage systems, terrestrial topography, electrical grid, etc. and even more different in the weather conditions. Although they have a similar areal extent (Bristol 111 km<sup>2</sup> and Barcelona 102 km2) the population density in Barcelona is three times bigger than in Bristol, having around 1,621,000 inhabitants while Bristol has only 460,000. However, the studied area for this energy analysis in Barcelona has been reduced up to 33% due to key data availability, therefore considering only the inhabitants living in the main city area (i.e., 326,000 inhabitants).

**Figure 2.** Areas of study considered. (**a**) Bristol city area, (**b**) Barcelona city area.
