The apartment was warm enough during the winter months to live and we managed it with only one electric heater provided. The temperature would be between 18-19'C during the cold months in the living room which is the coldest room due to the position and not much sun. All other rooms have a lot of sun during the day.
We've been quite unlucky to have the scaffolding outside the building for 2 months and had to deal with some issues related to that. The good news is that you probably don't have to worry about this in the next couple of years!