robur, You are correct as to the location and the temperature. I, do not know your location. But I'm willing to guess the outside walls of your residence are not 16"- 19", or a half a meter thick. That dimension is a guessed factor based on the wall thickness going out to the balcony from the bedroom.
The unknown factor is how the apartment is heated. Again I'm guessing the building has a central heat source of hydronic design. Most likely the tenants have limited control of the temperature. Also the outside temperature range in a twenty four hour span can be large.
With the thick walls, and again guessing, well insulated. The running of the fan, and the opening and closing of the doors going to the balcony, which is accessible from the bedroom, living room, and the bedroom, seems a logical approach for the tenants to stay comfortable.
Given the amount of clothing, or the lack thereof, it seems to me the apartment is toasty warm.
Just info from another mere mortal, who, shudder the thought. Once and a while looks past Leora, and studies the building.