Winnie, it could be that the very new buildings have individually- controlled units. When I lived in Gilo 25 years ago the apartment did not have such a unit. The vaad habayit (building committee) decided when to give heat (pretty good – baruch Hashem I thawed out very quickly after a big snowstorm) and charged a (substantial) addition to the maintenance fee. The really old buildings do not have anything. Each tenant must heat for himself. Electric radiators and blow heaters are very common (charitable organizations give them out to the poor).
Mazganim are not that necessary in Yerushalayim in the summer but in other parts of the country they are common. I heard that in Eilat they have (or at least had at one time) “desert coolers” which work better and cheaper in dry climates.
As for your acquaintance, how does he heat his apartment? As I pointed out, gas and kerosene heaters are not so safe so he is sacrificing a Torah prohibition for the sake of a chumra (which may be the same prohibition and worse as per Dor.