AviK, I think it has been a long time since you were in EY. Ever since the Gulf War, which was just before you were living in Gilo, according to your post, apartments have been built with sealed rooms and individual heating units. Ramat Shlomo, which was started around that time is the prime example. There is no longer any building since that time, at least here in Y-m area, that is built according to the technical details that you mention. They lay water pipes through the whole apartment before they put in the floors and hook them up to heating devices in each room, which connects to the main unit that is controlled ONLY by the person living in the apartment.
As far as air conditioning, again, it has been a long time since you were here. Back in those days (I’m here for 24+ years now), Y-m was a much cooler city and yes, you did not need air conditioning back then. Now it is just as hot as many other places, though not as humid. For example, we have days and weeks of 30+ weather, when 33 is not uncommon. That translates to around 90 degrees for people who speak in Fahrenheit. I would not want to just have a fan in 90-degree weather. Maybe it depends on how many batteries you have or how much you get allowed from your local generator, but perhaps you could have one room unit on that kind of electrical supply on Shabbos so that you do not melt.