The guy who organized the tour didn't mention anything about a heat pump - and he was the developer who had bought the building, so I guess he would have known.

The guy who organized the tour didn't mention anything about a heat pump - and he was the developer who had bought the building, so I guess he would have known. Heat pumps were invented much earlier, but didn't become commonplace for this purpose until after the oil crisis. Plus, IIRC the system was only HV without the AC. With added AC and heat pumps to reduce the heat loss, it definitely makes more sense...