Almost anytime I visit a hotel in the the warmer months, I almost get knocked off my feet as I enter the room. It is "freezing". Generally the dial on the air-conditioner is twisted way over to the cold side. At a recent stay the room had a digital setting. It was set at 65° F. (18° C.)!
Many people would not tolerate a temperature that low in the winter. Many energy experts recommend a heating temperature of 68° F (20° C.). On the other hand, they recommend a cooling temperature of 77° F (25° C.). That is the temperature of a nice balmy day in the summer.
I tried looking for something about the actual savings with Google, but most of what I found was either about guests complaining about rooms being too cold or about replacing old equipment with newer, more efficient equipment.
I did see one item about a hotel saving $21,000 per year by improved A/C.