HVAC is much cheaper centralized. Things like off peak in floor heating are just the start of optimizations that can be done. Heck, even having one building on something else leads to pain.
The reason? It was about 90°F (32°C) in the classroom.
On the previous Friday, one of the teachers turned the thermostat dial up as far as it would go. Presumably they intended to turn it down later but forgot.