I'm pretty sure they were accustomed to it and learned to adapt by layers of clothing, fireplaces, and hot drinks. Imagine the future, someone will ask: How did people live with what they called electricity?
Most old school houses didn't have more that 20-30 students and had a wood or coal stove in it for heat. Sometimes in the center of the room, sometimes in the corner. It provided limited heat as insulation in those days consisted of newspaper or whatever they could stuff in the walls and windows didn't close that well.
My husband went to a one room school where the students ranged from 1st to 8th grade. There was a wood burning stove and the older boys took turns bringing in firewood. They also pretty much stayed in their outer clothes and a number of them would carry a hot potato to help stay warm through the AM then eat it for lunch.
The same way you would heat your house and how some people still do today with a wood or caol burning stove the high school i went to was heated by a caol burning stove until about 15 years ago they still use it if the power goes out during the school day