Keeping classrooms warm in winter is often treated as a simple question of turning the heating on earlier. Using two winters of Twinview sensor data from 52 teaching spaces, this report shows how many rooms were still cold when the first lesson began, why Mondays were consistently the worst, and why other rooms in the same building were already warmer than needed. It explains how heating each room on time can improve comfort while reducing wasted energy.

Were your classrooms too hot last summer?

Scroll down for our first temperature report, 'Too Hot to Learn?', to see how often classrooms overheated and what schools can do about it.