This from one of my previous threads. It has been Edited

Summary: Spare heat is put into a bar at the bottom of the result screen, and when it fills up, you get 1 ME.

Details:
The size of the bar should hold the amount of heat gained within 5 clockworks tunnels, Which means the bar could fill up faster in arenas with more heat.
Remember, the bar gives you ME, NOT CE.
The amount of heat needed to fill the bar varies on the stratum (T1>smaller, T3>larger).