Edit:  Still bugged for bugged for 288927 which introduced even higher temperature materials and the ability to make buildings out of raw ore with the new refined materials.   See this thread:   Apparently, the code that actively deletes heat around an over-heating building resets to the building's base over-heating temperature -after- reloading the game/save.  Not the building's boosted over-heating temperature from the material it's built from. Lab7.sav