So let me get this straight. What you are saying is that this room, on fire, will generate more heat if there is a door on a 1 tile exit than not, because the game will lump all that fire together, separate from the outside temperature? Furthermore, the point of opening the door is to path the bugs through fire, and that even with temperature loss on the open, the heat still inside and the fire itself will together be more effective?

I get the first part but am unsure about WHY to open the door in the first place.

I am sorry to drag out these points but I would like to be totally sure I know the details before pulling this shit on a commitment mode colony