Held open Doors should transfer heat better.

[Simmin]

I recently had a room catch on fire from a zzzt, so to help my colonist not dies of heatstroke, I made the door to the outside be held open, inside the room was still 600 degrees, until 1 wall burnt down, then it instantly equalized to outdoor temperature, I feel like a 1 block open space, should have some sort of flow rate, and an open door should have a higher flow rate when the temperature is so drastically different.

[Perq]

While true that open door would lower the temperature inside (by ventilating hot air outside), opening the door would also let fresh air in, meaning there is more oxygen to burn.
Not sure if RimWorld considers this and makes fires worse if there is access to the outside (meaning fires burn faster), but normally you want to isolate the room that has fire in it and don't let any air in (so that fire extinguishes itself due to lack of oxygen).

I'd say the change should make fires burn faster when there is access to air, so that you don't want to open the doors.