Vents

[Drahkon]

Or a layer for 'thermal conduit' =)
Run it just like electrical, just red. Stick central air all up in that base.

Furnace, AC unit, and a.. radiator?

[Exe19]

There's already mod for it: Central Heating (includes vents)

[windruf]

maybe it could be just enough , if we can force door to be open. 

not even that is needed (as long you didn't build this door when there was -40 in this room)
if your base has a normal temperature inside and doors of your colonists rooms going to your base corridor, temperature in rooms will be around +-5 grad from your base temperature. and even the difference is so damn big, it will be gone in a few weeks.

[Mikhail Reign]

Unless it's really hot or really cold. My current base rooms will drop to below 0 over night without power, while others will stay just above it while others still will get to -50.