Insulated Walls

[Trylobyte]

A simple enough idea, and one that could probably even be done with a mod.  Insulated walls would come as an Industrial-level research project.  They would have a significantly reduced thermal transfer rate but would cost more (perhaps requiring some amount of plasteel) and take longer to build than regular walls.  This would provide a mid to late-game solution to heating and cooling issues without putting large numbers of heaters and coolers everywhere.  And hey, we insulate houses in real life, why not in the far future of Rimworld?

[Rock5]

I find that double layer walls work REALLY well at insulating

[DNK]

I find that double layer walls work REALLY well at insulating

They also take up a lot more space. Having a space-saving measure to get similar levels of insulation would be a very nice option.