Thermal conductivity of materials

[Veyda]

Every time I sit down to play RimWorld for longer than just a casual 3-hour quickie, it strikes me -

How come that walls built out of different materials have the same rate of temperature equalization (thermal transfer), based solely on wall thickness?

It would make a lot more sense if different building materials had different thermal conductivity values (watts per meter-Kelvin?) - so we would have stone caves that remain cool throughout the year (heat is dispersed by the immense bulk of the highly conductive mountain), stone- and steel-walled buildings that become sweat lodges mid-summer, and log cabins that are relatively comfortable all year round (thermal conductivity of wood is much lower), or even stone-wood wall sandwich constructions for an ultimate balance in defensibility and heat comfort.

All it would require is adding a Thermal Conductivity stat to all materials and slightly adjusting the temperature equalization equation.

What are your thoughts?

EDIT: After giving it a little more thought, it seems like the way equalization currently works, walls only transmit heat, but don't absorb and store it. A highly-conductive steel (to a lesser degree, rock) wall would not only transmit a lot of heat during the day, but also heat up itself and then radiate that heat throughout the night. Seems to me like the entire temperature equalization method could use some conceptual rethinking.