My uncle built his home from hardwood. No insulation. In sub freezing temps, you can put your hand in the wood and it isn't cold. Compared to my (poorly) insulated home, it b is significantly better.
That isn't a good way to measure because the inside of the house is warming up the walls. Hardwood is a poor insulator, but it is an insulator. If you touch wood it will feel warm, but it still loses a lot of heat compared to a properly insulated wall.
