Thermal conductivity of a material is its ability to conduct heat.

Good Bricks should have low thermal conductivity so that houses keep cool in summer and warm in winter. Special Insulating Bricks are sometimes required for thermal insulation in structures.

Common red bricks have a thermal conductivity of 0.6 Wm-1K-1 . For insulating bricks, the value is even lower 0.15 Wm-1K-1. [1]

 

References:

1. http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/thrcn.html