Question

Substances that don’t conduct heat are known as what?

Answer 1

They are called heat resistant,and in industries they are used as insulators etc.
Example of these heat or thermal resistant substances include Asbestos for example,which is also a prime insulator.
Heat resistant substances can be used to protect the surroundings of a heat generating substances,to prevent effects of it's heat,like scorching or burning to it's surroundings.
Heat resistance as a property is very useful in industrial settings where you want durability,for example,heat resistant plastic can be used to cook at very high temperatures,still it won't melt due to this property of heat resistance.
Property of hit resistance can be measured as it's R value.