What is thermal conductivity of rock wool?

The thermal conductivity of  rock wool is a measure of its ability to conduct heat.According to ASTM C518,it’s denoted by λ,the unit is W/m·K.

The thermal conductivity is lower,the conduction of heat is smaller ,insulation is better.

What will affect the value of thermal conductivity?

The moisture and temperature will affect it.the moisture and temperature is lower,the thermal conductivity will be also lower.

So the temperature must be fixed to measure the  thermal conductivity of  rock wool.At average 25℃,value of rock wool is not bigger than 0.04 W/m·K.