What is W/mK ?

What is W/mk?

The thermal conductivity coefficient k is represented as W/mK. If a material has a k-value of 1, it implies that for each degree of the temperature gradient between opposing sides of a substance, a 1 m cube of that material will transfer heat at a rate of 1 watt. A material will transfer less heat if the k-value is lower than 1. 

A material with high W/mK (watt meter kelvin) is known as a good heat conductor whereas a low W/mK material is a good heat insulator. Generally, a material is considered better if it has a low thermal conductivity because it transfers less heat energy. Unlike other physical qualities, thermal conductivity depends on many other factors; hence, the thermal conductivity of the same material can change under various environments. This comprises the material structure, temperature, humidity, density, pressure, ageing and phase.