Physics

Problem

A building code limits the heat flux through an external wall to

50\,\text{W\,m}^{-2}

when the temperature difference between indoors and outdoors is

25\,\text{K}

. What is the minimum thickness of glass-wool insulation (thermal conductivity

0.04\,\text{W\,m}^{-1}\text{K}^{-1}

) that must be used to satisfy the code? a)

4\,\text{cm}

0.5\,\text{cm}

2\,\text{cm}

1\,\text{cm}