A laboratory freezer has an insulating layer in its door. A replacement layer is being considered.
The two layers are tested using sections of equal area. The temperatures of the inner and outer surfaces are kept the same in both tests.
| Insulating layer | Thickness in mm\text{mm}mm | Thermal conductivity in W/m K\text{W/m K}W/m K |
|---|---|---|
| existing layer | 20 | 0.040 |
| replacement layer | 40 | 0.020 |
Explain, using the data in the table, why the replacement layer would reduce the rate at which energy is transferred into the freezer.