Heat loss in cabinet

[MvBurgh]

Hi All,

Im trying to calculate the heater sizing for an intertec cabinet that will be placed in a freezing location.

However im getting weird results based on:

k.A
--- * dT
L

I'm getting for a small window (0.36 m2) a heat-loss of 1440W.
Thermal conductivity of the glass is 0.8 W/m.K

Can someone indicate where im going wrong?

Best Regards,
Martin