13 Volts (approx) divided by 13,000 Ohms = .001A (1 milliampere). Power = Volts x Amps, right? So .001A x 13 Volts = .013 Watts (13 milliwatts).

Now you just have to decide how much power it should take to warm up a window. You can estimate this by comparing... Login to read more.