I have been trying to figure out a way to warm up the cool side of my rack system, in a room with ambient temps between 65 (winter) and 73 (summer)

My rack (which use to be 3 sided, but that wont work anymore), has 12" UTH FW which i will likely set for 92.

The suggestions have been:
-Oil filled heater-dont want to heat a whole room, and use that much electric
-Keep room temp at 80-Since my office and snake room are 1, this too is not practical, and with price of my heating oil...
-Portable heater-Possible, but not fan of those without tstat

So my 17 year old suggested this:

Cover the shelf (including the FW) with sheet metal. Since it will conduct heat, the portion not directly over the FW, will absorb some of that heat! It works! Snakes will now have a cool spot around 77 at the coolest point!

Feedback??