Petmate kennel 24w x 36d x 27h, 2" exterior insulation and an under floor heat source

** for easy transport, the insulation panels have been marked and removed from the foldable wire kennel. the top and one side are still connected together for easy placement of all sides. Gorilla tape.

pictures

1  kennel (removeable) on heatbox with access by 4 small screws and an added block that fits squarely into opening. small thermometer hangs on upper right side

2  panel removed for access 

3  70 watt bulb in plastic work-light cage, placed on affixed metal tray. it keeps the floor nicely warm underneath pets' bodies, with a lightweight blanket piece (or heavy fabric)  on the kennel tray. the work-light cage is connected by long electric cord leading out of box on back left.  (do not use more than 70watts)                       

4  tube in far back corner moves warm air from heatbox up into kennel

5  glass covering hole in heatbox on left side, to see if bulb needs replaced

6  since the heatbox is well sealed, we were advised to place balancing number of small holes in corner opposite heat tube, right front corner, to replace air moving to top

we layered blankets over the insulation and dooway, for 4 winters, inside our leaky old uninsulated garage. can't remember what the ambient temperature was, maybe mid 50's, though the floor was much warmer. to conserve even more heat, someone could use a carpet over the doorway or straw bales over the insulation. (another approach would be adding a paintcan bulb in the interior. DIY youtube)