Last week i lined the walls of my shed with radiator reflective foil and can't believe the difference,its an 8x8 shed lined the walls with a waterproof ground sheet,then 100mm insulation and 6mm of mdf,then finally the foil.temps in the whole shed is between 24 -25 (it was 12 outside) and that was with just 1 basking light on,I had to knock power off for a couple of hours to put more sockets in and after 2 hours it only dropped 1 degree,only trouble is when i move the other 6 torts in theres going to be 4 basking lights and probably going to be too hot.