I once read a good idea for heat covering:

Get thick pieces/slabs of foam... the ones that are 4 or 6 inches thick. Then, just line your walls and roof with it...
turtle420 Reviewed by turtle420 on . WORRIED about the heat with helicopters at night! Im growing 12 plants in a grow tent under a 600w light but i have to keep the tent door open otherwise the temp go up into the 100s so therefore the little extension that a got them in is getting quite hot i get lots of helicopters over at night im worried about there heat sensors ,i have a slate roof and the ceiling is plaster boarded but dont know wether they can still get heat sorce?? Rating: 5