Turns out i did remember slightly wrong, to enable your troop to build camp-fires you will need to enable a blizzard in map.
How-to: Blizzard in Custom maps
Deep snow and blizzards will make your troops cold.
A hight value higher than 0.05 counts as deep snow and will slow down and make infantry cold.
If you don't want a to have a blizzard but want to be able to build camp-fires the answer is a "Blizzard-less Blizzard" ^^
