e51fb627_Snow_Shelters__5
[0] COVERED TRENCH SHELTER [1] 15 man minutes if snow is deep enough. 1 man hour if you need to build walls for it. [3] Not as warm as an igloo but warmer than a tent. [4] Very little, you'll learn as you go along. [6] Very fast to make if you are in a hurry. Warmer than a tent but not as warm as an igloo since it normally doesn't have a cold sink. [7] how to build a snow trench shelter [5] 
Deep enough snow or at least enough snow to build walls.
Snow Shelters
5