Can I suggest she not be left out long enough to need a dog house. I have a fenced yard and through all my years of owning a dog, never once have any of the dogs I have had used a dog house. I got one of those igloo ones when I was working and the dog wanted to be outside, it sat there unused for three years! :)
If it is cold enough to be in a dog house, it is far better she is inside. Dogs left outside get a lot of behavioral issues. Get her a kennal/crate for inside if you are concerned about leaving her and it will help speed up the potty training process. Get a baby gate and put her in a laundry room inside if you need to keep her isolated.
I guess without a fence I am not sure why you would want her to be outside for too long and need a dog house? They aren't cheap and more often then not just ignored by the dog.