This is the doghouse we used for years for our outdoor Border Collie. I realize Alberta can be colder (although we have seen -30C at this location), but you are talking about daytime use, not overnight. We used straw for bedding, and when my dog emerged in the morning after a cold night, he was quite warm and the interior of the house was also (I checked). Sized and insulated correctly, this design will keep a dog warm. (you could obviously change the dimensions to allow for more insulation if necessary). The only caveat is, will he use it? My BC was happy to retire to his house for the night, but during the day tended to lie in the "porch" so he could see what was going on. Of course, much of the day he spent his time with me, so it was a non issue. (one addition…...we put a couple of cement blocks on the roof after it blew off one day in a windstorm!)
http://www.kwhumane.com/uploads/Documents/Ideal_Doghouse.pdf