I have 2 houses this size and one smaller for a single cat.  The cats love them and basically hibernate in them all winter.  Minnesota gets cold and I have one on the enclosed back porch and one in the garage.  Both are in unheated spaces and have one cat.  I like the wider house because I set their canned food inside with them so it doesn’t freeze and they have room to stretch out if they wish.  The heated mats are great and are NOT expensive to run.