At one point I was going to build a doghouse for Percy and went looking. This site had the best plan, in my opinion.
http://www.doghouseplans.com/about-the-dog-houses.cfm
It looks really useful. You have to buy the plans here, but I think after some looking I was able to find the same thing for free once I identified what I wanted. I think this was nice for cold climate because it has an adjustable roof and an insertable windwall that keeps cold air out. For the summer, you can lift the roof up some to allow for extra airflow. If I recall correctly, the plan also accounts fro putting some insulation in it. It also is built on a platform so if it rains, the floor won't flood. Also, it is supposed to be easy to clean.
I didn't end up building it because I realized:
A. my dog doesn't spend much time outside
B. Even when he does, he has never used ab doghouse made available to him, so I didn't want to waster my money.