Our house is built over an unheated crawl space. Because of this, the winter temperature of the floor tends to be as much as ten degrees colder than the air. Add to that the fact that I keep the thermostat at a conservative 60-68 degrees, and you'll realize that the floor can be darned cold!
Oskar has always preferred sleeping on the floor to being on the bed. Except in the winter, when he climbed up on the sofa to curl up and snooze. This year his arthritis seems to have taken his ability to clambor up.
I thought about getting him a heated dog bed, but I think it might be too much for a dog who never even had a bed of his own. So I got him a fleecy crate liner with a padded edge. Thought that might give him a small space heated with his own body heat. Want to see it?