The pilot reported that he had pulled the airplane out of the hangar, and that he believed that the airplane's wheels were stuck in the snow. During the engine warm-up, he had the seat all the way back and he was checking the weather, as he planned to perform a ten-minute run-up. After five minutes he noticed that the engine RPM increased from 800 RPM to 1,200 RPM. He recalled that when he noticed the increase in engine RPM, he was about to adjust the throttle, but the airplane began to roll and collided with a hangar. Additionally, the pilot asserted that the accident could have been prevented by keeping his feet on the brakes during the engine run-up. The airplane sustained substantial damage to the left wing. The pilot reported that there were no mechanical malfunctions or failures with the airplane that would have precluded normal operation.