I have a small room that was added on or partioned off from the back of a garage that is attached to the home. It is about 6 feet by 12 feet. There are two outside walls, on common wall to the house (door) and common wall to the garage (door). There was no insulation. I added R13 value to the 3 walls, there is some in the attic as well. The room has a hvac vent on the interior wall and I had added a small electric strip heater. The room with the hvac vent does not stay the same temperature as the home. I can leave the door open to the house and it does seem to balance otherwise with it closed which is preffered it is about 10 degrees less with heat, I have not tried cooling and it did improve obviously with the insulation but not what I was expecting. Any ideas? thank you..