My woodturning shop is 24 X 36 with 10' ceiling. R19 in the walls and R38 in the ceiling. Have the same furnace in the shop as in the house, fuel oil. I usually spend 4 to 6 hours daily and put the thermostat at 60 degrees until it stops and then turn it back to 50 while I'm in there. I use 150 to 180 gallons a year over the winter months.