I have what you could call a three seasons room off the back of my house. The stairs to the basement are located within this room. Wanting to semi-finish off the basement in the future I don't want to have to walk out in the cold to go into the basement. The walls are 2x4s with insulation and the ceiling has some insulation too. Three doors, 1 steel entry, 1 wood entry, and 1 wood to the garage.
There are 7 storm windows around the room. The storms are fastened to 1xs between them. I know the storms are the coldest part of the room.
What would the best way to keep this room warm year round?