The "back room" is a poorly enclosed former sunporch built a number of years before we bought the house behind the kitchen. When we tore apart the entire upstairs, it was our bedroom. Once we had a proper master bedroom, it was set up as a reading/guest room with bookshelves. It was cozy with the gas fireplace. But running the fireplace was expensive and it didn't produce much heat when its fan broke. That's when we began closing off the room in the winter time and it became a storage area.
The worst thing you can do to a room is make it a storage area, especially when you're doing renovations elsewhere (my husband has torn apart and rebuilt his office/studio -- the house is subsequently warmer because the walls are now R-22, but he had to put stuff somewhere while doing it).
One good thing about my husband's renovation was that he used a lot of material that we had in storage in that room. Then we got rid of all the computer carcasses that had accumulated over the past seven years (some from us, others from friends). A former employer (who never paid) finally took away the electrical stuff my husband had been storing for him. Suddenly we could see expanses of floor.
With winter coming in, we had to seal one window whose storm plastic had gotten ripped. Earlier in the week I got rid of a lot of books, boxes, and an awkward display rack (now in pieces in wood storage for next spring's projects). While my husband cleared space in front of the window so I could work on it, I cleared out the cabinet and reordered things there.
The window has sliding glass panes with no weatherstripping (it will be replaced next year), so I sealed all the edges. When I was done I could no longer feel the wind through the window. Next I put on plastic and sealed that to the window frame. Afterwards my husband arranged stuff along that wall. All of our travel gear (other than luggage) is in one spot now. We discovered that the roof leaks in the corner opposite the window. That will probably be the last repair of the season.
I beefed up the doorway partition between the room and the kitchen. The doorway is four feet wide. We have a two-foot false wall in it that is now insulated. I'm going to add another layer of Reflectix to the door as well. We'll probably continue with a heavy blanket in the doorway for January and February.
We actually can see the floor now. The empty bookshelves may become this year's "cold storage".