There are very few heated storage buildings in the area that can handle the 5th. If they did find one with a door and the length to handle it, the building lease and paying for enough diesel to heat the building, is going to cost way more than renting a house or apartment for the winter. Buildings of that size fetch premium rent during the winter months.
Then they'd have to figure how to hook up sewer in the building???
And unless they're going to keep the building at 65d, they're going to have to run their furnace inside the building. I guess they could use electric heaters, but all and all, just rent a place to live - the idea is to save money.
Bill