Unfortunately it's not remotely air-tight, so insulation wouldn't help - there are cm-wide gaps around the side-door and under the main door and neither window shuts properly (one is wedged open for the dryer vent pipe). My housemates are also horrible about shutting the side door, so it is often open and flapping in the wind until it wakes me up at night and I go out in the rain to shut it. It's more like a 1950's modular shed with a garage door (rusted shut with ivy growing through the cracks) at one end.

Someday I'll live somewhere with a climate-controlled garage or basement. Until then I'll have to make do. I'm lucky to have a garage in this city. Most everything around here is Victorian row houses.