The worst affected seems to be my room. It is the end of the turret with a massive vent (now gaffa-tape sealed) I will be sitting by the wall and actually feel the freezing cold air against my neck from the wall. The radiator seems to do nothing to help matters.
I have put tin foil behind the radiator (not sure if it has helped yet because the weather is warmer than what it was before I did it), but the radiator is on a different (and much less breezy) wall.
I took some steps to solve the draft in the flat (still a way to go mind), but I am at a loss on how to fix the back wall in a cheap way. I thought about tin foil but then I very quickly realised I would not be happy to have tin foil on my wall.
The landlord said he was sympathetic about cold but that they don't like vents being closed because of worry about damp/black stuff growing on walls. I did notice that some wallpaper came away from the wall when I closed the vent but at the same time it is in a stupid place if ever there was one.
Would stapling a decorative material help matters? Or maybe I could get away with hiding tin foil behind some decorative wall cloth so it does the job but looks half decent too?
Note about rental: I think I can get away with a bit of stapling/nailing but I cannot do anything to permanently alter the wall.
Best Answer
If you have a draft then the best thing is to seal the source of the draft. If this is a window, then as DA01 mentioned, you can install temporary plastic covers. If it is around a door then you should look into replacing the weather stripping. Also check visible gaps in the wall, floor, electrical and cable outlets - if they are drafty you can spray in expanding foam (e.g. Great Stuff) around the box (not inside). Check outside too for visible gaps around openings.
You mentioned you closed up a vent - hopefully this was not a cold air return. If the vent is the source of the problem then your best bet is to fill it in with rigid foam and seal the edges of the foam with caulking.
If the root issue is a lack of insulation in the walls then there is little you can really do that doesn't involve tearing up the walls. Hanging long thick curtains along the wall might help a tiny bit. I doubt tin foil will do anything besides making your friends suspicious.