This method uses non rigid plastic tumble dryer hose, by it's very nature it has to withstand/be inert to the elevated temperatures of a tumble dryer exhaust which is likely to be higher than most ambient temperatures.
http://www.johnwatkins.co.uk/personalpages/coldsmoking.htmI have used the above method extensively and never had a problem with the tube melting, giving off any burning odour or anything else untoward. It gets coated pretty rapidly with the same tar like substance that coats the inside of the BS smoker cabinet pretty in any case.
I would imagine aluminium hose would serve the same purpose but plastic is cheaper!
However, several reference I have come across refer to the fact that cold smoking it just impossible in some climates!
Maybe a combination of the above method plus ice pack in the smoker cabinet? Smoke late at night?
Or ask your better half if you can cut a couple of holes in the fridge to let the smoke in and out and turn it into the cardboard box in the above picture!! Try and keep a straight face when you ask!!