...well...We've brewed a lager in the basement last winter. Ambient temp was about 55* which I think was on the higher end for that strand. We didn't really lager but just let it sit in the coldest corner of the basement which I think eventually dropped to 50*. Tough thing about outside is the temp swings. It might be good for a day but then it might drop to -25* so you never know.
I hate Walder Frey...