I'm interested in brewing a lager (Hellesbock) this winter, but I don't have access to a fridge for storage/fermentation. I got the idea of lagering the brew in my dad's garage. The temperature flucuates throughout the day in winter but should never go above 5-7 degrees C. Would daytime/nighttime fluctuations in temperature cause any major problems?
It doesn't fall below freezing does it? Given the mass of the beer it will not fluctuate as much as the ambient temperature does in the garage. In an ideal situation you would have little if any fluctuation but we all have to improvise/compromise. I have used a back (North side) room to lager in the winter with good success. Currently I use a crawl space that throughout the winter is about 45-48F.