I have experimented with this and it worked fantastic! I set the fridge thermostat as high as it would go, it stabilized at 44 degrees, after watching it for a week and I was sure that was the consistent temp........I brewed a batch. I chilled the wort to 70 degrees, racked it to the carboy and placed it in the fridge. Pitched the weast, and let 'er rip. If I remember right, I got airlock activity about 8hrs after pitching the last time I did this. I used a WL pitchable tube, no starter. At the time the airlock began showing activity the temperature of the wort was down to about 58 degrees. The next morning the wort was at 55 degrees and was fermenting nicely with a nice krausen. The temp of the wort slowly dropped down to about 50 degrees over a period of 3 days. The entire time, the fridge thermometer stayed at 44 degrees. After another couple of days, the temp finally dropped to 44 degrees in the wort. I left it like that for a month, then bottled it. Came out great. My theory is........the yeast activity will keep the wort temps up sufficiently to ferment, and as it finishes, will simply cool off to lagering temps. If you are worried about incomplete fermentation, you could probably let it go a week or so, then take it out of the fridge, let it sit at room temp for 24hrs, then put it back in and cold crash it.
