So I'm still pretty new to brewing and Saturday I brewed my first below freezing batch, fifth overall. I have an all grain set up in my uninsulated garage and every time I took a temperature reading the temperature seemed to drop 5 - 10 degrees. I have a space heater I use to heat the space, but it didn't get above 40 for the five hours I was out there. I use 10 gallon Rubbermaid coolers for the MLT and HLT and having the top off for the ten seconds the lab thermometer took to get a reading seemed reckless. I let the mash set for the entire hour after taking the initial reading so not to lose the heat and I reached my target OG so I can't complain too much though it may have been more luck than anything.
I guess my question is does anyone have a good solution to compensate for such temperature loss, or should I just break down and insulate the area I brew in? I refuse to wait until spring to brew my next batch so any advice is greatly appreciated.