My supply of food I keep in an insulated out building, and I'm concerned with freezing at this time of year where one night might be above 32, and the next day or two, in the mid to upper 20''s. I do have a small heater out there to keep the temps above freezing but only turn it on if necessary. At what outside temps should I be concerned, as I sure don't want the products damaged, or use electric when not needed. I have always heard people talking about freeze, and hard freeze.