I smoke mine at what would be considered medium heat. Ambient temps play a big role, as my smoker is outdoors. Cold smoking is technically no hotter than 70F, I believe, kinda hard to do in the summer here. Winter, maybe. My smoker temp usually doesn't get over 125F. I burn down some oak logs in a pit, then shovel a small amount of coals into the smoker and add wood chips/chunks, a big handful maybe 3 times over 3-4 hours. Ends up great. BTW my 'smoker' is a horizontal barrel type grill (mfg by Royal Oak, from Lowe's) that has a side mounted fire box.
Fat will render out during smoking if the temp gets too hot, changing the character of the meat. I dry rub mine for a week, rinse in fresh water, hang to dry overnight, then smoke, then hang for a few weeks in a temp controlled fridge at maybe 45F. The dry aging creates a really nice product, where the bacon is firm and is easily cut. The flavor concentrates and storability is greatly lengthened.
Bacon is proof that God loves us. Bacon makers unite