You know a heck of a lot more than I, but I was told by the tour guide that they can control the temp -- from cooling to heating -- to get 'optimal' aging from their bottles. I didn't inspect their system, and it is very possible that the tour guide was wrong, but he did tell the group that they can heat and cool the warehouse.

Funny thing for me is that it actually made me think less of the place. In fact, most of my tours (Wild Turkey Excluded), left me with a much less romantisized view of the whole bourbon industry.