I toured their facility last year, and I asked a lot of questions. I think I annoyed the guy giving the tour a little in fact.

Their barrels are all stored inside, in a climate-controlled environment. I imagine it gets pretty warm in there in summer, but not very cold in winter.

What surprised me is that they said have no current plans to age anything long-term, which is counter to what I hear from most micros. It seems they usually sell some young juice to recoup costs, and keep some older stuff aging for later. According to this guy, that's not the plan at Koval. He gave me the line about letting the flavors of the grains really shine by aging them very gently etc...