Why the Location of a Whiskey Barrel in a Warehouse Is Important

Talk to any distiller and they’ll tell you that the location of the barrel in the rickhouse can greatly change the composition and flavor of the spirit within that vessel. Which sounds right, but getting scientific data to back up that very plausible claim has been difficult. Thankfully, an ongoing study by the Independent Stave Company (ISC) suggests that, yes, heat and humidity do vary greatly within a barreling warehouse, and those variables do have an effect on the booze.

ISC has been making barrels and working with distilleries for over 110 years. Per Distillery Trail’s blog, the company began a multi-year study into how barrels are affected in multi-story warehouses. ISC installed temperatures and humidity sensors on each floor of a five-story rickhouse and filled 30 identical barrels full of whiskey and placed them evenly across all levels of the rickhouse, with six barrels on each floor). The warehouse is located atop a small plateau about 650 feet above sea level in Bardstown, KY.

The results in year one aren’t that surprising: Floor 5 was just under eight degrees warmer than the first floor on average and the highest temps reached got 20 degrees warmer. Meanwhile, the average relative humidity was much greater on the lower floors.

Look at the extraction curves for whiskey aged on each floor — a measurement of organic compounds like guaiacol and vanillin — and you’ll find some interesting conclusions, at least in year one. “Extraction curves are not proportional to the yearly average temperature values with respect to each floor,” writes Andrew Wiehebrink, head of Research and Development at ISC Barrels. “In other words, it’s not how hot it gets in the warehouse, it’s more to do with a combination of how fast the temperature fluctuates and the degree of fluctuation.”

Basically, the temperature swing is more important than the actual temperature, and the swing is felt significantly more in this experiment on floors four and five. This is “perhaps useful to those who are doing some temperature-controlled aging,” as Wiehebrink concludes, which seems like a big emphasis at distilleries, particularly those which are releasing bottles that have specific warehouse locations attached to them.