>you cannot enclsoe the barrels in a air-controlled room since that will siply stop the agin process qutie a bit Rackhouses are already build air control into

>you cannot enclsoe the barrels in a air-controlled room since that will siply stop the agin process qutie a bit Rackhouses are already build air control into their design, they just don't care where the air containing alcohol vents to. If preventing the alcohol in the air from entering the atmosphere were a design goal, a negative pressure design is an obvious implementation that maintains flow. Although a sealed barn could work too, if it had a recirculating processing loop that maintains the air properties conductive to aging. -- Using such a system might even be a positive for bourbon makers by giving them direct control over the level of ambient dissolved alcohol during the aging process.