Reducing Product Loss Through Ventilation in Bourbon Maturation Warehouses

The aging process of bourbon within rickhouses is influenced by various environmental factors, including temperature, humidity, air flow, and air quality. Most rickhouses are not climate-controlled, and natural ventilation is a major contributor to airflow. The corrosion of the steel hoops on bourbon barrels occurs due to the presence of ethyl alcohol vapors and has become an issue for the distilling industry. The loss of a barrel or product is the loss of all of the energy and materials that went into the distillation, as well as the removal of the barrel from the secondary market. Despite the large economic and sustainability impact of barrel losses, there is limited published research with respect to corrective actions. This paper investigates airflow patterns within a bourbon rickhouse using a combination of differential pressure surveys and smoke tracing techniques to understand how natural ventilation impacts the aging process and potential for corrosion. A newly constructed rickhouse was surveyed using a micro-manometer to measure differential pressure and a sheet laser with smoke to visualize airflow. This study revealed significant zones of stagnant air and minimal recirculation within the ricks, which are the structures that hold the bourbon barrels. Airflow was found to primarily enter through windows and ground vents, moving along the walkways before exiting through other openings, with minimal penetration into the ricks. Differential pressure measurements generally indicated a lack of significant airflow, while smoke tracing showed that air entering the side of the building does not circulate into the ricks. This lack of airflow promotes the separation of ethyl alcohol vapor due to density, leading to its accumulation on the floor of the ricks. The findings of this study highlight the need to consider how rickhouse design impacts airflow and the potential for the corrosion of metal hoops on barrels due to the presence of ethyl alcohol vapor, and provide insight into optimizing the ventilation of rickhouses for more efficient and sustainable bourbon maturation.