Project Overview
Commodities
Practices
Proposal abstract:
Sustainable Ventilation Strategies for Calf Barns: On-Farm Computational Fluid Dynamics (CFD) Modeling and Ammonia Sensor Integration
Dairy farmers in the North Central region often rely on naturally ventilated group housing systems to raise calves. These systems are energy-efficient, easy to manage, and promote animal well-being. However, they can be vulnerable to inadequate airflow and shifting microclimates, especially when nearby structures disrupt natural wind patterns. As the weather becomes more unpredictable in the region, with increasing variability in wind speed and direction, it becomes more difficult to maintain adequate natural ventilation. This can lead to localized accumulations of ammonia, a respiratory irritant linked to higher calf mortality. Even at concentrations as low as 4 ppm, ammonia can impair calf lung function, and levels in poorly ventilated areas have been observed to reach 10 to 20 ppm.
This project began when a producer contacted our team with concerns about air quality issues and elevated calf mortality in their compost-bedded pack barn. Our initial visits revealed that wind shadows created by surrounding structures were limiting natural ventilation and contributing to stagnant zones with elevated ammonia concentrations inside the building. In response, we developed a collaborative project that integrates computational fluid dynamics (CFD) modeling with field measurements to evaluate ventilation performance and identify strategies for reducing ammonia buildup. A 3D model of the barn and surrounding wind obstructions will be created in SolidWorks and simulated in ANSYS Fluent to evaluate the effects of wind shadows, curtain adjustments, and supplemental ventilation across seasons. Seasonal field data on airspeed, temperature, and ammonia concentrations will support model validation.
The project's objectives are: (1) to design and validate CFD models of a full-scale, naturally ventilated calf barn accounting for wind shadow effects and seasonal variations; (2) to conduct a spatial sensitivity analysis to develop recommendations for the placement of low-cost ammonia sensors; and (3) to develop and disseminate science-based guidance for improved ventilation strategies through Extension and outreach.
Expected outcomes include increased producer knowledge about calf barn ventilation, as well as the adoption of practical solutions. Our collaborating producer will provide feedback during each stage of the study. Extension efforts will include fact sheets, podcasts, webinars, and site visits. The change in knowledge, action, and condition will be tracked through surveys, web metrics, and QR code scans.
This work aims to provide scalable, cost-effective strategies that improve calf health and barn management across the North Central region.
Project objectives from proposal:
This project will achieve learning, behavior, and broader condition outcomes for Midwest calf producers and agricultural stakeholders.
Learning Outcomes:
Producers will gain insights into ammonia dynamics in naturally ventilated barns, how the microclimate influences ammonia movement, and the importance of strategic sensor placement when budgets limit the number of monitors. They will also learn to identify airflow dead zones and understand supplemental mechanical ventilation options, including positive pressure tubes and fan placement strategies. Knowledge will be delivered through an extension of webinars, podcasts, and accompanying fact sheets in collaboration with the Agriculture Institute dairy educators. Success will be measured by attendance and surveys.
Behavior Change Outcomes:
At least one collaborating producer will directly implement practices based on the project's findings, including purchasing and installing two supplemental fans and adopting three low-cost ammonia sensors at optimum locations identified through CFD modeling. The producer will also implement a winter management strategy of slight side curtain opening to improve air quality. These early efforts are expected to encourage broader adoption among producers following the project's completion. Behavioral change will be measured by follow-up site visits assessing airflow improvements, ammonia concentrations, and surveys.
Condition Outcomes:
The project will generate educational material to support the broader adoption of the outcomes. Outcomes will promote sustainable calf housing and improved calf health through engineering-based solutions, integrating economic, environmental, and social benefits. Success will be measured by online engagement and dissemination metrics.