From low temperatures to fluctuating above and below freezing, and from high humidity to condensation, winter can present a unique set of challenges when it comes to managing a barn. However, there are a few simple principles dairy producers can follow to keep air fresh and cows healthy during the coldest season of the year.
The goal of every barn should be consistency, from moderating temperature swings to making sure that when a cow lies at either end of a row, she is getting similar air quality. This consistent barn environment is vital to your herd’s health.
Producers must keep in mind that when environmental conditions change, the solution is not as simple as just running the summer fan system less as a winter ventilation “strategy.” Cold weather requires its own specific approach.
Rules of the game
No two barns are the same, and what works in one barn may not work for another, but there are some basic concepts dairy producers should keep in mind when it comes to providing a consistent barn environment for their cows.
For both barn management and animal health, keep the following guidelines in mind:
- Focus on fresh air, not wind speed. The object should always be to deliver fresh air by focusing on air exchange to remove gases and humid air.
- Aim for a total barn cubic footage air exchange every 15 minutes during freezing conditions.
- Move air evenly throughout the barn. Inconsistent air movement can lead to unintended air speed in some locations and humidity and fog pockets in others. This can be measured using a wind meter. Walk through the barn in areas where cows loiter, and hold the meter at cow height.
Air speed should be the same whether the cow is lying down in the freestall or eating at the bunk. Achieving this may require smaller-sized fans with more spacing than what your barn needs in the summer, especially in power-ventilated facilities.
Depending on the style of barn you have, the solution for winter ventilation can differ. Here are a few tips for common dairy barn types:
Naturally ventilated barns
- Consider tilting a portion of your circulation fans up to stir and mix the air. This can be especially helpful in lower-pitch barns or in temperatures a few degrees above freezing, where the chimney effect can develop slowly.
- Look at ways you can manage the open ridge. Have a contractor install an adjustable ridge system for better air flow control or by closing it off altogether and power-ventilating your barn with chimney fans. (Note: This will commit you to running them in the summer as well, so make sure you examine your electrical costs.)
On one farm I’ve worked with, the owner temporarily closed the ridge and installed exhaust fans (size and quantity to match winter exhaust requirements) in the gable ends on a 1,200-foot barn.
While this is not recommended, and we would not design a new facility this way, the owner was happy with the results and only noticed mild fogging in the center of the barn during temperature fluctuations.
Cross-ventilated barns with baffles
- If your baffles run all the way to the roof, cut open a 12-inch gap between the top of the baffle and the roof to create air flow. The air you pull will help to cut down on moisture and condensation on the underside of the roof as well as help draw air out from between the baffles.
Don’t worry; the resulting gap will have little effect on your summer air speed as the easiest place to draw air is still below your baffles, with the suction of all your fans running, but the small amount pulled in the winter can have a big effect.
- Positive-pressure tubes between the baffles can create the necessary air stir to push the humid air down into the cross-ventilation below the baffles. Properly sized, these can supplement or meet your winter inlet requirements and help you avoid freeze-up on your inlet side of the barn.
- If your barn was built with permanent baffles, consider changing them out to a roll-up or adjustable baffle. While a significant cost, the resulting improvement in your barn environment can be well worth it in terms of moisture control and herd health.
Cross-ventilated barns with no baffles
- Open cross-vents do well with supplemental air inletting beyond the curtain wall. Consider installing roof inlets or opening a portion of your ridge for fresh air intake.
These need to be sized and spaced properly to still allow proper air distribution throughout your barn but can help to provide fresh air to all your cows and avoid first-lane freeze-up.
- On your inlet wall, manage your curtain opening with care. Curtains should ideally drop from the eave, and the inlet should be designed for some air speed so the air is brought in 20 feet or more as it mixes. Larger inlets allow the cold air to come in slow and drop down before it is dispersed, which is a common cause of first-lane freeze-up.
Tunnel-ventilated barns
- Spreading out your inlet area can be key to avoiding a barn that is cold in one half and warm on the other. Installing small inlets (properly sized and spaced) throughout your barn can create a better environment than the conventional method of an inlet at one end and exhaust at the other.
Inlets should decrease in size and spacing as you get closer to the exhausts to ensure even air movement.
- Consider an alternate exhausting strategy altogether through the ridge by chimneys or cupolas. This does require air inletting throughout the barn but eliminates cold, fast air and pulls moisture and gases evenly out of the barn for all the cows.
No matter what type of barns you have, take the time to make the necessary adjustments for winter conditions in order to keep cows healthy and comfortable. 
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Jeff Bowman
- Artex Barn Solutions Ltd.
- Email Jeff Bowman
