A breath of fresh air

Editor’s note: Proper horse barn ventilation is a complex and crucial aspect of keeping horses healthy. It’s a far more complicated question than meets the eye. Contributing editor Mark Ward recently interviewed Eileen Wheeler, a Penn State professor of agricultural engineering who has written numerous extension publications. She is the author of the 2006 book,”Horse Stable and Riding Arena Design.”

Mark Ward: Though you’re an advocate of natural ventilation, you also point out that designing a horse barn for good ventilation doesn’t just “naturally” happen.

Eileen Wheeler: Poor ventilation is the most common mistake in horse stable design and construction. In fact, I’m stunned by the number of barns with no ventilation. That can happen, for example, when the owner has a house built and then asks the architect to also design a horse stable. But a horse stable isn’t like a house. Houses are airtight, but stables aren’t.

The conventional approach of the metal building industry is to design structures with no holes for air entry. Holes would look too unfinished. But soffit vents typically used in metal buildings aren’t enough for livestock. Horses produce 50 pounds of manure per day. Moisture, mold, and ammonia will accumulate without those holes to vent stale air and admit fresh air.

Ward: The idea that horses need fresh air seems intuitive. Why then do horse barns continue to be designed with inadequate ventilation?

Wheeler: Two major factors contribute. First is the unfamiliarity of some stable designers with how much air exchange is needed in a horse stall. Second is the tendency of horse owners to follow residential building practices.

In fairness, however, very limited reference information has been available for designers and builders. They are often more accustomed to types of structures where, compared to horse stables, the loads are much lower for moisture, odor and dust. Or they may simply lack the knowledge of how to get fresh air into each horse’s stall.

This kind of knowledge is often being lost because fewer builders today are specializing in agricultural construction. If a horse owner can find an experienced horse barn builder, so much the better. But it’s possible for new builders to enter the stable construction market if they learn the needed concepts for stable design and ventilation.

That’s especially true since horses are stabled at less density than animals kept in commercial livestock enterprises. Most stables average about 4 pounds of horse per square foot, compared to 13 pounds of cow in a freestall dairy. Also, horses are outside during a large portion of the day. So if the stable ventilation design is a bit imperfect, the stable can still be somewhat forgiving.

Another change that affects ventilation design is the fact that most horses today are kept in suburban settings. Their owners are unfamiliar with ventilation performance and benefits. In a commercial livestock operation such as a dairy, the effects of poor ventilation show up very quickly as a measurable drop in milk production. But because horses are kept for recreational purposes, they only show the effects of poor ventilation through chronic but mild respiratory conditions.

Finally, with horses being kept in the suburbs for the owners’ recreation, even knowledgeable builders can be caught in a bind. Horses need open environments and, in fact, are healthier when kept outside most of the time. But owners, who are often investing major dollars to improve their properties, may want horse stables with a residential flair. So the builder may be asked to compromise proper ventilation when the client requests an airtight building. Or the owner might get irate at the idea of ventilation openings which allow some snow and rain to blow into the building.

The answer to these owners’ concerns, however, is to educate them about the benefits of well-ventilated facilities. And for that, designers and builders must first educate themselves. For example, it’s better to allow a bit of precipitation to enter the stable a few moments a year, than to endure whole seasons when the barn is too stuffy.

Ward: We’ve moved from horse barns as agricultural structures to barns that serve as gathering places for people as well as places for horses. Can we go back to the old construction techniques meant for the way barns used to be?

Wheeler: It’s true that horse stables have undergone changes and that a good portion of the building’s footprint is now for people-related activities. And of course, those areas can use residential-type construction. The problem is when that type of construction is used for the entire building. In older barns you had “breathable walls” because there were miles of cracks between each of the wooden barn boards. Now we often use big metal panels that don’t admit any air.

To be honest, we haven’t come up with a new framework for housing horses. In the past, horses would go out and work all day, so that the stable was a place for them to rest. Today a horse might be used one hour a day — and yet stable design hasn’t changed. As horse stable designers and builders, we need to give this problem more thought. For example, maybe a paddock-based design for housing horses would let the animals spend more time outdoors.

But then or now, the basics of good ventilation come down to two things: exchanging fresh air for stale air, and distributing that fresh air to each horse’s stall.

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