[QUOTE=PaintPony;8196664]
How do you know this? Are you the BO? 
[/QUOTE]
Post #1 says there is a dutch door left open.
[QUOTE=Ghazzu;8196361]
One of the things I find curious about horse people as opposed to farmers of other types of livestock is the tendency to absolutely omit any planning of rate of air exchange when designing and utilizing a facility.[/QUOTE]
I am inclined to agree with Ghazzu. Old Dairy barns make the BEST horse barns. Concrete aisle, excellent facility, no dust in the barn except when they’re cleaning the aisle…facility not perimeter fenced so it’s best if, in all weather, all of the doors are shut (you know, so we don’t have loose horses running around.)
However, thank you dairy farmer, barn has these AMAZING sliding walls. No kidding. Go to kitchen (old milk-tank room), walk to control pannel, drop walls. If the weather goes to crap and it gets retarded windy, raise walls. In the winter, walls stay up (seriously, who wants the aerate the barn in -30C weather? The clipped horses prefer not, thanks).
In the summer they are almost always open, or partway open, because you can pretty much go anywhere from an eights of an inch to all the way down. Pick a level of open, and enjoy. The only catch is that the mesh screen is big enough that if the mosquitos are absolutely awful, the walls end up shut at night for the horses’ sake. 90% of the time, though, in the summer, they are open to some degree. Seriously, it’s the best thing ever.
