We are outside of Knoxville. When we considered “covered vs. indoor” we went with the cover because the enemy of horses is heat, not cold. We lived in Silver Spring for six years. If I were going to build there (and that’s not so far from you) I think I’d still go with a cover vice full indoor.
My decision would be based on the fact that horses handle cold quite well and heat less well. We are “down” right now because of ice and snow and cold with wind. The horses are fine; the humans right now are in the “wuss” category.
But we lose, maybe, 30 days per year for heat and cold (our climate is damp and when you get 90 degree temps with 60% humidity you have to be really careful even if you’re not in the Sun). It would be possible to build a “wind break” on the northern corners of the arena but the cost is well outweighed by reality of local climate.
One of the downsides of an indoor is that in the winter it will break wind (no pun intended, here
) but will trap cold air. It can become a “cold box.” The horses handle that just fine; riders, not so much. So if you’re going for rider comfort you’ll need a heat source. In the summer they can become “hot boxes.” That’s bad for horses and riders; you’ll need some sort of “cooling” system. That doesn’t need to be HVAC; maybe just ceiling fans will do. Or maybe lots of turbo-vents. It is something that has to be done.
Covers are not necessarily cheaper than indoor structures. The indoor has the strength of integrated walls and roof to give it rigidity. The outdoor can become an “airfoil” and must be built of significantly stronger material.
You can work more hours in an outdoor without artificial light than in an indoor.
An indoor with lots of windows and some large doors can address many of the indoor’s problems. Windows and doors, however, increase the cost of construction significantly (both in cost of the item and the labor to install it).
It’s a closer call in MD than in TN, but I’d still likely vote for the cover over the indoor.
Good luck in your program.
G.