One afternoon last week it was too hot in the shul, so we davened Mincha just outside the shul on the patio. The shul has an aron Kodesh, and while we were on the patio, and the Aron was visible through the window, the congregation fell on their faces during Tachanun.

I had learned that one falls on his face only in a shul that has an Aron Kodesh. We were not in the shul itself, but rather, on the patio next to it. Is that still considered a valid criteria for falling on one's face?