For patios without a roof, consider having more than 25% of the wall space completely open to outside air.
For patios with a roof, consider having more than 50% of the wall space completely open to outside air.
Walls that are open on opposite facing ends help enhance the smooth flow-through of air into and out of the patio.
Try to avoid having closed intersecting walls (closed corners), which can prevent a smooth flow-through of air into and out of the patio.
Consider moving line-ups, waiting areas, pay stations and other areas of congregation away from areas that are completely open to outside air where air flows into or out of the patio. This can help to reduce the risk of COVID19 transmission from people in those congregation areas to people on the patio and from those on the patio to the people in those congregation areas.
A partial wall (e.g., pony wall) should be no higher than 1.2 m above the floor or ground to avoid impeding the air flow of seated patrons.