Air curtains vs. Vestibules

ASHRAE 90.1-2007 does not have any language addressing air curtains that I am aware of. You need to provide a vestibule. Vestibules are required on any entrances that "separate conditioned space from the exterior". I think your roof entrances are included in that.

Let's say you have a semi-exterior building envelope, a big roof for example with open facade containing a open walk through "building entrance". Then inside (building in building style) are your shopping mall spaces all conditioned. Each mall space has doors, but these are not building entrances, since you are already inside the building. Then you have the following: 1) Building entrances that don't seperate conditioned space from the exterior --> 5.4.3.4 no vestibule required. 2) 5.4.3.4 Exception b. Doors not intended to be used as a building entrance. If your roof enterances enter into semi-exterior space (3.2 Definitions "building envelope: building envelope, semi-exterior") then you may find that you fall into a similar scenario as above. I think then that you do not need vestibules. This however means that you may not condition the semi-exterior mall space at all...only the shops. Also, what I personally don't get, is that there is nothing saying that my super sealing doors aren't allowed to constantly stand open...such as in a mall scenario. What do you think Christopher?