I see that ASHRAE 90.1 requires a vestibule in most cases, but I don't
know if it is modeled or if it is just mandatory. It would seem to me
that if it was modeled, showing compliance using modeling, without a
vestibule, would be OK (you would make it up somewhere else in the
envelope). Does anybody know if the vestibule is modeled anywhere, and
how to take it out or put it in?

Since LEED requires compliance with ASHRAE 90.1 Mandatory measures, this
makes a vestibule a mandatory requirement unless I can model it with and
without. If this is even possible.

Otherwise we must put in a vestibule to comply with LEED.

Is this correct? Does anybody have other thoughts or ideas? We have a
very efficient building, modeled without the vestibule in Climate Zone
3B. I would think that we could take a heating penalty and not install
a vestibule AT EVERY DOOR.

I appreciate your thinking about this.

--
Robert Wichert P.Eng. LEED AP BD&C