I initially posted this on Al's Update thread, but it seemed to deserve a thread of its own. It seems like there is a fairly simple solution that should satisfy both the retailers, and the "Green" team (at least to an extent). I'm surprised they haven't done this already, actually.
Why not install "air curtains" to be installed over the doorways? These are used a lot in Minnesota where our hot, muggy summers and cold winters cause a dilemma of air rushing out of the building, even with vestibules installed.
My gym has one of these over the sliding automatic doors; essentially they push a strong current of heated or cooled air down over a doorway to create a "barrier" that doesn't allow conditioned air to seep out as quickly as it normally would. I have seen these over doors that need to stay open all day long too.
They also work great at keeping our State Bird -- the mosquito -- OUT.