I posted this in the controls area and didn't get any response, so hopefully you commercial gurus will have some ideas.

I have a customer that has purchased a commercial office building, the kind where you may find small offices for accountants and the like. Most of the rooms are maybe 12 x 12 with a few larger. Building is a rectangle in shape, laid out king of like ffices on front, hallway, offices in middle, hallway, and then offices on the back side of building.
So the hvac is (2) 4 ton heat pumps. One old Trane, one new Carrier. One does the front portion of the building , the other does the back side of the building, and for some reason they fed each of the center offices with a branch off of both units, which makes no sense to me. There are only 2 thermostats, and they are located in the hallways, which have no supplies or returns, so the thermostats are not measuring a realistic sample of the office temps.
The owner is wanting to add a system for one problem area, but I think he has enough air, it just isn't zoned or being sampled for temperature in a proper way.

So my first option to him is to place the thermostats in an office on their respective sides of the building to at least see what a room temperature is, instead of sensing an unsupplied hallway. Then ofcourse we have to ask which office.
My next option is to find a sensor type thermostat that will sense the return air temperatures (ceiling return, but this is the bottom floor of a two story building, so it should be a decent sample of the combined room temps) in hopes that a mixed sample of the room temps will find a median. And lastly we can add a zoning system, but it will have to cover 5 to 8 zones for each system. I will have to seperate the middle rooms to only be supplied by one unit and just zigzag the rooms. The supply duct is a straight sheet metal run, so if zoned each room will have to have a sensor and damper. The dump zone can be the hall way or the ceiling return plenum.
Anyway, I am hoping for some good suggestions and maybe a good brand of zoning system for an application like this. Hopefully the dampers can be mounted right on the 2x2 ceiling diffusers.