Hello all, I'm working on a C&S project. The whole building is already leased to one client, who wants to use one half as laboratories and the other as offices.
For the ventilation of the laboratories a 100% OA-system is part of the C&S-development, with the ducts ending right in the shaft.

The office spaces are ventilated naturally.
Chillers are installed on the roof (as part of C&S) and cw-pipes are installed, ending right in the shaft, too.
These can be connected to fancoils, working only with recirculation air, but this is part of the tenants work (and most likely to be done as we are planning with cooling loads > 100 W/m² in the laboratories). There are no agreements with the tenant facing this.
The Baseline is simulated with System 5.

In my understanding, equipment, that is not part of C&S should be modeled the same in Proposed and BL.
But having a 100% OA system on the one hand and System 5 on the other, I really don't know how this equipment should be modeled.
I thought of adding Fancoils in both systems, sized equally, that make up the recirculation air. But then I fear frictions in the autosizing of the Baseline.

Would be glad to get your opinions.