Have you tried using the Reset schedule? I believe you will need to switch to a packaged VAV for this to work. If you want to model a constant speed fan you can use the fan control option to for the VAV to Constant Volume.

For the SAT reset:

1. Airside parameters screen -->Cooling Tab --> "Cool Control" = Reset.
2. Use the library to find a default reset schedule from the "starting points" family. (should be called "Schedule RESET-TEMP")
3. Open and edit the schedule