Fan Powered Terminal Boxes (input at the Zone level of the building tree) can only be modeled with Chilled Water (Built-Up) Variable Air Volume (VAV) systems. This is a modeling limitation of the DOE-2 Simulation Engine. These types of terminal boxes cannot be selected when the system type is a Packaged VAV system.
At the Zone level of the Building Tree, in the Mechanical tab, you can select a different type of terminal box that is not fan powered, or you can edit the selected terminal box and change the type to a non-fan powered version.
At the System level of the Building Tree, you can select a different system type, or you can edit the current system type and change it to a Built-Up VAV system. However, keep in mind the Built-Up VAV system will require the definition of the chiller and pumps.
Some users have opted to model the fans as exhaust fans at the Room level of the building tree. Some have opted to model the DX compressor and an air cooled chiller and thus select the system type as Built-Up VAV.
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