How do I model a Dedicated Outdoor Air System (DOAS)?

When modeling this type of system with the DOE-2 calculation (used in the 90.1 calculations), you would  put in a dummy zone. That is not needed, nor should you do that with the new CBECC Com calculation running under the Nonresidential T24 Performance calculation. Note that currently, this calculation only permits a DOAS systems feeding Zonal Type Systems (Four Pipe Fan Coil, Packaged Terminal Air Conditioners and Heat Pumps, Hydronic Heat Pumps, SplitDX , PackagedDX, Single Packaged Vertical Units and VRF). Simply create that system as you have per prior instructions, and select the “Outside Air From” setting at the system level of the tree. See the DOAS.bld example we include in the sample files section.


Categories: 7. Nonresidential Mechanical

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