Re: [EnergyPlus_Support] Re: Why Autosize does not consider System Outdoor Air Loads

["Jean Marais jeannieboef@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>]

You are partly right. It has nothing to do with outdoor air thermal load, but supply load, whether mixed, 100% oda is not relevant. Air at a specific temperature and flowrate enters the zone and adds or subtracts to the total loads on the zone air node.

The "designday" terminology is maybe a bit misleading in the sizing:zone object. The loads are always calculated on the design day. If you don't want your systems to size all the componants as if your zone is conditioned by air, then you MUST change the option in the sizing:system object to size on "Ventilation Rate" instead of "Sensible", because it also 'tells' your zone equipment that the air that it should expect to size on is only that of the Ventilation Rate (ODA).

***Nothing is a MUST and there are other ways...but this is certainly the easiest.

2014-07-02 13:35 GMT+02:00 ecoeficiente@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx>:

 

Design supply airflow is usually configured as to be calculated for the DesignDay, although you may hard set a value. That airflow is used to size fan equipment at the zones and to feed the system:sizing. It has nothing to do with outdoor air thermal load.

If you have an AHU for mechanical ventilation without any heating or cooling coil which supplies airflow to the zones, the Autosized zone equipment does not include that thermal load.

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Posted by: Jean Marais <jeannieboef@xxxxxxxxx>

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