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Why are zone ventilation loads not showing up in zone component summary

asked 2017-06-09 15:41:31 -0500

RBallard gravatar image

updated 2020-01-27 18:45:05 -0500

Openstudio 2.1.0: I have zones with baseboard heat and individual fan unit with 100% outside air and electric heating coil. The simulation with graph of outside air flows (using any of the variables for outside air flow by volume or mass) shows a constant volume of outside air into the zones, consistent with the input values for the zone and schedules. But the zone component load summary reports 0 for zone ventilation in both heating and cooling. This is true for all such zones. Why is ventilation missing in this report, when there is clearly outside ventilation air coming into the zone?

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answered 2017-06-09 17:44:38 -0500

updated 2017-06-09 18:15:19 -0500

After doing some testing, I'm confident that the Zone Ventilation column in the Zone Component Load Summary report will show loads for outdoor air entering the zone or air exhausted to outdoors from the zone that are defined by zone ventilation objects like ZoneVentilation:DesignFlowRate. These are meant to model natural ventilation or zone intake / exhaust fans.

The outside ventilation air that you defined using the DesignSpecification:OutdoorAir object will pass through the individual fan unit, which is an HVAC object and not a zone ventilation object. Notice that there is a Cooling Peak Conditions and Heating Peak Conditions table for each zone that lists the outdoor air condition and zone air condition at the time of peak load that occurs on the respective design day. EnergyPlus uses that information, the outside ventilation air you specify, and the loads generated for the zone to calculate the HVAC capacity that is required.

You can refer to a related question here and the Engineering Reference documentation about the Zone Component Load Summary report here for more details.

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Asked: 2017-06-09 15:41:31 -0500

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Last updated: Jun 09 '17