Re: [EnergyPlus_Support] Outdoor air for an AHU connected with zones having different schedules

My understanding is that DesignSpecification:OutdoorAir will ensure the minimum ODA required to the zone and all zones as specified at all times. You may specify the minimum to be any number at anytime which you do in schedules.

If you are space heating with the AHU as well, then you may need to restrict the minimum ODAfraction to something like 50%...otherwise a zone requiring no conditioning may require exorbatant amounts of air to satisfy it's ODA requirement if the air it gets only has a small fraction ODA.

However doing this, you may find that you're sucking in loads of generally wastes ODA if the predominant areas require conditioning and not ODA.

Like zones should belong to the same AHU. The exceptions will require a seperate system either to meet the load requirements or ODA requirements.

The other option is to leave the AHU ODAminfraction to zero and instead limit the max flow through the zone terminal unit to something like twice minODA rate, meaning it will get all it's needed ODA until the ODAfraction drops to 50% after which smaller ODAfractions will steadily underscribe the required minimum ODA of the zone.

Mit freundlichen GrÃ¼Ã?en- Sent from my iPhone (excuse the brevity)

i. A.

Jean Marais

b.i.g. bechtold

Tel. +49 30 6706662-23

On 13.09.2013, at 15:40, <fpasserini.tn@xxxxxxxxx> wrote:

In DesignSpecification:OutdoorAir I specified the outdoor air flow that is requested for every zone. The DesignSpecification:OutdoorAir objects are referenced in the Sizing:Zone objects. To specify the outdoor air for the annual simulation I use the Controller:OutdoorAir objects. The problem is that some AHUs are connected with many zones and such zones have different schedules for the outdoor air flow. Therefore I should create new schedules and I should calculate their values in a spreadsheet in order to use them in the field "Minimum Outdoor Air Schedule Name" of the object Controller:OutdoorAir. I can do it, but does a faster solution exist? Can I use the DesignSpecification:OutdoorAir objects also for the annual simulation?

Best Regards

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