Design Specification Outdoor air Object name blank

asked 2021-02-15 14:54:12 -0500

student gravatar image

updated 2021-04-02 12:17:27 -0500

I am a student working on my thesis. I am modelling a building in OS 2.7.0

I have done some research and found the following (, they say that design specification outdoor air object is optional and you can leave it blank.

But I get for my rooms where there is supply air with a diffuser the following error.

 ** Severe  ** Controller:MechanicalVentilation="CONTROLLER MECHANICAL VENTILATION 1", Design Specification Outdoor Air Object Name blank
   **   ~~~   ** For Zone="THERMAL ZONE 10".
   **   ~~~   ** This field either needs to be filled in in this object or Sizing:Zone object.
   **   ~~~   ** For this run, default values for these fields will be used.
I also get following warning
** Warning ** GetOAControllerInputs: Controller:MechanicalVentilation="CONTROLLER MECHANICAL VENTILATION 1
   **   ~~~   ** Cannot locate a matching DesignSpecification:OutdoorAir object for Zone="THERMAL ZONE 10".
   **   ~~~   ** Using default OA of 0.00944 m3/s-person and 0.0 m3/s-m2.

this error occurs if i don't put in a design specifiaction outdoor air object (blue circle) image description

As you can see this room "hobbyruimte" part of thermal zone 10 has a diffuser image description

the air system has no cooling or heating control just a heatexchanger and evaporative cooler, the diffusers are hardsized. image description The problems are solved if I place a design specification outdoor air object but I don't want that.

If I delete more design specification outdoor objects then i also get more errors in my plant loop?

Someone with a solution or knows what causes the problem? you can find the OS files in this link ( error file 11-45(error) and openstudio, implementing design specification solves that problem but then I need to implement a design specification outdoor air object in space types which isn't what I want.

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I have not looked through this in detail, but if you have an air loop that has an outdoor air object, then one or more of your zones on that air loop needs a DSOA object. Maybe you are hitting a different error, but if this is what you are seeing you can just add a DSOA but with a value of 0, or remove the OA from the air loop.

David Goldwasser gravatar image David Goldwasser  ( 2021-02-16 16:51:03 -0500 )edit

You do not need this object if you HARDSIZE your flows. If you are trying to autosize, then you need to input it.

Julien Marrec gravatar image Julien Marrec  ( 2021-02-17 02:27:10 -0500 )edit

Julien, the diffusers are hard sized and I still get the error? How does this come?

student gravatar image student  ( 2021-02-17 13:21:08 -0500 )edit

check the outdoor air system too. that's the component left of your supply fan on the airloophvac.In there you will find the Controller:OutdoorAIr.

Julien Marrec gravatar image Julien Marrec  ( 2021-02-17 14:29:22 -0500 )edit

julien, I have hard sized the minimum and maximum outdoor air Flow rate but still get the warnings and severe error. What should I do or check next?

student gravatar image student  ( 2021-02-17 15:18:55 -0500 )edit