Mechanical Ventilation issue

Replies to This Discussion

Permalink Reply by Mostapha Sadeghipour Roudsari on October 16, 2016 at 7:40am

Hi Claudia, Chris will get back to you on this with more details. I assume you're using the EnergyPlus component and not the OpenStudio one. Is that right?

Permalink Reply by Chris Mackey on October 16, 2016 at 10:06am

Claudia,

The results that you have posted here make sense to me.  The ventilation seems to be typically at 3 ACH and it is only increasing this ACH in order to recirculate air to meet the peak cooling loads in summer.  In these peak cooling conditions, it likely needs to force more air past the cooling coils in order to remove the heat from the space (hence, why it jumps up to 5 ACH).  Of course, this is all assuming that you are using the OpenStudio component and you are modeling a HVAC system with recirculation (like VAV).

If you are not modeling something like this, please upload the file so that I can see what is being modeled.

-Chris

Permalink Reply by Claudia on October 17, 2016 at 3:11am

Thanks Chris and Mostapha for your reply.

Actually i am still using the EnergyPlus simulation component (the one updated on the 4th of september 2016) because i thought it was still working correctly and also because I always get strange errors using the open studio one.

For example, if i put in my workflow (which is working with E+) the openstudio component instead of the E+ one, once i run the simulation i receive these following errors:

- 1. The simulation has not run correctly because of this severe error:
   ** Severe  ** IP: IDF line~729 Error detected for Object=DESIGNSPECIFICATION:OUTDOORAIR

- 2. The simulation has failed because of this fatal error:
   **  Fatal  ** IP: Errors occurred on processing IDF file. Preceding condition(s) cause termination.

Do you know why?

Can I still use the EnergyPlus simulation component?

Thanks in advance

Claudia

Permalink Reply by Chris Mackey on October 17, 2016 at 6:26am

Claudia,

Upload you GH file and let us know what version of OpenStudio you are using.  I'm afraid that I can't know what is happening without being able to see the full script.

-Chris

Permalink Reply by Claudia on October 17, 2016 at 6:47am

Hi Chris,

i have tried to upload my GH file, but nothing changed.

As regards the Openstudio version i have the 1.12.0.

Should i install the 1.13.0?

Thanks again

Claudia

Permalink Reply by Claudia on October 17, 2016 at 8:16am

Ehi Chris,

I had a look with a collegue and it seems that there is a sort of "bug" on the openstudio's idf file: as you can see from the following part of the text, after SCHAlways ON there isn't anything but i guess there should be the semi comma (;), is it right?

DesignSpecification:OutdoorAir,
  Room2_DSOA,                      !- Name
  Sum,                                    !- Outdoor Air Method
  0,                                      !- Outdoor Air Flow per Person {m3/s-person}
  0.00215901630740211,                    !- Outdoor Air Flow per Zone Floor Area {m3/s-m2}
  0,                                      !- Outdoor Air Flow per Zone {m3/s}
  0,                                      !- Outdoor Air Flow Air Changes per Hour {1/hr}
SCHAlways ON

ZoneHVAC:EquipmentList,
  Room2 Equipment List,            !- Name
  ZoneHVAC:IdealLoadsAirSystem,           !- Zone Equipment Object Type 1
  Zone HVAC Ideal Loads Air System 1,     !- Zone Equipment Name 1
  1,                                      !- Zone Equipment Cooling Sequence 1
  1;                                      !- Zone Equipment Heating or No-Load Sequence 1

How can i solve this problem for the following simulations?

Thanks

Claudia

Permalink Reply by ao on October 17, 2016 at 8:21am

Chris and Claudia,

Just a note- this is probably economizer behaviour. The HB default is to set an economizer, the ACH spikes will disappear if you manually set to 'no economizer'.

A

Permalink Reply by Chris Mackey on October 17, 2016 at 10:02am

Claudia,

The economizer makes sense since it mixes in more outdoor air when the space needs cooling and the outdoor air is cold.  Please upload the GH file with the OpenStudio component so that I can see the potential bug.

-Chris

Permalink Reply by Claudia on October 18, 2016 at 3:50am

Hi Chris,

Here there are the rhino and gh files.

Thanks a lot

Claudia

Attachments:

• 161018.3dm, 108 KB
• 161018.gh, 840 KB