Centralised Mechanical Ventilation and Zone Level Split Systems

I have been trying to represent a centralised HRV with individual reverse cycle split systems per zone (which is very common in Passivhaus projects), however the system is not passing through correctly to OpenStudio. Please see attached script and screenshots below.

Split System in Ironbug_MS.gh (55.4 KB)

I have merged the ‘Airloop’ (MVHR) and ‘No Airloop’ (zoned split systems) together before passing them into ‘HVAC system’ component.

This appears to work, as the HVAC system outputs the result that “IB_HVACSystem - Zonal-system: 4 - Air loop: 1”, however for some reason these zone equipment systems still do not appear in the OSM model. I must be doing something wrong, but I’m not quite sure what.

@MaxMarschall it appears that you worked on something very similar in this LBT post. Do you perhaps have any advice?

Oof that was a long time ago and I haven’t worked much with detailed HVAC systems since, so wouldn’t know this one unfortunately, sorry! I’m sure there are others that can help though

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Hi @Stranga

You cannot create more than one ThermalZone per Room. You have the same room added in both above “Airloop” and bottom “NoAirloop” which is causing the issue.

You can add the ThermalZone that contains PTAC to the demand branch of the first Airloop:

Thanks Mingbo,
Good to know why my first approach was incorrect.

I tried the second approach as well , but it seemingly had more issues than the first approach. For instance, the zone equipment does not appear to flow through to the ‘HVAC systems’ component.


In the OSM file, the zone equipment does not appear in the ‘thermal zones’ tab (which makes sense due to the above issue). However, for some reason the air loop also does not appear in the ‘HVAC systems’ tab.


Any thoughts why this might occur?

Hi @Stranga, I am going to reply your email here so that others with the same issue could also see it.
In the new workflow with LBT, there was a bug when applying the schedule to an HVAC component and that leads to a translation failure. This was fixed last week, and you can download the latest version of the Pollination installer or Ironbug installer to update it.

Please let me know if you have any other issues.

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