HVAC system not applied to zones

Hello everyone, first time I have seen this happen, attaching OSHVACSystem 3 to my zones, simple HB operation, report states HVAC system not applied, replaced with Ideal Air Loads system when IDF is written. Any help appreciated. GH attached.

EnergyModel.gh (586 KB)


HVAC systems are only supported on the “Export to OpenStudio” component. We are going to phase out the Run Energy Simulation component after the next release since the OpenStudio component presently does everything that the E+ component does (it just has the added benefit of detailed HVAC systems and other great benefits of OpenStudio development). I would suggest starting to change your workflows over to use the OpenSrudio component instead of the E+ component.

Does the “Export to OpenStudio” component still permit iterative runs from within GH, and bringing results back in and mapping to geometry? Sounds like “Export to OS” is more like “Run via OS” and has the same GH functionality as “Run ES”. True?

You are absolutely correct. The resultFileAddress output of the OpneStudio component is functionally the same as that on the Run Energy Simulation component.

It works! Building on a previous question of building custom libraries, is it possible to build custom OS HVAC systems and then bring them in through the " openStudioHVACSystemsList "?


The answer to your question here is very similar to that for the building programs. You can add in new HVAC systems to Honeybee by editing the code, especially if learn to use the HVAC- generating functions that I put into the OpenStudio component. If you add in a HVAC system type that is becoming common through the industry, you can send a pull request to the Honeybee github and we will merge the work into the code base for all to use.

However, editing the code is certainly a longer operation and you will likely make much more progress in the meantime using some other workflows. Notably, if you generate your model with the “-1. Thermostat Only” hvac system type and then open your model in the OpenStudio interface by hitting the openOpenStudio_ boolean on the OpenStudio component, you can add a much larger range of HVAC types in the OpenStudio interface. In particular, OpenStudio has a growing number of user-contributed HVAC system templates that have been integrated into a set of scripts called “Measures” that you can apply to your OpenStudio model. You can find these system templates by searching for them in the building components library. Here is a good tutorial video on how to apply measures to your model within the OpenStudio interface.

I should also note that you can build an entire custom HVAC system from scratch within OpenStudio by going to the HVAC tab and adding air/water loops and any HVAC components that you desire from the library on the right-hand side of the interface. However, I recommend starting by observing the HVAC templates and, once you understand how they work by editing/customizing the templates in the HVAC tab, then you might attempt to build your own system this way.

If you add a HVAC in the OpenStudio interface (either with measures or your own custom system), you can save the OpenStudio model and continue the workflow in Grasshopper by running the .osm file with the “Honeybee_Re-Run OSM” component. Of course, while this workflow offers a lot of freedom to create any HVAC you want, we understand that the jumping over to the OpenStudio interface can interfere with iterative simulations in Grasshopper (like running through a slider of glazing ratio using a certain custom HVAC, for example). As such, we are in the process of enabling people to run OpenStudio measures in GH as you see in Mostapha’s demo video here. However, the measure components are currently in WIP because OpenStudio team is still in the process of standardizing the measure file structure. After a couple more releases of OpenStudio, this should hopefully be stable enough for us to take the Measure components out of WIP.

So the ultimate intended workflow for customized HVAC is that you will apply OpenStudio measures to your model in GH. These measures can have custom inputs depending on the HVAC properties (as you see in Mostapha’s video) and there will hopefully be many user-contributed templates available in the Building Components Library. If you want to build an entirely custom system that does not exist in the library, we will recommend that you make your own OpenStudio measure and contribute it to the Building Components Library. While we are getting this ultimate workflow ready, there is a lot that you can do in the OpenStudio interface presently (as mentioned above).

Hope this answers the question,


Looking at the BCL, I am unable to find the exact same systems shown in HB, e.g. 90.1 System 1, System 2, etc. Should I be looking elsewhere? https://bcl.nrel.gov/search/site/?f[0]=im_field_measure_tags%3A956&f[1]=im_field_measure_tags%3A976

Hi Chris, sorry for intrusion but I have a problem with the component of HVAC of OpenStudio.

If I open a new file of OpenStudio I have all elements of HVAC in library.

If I export the model from Honeybee to OpenStudio and later I open the file with OpenStudio I haven’t elements in library (of HVAC), zero elements.

Do you know why this?

I’m trying download components from BCL but I can’t see these in library in my model Honeybee/OpenStudio.

Thank you very much!


This is an issue in the latest version of OpenStudio that NREL will hopefully fix soon. For now, you can get the libraries to display in OpenStudio by opening the application first and then opening the file that HB exports. See the response here on the unmethours forum:


Sorry for digging this post out but I just want to confirm if “honeybee HVAC system” still supported on the “export to open studio” component? the “export to open studio” component asks hvac system from ironbug but we are trying to avoid ironbug by using honeybee hvac system list.
Also, thanks for releasing the LBT 1.0.0. looking forward to radiant system in the next release!

Yes, @gqiu . Both Honeybee-Legacy and the new LBT plugin support Honeybee HVAC functionality in the export to OpenStudio workflows. Of course, it’s a new component for the LBT Plugin but it looks and works a lot like the legacy one.