Unit incosistency between input values vs. OpenStudio report

furtonb · September 1, 2022, 3:58pm

Hi,

When comparing the Program Type inputs of the PO model (Flow/Area, Infiltration), the displayed units do not match the units being shown in the OpenStudio report:

Are the units m3/s/m2 or m3/h/m2?
We calculated the model assuming the input for seconds, which is incorrect, if the values are being used assuming per hour values.

Thanks!

mostapha · September 1, 2022, 6:55pm

Thank you, @furtonb for bringing this to our attention. I’m also copying @chriswmackey here. Between him and @mingbo we should be able to help you with this issue.

furtonb · September 6, 2022, 8:26am

Hi @mostapha ,

Is there any news on this?

mingbo · September 6, 2022, 1:30pm

Hi @furtonb,

I did a quick test on my end to verify which part went wrong. It seems it is an issue happening within the OpenStudio Report’s unit conversion. The number with the default unit (CFM/ft2) from the OpenStudio report is correct and aligns with the raw EnergyPlugs’ value which is the same input from the Honeybee. But when you ask OpenStudio to convert the report to a different unit system, it messes things up.

This is a critical discovery, I think we should have another person @chriswmackey double check to ensure my conclusion is correct.

chriswmackey · September 6, 2022, 3:40pm

Hey @furtonb ,

It’s definitely m3/s/m2. So the Rhino Plugin, LBT Grasshopper plugin, and all of the input interfaces are correct.

@mingbo is right that this is a bug in the OpenStudio Results report, which we hadn’t caught because NREL developed this measure and maintains it. And I guess NREL probably does all of its testing using IP units so that’s probably why they didn’t catch it either. I just reported the bug to them:

github.com/NREL/openstudio-common-measures-gem

OpenStudio Results Measure Reports Infiltration in Incorrect SI Units

opened 03:33PM - 06 Sep 22 UTC

chriswmackey

We have found a bug in the [openstudio_results measure](https://github.com/NREL/…openstudio-common-measures-gem/tree/develop/lib/measures/openstudio_results) in how it reports the infiltration units in SI. The HTML output by the measure says that the units are m^3/**h**/m^2 but the values are very clearly in m^3/**s**/m^2. The units and values are correct when IP units are used. ![image](https://user-images.githubusercontent.com/5567574/188675542-f3d65f1f-db9a-4dc4-93c0-1f9e0f137e86.png) Recreating the issue should be easy enough as you only need a model with infiltration and you need to use SI units for the measure. More information from the user who identified this bug can be found here on the Pollination forum: https://discourse.pollination.cloud/t/unit-incosistency-between-input-values-vs-openstudio-report/1938

In the meantime, I can push a fix to the recipe on pollination. I’ll post back here once it is implemented.

chriswmackey · September 6, 2022, 4:08pm

@furtonb ,

I pushed a fix so that, if you use the LB Versioner and then run the recipe locally, the units will be correct:

It’s going to take a little longer to get the recipe updated on Pollination but I’ll let you know when it’s ready.

chriswmackey · September 13, 2022, 5:22pm

FYI, @furtonb . Sorry it took a while but the version of the recipe on Pollination has been updated with the latest measure:

So the units will now also display correctly there.