Materials from EP DataSets

Hi Mostapha, Chris and team HB.

I’m trying to load materials and specs included in the EP DataSets folder (C:\EnergyPlus\DataSets*plenty files here*) as the materials there included are not within the default OpenStudioLib file.

I cant use the import idf component because it discards materials, any suggestions?

On the same note, the EPWindowMaterials loaded by default, using the callfromEPContructionLibrary, are weird. Most of them are Fixed windows and theoretical glass. One of them has a U-Value of 700, which I suppose could refer to a 1.3mm glass pane.

Aren’t the EP materials from Data Sets supposed to be included in the default lib? perhaps I’ve inadvertently done something to break the import function.

kind regards,



Look for the userCustomEPLibrary.idf file (probably in c:\ladybug). There you can add manually the materials/constructions you like. Just remember that for the constructions to work you need to include the single materials also in the file.


Thanks Abraham,

worked like a charm!

all the best,


P.S. I have a question regarding the glazing generator but I’ll open a new thread.


I am getting a weird behaviour with constructions in the userCustomEPLibrary.

Adding materials work great, U-value calculations are spot on, based on conductivity.

But when I add window construction (with prevously defined U-Values, shgc, and VT), the U-value comes out negative ( find attached my gh file and idf file, also see screencapture).

The “DecomposeEpConstruction” component seems but when testing the code its shows “KeyError(“KRYPTON 8mm”)”



No attachments.


ooops, srry! (481 KB)
userCustomEPLibrary.idf (25.8 KB)

If you check your custom liibrary with the idf editor you"ll see that the file is missing all gases definitions (air, argon …). So no wonder why it is making you trouble.

Just fill in with the missing data and you will be set.


Here you go.

userCustomEPLibrary.idf (25.8 KB)

Thank Abraham,

Makes perfect sense. I wont be able to try until tomorrow, but I’m sure it’ll be fine.

best wishes,



The U-Value is still off. I tried both your idf and mine.

Now I’m getting the following message on the component:

UnboundLocalError(“Local variable ‘UValueSI’ referenced before assignment.”,)

please see attached image.



Can’t tell.

I rebuilt the construction inside the file (attached) and i get the same negative U value. Take in consideration that this is an icredible well insulated window!!

Can you try to use it in a simulation and report the materials? There you’ll see the U that E+ calculated for this construction.

I’m lazy now to calculate it myself, but i would also try to do so.

-A. (488 KB)

I’ll simulate and observe how it behaves.

What puzzles me is that the idf for the window construction includes the U-Value. How is the idf file being parsed that it doesn’t pick up on that line of text?



The idf doesn’t include U value!! It is calculated during the simulation. The HB component calculates it in GH.


Maurico and Abraham,

This is a very interesting discussion here and a lot of good is coming out of it. The heart of the issue comes from the fact that EnergyPlus calculates a custom U-Value for gas materials using a complex algorithm that accounts for convection of the gas depending on the thickness of the gap, the temperature difference across it, and the gas molecular properties. Including this algorithm in Honeybee would involve a great deal of time but, if we are just looking for a back-of-the envelope estimate assuming fairly standard gap thicknesses (like 1 cm), this is relatively straightforward. This ‘back-of-the-envelope’ estimate is what we had been doing for the air gap material but we had not included the other 4 gases used in windows. I took a look at the properties of these gases in LBNL WINDOW and just added them to the Honeybee ‘CalculateU-Value’ function:…

Now you should see the U-value of a glazing assembly with krypton computed correctly by Honeybee in the attached file. Note that all of your EnergyPlus simulations with Honeybee will be fine with whatever EP material you assign. In other words, the production of a negative U-Value here was purely an interface error in HB and not a simulation one.

On another note, the inclusion of these EnergyPlus DataSets materials in the userCustomLibrary is something that I could imagine a lot of people desiring and so I have added the idf that you have built here to the Honeybee ‘resources’ folder in case anyone wants this feature in the future:…

Lastly, Mauricio, if you are interested in extending the types of glazing that you can run with Honeybee, I just added a new component in the last release that allows you to take any glazing assembly that you create with LBNL WINDOW and assign it to windows in Honeybee. LBNL WINDOW includes a continuously-updated database with every type of glass and gas currently on the market and so you should always be able to find what you need there. Here is an example file showing you how to use the new LBNL WINDOW component:…

Great work, gentlemen!


Forgot to attach the GH file (477 KB)


Great work! Thank you very much.



This is a great discussion!

Mauricio, Honeybee uses OpenStudio template as the default library. I’m sure OpenStudio team would be happy to hear your comments about the glazing data-set. In the next version we will add a new input to set-up the construction based on climate zone and modeling standard (

Chris, The import Window material is huge. I wasn’t actually aware of it. Well done!



I’ll comment on the OpenStudio forum.

Construction set-up based on climate zone sounds like a sweet time-saver. Let me know if you need input on the subject. I’ve mostly dealt with Passivhaus standard and UK L regs.



Sounds great. OpenStudio library has construction set for ASHRAE and CIBCE. It would be great to have construction sets for other standards. I’ll let you know once I start the development.

Hi Mostapha,

I could potentially help for SEA. I will do a review of local regulations once I get the time.

Kind regards,