Green roof issue (u-value and material problems)

Hi Mostapha, Chris and group members,

There are two questions about the Green roof issue as I ran the gh file named “Green Roof In Energy Model” . I’ll appreciate it if you give me a hand.

A. Can’t run correctly within Honeybee_Export To OpenStudio as opposite to the Honeybee_Run Energy Simulation. After I uploaded the Green roof construction setting into honeybee library, it still can’t work. The error said:

  1. Honeybee currently can’t calculate U-Values for Material:RoofVegetation.

Your Honeybee EnergyPlus simulations will still run fine with this material and this is only a Honeybee interface limitation…

Let us know if you think HB should calcualte this material type and we will add it to the list. :slight_smile:

  1. The material type Material:RoofVegetation hasn’t been implemented yet!

Solution exception:openstudio::model::Material const & type is null

**So how could I manage to calculate the influence by green roof in openstudio component as I also tend to calculate Light Control in openstudio component? **

B. I used Honeybee_Decompose EP Construction to check the Green Roof construction’s U-value_SI, it is -1.133198. Why it could be negative, what does it mean when u-value is negative?

Thank you in advance.



I have not yet implemented green roof materials in OpenStudio but I can add it in now. I’ll post back here when it’s done.



Roof vegetation now works with OpenStudio:…

See attached for an example file.


GreenRoof With (532 KB)


I checked the file you uploaded. That’s really a great help. Many thanks for your excellent work.


Hello Chris,
This file is not accessible for me!!
Would you please share it again.

Hi -

You can download that from the original thread in the old forum: