ETFE simulation_ EP and Radiance

Hi,

I have been trying to model ETFE cushions for EP and Radiance. For Radiance I am introducing manually results as produced by LBNL but for EP I have my doubts if a representation of a single layer using “windowMaterial” component is enough as ETFE cushions have a different behavior than that of a glass window. Especially when it comes to model more complex ETFEs with extra (shading/printed) layers and varying behavior during time I think that any simulation that is currently available is not representative enough. Any ideas/thoughts?

I am attaching a paper “ENERGY MODELLING OF ETFE MEMBRANES IN BUILDING APPLICATIONS” from H. Poirazis et al explaining the behavior of ETFEs (p. 701) with with a frit intermediate layer as a reference.

Thank you in advance

Tasos

ETFE_Paper from IBPSA.pdf (235 KB)

Hi,
I’m actually struggling with the same problem and I would be interested in hearing what other people think about this topic.

I’m thinking about modeling just one planar surface and then assigning it the properties of an entire ETFE cushion too.

Regards,
Claudio

Hi Caludio and Tatos,

For Daylight modeling you can use Radiance’s image-mapping. I published a paper recently that discusses the process (http://www.simaud.org/2015/program.php#a-new-approach-to-modeling-f…). They haven’t send it online but I can email you the paper if you’re interested to read it in details.

For EnergyPlus, I would say the best solution is to generate a BSDF material using the pillows and image mapping process that I mentioned above and apply that to the surface. I’m not an expert in either creating or using BSDF materials though. Andy Mcneil has recently published a tutorial on BSDF which might be useful for this case.

Mostapha

Thanks for the info guys!

Mostapha I’d love to take a look at that paper!

Here is the link to the paper: https://copy.com/okY7JzPoVjbF6LrL

and while we’re talking about BSDF materials I recommend everyone to check this presentation: http://www.radiance-online.org/community/workshops/2014-london/pres…

Hi all, thank you for replying. Mostapha thank you very much for both links they are very useful. I am not familiar with BDSF materials either but I will try to set it up for E+. Can I use the “radBSDF” material component to export it also as an EP material or I should export it in another way? Finally is there any chance you publish the custom component you created for this study in HB?

Looking forward!

Tasos

Hi Tasos (Sorry I misspelled your name up there!),

I have never used BSDF in EnergyPlus but I think the structure should be different. Looks like you can use Window to generate BSDF definitions for EnergyPlus (https://windows.lbl.gov/software/window/7/7.3.4/w7_releasenotes.htm). Then you should be able to copy the string and apply it as a construction to Honeybee surfaces. Please keep me posted. We can see if there is a better way to implement it to Honeybee.

I developed the component while I was working for the company and technically they own the code. I may re-write a similar component in the near future but for now I don’t have the ownership to make the decision. :expressionless:

Mostapha

Hi Mostapha,

Thank you for your reply, indeed you can create. I exported some material already and will apply them. I will update the post soon. Is a pity but understand the copyrights issues! :slight_smile: One thing that bugs me is that the evaluation of the results is more based on common sense rather than accuracy since I am not really sure if E+ will actually reads the created BDSF correctly. Do you have any sort of checkpoints for this? for example when you create material (in HB) and write them in the material library how do you check if E+ runs a correct simulation with the new material? (except from a qualitative evaluation)

Tasos

Hi Tasos, For examples like this I would check the solarGains from the window and make sure the results are changed as expected.

Hi Taso,

I was wondering if you had any success with linking BSDF materials to EnergyPlus. I would love to be able to use the vast database and ease of Window 7.3 in my simulations.

As for the non BSDF idf files that window can create, is there an easier way of importing them in HB than simply copying all the values manually to a new material construction?

Thanks in advance.

Kind regards,

Theodore.

GlzSys_LowE_Avg.idf (1.59 KB)
GlzSys_LowE_Bsdf.idf (997 KB)
GlzSys_LowE_Spec.idf (18.2 KB)

Hi Theodore,

I still haven’t tried as I got stuck in some other projects but is first on my list for the upcoming week. I am not sure though what to do with new materials .idf’s that I have generated. Only thing that I have tried is to copy the generated Text file inputs (from the idf Text editor) into GH like Chris is doing in this example but still need to test if it works properly. As for the nonBSDF material I would try to create a common directory and save the properties in a .csv and read them in GH from there to assign them “automatically” to new constructions? Still though a workaround and probably not less of a work than inputting values manually.

Any better ideas?

Regards,

Tasos

Hello!

Reviving this.


I am trying to model an ETFE canopy and I was wondering if someone has radiance material definition created for a ETFE. I will be trying with Window and BSDF file but thought I’d ask first.

Thanks in advance.

Kind regards,

Theodore.

Hi Theodore,

I tried importing from WINDOW with the new components of the new release and I get results in the right directions. My biggest question mark though was the actual modelling of the cushions in WINDOW as I couldn’t find a direct way to model the ETFE layer itself. If you have any updates with this please let me know, I am highly interested :slight_smile:

Thanks

Tasos

Hi Tasso,

Do you mean you managed to import typical glazing with Window+BDSF? I think I’ve managed that as well. But yes, the problem in this case is that there is nothing in the database of Window for ETFE. For my part, what I did was a very simple custom radiance material in HB, using quite high numbers of transmittance (smth ETFE is famous for?).

I’m lucky enough to be doing outdoor studies so I mostly care about shading of an area almost 30m below. In which case I’m assuming small impact by modeling them as a simple radiance surface. Sorry I can’t help more. I will look into it in the future, perhaps I am lucky and I am able to drill some info out of a supplier.

I also did not use Mostapha’s method since it involves a number of custom made components and radiance functions I don’t have the time to learn now. However, I was wondering if anyone has modelled ETFE as simple radiance materials to see if I’m close.

@Mostapha

For the printed pattern I used intermediate panel surfaces made from Lunchbox and made them opaque (for the first test). Is this crude method anywhere close to what you’re doing? :slight_smile: Is it smth I can use for a simple outdoor radiation study?

Kind regards,

Theodore.

Hi Folks,

Can anyone share a gh file with how to map an image in radiance? I am trying to study a frit pattern on the glass.

Thanks,

mostapha -

It seems this link has expired and the paper is unavailable (openly) on other online journals/websites. Would it be possible to share the paper again?

EDIT: link found here:

Thank you, Mostapha!
Kit

2 Likes

Hi @mostapha,

Prior to assigning the frit pattern, did you model the cushions and assigned its layers to a trans material? Also may I ask how did you define the trans material properties?

Kind regards,
Olivier

Hi @mostapha,

It’s been awhile since this chat was active, but I bumped into it again and very keen to have a read through your paper, if you could share it again.

Cheers,
Alex

Actually, think I found it just above, @KitElsworth shared an updated link.

Thank you