Grasshopper

algorithmic modeling for Rhino

Hi,

I've been preparing this discussion for some time now.

I was in doubt if continue this discussion or start a new one. So here we are: a new one.

There are 2 issues that are bothering me with the radiation results, specially when comparing the results from LB with those of HB.

Issue 1: Results so different.

In the attached file upper part to the right of the canvas you see both definitions (LB and HB). The images obtained show results so different that i can't find a logic explanation (2.46 vs 41 kWh/m2 for the same period of time). I believe that LB are in the OK range. HB are to high for just 5 hrs of calculation. I don't believe the material definition are making such a big difference (though i tried to have them similar).

Issue 2: Can't get annual grid based calculations plotted.

In the attached, right side at the bottom. I get the calculation, but after connecting the results to the HB_readAllTheDSHourlyResults it takes ages to calculate and at the end rhino crashes. Can be that this is a memory problem? Or there is a way to make this work (total annual radiation for GridBased simulation)? For now i disabled the component, but i just wonder ...

Words of wisdom for both issues will be appreciated.

Thanks,

-A.

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Hi Rob. I think it's fine for now but if you have any follow up questions it should be a good idea to open a new discussion. Cheers.

Hi Abraham, Let me report first what I have done so far and then give a suggestion.

I compared the skies and the difference is acceptable. The 145 values are the values for 145 different sky patches. You can see that specially for patches that involves higher values (direct sun) the differences are happening but they are not major. Here is the results for the whole year:

Then I set-up a box and run the analysis using Ladybug vs Honeybee. Here is the results.

Finally I connected the analysisPeriod that you were using and you can see the difference in sky is higher and as expected the results is a more different between Ladybug and Honeybee but still close.

Here is my suggestions:

1. Can you integrate your geometries into this workflow so we can compare point values with point values. I attached the definition.

2. Do you mind to open a new discussion for the second issue. It's very hard to follow all these discussions on the same thread.

PS: Gencumulativesky is developed by Darren and Modified by Christoph and is part of Daysim's distribution vs gendaymtx which is recently developed by Greg Ward for Radiance daylight coefficient methods. I understand gendaymtx much more since it gives you the results for every single hour and then you can add them up for cumulative sky however gencumulativesky just gives you the total results.

Hi Mostapha,

Thanks, i will do. But the attachment wasn't there :-)

-A.

oops! attached.

Attachments:

Hi Mostapha,

Attached the geometries to your workflow.

There are some surfaces that present relatively big differences ...

I'll open a new discussion for issue 2.

Thanks,

-A.

Attachments:

OK. I need to be fair and say that i never will suspect the data of the EPW.

Following this other thread i opened, i restarted from fresh the loading of the EPW. I've found that the file i was using has 0 Global Horizontal Radiation. I don't know how thisd can happen. Now i'm using an alternative file and the results make MUCH more sense now.

This leads again to the saying: Garbage in, garbage out. Always check your results and don't say that they shoulb be right because the computer says so.

So, from my point of view i can close this issue.

Thanks Mostapha and sorry for the bothering.

-A.

Hi Abraham. Thanks for reporting. It actually give me the hint that maybe we should add some data check in import epw file and genCumSky and give warning to user.

Hi Abraham,

I've only dipped my toes in LB/HB and as you know I tried doing a radiation analysis of an office building using the Ladybug 02_Radiation.gh template which you advised was wrong to determine indoor radiation.

http://www.grasshopper3d.com/group/ladybug?commentId=2985220%3AComm...

So a beginners question...Can physical model elements (modeled in Rhino or GH generated geometry like spandrels, sunshades, window apertures, glass planes) be used instead of the HB_GlazingBasedOnRatio component?...used as a sort of 'context" element to block insolation? If so is there a tutorial I can jump to that would better explain that process?

Hi Robert,

There is plenty of material to start from, if i understood your question/request.

I suggest all those wonderful video tutorials that Mostapha prepared for Daylight analysis using HB: https://www.youtube.com/playlist?list=PLkjfDmSc5OryXkWSt57ltJFU4qXD...

There are also excellent videos that Chris prepared for E+ simulations, but they can also be used for Daylighting purposes. See: https://www.youtube.com/playlist?list=PLruLh1AdY-SgW4uDtNSMLeiUmA8Y...

Basically the answer to your question is YES. You can use rhino models/GH generated geometry and use them for the simulation purposes. But i don't want you to get this answer as absolute. There are many considerations that according to them you want to use HB definitions, that in many cases make your life more comfortable. There are other cases where you do want to define your own model and input it on HB. So each case has its own constraints.

Hope it helps a bit.

-A.

Hi Robert,

If you can provide a simple example of your geometries I can put a Hydra together on how to prepare your geometry surface by surface.

Mostapha

M,

I've only modelled a building mass and context. Was going to model skins in either Rhino/GH or Revit but didn't do so becuase I was unsure about what kind of geometry LB/HB would accept.

Honeybee can handle mesh or breps. The workflow with brep is more straight forward. If you can share part of your file I can put a workflow together as I have been thinking to do it for a very long time.

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