R: RE: TRNSYS: LIGHTING

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Hello FredThank you for your message.Do you use the same geometrical model for TRNSYS and Radiance, e.g. a model created with Google SketchUp?Best RegardsFrancesco Passerini

----Messaggio originale----

Da: fbetz at aeieng.com

Data: 01/05/2012 16.27

A: "francesco.passerini at inwind.it", "bldg-sim at lists.onebuilding.org"

Ogg: RE: [Bldg-sim] TRNSYS: LIGHTING

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Francesco,

I don?t believe TRNSYS can model daylighting, but I would email the TRNSYS list to be sure, trnsys-users at cae.wisc.edu.

What we do is model the daylighting using Radiance/Daysim, and then integrate those results into TRNSYS by adjusting the artificial lighting schedule.

In general it is difficult to model ASHRAE 90.1 system types in TRNSYS, but doable. Also, I would discourage you from modeling more than 20-30 zones as it gets
cumbersome in TRNSYS.

We typically use TRNSYS to design complex systems, and then adjust other software such as eQuest to match for compliance modeling. Sometimes an exceptional
calculation is required when the changes are just too much for eQuest.

Our experience is that model reviewers don?t understand TRNSYS as it doesn?t provide ?canned? reports like TRACE or eQuest that are familiar to them.

Good luck.

Fred Betz PhD., LEED AP

francesco.passerini at inwind.it's picture
Joined: 2012-01-13
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Francesco,

Yes, you?d have to export the geometry from sketchup into a format that radiance can read such as .3ds.

One concern is that the TRNSYS model won?t have all the internal geometry that Radiance expects such as light shelves, etc. Adjusting geometry within Radiance is very complex as its all based on editing a text file.

Therefore, create a separate copy of your TRNSYS Sketchup model, and then add any objects that have an effect on lighting (trees, other buildings, etc. ). Then export to .3ds so that can be imported into Radiance.

Good luck.

Fred Betz PhD., LEED AP

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Hi Fred, Francesco,

You could also use OpenStudio and the SketchUp plugin to create and export Radiance-ready geometry. We are working on Radiance+EnergyPlus integration in OpenStudio now, and the API allows you to write any translator you want; I believe a grad student has already created an OpenStudio --> CONTAM translator. One of the main ideals of the OpenStudio project is the "One Model" concept. You make one model, with all geometry/material/schedule/load assumptions, and at runtime, simulation-specific models are auto-generated on the fly.

We currently have this round-trip capability: OpenStudio-->Radiance-->EnergyPlus-->OpenStudio. The model is created in the SketchUp plugin, is further populated with energy model parameters in the OpenStudio application, the OpenStudio model is converted to a Radiance model, annual daylighting simulation is performed, an electric lighting schedule is generated (from dimming setpoint and occupancy schedules pulled from the OSM), a schedule is injected into a new OpenStudio model, which can then be run through EnergyPlus via the OpenStudio RunManager application; results can then be viewed in OpenStudio's RunManager application.

Further, Fred's point about internal geometry needed for Radiance is handled with OpenStudio "Interior Partition Surface" objects; these can represent furniture, interior walls, etc. Conversely, we have "Air Wall" constructions which can be applied to thermal zone boundaries that have no actual architectural geometry associated with them. These air walls are not exported to the Radiance model. With these two elements, one can build a model that is faithful to both the EnergyPlus model as well as the Radiance model.

Again, TRNSYS is not directly supported, but the OpenStudio Radiance translators may still be helpful for you in your workflows.

Check it out: openstudio.nrel.gov

Rob Guglielmetti IESNA, LEED AP

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Joined: 2011-10-02
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Dear Francesco,

The IES VE can do all of this and create the required reports for ASHRAE 90.1 - and all from one model. You can use our free SketchUp plugin to get the geometry from SketchUp into the VE - or you can create the geometry easily in the VE - run loads, CFD, and more.

I apologize if this sounds like a "sales pitch", but I'm merely trying to point out there are other options that you may find easier than the described workflow in this thread.

If you'd like a demo, I'd be happy to provide one.

Nathan Kegel

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