Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question

Use Radiance for thermal load calculation

asked 2015-12-25 15:43:02 -0500

Dinosaver gravatar image

Radiance is a great tool when we need to simulate daylight but it provides only illuminance values. Can we use Radiace results in thermal load calculations in E+? E.g. through using BCVTB or somehow else..? The question arises from E+ limitation for "Full internal" and "Full external" algorithms - the spaces must be convex. Radiance has no such limitation.

edit retag flag offensive close merge delete

3 Answers

Sort by ยป oldest newest most voted

answered 2015-12-28 10:27:18 -0500

updated 2015-12-28 12:06:18 -0500

Indeed, Radiance is quite a bit better suited to exploring geometries more complex than a box. Radiance also provides radiometric results by default (though only for energy in the visible spectrum), most people just immediately push those numbers through V-lambda since most Radiance users are interested in photometric answers. I digress.

Radiance's geometric prowess was exploited for an EnergyPlus-related Radiance utility released earlier this year, called "eplus_adduvf". This utility takes an idf as input and computes view factors for all the surfaces, or something. I don't think there's a manpage for it, but the source code is here.

I believe it was Tianzhen Hong at LBL who got the ball rolling on Greg Ward's (GregWard) development of eplus_adduvf, and probably knows the most about the proper application of the utility toward thermal load calculations. LBL also did some other work internally on this, but I don't know if anything was ever published. Andy McNeil (andyrew) presented the status of that work at the time, at the 2011 Radiance Workshop in Berkeley. Have a look here.

If only there was a model and API that would allow users to tie these elements together. (ahem) =)

edit flag offensive delete link more



The internal work done at LBL was intended to allow us to use BSDF data to distribute solar energy to the interiors while we waited for BSDF support to be added to Energy Plus. Once direct support for BSDF files was added to energy plus, we stopped using our work around. The side benefit of permitting non-convex spaces wasn't something we needed.

Andyrew gravatar imageAndyrew ( 2016-01-11 12:02:22 -0500 )edit

Our method was used for early stages of the work published in these articles, though I think we switched to the built in BSDF support before the final versions of these papers were published:

Andyrew gravatar imageAndyrew ( 2016-01-11 12:03:26 -0500 )edit

answered 2015-12-28 14:33:26 -0500

Archmage gravatar image

One path for using Radiance results in EnergyPlus's thermal load model is with the input object called SurfaceProperty:SolarIncidentInside. The idea is to schedule the solar gains on indoor surface faces with the schedule values coming from Radiance models of the inside solar distribution.

edit flag offensive delete link more

answered 2016-06-29 09:01:57 -0500

Dinosaver gravatar image

Any news so far in this area? Chance to write a measure for OS? Upcoming breakthrough in new version of E+..?

edit flag offensive delete link more



First of all, this is not an answer to the OP. Second, there is no news.

rpg777 gravatar imagerpg777 ( 2016-06-29 12:16:51 -0500 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer


Question Tools

1 follower


Asked: 2015-12-25 15:43:02 -0500

Seen: 388 times

Last updated: Jun 29 '16