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

# Glare Simulation in Openstudio

Hello all,

I wanted to get some glare results in Openstudio. I know that Openstudio uses DGP for calculating glare and vertical eye illuminance+source luminance are important components of the formula. I have placed a glare sensor in my model and I assume that the location of this sensor represents the location of the eye and the direction of the arrow corresponds to the direction of view. But is that correct/sufficient to obtain accurate results?

Also, is there any way that I can view the results of vertical eye illuminance and source luminance?

Thanks

edit retag close merge delete

Sort by ยป oldest newest most voted

Technically, OpenStudio reports DGPs (DGP-simplified), which does not take specific source luminance into account, at least not source size and position index. It just calculates illuminance at the point, which is meant to represent the eye. So you have the cosine weighted integral of all the luminance in the hemisphere. It's very much a dumbed down metric, but it's easy and fast to calculate.

Yes, the glare sensor is meant to represent the (seated) eye (hence its default height of 4'0" AFF), and the arrow points in the direction of the viewer, or represents the primary view. You can add additional view vectors, or vantage points, arrayed about that point. They are evenly distributed about the point, for the full 360 degrees. The idea there was to support the "adaptive zone" concept by Jacubiec, albeit crudely.

The results are saved in output/glare.json; you get the 8760 values of DGPs and the eye illuminance they were calculated from. Unfortunately, we do not have a report measure that visualizes this data.

more

1

Thank you! But for analyzing the results, I was wondering if the 4 classes of glare (defined by Wienold) still apply to this DGP-simplified?

Also, in 'glare.json', does the value of "raw" correspond to the eye illuminance?

( 2017-03-06 17:57:51 -0500 )edit
1

The simplified metric is intended to be used with the same classes of glare, yes. However, you gotta (scholarly term) bear in mind that there is a large error potential for the metric due to the fact that source size and location are ignored. This presentation has some good discussion on how the correlation falls apart with the simplified versus image-based DGP methods.

The 'raw' value is the Ev (vertical illuminance) at the glare sensor's view(s). Probably should have named it Ev, eh?

( 2017-03-06 21:26:48 -0500 )edit