Hi all,

I'm using Diva to calculate annual illuminance and annual glare in a room (25' x 15' x 10') which has 5 windows (5.5' x 2.5') on the south wall and 2 glass doors on the west side. I was wondering what the best settings are for Radiance parameters to have credible and valid results. Also, I wanted to know if there are specific settings for the camera so that it would represent the human eye accurately when calculating glare.

Thanks,

Maryam

Tags: Camera, Glare, Illuminance, Parameters, Radiance, Settings

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Hi Maryam,

When you calculate annual glare in DIVA, the camera is automatically set to a 180 degree angular fisheye, which is the preferred projection of evalglare, the glare analysis tool distributed with DIVA. I strongly recommend to run a point in time glare analysis, and make sure that the appearance of the rendering matches up with the location in the space you would expect it to be from before running the annual analysis.

As for Radiance parameters, it will vary with your simulation model. A reasonably safe set of parameters would be,

  • -ab 7
  • -ad 2500
  • -ar 1000
  • -as 250
  • -aa 0.1

But you could likely get away with worse quality settings in most models.

Best,

Alstan

Hi Alstan,

Thank you for your response. I also have a question about the algorithm Diva uses for calculating annual daylight levels. As far as I know, according to a paper authored by you and Christoph Reinhart (http://www.ibpsa.org/proceedings/bs2011/p_1701.pdf), Diva uses Radiance as the simulation engine and employs daylight coefficient methods using DAYSIM. Is that still the case? I'm asking because this paper was for Diva 2.0 and I wonder if there is any change since that version. I would also appreciate it if you could tell me if there are other papers or references about Diva where I can find more information like that. The only paper that I have found so far is the one I mentioned.

Thank you!

Maryam

Hi Maryam,

That is still the case. Annual illuminance in DIVA is calculated using Daysim's DC approach.

Best,

Alstan

Thank you.

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