Accelerad & IES VE Radiance 2025.2.0.0

[Jamie Renwick]

Good afternoon,

I work as a Sustainability Consultant for a Building Services company in the UK and I've been involved in several Climate Based Daylight Modelling assessments for Schools, Offices, Leisure Centers etc... via the built in Radiance app within IES VE.

However, we've recently acquired a laptop with an NVIDIA Quadro P5200 with Max-Q design graphics card and IES have sent me the file that enables Accelerad.

I've completed an initial simulation without an errors and the quality of the UDI results looks much better and the simulation time was reduced from 1 hour 12 mins to 24 mins.

However, other than the definition of the input variables from here Accelerad and here 16.2.1. Description of Accelerad parameters are there any guides on what changing the parameters in the below would do to the simulation?

Any help or support would be appreciated.

Kind regards,

Jamie

[Jamie Renwick]

[Nathaniel Jones]

Hi Jamie,

As the -a prefix suggests, these parameters affect the ambient calculation, which is necessarily different in Accelerad's parallel execution than in Radiance's serial execution. If you are getting good ambient coverage, then there's not necessarily any reason to change them. You may see a time advantage in decreasing -ac, but this can also lead to poor ambient coverage, which will be obvious in renderings and is to be avoided. For details on the method used, see Irradiance Caching for Global Illumination Calculation on Graphics Hardware.

Best regards,

Nathaniel