ambient bounces set to 0

Forum for users to discuss the DesignBuilder Radiance daylighting tools and ask questions

Moderator: DesignBuilder Support

Posts: 35

ambient bounces set to 0

Postby ondrejg » Fri Sep 19, 2014 12:53 pm


I found this tip in the help file: "It is possible to calculate the fraction of the working plane that has a view of the sky by setting the Ambient bounces calculation option to 0 and the Illuminance threshold display option to 0, then viewing the Floor Area above Threshold data in the Grid output."

However, when I set the ambient bounces to 0, the results come out with a daylight factor of 0 for the whole zone. Attached is a sample file. Am I doing something wrong?


Daylight test.dsb
(2.52 MiB) Downloaded 297 times
Luis Sousa
Posts: 372
Location: Stroud

Postby Luis Sousa » Fri Sep 19, 2014 2:03 pm


Are you using a sky model that includes direct illumination from the sun?

When the number of ambient bounces is set to 0 only direct sun/sky light patches are considered.

Posts: 35

Postby ondrejg » Mon Sep 22, 2014 12:21 pm


Thanks for your answer. However, there is one important point: Are direct sun AND sky patches considered? If yes, then it should show non-zero daylight in zone under overcast sky. When I run the simulation with 0 bounces on clear sunny day, I get the area of room which receives direct sunlight. With overcast sky I get no daylight in the room.
All I want is to find out fraction of the working plane that has a view of the sky. When using clear sunny day, the simulation gives me the area of which has a view of sun.


Posts: 7

Re: ambient bounces set to 0

Postby kpx » Thu Nov 03, 2016 10:13 am

I agree with ondrejg,
"ambient bounces" does not really mean BOUNCES since setting it to 0 it couses no daylight with skies without direct sunlight (beam).
There is a way to show only the arriving sky radiation (so only sky component and actually no bounces fron outside/inside obstruction and room enclosing surfaces)?
Thank's in advance

Return to “Radiance Daylighting”

Who is online

Users browsing this forum: No registered users and 1 guest