Daylight autonomy: individual interior point with too high local illuminance

Hi

I am simulating the daylight autonomy for the internal wall surfaces in a few rooms. When looking at the local illuminance values over the year, I have one point which gets much higher illuminances than the surrounding points. This happens on several days in summer, typically around 10 am: 5'000-15'000 lux compared to the surrounding points at about 300 lux. I tried running the simulations with 4 and 6 atmospherical bounces, but get the same pattern.

For me, the most logical reason would be that I have somewhere a gap in the ceiling/roof, though I cannot find any.

Any tips on what else to check or try?

I am assuming that it is not a bug, as the pattern is too consistent when simulating with slightly different parameters, with and without dynamical shading etc.

Thanks

Sarah

Tags: autonomy, daylight, illuminance, local

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Hi Sarah,

Its a little tough to say without seeing more of the model details. Can you share your files with us, either on the forum or via alstan@solemma.net?

Thank you,

Alstan

Hi Alstan

Thanks for your reply.

It is a room with 3 rows of 7 roof windows. I have narrowed it down to the daylight passing through one row of 7 windows with NE-orientation. Each of these windows causes one or two "points" on the east-facing wall where the local illuminance peaks.

- The peaks occur 63 to 72 days per year.

- Each peak occurs always at the same time of day, either hour 9.5 or 10.5.

- The peak internal illuminances are at 20-45 % of the exterior horizontal illuminance. Max. direct transmission allowed by geometry (shades+glazing) is 52 %.

- The timing of the peaks corresponds with the orientation of the windows and the solar position.

I think the logical conclusion is that we have direct sunlight passing through the windows at specific solar positions, hitting these points. I am running an extra simulation with a finer grid (0.1 m instead of 0.4 m) in this region to check.

Thanks,

Sarah

Hi Alstan

We are still not entirely sure what is happening here. I would like to send you the files, with the problem narrowed down to one small nodegroup. The model is quite large, I hope it is ok for you to take a look?

Thanks,

Sarah

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