Simulating Light shelf with Honeybee plus Daylight coefficient

I have been trying to simulate the effect of a light shelf using the new daylight coefficient method. and I got strange results at the back of the room as it decreases when I add the light shelf. Is this reasonable, and are there ways to improve the effect of the light shelf. The aim was to run a parametric simulation to optimize the position and the size of the light shelf for this room.

I am already using 8 bounces, and was testing different radiance parameters but it is still not improving. I am attaching both images that were simulated with and without the light shelf, and how it looks in the model now,

The wall thickness seems to be almost equal to the length of the shelf outside the room. I am not sure you can get too much radiation into the room with those dimensions.

If you are looking to push light deeper into the room you’d have to increase the width of the window aperture, reduce the length of the lightshelf inside the room and also ensure that light shelf material is reflective enough to push all the light through.

If you are using HB[+] also ensure that, the ambient divisions are sufficiently high (-ad 10000 should be enough). The value for -lw should be lower than 1/ad (…eg 0.01 if -ad is 100 and so on).

1 Like

Hey Sarith,
Thanks… I changed the parameters of the wall thicknesses, the window width, and the light shelf length inside too. The settings were already high, -ad 25000, as i was using the default settings in the example file. I changed the specularity of the light shelf to 1, is this realistic if we consider it is a metal, or is it too much.

People have been tinkering with design of lightshelves for many years…here is a patent that uses both curvature and specularity to redirect light :

There has also been some published research on it: . An exhaustive parametric study on the climate-based application of lightshelves seems like a decent topic for research (especially now that have HB[+]). If you’ve gotten bored of spectral daylighting, this might be something new to look into !

Accurately simulating metallic lightshelves, especially the ones that are specular and redirect light and have caustics-based effects might be a challenge as we still don’t have photon mapping integration. If you are using DA, which will be on the workplane, ensure that the ceilings and walls are sufficiently reflective (>0.9 and >0.7 respectively). Additionally, UDI might be another metric worth looking into.


That was very helpful, I looked into ur comments, and hopefully will get some interesting results out of the simulation.
thanks alot,

Just to be safe, and be closer to the reality, let’s not forget about the dust which will cover the horizontal surfaces and will affect the reflectivity of the surface.