Daylighting simulations for different room depth

Dear expert,

About a month ago, I have asked you about the design of an outdoor test
facility. Below some results.

Cell height: 2.7 m and cell width: 5.5 m. The transparent facade faces
south and it is divided in 2 windows, the bottom one has a fixed shading
system composed by simple lamella at 45° tilt angle. For the upper one two
systems has been tested:

- Complex lamella for light redirection

- Internal light shelf (width 1.2 m) with clear glass

The cell is located in the northern Italy.

The reflectance coefficients used are the common one except for the ceiling
set at 0.9.

I have performed three (one for each depth) annual simulations
climate-based with the 3-phase method. Then, the UDI index has been
analyzed (images at the link below). Observations:

1. From your knowledge, are the results reliable?

2. From the 4 meters the two systems seems to be equivalent. Can it be
since the systems do not influence the daylight trend from that distance?

3. Until the 7 meter, the daylight trend seems to be equal comparing the
three scenarios. After, we have the largest differences.

4. It is interesting to note as the UDI300-3000 on the 9 m pass from the
60% of the working hours (image 45 - 9m) to almost 40% (image 45 - 10m)
going under the UDI>3000 extended the depth from 9 to 10m.

Here the images:

http://s8.postimg.org/w22xxny9h/45_8m.jpg

http://s8.postimg.org/ht3bfljqt/45_9m.jpg

http://s8.postimg.org/fd1i1r1o5/45_10m.jpg

Any comments on the results?

For the next step, I would like to use a reflectance coefficient very low
for the bottom vertical wall.

Many thanks in advance for the feedback.

Best,
*Giuseppe*

It could be that you need more -ab bounces, or more -ad rays traced in order to avoid the unexplained divergence you see for the areas farthest from the windows in the 10m deep room. This could also impact your drop from 60% to 40% UDI when increasing room depth to 10m.

It’s possible that the solutions do perform similarly at more than 4m from the glass, unless your lamella or your light shelf have special specular or prismatic materials or shapes intended to really redirect light farther into the space. By that distance from the window, the light has bounced so many times that the reflectance of the floor and ceiling probably have a bigger impact than either of two relatively comparable window systems. Or, at that distance the illumination could be reliant almost entirely on the view of the sky from each point on the workplane which could be similar for both systems at a distance.

2. From the 4 meters the two systems seems to be equivalent. Can it be since the systems do not influence the daylight trend from that distance?
3. Until the 7 meter, the daylight trend seems to be equal comparing the three scenarios. After, we have the largest differences.
4. It is interesting to note as the UDI300-3000 on the 9 m pass from the 60% of the working hours (image 45 - 9m) to almost 40% (image 45 - 10m) going under the UDI>3000 extended the depth from 9 to 10m.

···

From: Giuseppe De Michele [mailto:[email protected]]
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