Getting daylight by raising glass VLT

grasshopper honeybee-legacy
1

Hello everyone, I´m doing preliminary daylight studies for a tall building in Mexico and I am getting weird UDI results as can be seen in the attached image.

I only changed the VLT value of the glass in each run 0.17, 0.25 and 0.38 left to right in the image and would seem that lower transmittance values give quite optimistic results. I´ve checked the normals of the geometry and tried with other files. I´ve run point in time illuminance tests that do make sence. It is the annual results that I´m concerned about. I´ve attached the grasshopper definition as well. I don´t know what I could be doing wrong.

I would be really grateful if someone can check it out.

Cheers.

Arturo


UDI190517.gh (879 KB)

2

You are using the 100-2000 Lux range within UDI to compare the performance of your building. As you start increasing visible transmittance of your glass, more number of points will be above the 2000 lux mark, thus decreasing the values within the 100-2000 category.

If you are concerned about estimating the increase in amount of Daylight as a function of VLT, Daylight Autonomy(DA, called DLA in Honeybee) or Spatial Daylight Autonomy (sDA) will be a better metric than UDI as both sDA and DA are measures of sufficiency.

3

Thank you very much for the clarification!. It does make sense under those terms.

Cheers.

Arturo