What is the impact of glazing percentage and Visual Lighting Transmittance (VLT) on the Useful Daylight Illuminate level (UDI) of an office building?



Submitted by:  Olivier Brouard

Firm Name:

What kind of graphic is this? daylighting heat map


What are the primary inputs of the analysis that the graphic describes?  

Window-to-wall ratio, Visual Light Transmittance

List the primary outputs/metrics that the graphic describes?  

Useful Daylight Illuminance level (UDI)

What is this graphic showing? 

The graphic shows a heat map of 285 simulations computed using grasshopper parametric script and DIVA with radiance as a back engine. The vertical axis represents the Visual Light Transmittance of the glass and the horizontal axis the variation of window-to-wall ratio. The % represent the UDI of the office space, seeking to find the sweet point between zones with too high illuminance level over 2000 lux and those below an underlit threshold of 200 lux. Reduce VLT with higher WWR For best daylighting, higher WWR on north, lowest on south, middle value on east and west Lower VLT on south and west, higher on east and north

How did you make the graphic? 

The graphic is a conditional formatting rule using a color scale from low to high to represent visually the range of values computed from the output of the simulation.

What tools did you use to create the graphic?

What specific investigation questions led to the production of this graphic?

The production of this graphic was initiated through various internal design team conversation seeking for optimal daylighting penetration.

How does this graphic fit into the larger design investigations and what did you learn from producing the graphic?

This graphic is referenced as a back end to dimension an office space with an acceptable depth and optimized window to wall ratio and visual light transmittance glazing selection. PURPOSE Evaluation of daylight performance for an office floor Window-to-wall ratio (WWR) and visible light transmittance (VLT) varied in 5% increments

What was successful and/or unique about the graphic in how it communicates information?

A single simple output color-coded showing 285 simulations showing the sweet spot range to reach.

What would you have done differently with the graphic if you had more time/fee?

More locations could have been run showing how the latitude and longitude could impact daylighting penetration.