# Internal blinds schedule based on DGP from Imageless Glare study

Hi guys

At all the offices I’ve worked at, our only recommendation for glare have been “make sure to buy manual internal blinds/venetians, so that the occupants can shield themselves from glare”. But what does that mean in the real world? How many hours a year will the occupants have to have the blinds drawn due to glare in our modern highly glazed buildings?

For external shade, I could make a schedule based on the illuminance on the window surface, but occupants don’t react to high illuminance levels, they react to glare.

So what I would like to is:

1. Make a glare simulation without internal blinds to find the glare probability
2. Use the glare levels (DGP) to create a list of hours where the occupants would draw the blinds (read: a list of hours where the glare level exceeds a certain threshold)
3. Describe the hours over a year and over each month of the year, so that the building owner gets an understanding/estimate of how much the blinds will be drawn in real life
4. And then maybe rerun the glare simulation with the new blind schedule applied to each window in the building

So my question is, whether it is possible to make an internal blinds schedule based on annual DGP results from the imageless glare recipe?
I would need to make a list for each window in the building, as each occupant would draw and retract the blinds at different times during the day based on where they sit.

And if so, how would you define the DGP-level for which the internal blinds are drawn??
The tables below are taken from EN17037 and might be used as reference. But I am far from a glare expert though, so I’m having a hard time making the connection between the glare definitions in the norm and determining the glare level for which the blinds will be drawn.

/Mark