What would be the proper way to simulate partially open roller shade?

Hi all,

I have been curious about this for quite a while, but what do you think is the most proper way to stimulate a partially open shade with the shade opening/close status vary by the hour?

My idea was to divide the entire window by two parts (shaded part and unshaded part); essentially to have two windows side by side.

While I am not aware of a way to implement shade control in Radiance, my solution was to have several full-year simulations each correspond to a different shade opening fraction and then post-process the results by picking the illuminance results from all of these full-year simulations based on shade status of each hour.

Am I doing it right through?

Thanks in advance

Hi Zha(?),

I believe that’s a fairly well-used approach now (I first used it in 2004/5 for modelling the blinds in the New York Times evaluation). It also has the advantage that you can investigate numerous control algorithms from the precomputed illuminance data (which should be, computationally, a swift process). Provided the number of discrete states that you need to account for is not that great, the approach has the attraction of conceptual simplicity.


John Mardaljevic PhD FSLL FIBPSA
Professor of Building Daylight Modelling
School of Architecture, Building & Civil Engineering
Loughborough University
Leicestershire, LE11 3TU, UK

Daylight Experts Ltd.
Expert Witness | Simulation | Measurement | Conservation

Associate Editor Lighting Research & Technology

Hello @John_Mardaljevic,

Perfect! Thank you for your advice!