Simulating fiber optic cables in Radiance

grasshopper honeybee
1

We have a project where we would like to simulate the use of fibre optic cables to illuminate an underground train station.

The way this works is that sunlight collectors are mounted on the roof and follow the orientation of the sun throughout the day. Each collector directs the sunlight through fibre optic cables to a ceiling light fixture underground. The idea is to have free, quality daylight in underlit spaces, at least for the time periods in which the sun is out. For reference: https://www.parans.com/parans-light/how-it-works/

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This also means that the light intensity (and color) changes over time. How would I model this in Honeybee?

In this datasheet it says that one of the products emits 8800lm when the solar illuminance is 100000lx (for short cable lengths):

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My instinct is to use the direct normal illuminance values from the weather file to create a lighting schedule (in lumen). However, how do I connect this schedule to Honeybee/Radiance?

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fibre optic cables.gh (540.7 KB)

There don’t appear to be ies files for the above products so I just used another one from the internet: 8333691253300.ies (1.9 KB)

2

This approach, and the datasheet from the manufacturer, does not make a whole lot of sense (to me at least). For one, you will have to generate a separate IES file for every value of solar illuminance, effectively running 1000s of independent ray-trace calculations over and above your annual daylight simulation.

Anyway, to answer your question directly, you cannot connect the schedule to the IES file that you have posted. That IES file appears to be in Absolute Photometry format, implying the light output of the luminaire in the simulation is based on candela values alone. You could, however, scale up and down the candela multiplier to accomplish what you want to.
For example, if the luminaire is rated for “solar illuminance” of 100000 lux and the measured value from your schedule is also 100000 lux, then the candela multiplier will be 1. For 50000 solar illuminance of 50000 lux, the candela multiplier would be 0.5 …and so on.

Regards,
Sarith

3

Hi! Did you ever find a solution for this? And if so - Could you please share the script?