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Does the Radiance Daylighting Measure install illuminance sensors or do these need to already be present in the model?

asked 2018-10-17 10:18:19 -0600

jmbattis gravatar image

updated 2018-10-17 10:21:08 -0600

I'm a little confused by the language used in this measure. To me it suggests that the measure is simply switching the software that is used to perform illuminance calculations (in which case I would need to manually install sensors and controls in the appropriate zones). Is this understanding correct?

Thanks!

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answered 2018-10-17 11:11:12 -0600

Correct, the measure looks for daylighting controls -- and illuminance maps, both must be present -- extant in the model, and will perform an annual CBDM on the points found there, using Radiance. There are some measures out there that will place sensors for you, but nothing public that I know of that will do the illuminance maps for you.

Honestly, it makes more sense to do the illuminance points yourself, via measure, after the OSM has been translated to Radiance format. That way you're not constrained to the rectangular inputs like you are with an illuminance map. The illuminance map data is used for daylight metrics, so the more spatially accurate the points, the better.

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Great thanks! Just as a follow-up: I implemented the "Add Daylight Sensor at the Center of Spaces with a Specified Space Type Assigned" measure. This measure does not take sensor orientation as an input and when I viewed my model in Sketchup, I saw that all sensors were facing North (regardless of which facade the space is on). Does the orientation matter and, if so, is there a way to control it without manually adjusting each sensor? I'm also a little uncertain by the second part of your response. I add illuminance points after translating to radiance? This doesn't already need to be present?

jmbattis gravatar imagejmbattis ( 2018-10-17 11:23:32 -0600 )edit

OK so that orientation does not matter, since the sensor is calculating horizontal illuminance (luminous flux integrated over the entire hemisphere). That (z-rotational) orientation is used by Energy plus for some of its "glare" calculations, but if you are not relying on them, then no, the rotational orientation does not matter.

rpg777 gravatar imagerpg777 ( 2018-10-17 11:43:48 -0600 )edit

Sorry, that other bit was confusing. You need some illuminance map in the spaces for the Radiance translator to work, but you could do a secondary process in the Radiance measure itself that re-does all the illuminance map points and overwrites the .pts files that the Radiance ForwardTranslator writes out. Make sense? In short, the Radiance Measure is a proof of concept that tries to do a lot for you, and makes a lot of ASSumptions. It makes sense to kinda get in there on your own, make a copy of the thing, and write some new methods that kinda step into the workflow and do things better.

rpg777 gravatar imagerpg777 ( 2018-10-17 11:47:16 -0600 )edit

You could add a routine to the "add sensors..." measure that just plops in a dummy map that's wired to the space, it could be centered in the space and like 1mx1m, and then in (your) Radiance measure you could totally rewrite the maps points based on the actual geometry (what a concept!), or something. If you do it right, you could just insert yourself in the workflow there and let the original Radiance measure pick up from there, using your new points files for the calculations, and that data for the daylight metrics.

rpg777 gravatar imagerpg777 ( 2018-10-17 11:50:46 -0600 )edit
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Okay great! Thanks for the thorough response. So in summary: add sensors and arbitrary illuminance maps just to get Radiance to work and then edit the maps later if necessary.

jmbattis gravatar imagejmbattis ( 2018-10-17 15:53:21 -0600 )edit

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Asked: 2018-10-17 10:18:19 -0600

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Last updated: Oct 17 '18