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Daylighting Fraction Controlled

asked 2019-11-15 17:32:55 -0500

nsimhai gravatar image

updated 2019-11-22 11:50:28 -0500

I have placed an illuminance map and daylighting control in a space, and applied the OS Radiance measure, but it does not seem to be beahving as I would expect. I have set the thermal zone's "Fraction of Zone Controlled by Primary Daylighting Control" to 15%. My understanding is that the Radiance measure creates a new schedule based on the daylighting control's setpoint, and applies this to 15% of the lighting power in that zone, leaving the remaining 85% on the original lighting schedule I've indicated for that load.

Inputs in Sketchup:

C:\fakepath\daylight control.JPG

C:\fakepath\zone daylighting.JPG

What appears to be happening instead is that 85% of the zone lighting load is getting the Radiance schedule, and the other 15% is removed entirely. See the interior lighting outputs for the zone named "S CLASROOMS 2ND FLR TZ".

Without daylighting: C:\fakepath\before daylighting.JPG

With daylighting: C:\fakepath\after daylighting.JPG

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answered 2019-11-18 18:15:38 -0500

That measure only supports simulating the effect of a primary control; it's also possible that the zone area percentage is not being applied properly, though your method for checking that seems open to error. Regardless, that measure was written as a proof of concept and development hasn't been supported since 2015 (arguably, even before that), so you get what you get. ¯_(ツ)_/¯

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Yeah I have only a primary control set up in the zone, that's why I'm confused. Is there a large difference in accuracy between the built-in E+ daylighting calculations and using the Radiance measure? i.e. should one not bother with Radiance?

nsimhai gravatar imagensimhai ( 2019-11-18 18:28:49 -0500 )edit

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Asked: 2019-11-15 17:32:55 -0500

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Last updated: Nov 22 '19