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Open Studio Radiance Measure Capability and Limitation

asked 2018-09-18 20:38:25 -0500

zahro's avatar

Hello, I am new to learn Open Studio and EnergyPlus.

Recently, I want to have a daylight autonomy distribution result from my building model simulation.

I use open studio and energy plus to develop my building model, would it be possible for me to get the Daylight Autonomy Distribution from the radiance measure result?

As I know from the experience using the Radiance measure, I only could get the accumulated spatial daylight autonomy for area in my illuminance map.

I also read several question in UnmetHours like this, but I still don't understand the limitation and capabilities of radiance measure provided in Open Studio.

Does the radiance measure allow the user to change the daylight parameter calculation inside it such as changing the occupied hour and illuminance limit for the daylight autonomy distribution or is it limited to the IESNA standard (300 lux, 08.00 - 17.00) ?

If my model has a non-rectangular shape, can I obtain the accurate sDA calculation in open studio considering the limitation of rectangular illuminance map in the software?

Thank you for your consideration to answer my question.

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answered 2018-09-19 10:43:02 -0500

The Radiance measure published on the BCL is limited to working with the illuminance map data only, and as such it's limited to rectilinear grids. And the sDA reporting is fixed per the LM-83 standard, as you state. These are both limitations (among others) that we acknowledge in various publications about the Radiance work; there is no funding to make these improvements internally.

The beauty of the OpenStudio measure system and API is that you can easily(?) improve these capabilities yourself.

The calculation points for the Radiance measure are derived from the illuminance maps, but you could write your own function to rewrite them based on the geometry or whatever, and let the Radiance measure use those instead. Same for the metrics calculations; those happen downstream from the OpenStudio model so you could change the metrics report function to use different parameters, or make it an input (the sDA setpoint and hours are hard coded, but the others are automatically based on the daylighting control setpoint). The metrics functiom simply works on the points that are supplied to it, so if you rewrote the points files with points covering the real area(s), it'd be none the wiser, and you'd get valid, truly representative spatial daylight metrics. The big missing piece is lack of support for the 5-phase calculation method, which you kinda need for the ASE calculation. This is a bigger lift, unfortunately.

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Thank you for your explanation

zahro's avatar zahro  ( 2018-09-20 01:14:51 -0500 )edit

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Asked: 2018-09-18 20:38:25 -0500

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Last updated: Sep 19 '18