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How can I calculate daylight autonomy from energy plus -Illuminance output (that is point in time)?

asked 2014-11-07 10:47:44 -0600

hema gravatar image

updated 2017-05-04 08:54:33 -0600

I have energy plus illuminance map output for each day and each hour in .csv file type.I need to calculate daylight autonomy from that. Please help.

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This sounds like you are using OpenStudio, correct? If so, do you have a DaylightingMetrics.csv file in your project file support directory?

keb gravatar image keb  ( 2014-11-07 11:31:47 -0600 )edit

Yes, I have used open studio. Actually I need a tool that takes the illuminance map output and computes the daylight autonomy values. Or if any one can help me to use excel (or equivalent) to compute the autonomy values.

hema gravatar image hema  ( 2014-11-07 11:45:27 -0600 )edit

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answered 2014-11-07 11:54:35 -0600

If you have the daylight illuminance, all you need is the illuminance target (setpoint) -- which you can get from the daylighting control point in the EnergyPlus model -- and then it's just a simple calculation for DA:

if daylightIlluminance >= illuminanceSetpoint DA=1 else DA=0 end

Typically, DA is calculated spatially (i.e. for all the points in the illuminance map), for the entire year, and then is plotted with respect to the percentage of the year (usually occupied hours) that DA is met. If you have the values in a .csv file already, you could whip up something in Excel or the plotting tool of your choice to visualize this data easily.

For what it's worth, OpenStudio exports DA (as well as cDA and UDI) to a csv file for you automatically, if you use Radiance for your daylighting simulation engine (in lieu of EnergyPlus' built-in engine). If you look in the project directory, locate the file /run/1-Ruby-0/DaylightingMetrics.csv. This has a space-by-space summary of DA, cDA, and UDI. You get the total-hours and percentage-of-analysis-period each metric's standard is met, for daylit hours, occupied hours, and daylit+occupied hours -- all based on the setpoint found in the space's primary daylighting control point.

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Thanks for the answer. Actually I have an .idf file (which has CFS data).This file generates illuminance map output from energy plus. I understand the concept of DA, but to calculate it manually is a tidious job..I want to know if i can directly use this .idf file in any other tool/software to calculate DA?

hema gravatar image hema  ( 2014-11-07 12:09:19 -0600 )edit

Please see this reply for additional detail.

rpg777 gravatar image rpg777  ( 2014-11-07 15:52:13 -0600 )edit

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Asked: 2014-11-07 10:47:44 -0600

Seen: 921 times

Last updated: Nov 07 '14