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Calculating Photosynthetic Photon Flux Density (PPFD) - Procedures
Specifying PPFD as a calculation metric is done in the Automatic Placement dialog. Therefore, calculation points must be placed on a surface or on an imaginary work plane, as specified in the dialog. Once PPFD has been selected as the metric, a PPFD Factor may be specified, which AGi32 will use to convert illuminance to PPFD in micromoles per second per square meter (μmol/s-m2). (An illuminance grid does not need to be specified.)
For general information on Photosynthetic Photon Flux Density calculations and conversion factors, click on the Concepts tab at the top of this topic.
AGi32 assumes that all sources contributing to the calculation grid have the same PPFD Factor, as selected in the PPFD Conversion Factors dialog.
PPFD can only be calculated with the Full Radiosity calculation method.
PPFD is not available as a Statistical Area metric, but it is available in the Schedules, Isolines, and Highlight Values commands.
To calculate PPFD:
- Begin with a Room or Object that will have the calculation points in or on it. Initiate the Automatic Placement command.
- Navigate to the Workplane or Tag the surface(s) where you wish to place the points.
- Set the Point Spacing.
- For the Calculation Type, select 5-PPFD.
- For the PPFD Factor, click in the field to see the ellipsis (...) button, and then click on that button to open the PPFD Factors dialog.
- Select one of the listed light sources, or enter a new source name in the blank field at the bottom (marked with an asterisk) as well as a PPFD Factor (the conversion factor) in the second column.
- You may delete a row that you have added by clicking on the row to highlight it and then pressing the Delete key on your keyboard.
- You cannot delete or edit factory-supplied entries (gray rows).
- Click OK to return to the Automatic Placement dialog. The PPFD Factor and the source description will appear below the Calculation Type (5-PPFD).
- Turn the Calculation Points On. (Default condition is Off.)
- Click OK to complete the command. The points will be placed as specified.