HemiView - How can I get site factors ISF DSF and GSF from a particular photo for a particular day or for a range of days?
ISF: indirect site factor is time-invariant
DSF: you can calculate daily DSF values by summing DirAb and DirBe (or DirAbU and DirBeU) columns in the TimeSer sheet and dividing one by the other
GSF: is defined as (direct + diffuse below) / (direct + diffuse above). To calculate a daily value:
- Calculate direct above and below as for daily DSF (above).
- To approximate diffuse above, start with the annual DifAb (or DifAbU) value in the Values sheet, apportion according to the monthly weighting in the DifMonth sheet, and divide by the number of days in the month.
- Calculate diffuse below by multiplying diffuse above by ISF.
For values spanning a series of days, repeat the above operations for each day and sum the radiation values before calculating the site factors.
For periods of a month or more:
DSF: you can calculate monthly DSF values by taking the appropriate values from the DirAb and DirBe sheets, and dividing one by the other.
GSF: is defined as (Direct + Diffuse below) / (Direct + Diffuse above).
- Take Direct above and below from the DirAb and DirBe sheets.
- Calculate Diffuse above as DifAb annual value multiplied by the appropriate month fraction from the DifMonth sheet
- Calculate Diffuse below by multiplying Diffuse above by the ISF value