How do I add materials in ALFA?

You can add any of the spectral material definitions from http://spectraldb.com/ to ALFA (for example, http://spectraldb.com/measurements/00540/ by downloading the spectral CSV). In addition, any measured data at a 10nm wavelength interval can be imported into ALFA.

Why are ground planes important?

The benefit of creating a ground plane is that it can receive shadows cast by the building itself and other urban objects (trees, other buildings, etc.). The default ClimateStudio ground albedo won't account for this -- it will 'reflect' light as if it is unshaded.

Can I create a custom Spectral Power Distribution (SPD) in ALFA?

You can make a custom SPD, which is loaded from this directory following the format of existing files using your specific manufacturer SPD information: c:\ProgramData\Solemma\ALFA\Luminaires\Spectra\