There are two places I have been able to find reporting on diffuse
radiation in eQuest using California TMY2 weather files. The first is
"Surface diffuse solar rad, after shading (Btu/hr-ft2)" which is
reported under Variable Type - Exterior Wall, the other is "Clear day
diffuse horiz solar rad x CLDCOV (Btu/hr-ft2)" reported under Variable
Type - Global. Other diffuse radiation reporting variables do not
appear to be populated.

Chris D. Buntine, CEM, LEED AP