[EnergyPlus_Support] Summer Design Day -- Direct Solar Radiation Calculation

[Feng Kelvin <kelvin.tju@xxxxxxxxx>]

Hi group,

I am using my E+ v2.2 design day to simulate a simple concrete two rooms case. I found E+'s Direct Solar Radiation output result doesn't match with direct normal solar radiation calculation equation:  EDN = A / exp ( B / sin(beta) )

I pick up my case at 6:00am simulation results. E+ results give:

solar altitude angle, beta = 12.049 [deg]
direct normal radiation, EDN = 201 [W/m2]

I calculate solar altitude myself by inputting building altitude, declination angle and solar time and found the solar altitude angle, beta = 12.049 is correct. However, when I use

EDN = A / exp ( B / sin(beta) )
where A = 1093 [W/m2]
          B = 0.186

I got EDN = 449.98 [W/m2], not 201 [W/m2] calculated by E+.

Am I missing sth in this, or this has been fixed in new E+ version?

-- 
Best Regards

Kelvin

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