First,
G_global = G_horzdirect_Solar (i.e. G_direct_normal *SIN (solar_height))
+ G_Diffuse_Horz
I expect your differences are due to the interpolation that EnergyPlus
does.
At 02:10 AM 9/2/2016, theisped@xxxxxxxxx [EnergyPlus_Support]
wrote:
How do you extract the Global
radiation from Eplus? I've been looking into the weatherfiles and the
data entries for Global radiation does not seem to correspond with those
reported by EnergyPlus under following two outputs:
- Site Diffuse Solar Radiation Rate per Area
Diffuse solar is the amount of solar radiation in W/m2 received from the
sky (excluding the solar disk) on a horizontal surface.
- Site Direct Solar Radiation Rate per Area
Site Direct Solar Radiation Rate per Area is amount of solar radiation in
W/m2 received within a 5.7�° field of view centered on the sun. This is
also known as Beam Solar.
I'm aware that you have to adjust the direct solar with respect to solar
angle, but even then i do not seem to get the same results. I've been
using the following formula for the conversion:
G_global =
G_direct*cos(90-SolarAltitude)+G_Diffuse.
Thanks in advance for any assistance.
EDIT: By the way, the specific values i see in the weatherfile and from
EnergyPlus output is as follows:
At 12:00, the weather file reads: Global radiation: 103 W/m2 Diffuse
radiation: 63 W/m2 Direct radiation: 264 W/m2
Energy plus outputs (also 12:00) read: Solar Altitude: 11.2 degrees Site
diffuse: 50.5 W/m2 Site direct: 188 W/m2