Issue with Solar Radiation collection

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I've just noticed that you have also posted this same question on EnergyPlus_Support, to which I had questioned the constant direct and diffuse radiation in your epw file. After you explained you were overwriting the solar in EP using actuators (first I've heard of this feature) as you also explained here, I thought of something else that might explain the dissymmetry between the solar gain on the east and west facades. (following is quoted from my post on EnergyPlus_Support):

"Since you said you used a Monteith model that I've not heard of to generate the hourly profiles of solar radiation, I wonder if it's of European origin, in which case it might be giving you the solar radiation at the hour, while EnergyPlus and other North American simulation programs expect the solar radiation to be for the previous hour or averaged for 30 minutes before the time stamp. If this is what's going on, the solar you've calculated would be 30 minutes later than what EnergyPlus assumes it to be. This difference can have a major effect on the radiation during the sunrise and sunset hours, since in addition to the 30 minute shift, EnergyPlus will be cutting off the radiation when it thinks the sun is below the horizon."

"The easiest way to test if that's the cause of the dissymmetry between the east and west solar loads is to shift your building east by 7.5 degrees longitude. You could of course also calculate the solar at the 30 minute mark instead of on the hour."

Let me if that helps."

As a secondary comment: I don't think it's wise to post the same question simultaneously on multiple bulletin boards, or at least you should point out that fact and keep readers informed of all responses. Otherwise, as in this case, I'm reading stuff now that would have answered my questions on EnergyPlus_Support.

Joe

What is your weather file location? Western facades with higher solar gains is a pretty common result to see. The solar radiation on a surface is dependent on the direct normal, diffuse horizontal, and global horizontal radiation. As you may know, direct normal radiation is often highest between late morning and late afternoon, such as between noon and 5 pm. If you plot the Direct Normal Radiation from your weather file, I suspect you will see that during the time the peak occurs on the western facade, its higher, and during the time the peak occurs on the eastern facade, it is much lower.

When I plot results for a box model using a Sydney weather file, I get very similar results as you, with the western facade at almost double the peak of the east.

Update: since you overwrote your weather file data, then my above explanation doesn't hold true like it would for typical weather data. Though when I look at your model and plot the results, I don't get the same plot that you attached. Double check that you are outputting Surface Outside Face Incident Solar Radiation Rate per Area [W/m2]. When I plot this, the results are not identical but are very close to being mirror opposites of each other for the east and west facade on Jan 1, with a peak at 2597 W/m2 for Surface 3 and 2384 W/m2 for Surface 4.

You also need to consider Site Ground Reflected Solar Radiationwhich has some slight variation.