Sorry for being so late to post an update here. You can see that I recently posted an explanation for why we have been so delayed with updating to the latest version of OpenStudio/E+.
But I am happy to say that we finally updated the development version of LBT Grasshopper to use OpenStudio 3.9 (and EnergyPlus 24.2) a few days ago. We should also have updated Pollination Rhino/Grasshopper installers that include OpenStudio 3.9 by the end of today.
With this, I removed the “fudge factor” that was trying to make up for the bug in EnergyPlus’s solar reporting and I ran some tests to confirm that things are much better with E+ 24.2. To give a visual comparison, this is what a fully-glazed, unconditioned, single-zone model with no internal loads was doing previously (with no fudge factors):
… and this is what it does now:
So nearly all of that “Unidentified Heat Loss” is now accounted for with Michael Witte’s fix to E+. Granted, if you look closely at those images, you will see that the new E+ isn’t 100% perfect as there is still a very tiny storage term there, which results from the E+ fix not being an exact report of the window heat balance but just a greatly improved version. But, it’s not off by more than 1% and, in the words of Michael Witte on his PR “Not perfect, but balancing within 0.2% is much better than 8%.”
So this will hopefully let us all sleep better knowing that our load balance graphics are very close to perfect representations of the real E+ load balance.