Hi Chris,
I just found out the surface temperature difference by comparing PixelCounting vs PolygonClipping.
My model has quite a few shading louvers. So I think maybe I should use PixelCounting in the Adaptive Comfort run.
My question is: how do I change the shadow calculation method in HB Adaptive Comfort Map recipe (I’m using LBT 1.6)? The recipe allows me to add additional string, but how to overwrite? Thanks.
Hi @XavierZhouLadybug ,
Sorry that I only just realized that you posted this several months ago but it was added to an unrelated topic and so I missed seeing it. It’s a good question because I debated a few times which of the two methods should be used in the comfort maps.
At the time that I am writing this post, all of the comfort map recipes currently use PolygonClipping. The main thing that drove the decision is the fact that the EnergyPlus PixelCounting method does not support shade transmittance at all (all shades are 100% opaque), which was going to be a deal breaker for many of the simulations that I imagined people would run with the comfort maps. You can see that this limitation is confirmed here by the EnergyPlus developers. Given that the only major advantage that the PixelCounting method seemed to have over PolygonClipping was that it was faster and used less memory when there were a large number of shades, it seemed like defaulting to PolygonClipping was the right thing to do.
So, if you’re still interested in this, I would first ask if any of the shades in your model there have a transmittance schedule assigned to them. If so, then it makes sense that the PolygonClipping temperature would be higher since this is accurately accounting for the shade transmittance while the PixelCounting is not.
If there is no shade transmittance in your model and you have good reason to believe that the PixelCounting method would be suitable for your case, let me know and I can at least tell you how to tweak the source code so that your comfort maps use PixelCounting.
