SolarAdjustTemperature - validation against ASHRAE55-2017

I recently got my hands on a copy of ASHRAE55-2017 and decided to do a quick validation check using the C4 validation table. I made some adjustments to the grasshopper script as to adjust inputs (Fbes, Tsol, fsvv etc.). I ended up with the following:

There is consistent errors at each of the validation rows which i isolated to line 1448 in the code (when doing the parallel calc). The formula:

hourERF = ((0.5 * fracEff * skyViewFac * (diffRad + (globHorizRad * groundR))+ (fracEff * ProjAreaFac * fBes * dirNormRad)) * winTrans[HOYS[count]-1]) * (cloA/0.95)

should be (to yield the results in the validation table)

hourERF = ((0.5 * fracEff * skyViewFac * (diffRad + (globHorizRad * groundR))+ ((ProjAreaFac/1.8) * fBes * dirNormRad)) * winTrans[HOYS[count]-1]) * (cloA/0.95)

with 1.8 being the DuBois surface area.

Thoughts? Willing to dive deeper on this as I use this component very frequently.


@chris @mostapha any thoughts?

We actually use the ASHRAE55 validation table in the tests of Ladybug[+]:

So, if you want something that you can be certain always aligns with ASHRAE55 perfectly, you might want to use Ladybug[+] instead of ladybug legacy.

But I think the fracEff (which seems to be the only thing you changed in your formula there), is equal to 1 / 1.8. So your two formulas there should be equal to one another.

Thanks for your response @chris. Will use ladybug[+] going forward.

Although 1/1.8 = 0.55 whereas fracEff is = 0.696 or 0.725 depending on posture so that is most likely the source of the error.