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NREL / EnergyPlus

EnergyPlus™ is a whole building energy simulation program that engineers, architects, and researchers use to model both energy consumption and water use in buildings.
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Negative Surface Window Total Absorbed Shortwave Radiation Rate #5591

Open JasonGlazer opened 8 years ago

JasonGlazer commented 8 years ago

When working on #5312 noticed that many files were causing diffs when line was added to make sure that the three following output variables were never negative:

Surface Window Total Glazing Layers Absorbed Solar Radiation Rate W
Surface Window Total Glazing Layers Absorbed Shortwave Radiation Rate W Surface Window Total Absorbed Shortwave Radiation Rate Layer 1 W

Which are all based on QRadSWwinAbs. Code as added in HeatBalanceSurfaceManager in many places after QRadSWwinAbs to ensure that zero was the smallest value but this caused lots of diffs so it was split out in a separate issue.

I added the output variables to the RefBldgSmallOfficeNew2004_Chicago.idf and it shows some negative absorption values. See the spreadsheet. Columns E to BO are the new variables and rows below 50 show the negative numbers some as large as -34W. See:

https://github.com/NREL/EnergyPlusDevSupport/tree/master/DefectFiles/5000s/5591

mjwitte commented 8 years ago

It may not be enough to just clip QRadSWwinAbs at 0. Is it calculated independently, or is it the remainder of Incident less Reflected and Transmitted?

EnergyArchmage commented 8 years ago

The windows can transmit shortwave from the zone to the outside. Make sure these negatives aren't related to that.