Window heat transfer
Hello all,
I already looked at previous questions but I still can not find an answer:
For a simple energy plus model, a room with one southside two pane glass window ( no frame, no divider, etc...)just glass:
(Surface Window Heat Loss Energy) is not equal to (Window Inside Face Net Surface Thermal Radiation Heat Gain Energy) and (Window Inside Face Convection Heat Gain Energy).
The calculation is for 1 am, so there is no solar radiation. There is no light and internal heat, so heat loss through inside window face should be only by convection and radiation. The difference is small but I wonder what cause this difference.
(Surface Window Heat Loss Energy) is a little higher than the sum of (Window Inside Face Net Surface Thermal Radiation Heat Gain Energy) and (Window Inside Face Convection Heat Gain Energy). This is also the same for single glass window, Why?
Thank you,
Comments
To clarify
In energy plus example also is the same: CmplxGlz_SingleZone_DoubleClearAir.idf
If we change the output variables to hourly, when there is no solar radiation (1 am), Windows Total Heat Loss Rate is a little higher than (WINDOW:Surface Inside Face Convection Heat Gain Rate) + WINDOW:Surface Inside Face Net Surface Thermal Radiation Heat Gain Rate.
Why they are not equal?
Thank you
A follow up question: how can we output the components of convection and radiation? I have two kinds of building materials and want to compare the change in radiation. But radiation is the same. How could that be true?