[help] error message from running gencumulativesky

radiance-general
1

Dear Radiance experts,

I got a long list of error message in the terminal when running
gencumulativesky.exe in Win7

Error! Solar altitude < 6 degrees and Idh > 10 W/m^2 on day 1! Attempting
to continue!
Error! Solar altitude < 6 degrees and Idh > 10 W/m^2 on day 1! Attempting
to continue!
Error! Solar altitude < 6 degrees and Idh > 10 W/m^2 on day 2! Attempting
to continue!
Error! Solar altitude < 6 degrees and Idh > 10 W/m^2 on day 3! Attempting
to continue!
......
Error! Solar altitude < 6 degrees and Idh > 10 W/m^2 on day 347!
Attempting to continue!
Error! Solar altitude < 6 degrees and Idh > 10 W/m^2 on day 349!
Attempting to continue!
Error! Solar altitude < 6 degrees and Idh > 10 W/m^2 on day 359!
Attempting to continue!
Error! Solar altitude < 6 degrees and Idh > 10 W/m^2 on day 364!
Attempting to continue!
There were 4064 sun up hours in this climate file
Total Ibh/Lhb: 661.221506

The gencumulativesky command is:

gencumulativesky +s2 -a 51.15 -o -0.18 -m 0 -h -2 -G
./London_weather_file_global_and_diffuse_radiation.txt >
CumulativeSky_df_London.cal

The "London_weather_file_global_and_diffuse_radiation.txt" used contains two
columns of data extracted from London's epw file that are "global horizontal
radiation" and "diffuse horizontal radiation" for every hour of the whole
year.

The CumulativeSky_df_London.cal and a SunFile.rad files were generated. And
the SunFile.rad file contains 2165 sun position definitions.

May I ask:
1. Am I running the GenCumulativeSky.exe correctly?
2. What does the error message mean? and Why is the error generated?
3. Will the error affect the two files generated?

Thanks in advance!

- Ji

2

Dear Radiance experts,

I got a long list of error message in the terminal when running
gencumulativesky.exe in Win7

Error! Solar altitude < 6 degrees and Idh > 10 W/m^2 on day 1! Attempting
to continue!
[...]

May I ask:
1. Am I running the GenCumulativeSky.exe correctly?

If those are the only errors I expect that you do.

2. What does the error message mean? and Why is the error generated?

I haven't used GenCumulativeSky but from what I remember from the discussion
of this tool GenCumulativeSky uses gendaylit to create sky models. Gendaylit
has difficulties with low sky angles and doesn't create useful sky
descriptions for these times of day. There is only one or two errors per day
so I assume the errors happen for early morning or late evening (altitude <
6 degree). To solve this error properly we need a better gendaylit program.

3. Will the error affect the two files generated?

I would expect that these entries in your climate file are simply not
represented in the the cumulative sky model. A way to work around this might
be to hack gencumulativesky to provide gendaylit with explicit sun positions
and artificially increase the altitude to be above 6 degree.

Regards,
Thomas

ยทยทยท

On Sat, Jul 23, 2011 at 8:03 AM, Ji Zhang <hope.zh@gmail.com> wrote: