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Hi Phil,<br>
<br>
The gen_reindl program that comes with <a
href="http://daysim.ning.com/">Daysim</a> does this pretty well,
although it isn't documented on the Daysim website. Below is some
info I sent to a student using global horizontal irradiation from
our weather station for daylight simulation purposes.<br>
<br>
First you need to create a tab separated text file of the format <b>m
d h(decimal) gh_irrad</b> like the below.<br>
<blockquote><font face="Courier New, Courier, monospace">4 22
8.333333333 107<br>
4 22 8.416666667 121<br>
4 22 8.5 137<br>
4 22 8.583333333 151<br>
4 22 8.666666667 159<br>
4 22 8.75 169<br>
4 22 8.833333333 178<br>
4 22 8.916666667 184<br>
</font></blockquote>
Then the <font face="Courier New, Courier, monospace">gen_reindl</font>
program can be run. <font face="Courier New, Courier, monospace">-l</font>
is longitude (west positive), <font face="Courier New, Courier,
monospace">-a</font> is latitude (north positive) and <font
face="Courier New, Courier, monospace">-m</font> is the time zone
in a multiple of 15 degrees from the meridian. The command below is
for Singapore, and you note that it is in the wrong time zone. UTC+8
* 15 = -120, despite a -103.98 longitude. <br>
<font face="Courier New, Courier, monospace">> gen_reindl -m -120
-l -103.98 -a 1.37 -i input.txt -o output.wea</font><br>
<br>
After running the command, the output in the output.wea file looks
like this,<br>
<blockquote><font face="Courier New, Courier, monospace">4 22 8.333
12 103<br>
4 22 8.417 14 116<br>
4 22 8.500 17 131<br>
4 22 8.583 19 144<br>
4 22 8.667 19 151<br>
4 22 8.750 19 161<br>
4 22 8.833 20 169<br>
4 22 8.917 19 175<br>
</font></blockquote>
Where the 4th column is direct normal irradiation the the 5th column
is diffuse horizontal. <br>
<br>
Best,<br>
Alstan<br>
<br>
-- <br>
<small>J. Alstan Jakubiec
<br>
Assistant Professor
<br>
Architecture and Sustainable Design
<br>
Singapore University of Technology and Design
<br>
8 Somapah Road, Singapore 487372
<br>
telephone: +65 6499 4530, e-mail: <a class="moz-txt-link-abbreviated" href="mailto:john_jakubiec@sutd.edu.sg">john_jakubiec@sutd.edu.sg</a>
<br>
<a href="http://asd.sutd.edu.sg/faculty/j-alstan-jakubiec/">profile</a>
| <a href="http://diva4rhino.com/">DIVA</a> | <a
href="http://www.mapdwell.com/en">Mapdwell</a></small><br>
<br>
<div class="moz-cite-prefix">On 6/1/2015 2:04 AM, Philip Haves
wrote:<br>
</div>
<blockquote cite="mid:556B4D3B.4020709@lbl.gov" type="cite">I'm
looking for a simple tool (preferably free!) to estimate an
approximate split of hourly global solar irradiance into direct
and diffuse components.
<br>
<br>
Any suggestions?
<br>
<br>
Thanks!
<br>
<br>
Phil
<br>
<br>
</blockquote>
<br>
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