[Bldg-sim] Approx estimation of solar split from global?

[J. Alstan Jakubiec]

Hi Phil,

The gen_reindl program that comes with Daysim <http://daysim.ning.com/> 
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.

First you need to create a tab separated text file of the format *m d    
h(decimal)    gh_irrad* like the below.

    4    22 8.333333333    107
    4    22    8.416666667    121
    4    22    8.5    137
    4    22    8.583333333    151
    4    22    8.666666667    159
    4    22    8.75    169
    4    22    8.833333333    178
    4    22    8.916666667    184

Then the gen_reindl program can be run. -l is longitude (west positive), 
-a is latitude (north positive) and -m 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.
 > gen_reindl -m -120 -l -103.98 -a 1.37 -i input.txt -o output.wea

After running the command, the output in the output.wea file looks like 
this,

    4 22 8.333 12 103
    4 22 8.417 14 116
    4 22 8.500 17 131
    4 22 8.583 19 144
    4 22 8.667 19 151
    4 22 8.750 19 161
    4 22 8.833 20 169
    4 22 8.917 19 175

Where the 4th column is direct normal irradiation the the 5th column is 
diffuse horizontal.

Best,
Alstan

-- 
J. Alstan Jakubiec
Assistant Professor
Architecture and Sustainable Design
Singapore University of Technology and Design
8 Somapah Road, Singapore 487372
telephone: +65 6499 4530, e-mail: john_jakubiec at sutd.edu.sg
profile <http://asd.sutd.edu.sg/faculty/j-alstan-jakubiec/> | DIVA 
<http://diva4rhino.com/> | Mapdwell <http://www.mapdwell.com/en>

On 6/1/2015 2:04 AM, Philip Haves wrote:
> I'm looking for a simple tool (preferably free!) to estimate an 
> approximate split of hourly global solar irradiance into direct and 
> diffuse components.
>
> Any suggestions?
>
> Thanks!
>
> Phil
>

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