[Radiance-general] Daysim/Gendaylit

[caria.roberto at tiscali.it]

Dear all,
I have a question about Daysim and Gendaylit.

I`m simulating a simple room to link the lighting performance to 
thermal ones and to do it i`m using Daysim and gendaylit.

I add into Daysim the Direct Normal Radiation and the Diffuse 
Horizontal Radiation from epw file (London).

Then I lunched the simulation in Daysim only with an external sensor 
point, first simulation with no bounces and then with ab= 4 and I got 
Direct and Global Horizontal hourly illuminance values (Lux) and 
Irradiance values (W/mq)

The parameters used to do it are:    

-ab 4 -ad 1024 -as 256 -ar 512 -aa 0.1 -lr 2 -st 0.015 -sj 1 -lw 
0.004 -dj 0.5 -ds 0.001 -dr 2 -dp 512

Check: there are little difference (1-2%) about Horizontal DIffuse 
and Direct Irradiance and during sunrise and sunset this difference is 
about 5% for Direect Irrradiance.

Then I created a sky by gendaylit (Radiance) for 3 hours (9:30, 12:
30, 15:30) and for three days (21 March, 21 June and 21 December), 
adding the hourly irradiance values from epw, to check the difference 
to illuminace provided by Gendaylit (Radiance) and Daysim by means of a 
external sensor point.
Data values are:

Time	  Dir Norm Rad           Diff Ho Rad	
Mar 09:30	     420.00	                182.00	
Mar 12:30	     422.00	                238.00	
Mar 15:30	     184.00	                167.00	
			
Jun 09:30	      425.00	                 292.00
Jun 12:30	      316.00	                 374.00
Jun 15:30	      505.00	                 222.00
			
Dec 09:30	      162.00	                   50.00
Dec 12:30	      513.00	                   69.00	
Dec 15:30	          0.00	                   10.00

gendaylit $months $days $hours -a 51.5 -o 0 -m 0 -W $direct $diffuse 
> skies/perez_sky_$months.$days.$hours.rad


Dome.mat

skyfunc glow skyglow
0
0
4 1 1 1 0             

skyglow source sky
0
0
4 0 0 1 180

oconv -w skies/perez_sky_$months.$days.$hours.rad dome.mat > 
oct/perez_sky_$months.$days.$hours.oct

rtrace -h- -w- $param -I -opv oct/perez_sky_$months.$days.$hours.oct 
< point.grd | rcalc -e '$1=$1; $2=$2; $3=$3; $4=($4*0.265+$5*0.670+$6*0.
065)*179' > result.illum.$months.$days.$hours.rs &

Parameters for rtrace are the same used to generate the sky by 
Daysim.

I have found these difference (illuminance):

Time	  Dir Norm Rad           Diff Ho Rad      Horiz_Direct Ill (lux) 
- Daysim     Horiz_Direct Ill (lux) - Gendaylit         
Mar 09:30	     420.00	                182.00	          
18000                                        
18213                                              
Mar 12:30	     422.00	                238.00	          
24302                                        24494   
Mar 15:30	     184.00	                167.00	           
6319                                          6294
			
Jun 09:30	      425.00	                 292.00                        
30854                                        31099
Jun 12:30	      316.00	                 374.00                        
26763                                        26899
Jun 15:30	      505.00	                 222.00                        
31907                                        31870
			
Dec 09:30	      162.00	                   
50.00                        
1133                                          1197
Dec 12:30	      513.00	                   69.00	          
10444                                        10519
Dec 15:30	          0.00	                   
10.00                               
0                                              0


Time	  Dir Norm Rad           Diff Ho Rad      Horiz_Glob Ill (lux) - 
Daysim     Horiz_Glob Ill (lux) - Gendaylit
Mar 09:30	     420.00	                182.00	          
41477                                        30154       
Mar 12:30	     422.00	                238.00	          
54439                                        39691   
Mar 15:30	     184.00	                167.00	          
25891                                        16146
			
Jun 09:30	      425.00	                 292.00                        
66633                                        49155
Jun 12:30	      316.00	                 374.00                        
70027                                        48607
Jun 15:30	      505.00	                 222.00                        
59991                                        46200
			
Dec 09:30	      162.00	                   
50.00                        
7539                                          4463
Dec 12:30	      513.00	                   69.00	          
20718                                        15751
Dec 15:30	          0.00	                   
10.00                         
1144                                           597


As you can look at there are important difference in the Horiz 
Diffuse Illuminace.

I don`t know if my way is right but I`d like to know something about 
it and what sky is better to use to get the horly internal illuminace 
values to link these ones to EnergyPlus or Trnsys.

Thanks a lot


Sorry for my personal english.


Roberto










    


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