[Radiance-general] RE: DF calculated in Radiance and Relux
Per Haugaard
perhaugaard at yahoo.dk
Mon Mar 31 02:46:11 PDT 2008
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Dear Thomas and other Radiance users,
Thank you very much for your reply. I used the following rtrace command instead:
rtrace -w -h -I+ -ab 6 -aa 0.1 -ad 1026 -as 256 -ar 512 DF_OfficeLL.oct < DFcoordinates.inp | rcalc -e '$1=($1*0.265+$2*0.670+$3*0.065)*179/10000*100' > OfficeLL.log
which reduced the calculated DF in radiance to pretty much match the ones calculated in Relux.
Then I changed the transmittance for the glazing from 0,72 to 0,58 and made a new octree and re-calculated the DFs. I here after used the above rtrace command.
However, this had no influence on the calculated DF at all. I have also tried to alter the '-ad', '-as' and the '-ar' with limit results.
How can that be?
Below I have listed my window.rad command:
#
# An emissive window
#
# synlig rudetype til illum
void glass window_glass_58
0
03 .63 .63 .63
# hullet i vaeggen
window_glass_58 polygon window5
0
0
12
8.116 16.8 0.9
11.1 16.8 0.9
11.1 16.8 2.5 8.116 16.8 2.5
window_glass_58 polygon window6
0
0
12
5.133 16.8 0.9
8.066 16.8 0.9
8.066 16.8 2.5
5.133 16.8 2.5
window_glass_58 polygon window7
0
0
12
2.1 16.8 0.9
5.081 16.8 0.9
5.081 16.8 2.5
2.1 16.8 2.5
The data used for the pane with a transmittance of 0,72 is similar exept from void glass window_glass wich is set to 3 0.78 0.78 0.78.
Since there should be nowhere else where I should change the settings for the zone when I alter the transmittance, how can the daylight
factors be similar for to dirrerent types of panes???
I apreciate any input on this.
Best regards
Per Haugaard
______________________
On 29 Mar 2008, at 07:21, Per Haugaard wrote:
> Dear Radiance Users,
>
> In order to double check the DF which I calculated in Radiance I
> also calculated these for the exact same room with all the same
> settings (reflectance, transmittance, dimensions, areas of the
> pane, reference plance, reductions factor = 1 in Relux and city
> (Oslo)) in Relux .
>
> Surprisingly since Relux is based on Radiance the DF which I
> calculated in Radiance are about 1.7 higher than the ones
> calculated in Relux (DF calculated in Radiance = 17 and the ones
> calculated in Relux = 15,3 0.6m from the facade).
Are you sure Relux is based on Radiance? According to my knowledge
only the visualisation
add-on 'Relux Vision' is Radiance based. The calculation part uses
another approach (radiosity
I think).
Anyway a difference of 70 % is something to worry about. I have
compared Dialux with
Radiance in the past and the results differed by 10-15%. Have you
double checked your
geometry?
> I have used the folowing gensky and rtrace command in Radiance:
>
> gensky 6 21 12 -c -a 59.9 -o -10.8 -m -15.00 -B 55.866
>
> rtrace -w -h -I+ -ab 20 -aa 0.1 -ad 512 -as 64 -ar 128
> DF_OfficeLL.oct < DFcoordinates.inp | rcalc -e '$1=($1*0.265+
> $2*0.670+$3*0.065)*179/10000*100' > OfficeLL.log
'-ab 20' - impressive! I usually don't go higher than 6. If your
afraid of missing some
tiny value in the third decimal you should use '-av' to set a
background value. One
way to find this is described in RwR using rvu, another is to check
the output of the
gensky program for the 'Ground ambient level' and adjust that for
your indoor situation
(1-2% of the outdoor level).
If you have a detailed geometry (small windows and openings) you
should also
increase '-ad' (4096), '-ar' (512) and '-as' (256). The speed penalty
here is less than
that of an increase in '-ab' so I tend to be pretty bold about these.
I have noticed that Radiance seems to add to your rtrace results the
higher you
set your '-ab'. I'd have expected the values to approach an upper
limit where a further
increase makes no noticeable difference. In reality I could add a
significant percentage
to the DF simply by increasing the '-ab' value. So I assume that your
extreme
difference might be a result of the very high '-ab' setting.
Regards,
Thomas
______________________
Per Haugaard,
Griffenfeldsgade 33, 2.tv
2200 København N
Denmark
mobil: +45 26 39 06 40
E-mail: perhaugaard at yahoo.dk
Trænger du til at se det store billede? Kelkoo giver dig gode tilbud på LCD TV! Se her http://dk.yahoo.com/r/pat/lcd
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