Hello Everyone,
In the following report, the simulated illuminance (artificial lighting) is
un-reasonably high than the measured illuminance. I suspect that the issue
may be in the lumen output (or candela multiplier) in the IES file. Please
have a look at the report.
Artificial lighting report: http://bit.ly/1qXigtU
May I request your suggestions on how this issue can be resolved ? How much
shall I reduce the Candela multiplier, if that is to be done ?
Best regards,
Vaib
Hi Vaib
It is common to apply a reduction factor of up to 50 % to the light output
of a luminaire. This accounts for
a) reduced output of the lamps due to age,
b) dirt buildup within the luminaire,
c) failing lamps (in large arrays, if all your lamps are working you don't
need that).
d) probably something else that I'm forgetting right now
You also have to account for dirt on the walls unless you used measurements
for the room surface materials. In your case the reflectance of the ceiling
will have a big influence on the results.
The nominal lumen output of 4300 may also not be correct for your
particular type of lamp. Make sure you're using one in your fittings that
has the same specs as the test lamp, otherwise you have to scale the output
proportionally.
For fluorescent T8 fittings a total reductions to 75% output seems
appropriate (my quick estimate). You can look up the standard reduction
values for the above points in the lighting manuals (IESNA or SLL).
BTW: You seem to have table surfaces in your room. Usually illumination
calcs are done on an unfurnished room.
Regards,
Thomas
On Thu, May 22, 2014 at 5:03 AM, Vaib <[email protected]> wrote:
Hello Everyone,
In the following report, the simulated illuminance (artificial lighting)
is un-reasonably high than the measured illuminance. I suspect that the
issue may be in the lumen output (or candela multiplier) in the IES file.
Please have a look at the report.Artificial lighting report: http://bit.ly/1qXigtU
May I request your suggestions on how this issue can be resolved ? How
much shall I reduce the Candela multiplier, if that is to be done ?Best regards,
Vaib_______________________________________________
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[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general
What command line syntax and options do you use with the ies2rad command to create your radiance definition of the light fixture? It could be an error with the particular manufacturer’s IES file, if they’ve somehow made the IES file incorrect in the process of normalizing the IES file and applying the 8.6 multiplier. In other cases IES files are sometimes reported with a candela multiplier of 1.0 (instead of normalizing them first). Can you test with another manufacturer’s IES file of similar distribution, efficiency, and lamp type (maybe Zumtobel Claris).
From: Vaib [mailto:[email protected]]
Sent: Thursday, May 22, 2014 6:04 AM
To: Radiance general discussion
Subject: [Radiance-general] How to verify an IES file ?
Hello Everyone,
In the following report, the simulated illuminance (artificial lighting) is un-reasonably high than the measured illuminance. I suspect that the issue may be in the lumen output (or candela multiplier) in the IES file. Please have a look at the report.
Artificial lighting report: http://bit.ly/1qXigtU
May I request your suggestions on how this issue can be resolved ? How much shall I reduce the Candela multiplier, if that is to be done ?
Best regards,
Vaib
____________________________________________________________
Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses
Thanks Thomas, Christopher
I have used "ies2rad -dm -t white -m 0.85 TX4948.ies". I will now check
with similar luminaire of another make, and also calculate a representative
Lamp Loss Factor as Thomas suggested.
Best,
Vaib
On 22 May 2014 18:44, Christopher Rush <[email protected]> wrote:
What command line syntax and options do you use with the ies2rad command
to create your radiance definition of the light fixture? It could be an
error with the particular manufacturer’s IES file, if they’ve somehow made
the IES file incorrect in the process of normalizing the IES file and
applying the 8.6 multiplier. In other cases IES files are sometimes
reported with a candela multiplier of 1.0 (instead of normalizing them
first). Can you test with another manufacturer’s IES file of similar
distribution, efficiency, and lamp type (maybe Zumtobel Claris).*From:* Vaib [mailto:[email protected]]
*Sent:* Thursday, May 22, 2014 6:04 AM
*To:* Radiance general discussion
*Subject:* [Radiance-general] How to verify an IES file ?Hello Everyone,
In the following report, the simulated illuminance (artificial lighting)
is un-reasonably high than the measured illuminance. I suspect that the
issue may be in the lumen output (or candela multiplier) in the IES file.
Please have a look at the report.Artificial lighting report: http://bit.ly/1qXigtU
May I request your suggestions on how this issue can be resolved ? How
much shall I reduce the Candela multiplier, if that is to be done ?Best regards,
Vaib
____________________________________________________________
Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general
Hi Thomas, Christopher,
I used a similar luminaire of different make (Zumtobel Claris, Thanks!
Christopher), and it gave quite similar results to the initial luminaire.
That means that initial IES file was fine (even with Candela Multiplier of
8.6). I then reduced the luminaire's brightness to 50% (as Thomas
suggested) by using "-m 0.5" in ies2rad. Now the simulated illuminance are
quite close to the measured ones.
Though I will calculate Lamp Loss Factor using the standard method to fine
tune the results further. Thank you !
Best regards,
Vaib
On 22 May 2014 19:09, Vaib <[email protected]> wrote:
Thanks Thomas, Christopher
I have used "ies2rad -dm -t white -m 0.85 TX4948.ies". I will now check
with similar luminaire of another make, and also calculate a representative
Lamp Loss Factor as Thomas suggested.Best,
VaibOn 22 May 2014 18:44, Christopher Rush <[email protected]> wrote:
What command line syntax and options do you use with the ies2rad
command to create your radiance definition of the light fixture? It could
be an error with the particular manufacturer’s IES file, if they’ve somehow
made the IES file incorrect in the process of normalizing the IES file and
applying the 8.6 multiplier. In other cases IES files are sometimes
reported with a candela multiplier of 1.0 (instead of normalizing them
first). Can you test with another manufacturer’s IES file of similar
distribution, efficiency, and lamp type (maybe Zumtobel Claris).*From:* Vaib [mailto:[email protected]]
*Sent:* Thursday, May 22, 2014 6:04 AM
*To:* Radiance general discussion
*Subject:* [Radiance-general] How to verify an IES file ?Hello Everyone,
In the following report, the simulated illuminance (artificial lighting)
is un-reasonably high than the measured illuminance. I suspect that the
issue may be in the lumen output (or candela multiplier) in the IES file.
Please have a look at the report.Artificial lighting report: http://bit.ly/1qXigtU
May I request your suggestions on how this issue can be resolved ? How
much shall I reduce the Candela multiplier, if that is to be done ?Best regards,
Vaib
____________________________________________________________
Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general
Vaib
I also used to do a quick parallel simulation in something like Dialux
that's specialized in artificial lighting simulations. If you feed it with
the same input values for maintenance factor and room reflectance you
should get a similar output as with Radiance. You need to be familiar with
these tools though because they have some hidden or implicit options that
you need to account for. But then, so does ies2rad, I think.
Thomas
On Thu, May 22, 2014 at 12:31 PM, Vaib <[email protected]> wrote:
Hi Thomas, Christopher,
I used a similar luminaire of different make (Zumtobel Claris, Thanks!
Christopher), and it gave quite similar results to the initial luminaire.
That means that initial IES file was fine (even with Candela Multiplier of
8.6). I then reduced the luminaire's brightness to 50% (as Thomas
suggested) by using "-m 0.5" in ies2rad. Now the simulated illuminance are
quite close to the measured ones.Though I will calculate Lamp Loss Factor using the standard method to
fine tune the results further. Thank you !Best regards,
VaibOn 22 May 2014 19:09, Vaib <[email protected]> wrote:
Thanks Thomas, Christopher
I have used "ies2rad -dm -t white -m 0.85 TX4948.ies". I will now check
with similar luminaire of another make, and also calculate a representative
Lamp Loss Factor as Thomas suggested.Best,
VaibOn 22 May 2014 18:44, Christopher Rush <[email protected]> wrote:
What command line syntax and options do you use with the ies2rad
command to create your radiance definition of the light fixture? It could
be an error with the particular manufacturer’s IES file, if they’ve somehow
made the IES file incorrect in the process of normalizing the IES file and
applying the 8.6 multiplier. In other cases IES files are sometimes
reported with a candela multiplier of 1.0 (instead of normalizing them
first). Can you test with another manufacturer’s IES file of similar
distribution, efficiency, and lamp type (maybe Zumtobel Claris).*From:* Vaib [mailto:[email protected]]
*Sent:* Thursday, May 22, 2014 6:04 AM
*To:* Radiance general discussion
*Subject:* [Radiance-general] How to verify an IES file ?Hello Everyone,
In the following report, the simulated illuminance (artificial lighting)
is un-reasonably high than the measured illuminance. I suspect that the
issue may be in the lumen output (or candela multiplier) in the IES file.
Please have a look at the report.Artificial lighting report: http://bit.ly/1qXigtU
May I request your suggestions on how this issue can be resolved ? How
much shall I reduce the Candela multiplier, if that is to be done ?Best regards,
Vaib
____________________________________________________________
Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general
I'm late to this party, but I'd add that Axel Jacobs recently added a great Perl script to Radiance called "ltview.pl" which is useful for sanity testing your converted ies files in native Radiance. The script is available here:
https://github.com/NREL/Radiance/blob/combined/src/util/ltview.pl/
...and it's based on a thing I wrote a while back, which is documented here:
http://www.rumblestrip.org/2004/05/10/ltview-a-radiance-utility/
The idea was to look at the actual Radiance light source description that gets created by the ies2rad utility, in actual Radiance, so you are truly seeing what you're gonna get in a Radiance simulation. It's helpful for confirming orientation, distribution, and intensity (by running "trace" commands in the rvu window).
And of course everyone else who has contributed here is spot on. Photometry files are not magic, they are simply formatted data that can contain errors in assumptions and input. The user must know how to read them and be able to do their own fact checking. Familiarity with luminaire testing methods (and there's a big difference between SSL and non-SSL sources) and the IES-LM-63 specification, as well as the whole light loss factor issue which has been discussed, are critical to getting an electric lighting calculation right.
-rob
Rob Guglielmetti
NREL Commercial Buildings Research Group
Golden, CO 80401
[email protected]
-----Original Message-----
From: Thomas Bleicher [[email protected]<mailto:[email protected]>]
Sent: Thursday, May 22, 2014 01:21 PM Mountain Standard Time
To: Radiance general discussion
Subject: Re: [Radiance-general] How to verify an IES file ?
Vaib
I also used to do a quick parallel simulation in something like Dialux that's specialized in artificial lighting simulations. If you feed it with the same input values for maintenance factor and room reflectance you should get a similar output as with Radiance. You need to be familiar with these tools though because they have some hidden or implicit options that you need to account for. But then, so does ies2rad, I think.
Thomas
On Thu, May 22, 2014 at 12:31 PM, Vaib <[email protected]<mailto:[email protected]>> wrote:
Hi Thomas, Christopher,
I used a similar luminaire of different make (Zumtobel Claris, Thanks! Christopher), and it gave quite similar results to the initial luminaire. That means that initial IES file was fine (even with Candela Multiplier of 8.6). I then reduced the luminaire's brightness to 50% (as Thomas suggested) by using "-m 0.5" in ies2rad. Now the simulated illuminance are quite close to the measured ones.
Though I will calculate Lamp Loss Factor using the standard method to fine tune the results further. Thank you !
Best regards,
Vaib
On 22 May 2014 19:09, Vaib <[email protected]<mailto:[email protected]>> wrote:
Thanks Thomas, Christopher
I have used "ies2rad -dm -t white -m 0.85 TX4948.ies". I will now check with similar luminaire of another make, and also calculate a representative Lamp Loss Factor as Thomas suggested.
Best,
Vaib
On 22 May 2014 18:44, Christopher Rush <[email protected]<mailto:[email protected]>> wrote:
What command line syntax and options do you use with the ies2rad command to create your radiance definition of the light fixture? It could be an error with the particular manufacturer’s IES file, if they’ve somehow made the IES file incorrect in the process of normalizing the IES file and applying the 8.6 multiplier. In other cases IES files are sometimes reported with a candela multiplier of 1.0 (instead of normalizing them first). Can you test with another manufacturer’s IES file of similar distribution, efficiency, and lamp type (maybe Zumtobel Claris).
From: Vaib [mailto:[email protected]<mailto:[email protected]>]
Sent: Thursday, May 22, 2014 6:04 AM
To: Radiance general discussion
Subject: [Radiance-general] How to verify an IES file ?
Hello Everyone,
In the following report, the simulated illuminance (artificial lighting) is un-reasonably high than the measured illuminance. I suspect that the issue may be in the lumen output (or candela multiplier) in the IES file. Please have a look at the report.
Artificial lighting report: http://bit.ly/1qXigtU
May I request your suggestions on how this issue can be resolved ? How much shall I reduce the Candela multiplier, if that is to be done ?
Best regards,
Vaib
____________________________________________________________
Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses
_______________________________________________
Radiance-general mailing list
[email protected]<mailto:[email protected]>
http://www.radiance-online.org/mailman/listinfo/radiance-general
_______________________________________________
Radiance-general mailing list
[email protected]<mailto:[email protected]>
http://www.radiance-online.org/mailman/listinfo/radiance-general
Hi Rob,
You are right, its better to check the converted IES file, to have
confidence in what ies2rad has converted (as Thomas also pointed out). I
just did mine using ltview.pl, and it looks okay to me. Distribution looks
apparently similar to the polar diagram. I have included the image from
ltview.pl in the initial report on cloud.
Thanks for letting me know about the script.
Best regards,
Vaibhav
On 23 May 2014 02:18, Guglielmetti, Robert <[email protected]>wrote:
I'm late to this party, but I'd add that Axel Jacobs recently added a
great Perl script to Radiance called "ltview.pl" which is useful for
sanity testing your converted ies files in native Radiance. The script is
available here:
https://github.com/NREL/Radiance/blob/combined/src/util/ltview.pl/...and it's based on a thing I wrote a while back, which is documented
here:
http://www.rumblestrip.org/2004/05/10/ltview-a-radiance-utility/The idea was to look at the actual Radiance light source description that
gets created by the ies2rad utility, in actual Radiance, so you are truly
seeing what you're gonna get in a Radiance simulation. It's helpful for
confirming orientation, distribution, and intensity (by running "trace"
commands in the rvu window).And of course everyone else who has contributed here is spot on.
Photometry files are not magic, they are simply formatted data that can
contain errors in assumptions and input. The user must know how to read
them and be able to do their own fact checking. Familiarity with luminaire
testing methods (and there's a big difference between SSL and non-SSL
sources) and the IES-LM-63 specification, as well as the whole light loss
factor issue which has been discussed, are critical to getting an electric
lighting calculation right.-rob
Rob Guglielmetti
NREL Commercial Buildings Research Group
Golden, CO 80401
[email protected]-----Original Message-----
*From: *Thomas Bleicher [[email protected]]
*Sent: *Thursday, May 22, 2014 01:21 PM Mountain Standard Time
*To: *Radiance general discussion
*Subject: *Re: [Radiance-general] How to verify an IES file ?Vaib
I also used to do a quick parallel simulation in something like Dialux
that's specialized in artificial lighting simulations. If you feed it with
the same input values for maintenance factor and room reflectance you
should get a similar output as with Radiance. You need to be familiar with
these tools though because they have some hidden or implicit options that
you need to account for. But then, so does ies2rad, I think.Thomas
On Thu, May 22, 2014 at 12:31 PM, Vaib <[email protected]> wrote:
Hi Thomas, Christopher,
I used a similar luminaire of different make (Zumtobel Claris, Thanks!
Christopher), and it gave quite similar results to the initial
luminaire. That means that initial IES file was fine (even with Candela
Multiplier of 8.6). I then reduced the luminaire's brightness to 50% (as
Thomas suggested) by using "-m 0.5" in ies2rad. Now the simulated
illuminance are quite close to the measured ones.Though I will calculate Lamp Loss Factor using the standard method to
fine tune the results further. Thank you !Best regards,
VaibOn 22 May 2014 19:09, Vaib <[email protected]> wrote:
Thanks Thomas, Christopher
I have used "ies2rad -dm -t white -m 0.85 TX4948.ies". I will now
check with similar luminaire of another make, and also calculate a
representative Lamp Loss Factor as Thomas suggested.Best,
VaibOn 22 May 2014 18:44, Christopher Rush <[email protected]>wrote:
What command line syntax and options do you use with the ies2rad
command to create your radiance definition of the light fixture? It could
be an error with the particular manufacturer’s IES file, if they’ve somehow
made the IES file incorrect in the process of normalizing the IES file and
applying the 8.6 multiplier. In other cases IES files are sometimes
reported with a candela multiplier of 1.0 (instead of normalizing them
first). Can you test with another manufacturer’s IES file of similar
distribution, efficiency, and lamp type (maybe Zumtobel Claris).* From:* Vaib [mailto:[email protected]]
*Sent:* Thursday, May 22, 2014 6:04 AM
*To:* Radiance general discussion
*Subject:* [Radiance-general] How to verify an IES file ?Hello Everyone,
In the following report, the simulated illuminance (artificial
lighting) is un-reasonably high than the measured illuminance. I suspect
that the issue may be in the lumen output (or candela multiplier) in the
IES file. Please have a look at the report.Artificial lighting report: http://bit.ly/1qXigtU
May I request your suggestions on how this issue can be resolved ? How
much shall I reduce the Candela multiplier, if that is to be done ?Best regards,
Vaib
____________________________________________________________
Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general
Hi Vaib,
just to add to Rob's comment. There is also a new ltpict.pl script that
renders a four-view representation of the light output distribution of
a light fitting or IES file.
Conceptually, the ltview/ltpict pair is simular to objview/objpict:
One is interactive, the other renders an HDR image.
I don't think ltpict helps you with your particular problem, but I
thought this thread provides a good opportunity for promoting it.
Regards
Axel
On 23 May 2014 09:52, Vaib <[email protected]> wrote:
Hi Rob,
You are right, its better to check the converted IES file, to have
confidence in what ies2rad has converted (as Thomas also pointed out). I
just did mine using ltview.pl, and it looks okay to me. Distribution looks
apparently similar to the polar diagram. I have included the image from
ltview.pl in the initial report on cloud.Thanks for letting me know about the script.
Best regards,
VaibhavOn 23 May 2014 02:18, Guglielmetti, Robert <[email protected]> > wrote:
I'm late to this party, but I'd add that Axel Jacobs recently added a
great Perl script to Radiance called "ltview.pl" which is useful for sanity
testing your converted ies files in native Radiance. The script is available
here:
https://github.com/NREL/Radiance/blob/combined/src/util/ltview.pl/...and it's based on a thing I wrote a while back, which is documented
here:
http://www.rumblestrip.org/2004/05/10/ltview-a-radiance-utility/The idea was to look at the actual Radiance light source description that
gets created by the ies2rad utility, in actual Radiance, so you are truly
seeing what you're gonna get in a Radiance simulation. It's helpful for
confirming orientation, distribution, and intensity (by running "trace"
commands in the rvu window).
Hi Dr.Jacobs,
For me ltpict.pl also have been useful as I can clearly check the light
distribution for both the orientations, in one shot. Thank you for the
scripts!
I've included image from ltpict.pl too in my initial report/slides.
Best regards,
Vaib
On 23 May 2014 15:15, Axel Jacobs <[email protected]> wrote:
Hi Vaib,
just to add to Rob's comment. There is also a new ltpict.pl script that
renders a four-view representation of the light output distribution of
a light fitting or IES file.Conceptually, the ltview/ltpict pair is simular to objview/objpict:
One is interactive, the other renders an HDR image.I don't think ltpict helps you with your particular problem, but I
thought this thread provides a good opportunity for promoting it.Regards
Axel
On 23 May 2014 09:52, Vaib <[email protected]> wrote:
> Hi Rob,
>
> You are right, its better to check the converted IES file, to have
> confidence in what ies2rad has converted (as Thomas also pointed out). I
> just did mine using ltview.pl, and it looks okay to me. Distribution
looks
> apparently similar to the polar diagram. I have included the image from
> ltview.pl in the initial report on cloud.
>
> Thanks for letting me know about the script.
>
> Best regards,
> Vaibhav
>
>
>
>
> On 23 May 2014 02:18, Guglielmetti, Robert <[email protected] > > > > wrote:
>>
>> I'm late to this party, but I'd add that Axel Jacobs recently added a
>> great Perl script to Radiance called "ltview.pl" which is useful for
sanity
>> testing your converted ies files in native Radiance. The script is
available
>> here:
>> https://github.com/NREL/Radiance/blob/combined/src/util/ltview.pl/
>>
>> ...and it's based on a thing I wrote a while back, which is documented
>> here:
>> http://www.rumblestrip.org/2004/05/10/ltview-a-radiance-utility/
>>
>> The idea was to look at the actual Radiance light source description
that
>> gets created by the ies2rad utility, in actual Radiance, so you are
truly
>> seeing what you're gonna get in a Radiance simulation. It's helpful for
>> confirming orientation, distribution, and intensity (by running "trace"
>> commands in the rvu window)._______________________________________________
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[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general