[Radiance-general] How to verify an IES file ?

[Thomas Bleicher]

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 <vaibhavjain.co at gmail.com> 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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