[Radiance-general] Re: making my own ies file

[Fitzpatrick, Halley D]

Hi Chris,

I believe the <lumens per lamp> field is used to calculate fixture
efficiency (notice it is lumens per lamp, not total fixture lumens). If
you are not concerned with fixture efficiency, put any value you like
there. Osram HMI 4000 W/SE has a total lumen output of 380,000 lm, if
you'd like to have a realistic number there anyway.

Most photometric viewers can calculate the lumens out of a fixture
easily. I plugged your file (with an arbitrary number in the lumens per
lamp field) into a program called Photometric Viewer (from Acuity
Brands) and it showed the fixture to output 37,982 lumens. Based on the
number of lumens coming out of the Osram lamp, that would be about a 10%
fixture efficiency. Seems low, but then again, I don't know what a 4000W
Metal Halide fixture looks like anyway.

Hope that helps.

Halley

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