Gerry Deitzer gd3 at UMAIL.UMD.EDU
Tue May 19 10:47:30 EST 1998

The response below has it backwards.  27 umol/m2/s = ca. 2,000 lux or ca. 200

Gerald F. Deitzer

Warwick Silvester wrote:

> Can someone help me compare apples and oranges?
> I made some light intensity measurements in my lab using a quantum sensor
> for PAR (400-700 nm), so the units are umoles photons per m2 per sec.  My
> purpose was to help our operations folks design better room lighting.  I
> realize that architects are used to measuring light in units such as lumens
> or foot-candles.  My problem is to try to convert.  I know it can't be done
> exactly, because one is measuring different things.  But assuming the
> spectral distribution of a typical fluorescent light bulb, does anyone have
> a rough approximation of a conversion?
> Carl S. Pike                             (717) 291-3958
> Department of Biology                    FAX (717) 399-4548
> Franklin and Marshall College            Internet  C_PIKE at ACAD.FANDM.EDU
> P.O. Box 3003
> Lancaster, PA  17604-3003  USA
> PAR measurement under cool white fluorescent of 27 micro moles is equal to
> c. 200 lux ie 200 lumens per m2 or c. 2000 foot cadles (lumens per ft2).
> This ratio only holds for the particular light source but will be generally
> OK for  most fluorescents
> Warwick Silvester                      Ph. +64-7-838 4613  and voicemail
> Dept of Biological Sciences          Fax +64-7-838 4324
> University of Waikato                  Email w.silvester at waikato.ac.nz
> Hamilton, New Zealand

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