From: macrakis@osf.org (Stavros Macrakis)
Subject: Re: Need Info on Compact Fluorescents
Organization: OSF Research Institute
Date: 18 Aug 92 11:45:01

In article <25860027@hpcvra.cv.hp.com> susanw@hpcvra.cv.hp.com (Susan Wechsler) writes:

   ...replace my incandescent bulbs with compact fluorescents.  But, I
   do not care for the typically 'stark' light one gets from
   fluorescent light.  I am looking for information comparing compact
   fluorescents ..., and rating them according to how well they
   duplicate the color and warmth of incandescent bulbs.

There are two aspects of the `color' of fluorescent bulbs: the
correlated color temperature (CCT), which tells you how reddish
(`warm') or bluish (`cool') it looks, and the color rendition index
(CRI), which tells you how little it distorts color relationships.
`Starkness' is the typical effect of a low-CRI lamp (White, Lite
White, and Cool White are the worst, but Warm White is actually not
much better, although it IS warmer).

Compact fluorescents typically use rare earth phosphor technology to
get higher CRI's.  Most of them have a CCT of around 2700K, which is
similar to an incandescent bulb, and a CRI of about 85-90%
(incandescent and sunlight are 100%, cool whites are about 70%).

I personally find the 2700K lamps to look unnaturally pinkish, and
prefer to use 3000K lamps when possible (which are closer in color to
halogen lamps).  In fact, the 2700K lamps have slightly lower CRIs
than do the 3000K lamps, but I don't know if 3000K is available in
compact fluorescent.

So my recommendation is to look for lamps with a CCT of 3000K and a
CRI of 90% or more.

	-s

PS some more info below

----------------

Fluorescents are available in `correlated color temperatures' (CCT)
from about 2700K (the color of a 60W bulb, roughly) to something like
7500K (the color of (indirect) daylight).  They are called
`correlated' because only black-body sources really have color
temperatures.  CCT approximates the perceived color in terms of real
color temperature.

You can choose not only the CCT of a fluorescent bulb, but also the
quality of the light, measured by the color rendition index (CRI).
The CRI measures how much a given light distorts colors, and is NOT
closely related to color temperature.  Those orange sodium vapor
lights you see in tunnels, for instance, have a low CCT and very low
CRI.  Incandescents have a perfect CRI and a low CCT.  Daylight has a
perfect CRI and a high CCT (7500K).  Direct sunlight has a perfect CRI
and a high CCT (5000K).

The most common fluorescent bulb around is called Cool White (CW).  CW
has a medium CCT (4000K) and a medium CRI.  Lite White (LW) has a
medium CCT and a low CRI.  Warm White (WW), which is often recommended
for those preferring a nicer light, has a low CCT (3100K) and a medium
CRI.  For good quality light, look for either Deluxe series lamps (CWX
or WWX), which are high CRI but medium efficiency, or Specification
series lamps (SP or, even better, SPX), which are high CRI (but not as
high as Deluxe, and some feel they make colors look TOO vivid) and
high efficiency.
From: gt@hpfcbig.SDE.HP.COM (George Tatge)
Date: Tue, 18 Aug 1992 16:04:21 GMT
Subject: Re: Ridge Vents
Organization: HP SESD, Fort Collins, CO