icacy or effi-
ciency; typical incandescent lamps produce less than
20 lumens per watt (lpw) while typical fluorescent
lamps produce about 60 lpw. Another drawback is
the short life of incandescents (750 to 2,000 hours)
compared with the 15,000 to 20,000 hours expected
from a typical 4-foot fluorescent tube.
Lamp manufacturers have responded to this
situation by developing compact fluorescent lamps
that are not much larger than incandescent lamps.
Unlike the more familiar long, narrow tube fluorescents.
these lamps are folded into a u-configuration to in-
crease lumen output dramatically. These 5- to 40-watt
lamps vary greatly in size, shape, and appearance.
Typically, the lamps simulate incandescent light, but
lamps that blend in with the fluorescent lamps com-
monly used in offices are also available. Color rendition
is good to excellent, and the lamps produce 30 to 69 lpw
Most compact fluorescents have a life of 7,500 to 10,000
hours, based on 3 hours of operation per start.
Applications
Compact fluorescent
lamps may be used as
replacements for incandes-
cents in a variety of wall
and ceiling fixtures, or in
table and desk lamps.
Screw-in adaptors and bal-
lasts that enable many of
these lamps to be used in
standard incandescent
sockets are available. Some
versions enclose the entire
lamp and ballast assembly
within a globe similar to an
incandescent bulb or a
reflector flood. Detachable
reflectors can be combined
with some of the lamps to
improve their effectiveness
in recessed ceiling fixtures.
Many compact fluores-
cents will operate in
ambient temperatures as
low as 0
0
F, making them
suitable for outdoor use.
Their operating life is ten
times that of a standard
incandescent lamp, which
makes them particularly
useful where lamps are
operated for long hours or
where scaffolding is required for relamping.
Locations where the lamps
are turned on and off
repeatedly, such as utility
closets, are not suitable for
compact fluorescents. The
table below illustrates
typical replacements for
incandescent lamps.
Replace this
incandescent
lamp
With this
For initial light
compact
output* that is:
fluorescent:
5-watt
about the same
7-watt
9-watt
13-watt
18-watt
two 13-watt
about 20% less
about 20% more
about the same
about 6% less
about the same
In new construction,
compact fluorescent sys-
tems may be preferable to
Standard
fluorescent sys-
tems in applications where
smaller sized fixtures are
desirable and illumination
requirements are moderate.
A variety of new fixtures,
specially designed for these
lamps, are now available.
Most compact fluorescent
systems operate at a low
power factor, about 50%.
This means that, if used in
sufficient quantities, com-
pact fluorescent lamps have
the potential to affect circuit
sizing and electrical meter-
ing. A professional should
be consulted if large
numbers of these lamps are
to be used. Ballasts with
high power factors are
coming on the market, but
cost slightly), more.
These product lines are
still in the process of
development; new lamps of
various colors, shapes and
wattages will undoubtedly
continue to appear on the
market. New developments
include lamps that provide
light output equivalent to
that of a standard 4-foot
lamp, but are less than half
as long.
Predicting Savings
The potential savings
from using compact fluo-
rescent lamps rather than
incandescent lamps can be
predicted by examining
each of the three compo-
nents of the annual operat-
ing costs for lighting: lamps,
labor, and energy.
Compact fluorescent
lamps are significantly more
expensive that incandescent
lamps. However, since the
fluorescent lamps have
much longer lives than the
incandescents, the number
of lamps purchased and the
labor costs for relamping
will be reduced. Some
compact fluorescent lamps
have integral ballasts that
must be discarded when
the lamps fail; others have
separate, reusable ballasts
or adapters that will outlast
several replacement lamps.
Significant energy savings
can be expected in both
the consumption and the
demand portions of the bill.
To estimate the kWh
consumption savings, first
find the number of watts
saved per fixture by sub-
tracting the wattage con-
sumed by the new lamps
from the wattage of the
original lamps. (Remember
to account for ballast losses;
compact fluorescent ballasts
usually draw 3 or 4 watts.
For bulb-and globe-shaped
lamps, most manufacturers
include the ballast losses in
the stated wattage.) Next,
multiply the wattage saved
by the number of lamps
replaced. and divide by one
thousand to convert watts
into kilowatts. Finally,
multiply by the number of
hours the lamps are used
each year.
If the building is charged
for demand and if these
lamps are usually operated
during the buildings peak
demand period, the de-
mand charges will also be
reduced. In addition, less
energy will be required to
cool the building because
less heat is produced by the
lights. Neither demand
charges nor cooling savings
are accounted for in the
sample calculations shown.
Typical
Calculation
One hundred decorative
lighting fixtures in a shop-
ping mall operate about
4000 hours annually; 13
hours each day, 6 days
each week. Each of these
fixtures uses a 60-watt
incandescent lamp. Replac-
ing these incandescent
lamps with 13-watt com- I
pact fluorescent lamps,
using screw-in ballasts, will
reduce energy, labor, and
lamp costs. The 13-watt
lamps, which consume 16
watts including ballast
losses, provide about the
same amount of light as the
60-watt incandescents and
last more than ten times as
long. The screw-in ballasts
need not be replaced when
the fluorescent lamps fail.
North Carolina
Examples
At
the newly remodeled
United Way building in
Raleigh, shallow recessed
fixtures with compact
fluorescent lamps are used
throughout the corridors.
Each fixture uses two 13-
watt lamps, for a total
connected load of 2.5kW,
including ballasts. The
installation provides even
illumination of 20 foot-
candles while using only
six-tenths of a watt per
square foot in the corridors,
which is a fraction of the
typical power budget for
corridor lighting. The small
fixtures leave room for
extensive ductwork in the
ceiling plenum. Outdoors,
thirty incandescent lamps
are being replaced with 5-
watt compact fluorescent
lamps.
Eighteen-watt compact
fluorescent lamps are being
used in some Benetton (the
Italian manufacturer of
clothing) retail stores
located in the Triangle area.
The Benetton licensee at
Crabtree Valley Mall in
Raleigh reports that his
electric bills are 45% lower
than those for his Benetton
store at Four Seasons Mall
in Greensboro, which has
fewer square feet but uses
a different (non-compact
fluorescent) lighting system.
He also feels that the
Raleigh store is exception-
ally bright and that the
warm color temperature of
the compact lamps shows
off the stores colorful
merchandise to great
advantage.
How To Begin
Contact your lighting
supplier or your local
electric utility for more
information on these lamps
and for advice on using
them in your facility. A
North Carolina lighting
supplier list is available
from the North Carolina
Alternative Energy Corpora-
tion.
If you are considering
using compact fluorescent
lamps to replace incandes-
cent lamps in existing
fixtures, measure your
fixtures to determine how
large the lamp can be. A 9-
watt lamp from one manu-
facturer will be a different
size and shape that a 9-watt
lamp from another manu-
facturer. For new construc-
tion or remodeling, a
variety of fixtures expressly
designed for compact
fluorescents are now
available.
No. of fixtures
Lamp type
Lamp cost
Rated lamp life
Operating hours
Annual kWh usage
Lamps used per year
Incandescent
100
60A
$0.65
750hr
4000hr/yr
24,000
533
Fluorescent
-same-
13w compact
$4.30
10,000hr
-same-
6,400
40
Implementation costs
Value of discarded incandescents
(50%x100x$.75)
Lamps and ballasts
(100x$24)
lnstallation@$500/fixture
Total initial investment
$2033
Annual operating costs
Energy@$.O65/kWh
Replacement lamps
Relamping labor@$2.50
Total operating costs
$1560
$416
$347
$172
$1332
$100
$3239
$688
Annual savings
Simple payback
Simple R.O.I.
$2551
about 10 months
125%