This file contains Appendix A (Lighting Technology Characteristics) from
Vorsatz, Diana, Leslie Shown, Jonathan G. Koomey, Mithra Moezzi, Andrea
Denver, and Barbara Atkinson. 1997. *Lighting Market Sourcebook*. Ernest
Orlando Lawrence Berkeley National Laboratory. LBNL-39102. December.
Contact Leslie Shown (LJShown@lbl.gov) with questions on this report, or
go to the web page http://enduse.lbl.gov/Projects/LMS.html.

## LAMPS

### **Defining The Technical Characteristics of Lamps**

Various types of lamps differ from one another in numerous ways such as
how energy-efficient they are, what color of light they produce, whether
or not the level of light they produce dims over time, and whether or
not they can be dimmed by the user. Below, we define some of the
important characteristics by which lamps are often assessed and
compared.

[Lamp Wattage:]{.underline}

Lamp wattage is a measure of the power input to a lamp, measured in
watts (W).

[Efficacy:]{.underline}

The energy efficiency of lighting is referred to as \"efficacy\".
Efficacy is calculated by dividing the quantity of the light emitted by
the lamp (in lumens) by the power input to the lamp (in watts):

![](media/image1.emf){width="4.097222222222222in" height="0.375in"}

Different lighting mechanisms have different efficacies. The theoretical
maximum efficacy is 683 lumens/watt (lm/W) for a yellowish-green light.
The efficacy of a "pure" white light with equal energy at every
wavelength of the visible spectrum is about 220 lm/W, but a light that
is white in appearance can have efficacies of over 350 lm/W. The
lighting technologies available today have maximum efficacies over 100
lm/W for white lights, and up to 140 or 150 lm/W for yellow lights.

[Rated Lifetime:]{.underline}

The average rated lamp life of a given lamp type is the number of
operating hours after which only half of a large group of lamps are
still operating; this definition allows for the lifetimes of individual
lamps to vary significantly from the average (IES 1993) . Commonly used
incandescent lamps have relatively short rated lifetimes (\_750-3000
hrs); compact fluorescent lamps have rated lifetimes of about 10,000
hours; full-size fluorescents have rated lifetimes ranging from
12,000-20,000 hours; and general-use high-intensity discharge lamps have
rated lifetimes ranging from 3500-29,000 hours.

[Color Temperature:]{.underline}

A lamp\'s color temperature is a measure of the color appearance of the
lamp\'s light, expressed in degrees Kelvin (K). Conceptually, color
temperature is based on the fact that the emitted radiation spectrum of
a blackbody radiator depends only on temperature. A given lamp\'s
\"correlated\" color temperature is the temperature of the blackbody
closest in temperature to the light source. \"Warm\" white light that
appears yellowish or reddish in color is emitted by lamps with low color
temperatures (3000 K and below). \"Cool\" white light appearing bluish
in color is emitted by lamps with high color temperatures (4000 K and
above). **Table A.1** provides the approximate color temperature of
common light sources.

[Color Rendering]{.underline}:

Color rendering refers to the effect of a light source on the color
appearance of objects in conscious or subconscious comparison with their
color appearance under a reference or standard light source of the same
correlated color temperature. The color rendering properties of a lamp
are expressed in terms of a *color rendering index* *(CRI)*, which has a
value of up to one hundred. The higher a lamp\'s CRI (the closer to
100), the less a color shift occurs compared to the reference source. In
general, lamps with CRIs of 70--100 are considered to render color
excellently, a CRI of 60--75 is considered good, 50--60 is considered
fair, and less than 50 is considered poor (Ontario Hydro 1992) . Some
lamp types, such as low-pressure sodium, have CRIs of less than zero
(Clear 1996) . **Table A.2** provides approximate CRIs for common light
sources.

[Lumen Maintenance:]{.underline}

Typically, lamps continue to draw approximately the same amount of power
and yet produce fewer lumens as they age.[^1] A lamp\'s lumen
maintenance refers to the extent to which the lamp maintains its lumen
output, and therefore efficacy, over time.

[Dimmability]{.underline}:

Whether or not a lamp is dimmable refers to the user\'s ability to vary
the lumens that it emits. Lamp dimming is important for two reasons:
aesthetic lighting effects and energy conservation. Incandescent lamps
can be easily dimmed using a simple device to lower the voltage across
the lamp filament. Fluorescent lamps can be dimmed using dimming
ballasts; almost all dimming ballasts used today are electronic. An
electronic dimming ballast alters the output power to a lamp by sending
a low-voltage signal to the output circuit (Eley Associates 1993) . Some
high-intensity discharge (HID) lamps are dimmable with specialized
ballasts.

> Table A.1. The Color Temperature of Common Light Sources

  ------------------------------------ ----------------- -----------------
  **Source of Light**                  **Color Temp.     **Description**
                                       (K)**             

  Sky - extremely blue                 \_25,000          cool

  Sky - overcast                       \_6500            cool

  Sunlight at noon                     \_5000            cool

  Rare earth fluorescent               2700-5000         warm/cool

  Cool-white fluorescent               \_4300            cool

  Metal halide                         3000-4200         warm/cool

  Warm-white fluorescent               \_3000            warm

  Incandescent (100 W)                 \_2900            warm

  High-pressure sodium                 1900-2100         warm

  Candle flame                         \_1800            warm

  Low-pressure sodium                  \_1740            warm
  ------------------------------------ ----------------- -----------------

> Source: Ontario Hydro (1992) and lamp manufacturers catalogs for
> General Electric (1995) , Osram Sylvania (1996) , and Philips (1996)
>
> **Table A.2. The Color Rendering Indexes of Common Light Sources**

  ------------------------------------ -------------- --------------------
  **Source of Light**                  **CRI**        **Color Rendering**

  Tungsten-halogen                     \_99           excellent

  Standard incandescent                \_97           excellent

  Rare-earth fluorescent               72-84          good/excellent

  Compact Fluorescent                  \_82           excellent

  Metal halide (400 W, clear)          \_65           good

  Cool-white fluorescent               \_62           good

  Warm-white fluorescent               \_52           fair

  Mercury vapor (phosphor-coated)      45-50          poor

  High-pressure sodium (400 W,         \_22           poor
  diffuse-coated)                                     

  Mercury Vapor (clear)                \_15           poor
  ------------------------------------ -------------- --------------------

> Source: Ontario Hydro (1992) and lamp manufacturer catalogs for
> General Electric (1995) , Osram Sylvania (1996) , and Philips (1996)

### **Introduction to Incandescent, Fluorescent, and High-Intensity Discharge Lamps**

The primary categories of lamps that we address in this report include
incandescent, fluorescent, and high-intensity discharge. We describe the
basic operating principles of these different lamp types briefly below.
**Tables A.3-A.6** present primary physical characteristics for the lamp
types discussed below.

In addition to physical lamp characteristics, we also include lamp price
in Tables A.3 through A.6. Lamp prices are sensitive to demand; lamps in
higher demand tend to be less expensive. In general, commercial
customers buy lighting products in large quantities and thus pay the
prices at the lower end of the price ranges provided in this report;
residential customers typically buy lamps one or two at a time and thus
pay prices at the higher end of the range. Lamp prices also vary
depending on where they are purchased - for example, lamps purchased
from lighting design stores are likely to be more expensive than those
purchased from a do-it-yourself store such as Home Depot.

### Incandescent Filament Lamps 

In the late 1800s, the incandescent lamp was invented independently by
Thomas Edison in the United States and Joseph Swan in England (Atkinson
et al. 1995) . Today, incandescent lamps provide most of the light in
households and are also used widely for lighting commercial buildings.
Because about 90-95% of an incandescent lamp\'s emissions are in the
infrared (thermal), rather than visible, range of the electromagnetic
spectrum, incandescent lamps are much less efficacious than other lamp
types. However, as discussed in Atkinson et al. (1995) , aside from
energy-efficiency, incandescent lamps have many advantages:

> Although the prevalence of incandescent lamps in the residential
> sector may be partially due to historical precedence and inertia,
> these lamps do have advantages that, to some extent, counterbalance
> their relatively poor efficacies: they have excellent CRIs and a warm
> color; they are easily dimmed, inexpensive, small, lightweight, and
> can be used with inexpensive fixtures; and, in a properly designed
> fixture, they permit excellent optical control\...They are simple to
> install, maintain, and dispose of.

General service and reflector/PAR (parabolic aluminized reflector) lamps
are the most common types of incandescents. General service lamps (also
called \"A-lamps\") are the pear-shaped light bulbs that are regularly
used in households. Reflector lamps are typically used to highlight
indoor retail displays and artwork and to illuminate outdoor areas.

Modern incandescent lamps use filaments that are made of tungsten. When
electricity is used to heat a lamp filament to the point of
incandescence, light is produced. The efficacy of the light production
depends on the filament temperature. The higher the filament
temperature, the greater the portion of radiated energy that falls into
the visible part of the irradiated spectrum.[^2] Consequently, when
designing an incandescent filament lamp, it is important to keep the
temperature of the filament as high as possible while still maintaining
a satisfactory lamp life. See Table A.3 for more information on standard
incandescent lamps.

A *tungsten-halogen lamp*, which uses the halogen regenerative cycle, is
a variation of an incandescent filament lamp. The tungsten-halogen bulb
has a quartz envelope that is located close to the filament so that the
envelope can reach temperatures of 260\_ C or more in normal operation.
At this temperature, the halogen gas fill in the lamp reacts with any
tungsten that evaporates from the filament and deposits on the lamp
wall. The resulting gaseous tungsten-halogen compound circulates inside
the bulb until it comes in contact with the incandescent filament. Here,
sufficient heat breaks down the compound into tungsten and redeposits it
on the filament.

Tungsten-halogen lamps improve on regular incandescent sources because
of their excellent lumen maintenance, long lifetime, and compactness.
Although they are not as efficacious or long-lived as fluorescent or HID
lamps, tungsten-halogens offer excellent color, brilliance, and control
characteristics at a relatively low unit price (Eley Associates 1993) .
These lamps are most often combined with a reflector housing, and are
available in a wide variety of tubular forms, and in spotlights and
floodlights.

The *tungsten-halogen infrared-reflecting (HIR) lamp* is even more
efficacious than the standard tungsten-halogen lamp. As mentioned above,
90-95% of the energy radiated by incandescent lamps, including
tungsten-halogen lamps, is in the form of heat In an HIR lamp, a
multi-layer interference film-coating technology is applied to a
tungsten-halogen lamp to reflect the emitted heat back to the filament;
consequently, the required power input to reach the operating
temperature for the tungsten-halogen cycle is reduced.

HIR lamps have been available for a number of years as high-wattage
double-ended quartz lamps, and HIR PAR lamps only recently (1994) became
widely available (Atkinson et al. 1995) . HIR lamps have been promoted
to residential- and commercial-sector customers primarily as low-wattage
reflector lamps; general service HIR lamps have been developed as
prototypes but are not yet commercially available (Atkinson et al. 1995)
.

See Table A.3 and Table A.4 for more information on different types of
tungsten-halogen lamps.

*Reflector lamps* are standard incandescent or tungsten-halogen lamps
made in special or standard bulb shapes and with a reflective coating
applied to part of the bulb surface. Both silver and aluminum coatings
are used. In reflector lamps, better optical control directs the
illuminance to a specific area; thus, reflector lamps can be
energy-efficient alternatives to general service incandescents in
applications where illumination requirements are direction-specific. In
spotlight and floodlight applications, the filaments are concentrated
and are accurately positioned with respect to the base. When the
filament is placed at the focal point of a reflector or lens system, a
precisely controlled beam is obtained. See Table A.4 for more
information on reflector lamps.

### Fluorescent Lamps

The first practical fluorescent lamps were produced in the United States
in the late 1930s, and fluorescent lamps came into general use in the
1950s (Atkinson et al. 1995) . Fluorescent lamps are used to illuminate
most commercial buildings, and are also common in the industrial sector.
Only a small amount of fluorescent lighting is found in homes, primarily
in kitchens, bathrooms, and utility areas.

The most common fluorescent lamps are tubular and have a length of four
feet. Tubular lamps that have a diameter of 1.5 inches (38 mm) are
called T12s and tubes that have a diameter of one inch (26 mm) are
called T8s; the \"8\" and \"12\" refer to the number of eighths of an
inch in the diameter of the lamp tube. Lamp tubes are available in other
diameters as well.

Like most discharge lamps, fluorescent lamps must be operated using a
\"ballast\" to limit the current to the value for which each lamp is
designed and provide the starting and operating lamp voltages.
Typically, the ballast adds another 10-20% to the power draw, thus
decreasing system efficacy. A fluorescent lamp system\'s efficacy
depends on lamp length and diameter; the type of phosphor used to coat
the lamp; the type of ballast used with the lamp; the number of lamps
per ballast; the temperature of the lamp (which depends on the fixture
and its environment); as well as a number of lesser factors (Atkinson et
al. 1995) . Ballasts are discussed in greater detail below.

Technically, a fluorescent lamp is a low-pressure gas discharge source
in which light is produced when UV energy generated by a mercury arc
activates fluorescent powders that coat the inside of the lamp tube.
Fluorescent lamps are usually long and tubular with an electrode sealed
into each end; they contain mercury vapor at low pressure and a small
amount of inert gas for starting. Standard fluorescent lamps are filled
with argon gas. The interior of the bulb wall is coated with fluorescent
powders that are usually referred to as \'phosphors\'. When a suitably
high voltage is applied across the electrodes, an electric arc discharge
is initiated and the resulting current ionizes the vaporized mercury in
the tube. The ionized mercury emits mostly invisible UV radiation, which
strikes and excites the phosphor tube coating, causing a glow or
\'fluorescence\' and producing visible light.

The blend of phosphors used to coat a fluorescent lamp\'s inner wall
determines the color of light produced by the lamp. In the past, the
most frequently used lamps have been the halophosphate (\"standard
phosphor\") cool-white and warm-white lamps. In a newer type of
fluorescent lamp, the inside of the lamp tube is coated with a
combination of rare-earth (RE) phosphors that produce visible light at
wavelengths to which the red, green, and blue retinal sensors of the
human eye are most sensitive. Lamps using RE phosphors can withstand a
higher loading (arc power per unit of phosphor area) and thus provide
better lumen maintenance than standard-phosphor lamps. The arc power per
unit of phosphor area increases as lamp diameter decreases, and lumen
degradation in standard-phosphor lamps of small diameter is too severe
to make lamp production practical. The introduction of RE phosphor
coatings for lamp tubes, however, has made it possible to develop
fluorescent lamps with smaller diameters such as the T-8 and T-5. All
fluorescent lamps with diameters of one-inch or less use the new RE
phosphors. Rare earth coatings can also be used for lamps of larger
diameter. Although the use of RE phosphors increases the price of a
lamp, RE phosphor lamps provide improved lumen maintenance, color
rendering, and lamp efficacy.

See Table A.5 for more information on T12 and T8 fluorescent lamps.

*Compact fluorescent lamps (CFLs),* which are significantly smaller than
standard fluorescent lamps, were introduced in the early 1980s as an
energy-efficient alternative to incandescent lamps. As mentioned above,
the introduction of RE phosphor coatings for fluorescent lamps made it
possible to develop fluorescents with smaller diameters. In a CFL, the
small-diameter tube (T4 or T5) is bent into two to six sections.
Originally, CFLs were designed to be interchangeable with conventional
25--100 W incandescent lamps, but they are now available in various
sizes, colors, wattages, and bases.

Typically, a CFL produces three to four times more lumens per watt than
an incandescent A-lamp; efficiency increases with lamp wattage. In
addition, the rated lifetime of a CFL is about 10 times longer than that
of an incandescent A-lamp. However, factors such as ambient temperature,
switching, mounting position, lumen depreciation, and fixture size may
alter the laboratory-determined efficacies and lifetimes of CFLs. For
example, a CFL operating in a base-down position may produce 15-20%
fewer lumens than a CFL operating in a base-up position (Siminovitch and
Mills 1994) .

There are three different types of compact fluorescent lamp-ballast
systems (Eley Associates 1993) :

> • *Integral systems* are self-ballasted packages and are made up of a
> one-piece, disposable lamp, ballast, and socket adapter combination.
> Integral systems are designed to replace incandescent lamps in
> fixtures fitted for incandescents. A disadvantage of the integral
> system is that the ballast (which would otherwise have a life of
> \_45,000 hours) must be disposed of when the lamp fails (normally, CFL
> lamp life is about 10,000 hours).
>
> • *Modular systems* are self-ballasted packages as described for
> integral systems except that the lamp is replaceable. Like integral
> systems, modular systems are designed for incandescent retrofit
> situations, but are more cost-effective in the long run because the
> ballast does not need to be replaced every time a lamp fails.
>
> • *Dedicated (hardwired) systems* are new or retrofitted fixtures that
> are hardwired for CFL ballasts. These systems do not use socket
> adaptors; instead, they use a pin socket for the lamp.

See Table A.5 for more information on compact fluorescent lamps.

### High-Intensity Discharge Lamps

HID lamps are most widely used in the commercial and industrial sectors
and, for many commercial and industrial applications, provide the
most-cost-effective illumination. Low-wattage HID lamps can be used
effectively for outdoor security, corridor, and landscape lighting in
the residential sector, particularly in timer-controlled functions.

Like fluorescent lamps, HID lamps produce light by discharging a
well-stabilized arc discharge through a mixture of gases in a refractory
envelope. Unlike fluorescent lamps, HID lamps use a compact \"arc tube\"
in which the pressure and temperature are very high. Because the arc
tube is small, it permits compact reflector designs with good optical
controllability. Like fluorescent lamps, HID lamps require a ballast to
supply the correct voltage and control the current.

The three primary types of HID lamps in use today are mercury vapor
(MV), metal halide (MH), and high-pressure sodium (HPS). Mercury vapor
lamps were the first HID lamps to be developed. In MV lamps, light is
produced by the passage of an electric current through an arc tube
filled with mercury vapor; a small amount of argon is added to
facilitate starting IES (1993) . Metal halide lamps are similar in
construction to MV lamps, and produce light by passing a current through
an arc tube containing various metallic halides in addition to mercury
and argon (IES 1993) ; compared to MV lamps, metal halide lamps have
shorter rated lamp lives, but offer improved efficacy, color rendering,
and lumen maintenance In high-pressure sodium lamps, light is produced
by the passage of current through an arc tube containing sodium vapor
(IES 1993) ; HPS lamps are even more efficacious and have better lumen
maintenance than MH lamps.

HID lamps are most effectively used for applications in which switching
(turning lamps off and on) is limited. One reason for this is the amount
of time they require for starting (cold start) and restriking (hot
start). A mercury vapor lamp, once started, requires several minutes to
achieve full light output; restrike time (cooling time required before
the lamp will restart) is 3-7 minutes, depending on lamp type (IES 1993)
. A metal halide lamp, once started, requires about 2-10 minutes to
achieve full light output and equilibrium color, depending on the lamp
type; restrike time can be as long as 15 minutes because of the high
operating temperature (IES 1993) . A high-pressure sodium lamp, once
started, requires about 10 minutes to achieve full light output, during
which time the color of the light changes; restrike time is less than a
minute and full warm-up takes 3-4 minutes (IES 1993) .

For industrial and outdoor applications where color was not a priority,
MV lamps were the most efficient lamp type for many years. With the
introduction of higher-efficacy HPS and MH lamps, MV lamps are now the
least efficacious of the three primary HID lamp types and have lost a
significant portion of their original market share. However, although
many building owners have now replaced MV lamps with more efficient MH
and HPS lamps, many MV lamps are still in use because they are
relatively inexpensive and conversion to MH and HPS often requires
installation of new ballasts and sometimes requires installation of new
fixtures (Atkinson et al. 1995, Clear 1997a) .

See Table A.6 for additional information on HID lamps.

Lamp table - page 1

Lamp table - page 2

Lamp table - page 3

Lamp table - page 4

Lamp table - page 5

Lamp table - page 6

Lamp table - page 7

Lamp table - page 8

Lamp table - page 9

## BALLASTS

### **Defining The Technical Characteristics of Ballasts**

All discharge lamps must be operated with a current-limiting device
referred to as a \"ballast\". A lamp ballast is an electrical device
that controls the current provided to the lamp and provides the high
voltage necessary to start most discharge lamps. In addition, ballasts
can provide power quality correction and control features such as
dimming or compensation for lumen depreciation. Ballasts differ from one
another in numerous ways such as how energy-efficient they are, how much
distortion they cause in a power wave, and how much light a lamp
produces when using them. Below, we define the primary physical
characteristics by which ballasts are most often assessed and compared.

[Ballast Factor (BF):]{.underline}

The ballast factor provides a relative measure of how much light is
produced using a specific ballast. A meaningful comparison can only be
made between ballasts that are used to operate the same type of lamps.

![](media/image2.emf){width="3.138888888888889in"
height="0.3611111111111111in"}

For most ballasts, the BF is less than one; for some of the new
electronic ballasts, however, the BF is greater than one (Koomey et al.
1994) .

[Ballast Efficacy Factor (BEF):]{.underline}

The ballast efficacy factor is used to determine which ballast supplies
more light for a given wattage.

![](media/image3.emf){width="2.0694444444444446in" height="0.375in"}.

As with BF, BEF can be used to meaningfully compare different ballasts
only when they operate the same number and type of lamps.

[System Efficacy:]{.underline}

Like lamps, ballasts consume power. Consequently, the only meaningful
measure of the efficiency of a lighting system is the efficacy of the
lamp-ballast system. Typically, a fluorescent ballast consumes from a
few to a dozen watts. HID ballasts consume from 10--20% of nominal lamp
watts; this percentage is usually higher for lower-wattage lamps. System
efficacy refers to the efficacy of the lamp-ballast combination, and is
calculated as follows:

![](media/image4.emf){width="4.208333333333333in"
height="0.3611111111111111in"}

[Power Factor (PF) Ratio:]{.underline}

The power factor ratio represents, for a given ballast, the amount of
power that a customer is actually using as a fraction of what the
utility must supply. This ratio is used to determine how efficiently a
ballast uses total input power. To calculate the PF ratio, the power
(watts) is divided by the root mean square of the ballast volt-amps
(Eley Associates 1993) . Utilities may penalize customers whose electric
load has a low PF. Ideally, lighting equipment should have a PF greater
than 0.9 and as close to 1.0 as possible. PFs of less than 1.0 occur
when the voltage and current are out of phase or when the sinusoidal
shape is distorted.

[Total Harmonic Distortion (THD):]{.underline}

Ballasts, especially electronic ones, affect power quality by generating
harmonic distortion. Total harmonic distortion refers to the amount of
distortion that a ballast causes in the power wave form. Utilities often
require a THD of less than 20%, but the electric industry is considering
a standard that permits a THD up to 32% (Audin et al. 1994) . High THD
can disrupt powerline carrier controls and create unacceptably high
currents in three-phase systems. THD values are typically calculated for
ballasts based on their operation of a 4-foot fluorescent lamp.

### **Introduction to Ballasts for Fluorescent and High-Intensity Discharge Lamps**

The light output of a lamp depends on the ballast that operates the
lamp. Ballasts are often designed to operate a unique lamp type; some
ballasts, however, can be used to operate more than one type of lamp. It
is important to use the ballast specified by the manufacturers because
improper lamp-ballast combinations can result in reduced light output,
efficacy, and lifetime.

For all types of ballasts, rated lifetimes are in the range of 45,000
hours. Ballast life is rated for 12 hours of use per day. Ballast life
is very dependent on operating temperature -- an increase of 10°C over
the rated ballast operating temperature of 90°C can translate into as
much as a 50% reduction in ballast life (National Lighting Product
Information Program 1994) . Because manufacturers who specify
longer-than-usual ballast lifetimes may also prescribe lower operating
temperatures, it is advisable to check the ballast specifications for
the temperature to which a specific ballast lifetime corresponds.

Typically, fluorescent lamps are operated using magnetic core-coil or
electronic high-frequency ballasts; both magnetic and electronic
ballasts are available for most types of fluorescent lamps. Hybrid
ballasts are also available for rapid-start lamps. Typically, HID lamps
cannot be operated using fluorescent ballasts. The three primary types
of HID ballasts are magnetic ballasts: reactor ballasts, high-reactance
autotransformers, and constant-wattage autotransformers (Audin et al.
1994) . We briefly describe these different ballast types below.

### Ballasts for Fluorescent Lamps

*Magnetic core-coil ballasts* use a capacitor and a transformer with a
magnetic core coiled in copper or aluminum wire in order to control the
current provided to a lamp. A thermal cutoff switch protects the ballast
from overheating. Magnetic ballasts operate at an input frequency of 60
hertz (Hz) and also operate lamps at 60 Hz.

*Electronic ballasts* use integrated electronic circuitry rather than
magnetic components to control voltage and current. Like magnetic
ballasts, electronic ballasts use standard 60 Hz power; however,
electronic ballasts operate lamps at a much higher frequency
(20,000--60,000 Hz), which increases lamp efficacy. Lamp efficacy is
also improved because electronic ballasts are less sensitive to ambient
(room) temperature than magnetic ballasts. Although dimming magnetic
ballasts are available, almost all dimming fluorescent ballasts are
electronic (IES 1993) .

A third type of fluorescent ballast is the *hybrid ballast*, which is
also referred to as a cathode cut-out or heater cut-out ballast. In the
hybrid ballast, which is a modified version of the magnetic ballast and
operates at a low frequency, electronic circuitry is used to control
power to the lamp\'s cathodes and magnetic components drive the main arc
(Audin et al. 1994) . Energy consumption is reduced because the
electronic circuitry removes the power that is used to heat the lamp
filaments once the lamp has started. Typically, hybrid ballasts use
5--10% less energy than energy-efficient magnetic ballasts; however,
they can only be used with rapid-start lamps and are not dimmable.
Hybrid ballasts account for only a small share of the ballast market.

**Table A.7** provides a comparison of magnetic, hybrid, and electronic
ballasts.

### Ballasts for HID Lamps 

Typically, HID lamps cannot be operated using fluorescent ballasts. The
three primary types of HID ballasts are magnetic ballasts: reactor
ballasts, high-reactance autotransformers, and constant-wattage
autotransformers (Audin et al. 1994) :

> • *Reactor ballasts* consist mainly of an inductor coil. They are
> small, inexpensive, simple, and have low losses; however, their use
> leads to more rapid lumen depreciation than the use of other ballast
> types. Reactor ballasts have a low power factor, and can cause flicker
> or turn-off if power is unstable.
>
> • *High-reactance autotransformers* are more expensive and consume
> more power than reactor ballasts, but also have a more sophisticated
> design. Although they are similar to reactor ballasts, they are
> capable of boosting line voltage when it is insufficient to start a
> lamp.
>
> • *Constant-wattage autotransformers* are the most expensive of these
> three ballast types, but are also the most commonly used. Of these
> ballast types, constant-wattage autotransformers regulate power the
> best and their use thus reduces flicker and shutoffs when power is
> unstable.

There are several disadvantages associated with magnetic HID ballasts,
such as high internal losses (an especially high percentage in the case
of low-wattage lamps), audible noise, and bulkiness.

Electronic ballasts are now available for some low-wattage MH and HPS
lamps, but they are uncommon. Electronic ballasts for HID lamps do not
operate on the same principles as those for fluorescent lamps. The
primary benefits of an electronic HID ballast are reduced size and
weight, quieter operation, and increased control of the arc tube wattage
during the lamp\'s life. More precise arc tube wattage management
improves the color consistency over the lamp life, and can lengthen
expected life. Unlike electronic fluorescent ballasts, with few
exceptions, electronic HID ballasts do not significantly improve lamp
efficacy.

Ballast table - page 1

Ballast table - page 2

## FIXTURES

A lighting fixture provides physical support for lamp(s), ballast(s),
and wiring. The function of the fixture is to efficiently direct and
distribute light to the desired area without causing glare or
discomfort. The geometric design of a fixture, as well as the material
of which the reflector and/or lens is made, determines how the light of
a lamp is distributed as well as the overall efficiency of the lighting
system.

We use the term \"fixture\" to refer to the physical housing for a lamp,
including: sockets, lamp holders, and fittings to attach the lamp to the
fixture; reflectors to direct light in the desired direction; shielding
and diffusion components (such as lenses, diffusers, and louvers) to
shield the light from non-desired directions, reduce visual discomfort,
prevent glare, and distribute light evenly; and, for certain types of
lamps, ballasts to start lamp and control electric characteristics
during lamp operation. An efficient fixture optimizes the system
performance of each of its components.

If installed in the wrong fixture, even the most efficacious lamp can be
inefficient and provide light of poor quality. There are more fixtures
on the market today than any other type of lighting equipment.
Consequently, it is important that fixtures be selected carefully, based
on factors including the user\'s specific lighting needs, lamp
requirements, and environmental conditions.

Various types of fixtures differ from one another in numerous ways such
as reflector design, operating position of the lamp, ease of lamp
insertion and removal, thermal characteristics, and fixture life time.
Fixtures also differ from one another in terms of their energy use and
light distribution characteristics.

The performance of a fixture is assessed by evaluating its performance
as part of a \"luminaire\"; in this appendix, the term \"luminaire\"
refers to a complete lighting system including lamp(s), ballast(s), and
fixture. Below, we define some of the energy-efficiency and light
distribution characteristics by which fixture performance can be
assessed and compared.

[Luminaire Efficiency:]{.underline}

Luminaire efficiency is the ratio of the lumens leaving a luminaire to
the total number of lumens produced by a lamp (IES 1993) .

[Luminaire Efficacy Rating (LER):]{.underline}

As mentioned in the main body of this report, in response to EPAct\'s
call for a voluntary national testing and information program for
luminaires, a program has been created by the National Lighting
Collaborative (1996) . Members of the Collaborative include the National
Electrical Manufacturers Association, the American Lighting Association,
and other interested parties. The working group has introduced a new
tool for comparing luminaires, the LER, which is based on NEMA\'s LE5
standard for fluorescent luminaires. The LER is a single number
expressing luminaire efficacy in lumens per watt, and is calculated
using the following equation:

> LER = F(luminaire efficiency \* total rated lamp lumens \* ballast
> factor,luminaire input watts)

[Coefficient of Utilization (CU):]{.underline}

The coefficient of utilization expresses the ratio of the lumens from a
luminaire that are received on a room\'s workplane to the total number
of lumens produced by the lamps within the luminaire (IES 1993) .

## LIGHTING CONTROLS

A large variety of technologies are available for controlling the way
that lights are used in a building. These technologies can be mechanical
and/or electronic and range from a basic timer that turns the lights off
or on at a given hour of the day to a complex energy management system
(EMS) that controls not only the lighting in a building but also the
space conditioning system. Both simple and highly complex lighting
control systems are used in commercial buildings. In homes, lighting
control systems tend to be simple; however, the control systems
installed in the recently introduced "smart houses" are quite
complicated.

Common lighting control strategies and tools are summarized in **Table
A.8** and **Table A.9,** respectively. The choice of a lighting control
strategy and tools, which can be a combination of the options described
in Tables A.8 and A.9, depends on numerous factors -- including the type
of lamp one wishes to control. Not all lighting controls are appropriate
for all lamp types. For example, HID and fluorescent lamps may not be
ideal for applications where a motion sensor frequently switches the
lights on and off, because the lifetime of these lamps is very sensitive
to frequent switching. In addition, HID lamps may take too long to start
up. HID and fluorescent lamps are the ideal choice in time-controlled
applications where relatively long burning cycles are needed.

The type of controls one selects will also depend on whether they are
being installed as a retrofit, renovation, or for new construction. As
described in Koomey et al. (1994) , the electrical wiring configuration
is the major constraint in installing controls in buildings. Most often,
it is not cost-effective to substantially re-wire the ceiling electric
lighting system in an existing building in order to install lighting
controls. Consequently, lighting control systems for retrofits in
existing buildings tend to be simpler than the lighting control systems
designed for new buildings.

In new construction, it can be cost-effective to install more advanced
lighting control systems. As described in Atkinson et al. (1995) ,
integrated workstation sensors and energy management systems are two
highly promising efficiency options:

> Of the control systems available today, integrated workstation sensors
> and energy management systems are two of the most promising efficiency
> options. An *integrated workstation sensor* allows users to control
> lighting, electric heating and cooling equipment, and other electrical
> equipment (such as plug loads) for individual workstations or spaces.
> For example, user lighting controls might include dimmer switches for
> area and task lighting as well as daylight sensors. From their
> workspace, users can adjust lighting and HVAC controls according to
> their preference. Occupancy sensors automatically shut down electrical
> equipment when the space is unoccupied, and system memory allows the
> equipment to come back on at the same level when the occupant returns.
> Comprehensive, automated, *building energy management systems* are
> user-programmable and can control equipment for several energy
> end-uses including lighting, HVAC, security, and safety systems. A
> well-designed energy management system may offer greater energy
> savings than individual controls for single end uses; the \"systems
> approach\" is becoming more common in both new construction and
> retrofits of existing buildings.

For a clear and practical guide to the strategies and tools used in
designing lighting control systems for commercial buildings, see
Rundquist et al. (1996) .

Table A.8. Common Lighting Control Strategies

  ----------------- --------------------------------------------------------
  **Scheduling**    Scheduling is a lighting control strategy based on
                    turning lamps off and on according to the need for
                    illumination. *Predictable scheduling* regulates
                    illumination levels in a predetermined way, with the use
                    of equipment such as timed controls, and can be
                    effective for buildings in which activities follow a
                    similar routine from day to day. *Unpredictable
                    scheduling* controls lighting levels based on whether or
                    not someone is present; for example, occupancy/motion
                    sensors extinguish or dim the lights when a space is
                    unoccupied and turn the lights back on when someone
                    enters the space.

  **Task-Tuning**   Normally, spaces are illuminated uniformly. Using a
                    *task-tuning* control strategy and dimming devices,
                    however, the lighting levels of different spaces can be
                    adjusted to meet the needs of the different people using
                    those spaces. For example, workers performing visually
                    detailed tasks are likely to require more illumination
                    than workers who are primarily looking at their computer
                    monitors throughout the day. Additionally, lighting
                    levels can be reduced in spaces that are not oriented
                    towards visual tasks (e.g., hallways and reception
                    areas).

  **Daylighting**   In many buildings, the daylight coming in through
                    windows and skylights can provide a significant amount
                    of the light necessary for many visual tasks. After
                    decades of overdependence on artificial light, many
                    lighting designers are once again thinking in terms of
                    using sunlight to illuminate interior spaces. For
                    designers, the challenge of *daylighting* is to admit
                    only the required amount of daylight, distribute the
                    light evenly, and avoid glare. When daylight is used
                    within a building, the electric lighting levels can be
                    reduced. Using a control photocell, a dimmable lighting
                    system can be connected to the ambient light levels
                    within a room; in this way, electric light levels can be
                    reduced during the times when natural light is available
                    and supply most or all of the light needed when natural
                    light levels are low and when it is dark outside.

  **Lumen           Typically, electric lighting systems are designed to
  Maintenance**     produce light levels that are 20-35% higher than the
                    design minimum so that, as lamps age and the amount of
                    light delivered by the lamp-luminaire system diminishes,
                    the illuminance level will always meet or exceed the
                    minimum light requirement. Light losses over time are
                    the result of lamp lumen depreciation as well as the
                    accumulation of dirt on the luminaire and room surfaces.
                    *Lumen maintenance* is a control strategy that uses
                    photocells and dimmers to sense the actual illuminance
                    level in a space and reduce system power input to
                    maintain only the desired light level. In this way, a
                    lighting system can be designed with lower initial
                    lighting power densities and design-specified
                    illuminance levels are maintained at all times, rather
                    than only at the end of the maintenance cycle.

  **Load Shedding** In order to avoid brownouts and blackouts, many
                    utilities charge their larger customers based on peak
                    power demand. Selective reduction of lighting levels in
                    less critical areas of a building is an effective way of
                    reducing lighting power demand for short periods of
                    time. Typically, lighting levels can be reduced by 10%
                    or more with only minimal impact on the occupant\'s
                    visual performance or productivity. Automatic dimming
                    controls allow the reduction in light level to occur
                    without occupant awareness.

  **Adaptation      In places that are illuminated both during the day and
  Compensation**    throughout the night (e.g., 24-hour supermarkets or
                    entry foyers), the level of electric lighting needs to
                    be higher during the daytime because a person whose eyes
                    are adapted to daylight will need more light to see in
                    areas that are less bright. When a person\'s eyes are
                    adapted to the lack of light at night, however, they do
                    not require as much light to see indoors. An adaptation
                    compensation control strategy uses dimming devices or
                    switching relays in combination with automatic timers to
                    vary the lighting level accordingly.
  ----------------- --------------------------------------------------------

Sources: IES (1993) , Eley Associates (1993)

Table A.9. Common Lighting Control Tools\*

  -------------------- -------------------------------------------------------
  **Programmable       Programmable timers are used to implement time-based
  Timers**             control of electric lights. The usual method of
                       implementation is a system of low-voltage controlled
                       relays that are controlled by a programmable time
                       clock. These systems are primarily used to efficiently
                       schedule the operation of a lighting system in areas
                       where the occupant schedule is relatively predictable.
                       To accommodate lighting needs during off-hours, these
                       systems are typically equipped with overrides so that
                       building occupants can control the lights using a
                       low-voltage switch or a telephone override system.

  **Occupancy          Occupancy sensors are switches that are activated by
  Sensors**            detecting the presence or absence of people in the
                       sensor\'s field of view. There are two basic types of
                       occupant sensor: passive infrared sensing and
                       ultrasonic (some sensors combine these two methods).
                       These sensors are most effective in locations where
                       occupancy is not easily predicted (e.g., conference
                       rooms, restrooms, and storerooms).

  **Photo-Switches**   Photo-switches are photo-electrically controlled
                       switches that can be used to switch off lights in
                       building zones receiving daylight from adjacent
                       windows. These devices are usually installed in one of
                       three ways: on each fixture; on groups of fixtures
                       using intermediate relays; or as inputs to low-voltage
                       programmable relay systems.

  **Dynamic Controls** Dynamic controls are devices that allow standard
                       lighting equipment (including both fluorescent and HID
                       sources) to be continuously dimmed to an intermediate
                       level. These systems can control a single lamp or
                       entire branch circuits. Although these controls can
                       typically provide any light level within the control
                       range, they rarely permit dimming below 40% of maximum.
                       They generally accept an input from a photocell and/or
                       an input from an energy management system.

  **Static Controls**  Static controls are devices that allow the light output
                       of standard lighting equipment to be reduced to one
                       intermediate level. These systems can control a single
                       lamp or entire branch circuits. The larger systems
                       generally accept an input from an EMS system for
                       scheduling control. The smaller systems generally
                       control only a single lamp or ballast - their sole
                       function is to reduce input power (and light output).
                       The primary application of these systems is in areas
                       that are overlit.

  **Dimmable           With the use of dimmable ballasts, fluorescent lamps
  Ballasts**           can be dimmed over a wide range, and represent the
                       state-of-the-art in controllable lighting. Although
                       dimming magnetic ballasts are also available, almost
                       all dimming ballasts in use today are electronic (Clear
                       and Rubinstein 1997) . Typically, electronic ballasts
                       can be controlled using a low-voltage wiring network
                       that allows them to respond to inputs from a photocell,
                       occupancy sensor, or input from an energy management
                       system.
  -------------------- -------------------------------------------------------

**\*** Except where otherwise noted, the descriptions of these lighting
control tools were obtained from Koomey et al. (1994) .

# Appendix A references

Atkinson, Barbara, Andrea Denver, James E. McMahon, Leslie Shown, and
Robert Clear. 1995. \"Energy-Efficient Lighting Technologies and Their
Applications in the Commercial and Residential Sectors\" in the *CRC
Handbook of Energy Efficiency*. Boca Raton, FL: CRC Press, pp. 399-427.

Audin, L., D. Houghton, M. Shephard, and W. Hawthorne. 1994. *Lighting
Technology Atlas*. Boulder, Colorado: E Source, Inc.

Brown, Richard, and Barbara Atkinson. 1994. *Incandescent Reflector Lamp
Energy Efficiency Standard Analysis: Draft Report*. Berkeley, CA:
Lawrence Berkeley National Laboratory. Draft LBL-36223. September.

Calwell, Chris. 1996. *Halogen Torchieres: Cold Facts and Hot Ceilings.*
Boulder, CO: E-Source. September.

Calwell, Chris. 1997. *Personal Communication:* Telephone conversation
with Jonathan Koomey regarding review of April 1997 DRAFT Sourcebook.
May.

Census Bureau. 1994. *Current Industrial Reports: Electric Lamps - MQ36B
(93)-5, Summary 1993*. Washington, D.C.: U.S. Department of Commerce.
November.

Clear, Robert (Lawrence Berkeley National Laboratory). 1994. *Personal
Communication:* Memo to co-workers entitled \"Summary Statement on
Economics of IR-Halogen Lamps.\" May.

Clear, Robert (Lawrence Berkeley National Laboratory). 1996. *Personal
Communication:* E-mail to Jonathan Koomey regarding review of October
1996 DRAFT Sourcebook. October 21.

Clear, Robert (Lawrence Berkeley National Laboratory). 1997a. *Personal
Communication:* Written comments provided to Leslie Shown regarding
review of April 3, 1997 DRAFT Sourcebook. April.

Clear, Robert (Lawrence Berkeley National Laboratory). 1997b. *Personal
Communication:* E-mail to Leslie Shown regarding technical
characteristics of an HIR A-lamp. March 17.

Clear, Robert, and Francis Rubinstein (Lawrence Berkeley National
Laboratory). 1996. *Evaluating the Relative Efficacy of Incandescent
Lamp Technologies*. Unpublished report.

Clear, Robert, and Francis Rubinstein (Lawrence Berkeley National
Laboratory). 1997. *Personal Communication:* Conversation with Leslie
Shown regarding the dimmability of fluorescent lamps. March 10.

Denver, Andrea (Lawrence Berkeley National Laboratory). 1996. *Personal
Communication:* Conversation with Leslie Shown regarding lamp prices
(based on catalogs and survey of shelf prices at Bay Area stores).

Electric Power Research Institute (EPRI). 1993a. *Compact Fluorescent
Lamps: High-Efficiency Electric Technology Fact Sheet*. Palo Alto, CA:
EPRI.

Electric Power Research Institute (EPRI). 1993b. *Electronic Ballasts:
High-Efficiency Electric Technology Fact Sheet*. Palo Alto, CA: EPRI.

Eley Associates. 1993. *Advanced Lighting Guidelines: 1993*. San
Francisco, CA: Eley Associates. Prepared by Eley Associates, Luminae
Souter Lighting Design, and Lawrence Berkeley National Laboratory for
the U.S. Department of Energy, California Energy Commission, and
Electric Power Research Institute. DOE/EE-0008.

General Electric Company. 1995. *GE Lighting: Spectrum 9200 Lamp
Catalog*. U.S.: General Electric Company.

Illuminating Engineering Society of North America (IES). 1993.*Lighting
Handbook: Reference & Application* . 8th Edition. New York, NY: IES.

Koomey, J.G., A.H. Sanstad, and L.J. Shown. 1995. *Magnetic Fluorescent
Ballasts: Market Data, Market Imperfections, and Policy Success*.
Berkeley, CA: Lawrence Berkeley National Laboratory. LBL-37702.
December.

Koomey, Jonathan G., Francis X. Johnson, Jennifer Schuman, Ellen
Franconi, Steve Greenberg, Jim D. Lutz, Brent T. Griffith, Dariush
Aresteh, Celina Atkinson, Kristin Heinemeier, Y. Joe Huang, Lynn Price,
Greg Rosenquist, Francis M. Rubinstein, Steve Selkowitz, Haider Taha,
and Isaac Turiel. 1994. *Buildings Sector Demand-Side Efficiency
Technology Summaries*. Berkeley, CA: Lawrence Berkeley National
Laboratory. LBL-33887. March.

Lamp Manufacturer Catalogs for General Electric (1995), Osram Sylvania
(1996), and Philips (1996).

Leslie, Russell, and Kathryn Conway. 1993. *Research for \"The Lighting
Pattern Book for Homes\", Final Report*. Troy, NY: Lighting Research
Center, Rensselaer Polytechnic Institute.

Moezzi, Mithra. 1996-97. *Personal Communication:* Memos to Diana
Vorsatz and Leslie Shown regarding statistical distribution of
residential lighting fixtures and lamps based on data obtained from the
TPU analysis.

National Lighting Collaborative. 1996. *What is LER?: Announcing the New
Luminaire Energy Information Program*. Rosslyn, VA: National Lighting
Collaborative. July.

National Lighting Product Information Program. 1993. *Lighting Answers:
T8 Fluorescent Lamps*. Troy, NY: Lighting Research Center, Rensselaer
Polytechnic Institute. April.

National Lighting Product Information Program. 1994. *Specifier Reports:
Electronic Ballasts*. Troy, NY: Lighting Research Center, Rensselaer
Polytechnic Institute. May.

Ontario Hydro. 1992. *Lighting Reference Guide, 5th Edition*. Ontario,
Canada: Ontario Hydro.

Osram Sylvania Inc. 1996. *Osram Sylvania Product Catalog: 1996 Lighting
Technology in the Age of EPAct*. Danvers, MA: Osram Sylvania Inc.

Page, Erik (Lawrence Berkeley National Laboratory). 1997. *Personal
Communication:* Conversation with Leslie Shown regarding efficacies of
halogen torchieres.

Philips Lighting Company. 1996. *Lamp Specification and Application
Guide*. Somerset, NJ: Philips Lighting Company.

Rundquist, R.A., T. McDougal, and J. Benya. 1996. *Lighting Controls:
Patterns for Design*. Palo Alto, CA: Electric Power Research Institute.
Prepared by R.A. Rundquist Associates for Empire State Electric Energy
Research Corporation and the Electric Power Research Institute. EPRI
TR-107230. December.

Sezgen, A. Osman, Y. Joe Huang, Barbara A. Atkinson, and Jonathan G.
Koomey. 1994. *Technology Data Characterizing Lighting in Commercial
Buildings: Application to End-Use Forecasting with COMMEND 4.0*.
Berkeley, CA: Lawrence Berkeley National Laboratory. LBL-34243. May.

Siminovitch, Michael, and Evan Mills. 1994. \" Fixing the Fixtures.\"
*Home Energy* 11(6): 47-49.

U.S. House of Representatives. 1992. *Energy Policy Act of 1992*.
Washington DC: U.S. Government Printing Office.

[^1]: There are some exceptions to this generalization: for example,
    some HID lamps draw increasing amounts of power as they age (Clear
    1996) and some low-pressure sodium lamps maintain constant lumen
    output over time (Philips Lighting Company 1996)

[^2]: An incandescent source that emits the theoretical maximum amount
    of energy is called a "blackbody" radiator. A blackbody radiator
    emits energy at all wavelengths, but the amount and proportion of
    the energy that is potentially visible increases rapidly with
    temperature. A blackbody at 600° C will probably be visible under
    normal lighting. Objects below about 300° C are not visibly brighter
    than their surroundings even for the dark adapted eye.