Flip a switch, move a table
lamp a little to the left, adjust the Venetian blinds just so:
Interacting with light in the home environment is commonplace.
This intimate connection with lighting has been translating
into commercial facilities as well. Light fixtures and lighting
controls are becoming more responsive; the efficiency of lamp
technology is increasing; and the benefits of high-quality lighting
are adding up.
Curious about where to start?
Evaluate what occupants need, consider what types of tasks
are performed, and what features in the space may cause discomfort
(windows, computer screens, highly reflective surfaces, and
glass-framed artwork). The mission is to design
a system that
enables workers to perform at maximum efficiency, employing
the products and practices that lower costs and increase productivity.
With careful planning, facilities managers and design professionals
can create enhanced environments.
How exactly does lighting improve productivity?
Productivity is a lot like the weather; everyone talks about
it but no one does anything. Of course, the biggest problem
with discussing the lighting environment’s relationship
to work performance is that productivity is so hard to quantify.
“Productivity can be typing speed, rate of error, time
spent at your desk. It can mean a whole series of things,”
says Carol Jones, senior research scientist and lighting program
manager, Battelle, Cambridge, MA. Because of the ambiguity surrounding
the issue, according to Jones, many facilities professionals
are skeptical of improving end-user performance with lighting.
Fortunately, lighting researchers have honed their methodology
to mitigate extraneous influences. Light Right, a consortium
of lighting designers, researchers, and manufacturers, is engaged
in research to accurately measure the impact of lighting changes
on end-users. Adds Jones, “We believe there is as an impact
of lighting on people and their productivity.” The results
of Light Right’s experiments are expected in 2001.
“The ways in which lighting has become much more adaptable
at the individual workstation is of major interest to people.
Controllability is key,” explains Judy Heerwagon, a lighting
consultant based in Seattle. To create an enhanced lighting
environment, Heerwagon recommends facilities managers use questionnaires
after lighting upgrades to gauge end-users’ impressions.
Also allowing workers to choose elements in their office space
as much as feasible will lead to fewer complaints and an improved
Why is a lamp’s CRI or CCT important?
The Color Rendering Index (CRI) is the reason that the shirt
and pants you thought matched so well at home seem to clash
in the restroom at work. The closer the CRI of a lamp is to
100, the more “true” it renders colors in the environment.
For individuals, such as graphic artists who perform tasks that
require color precision or discrimination, lamps with a high
CRI are recommended. Full-spectrum lamps are available that
offer a CRI of over 90.
Warm and inviting are some of the words used to describe environments
that contain lamps with a Correlated Color Temperature (CCT)
of 3000K. Coffee shops, restaurants, and hotel lobbies are a
few applications in which cozy lighting environments are desirable.
Hospitals, cafeterias, classrooms, and conference rooms are
areas where an image of neatness is important. Lamps that appear
cool — measuring a CCT of 4100K — are most appropriate
for these types of applications. By comparison, daylight measures
5000K, and neutral lamps have a CCT of 3500K.
What are the differentiating characteristics of incandescent,
fluorescent, and high-intensity discharge?
• Appear “warm” in color and have excellent
• Are the least efficient of general lamp types due to
the amount of energy
consumed heating the filament in order
for the lamp to turn incandescent.
• Have a short lamp life of between 500 and 3,000 hours.
• Are easy to install because no ballast is required.
• Are available in a complete range of color combinations.
• Produce low heat.
• Require a more extensive installation because ballasts
are a necessary part of the fixture.
• Have an extremely long life of up to 24,000 hours.
• Due to smaller sizes and screw base features, fluorescents
can replace incandescent lamps.
High-intensity discharge (HID) lamps:
• Are ideal for large stores, warehouses, auditoriums,
outdoor parking areas, and applications where efficiency is
• Have a warm-up period, which results in slower start-up.
• Deliver a large amount of light over a wide area.
• Have a long life of between 5,000 and 24,000 hours.
• Require ballasts.
What does the nomenclature system for labeling and identifying
fluorescent lamps mean?
The most common fluorescent lamps used in commercial buildings
today are T8s. According to the Lighting Research Council (LRC),
Troy, NY, the ‘T’ indicates the shape of the lamp
— tubular, while the number following the T reveals the
diameter of the lamp in eighths of an inch. Therefore, a T8
lamp is tubular and 1-inch in diameter, whereas a T12 is likewise
tubular but twelve-eighths of an inch or 1.5 inches in diameter.
The National Electrical Manufacturers Association (NEMA), Rosslyn,
VA, has developed a system for designating compact fluorescent
lamp types as well. A lamp labeled CFT13W is a compact fluorescent
(CF), twin parallel tube (T), with a wattage of 13. The nomenclature
“equation” for compact fluorescent lamps is CF plus
(+) shape (T equals [=] twin parallel tubes, Q equals four parallel
tubes in a quad formation, S equals square shaped, M equals
any other multiple tube shape) plus (+) wattage. What follows
this designation is often a slash (/) and the abbreviated base
of mercury-containing lamps, such as fluorescent or
high-intensity discharge (HID), will eventually have
to decide the fate of expired bulbs. Due to increasing
concern about the dangers associated with human and
environmental interaction with mercury, the federal
government has strengthened, clarified, and modified
regulations. Less than a year ago, mercury-laden lamps
were added to the Universal Waste classification. As
of Jan. 6, 2000, says Steve Kirschner, marketing manager,
USA Lamp & Ballast Recycling Inc., Cincinnati, testing
lamps according to the Toxicity Characteristic Leaching
Procedure (TCLP) is no longer an option. Under the Universal
Waste rule, mercury-containing lamps can either be treated
as hazardous waste and disposed of at a hazardous waste
landfill or recycled.
The expense involved in these two procedures varies
greatly. “In order for us to pick up a shipment
five miles from here as hazardous waste, it’ll
cost close to $500 just in transportation,” and
this does not include other ancillary costs, Kirschner
says. Traveling the same distance to pick up the lamps
with the intent to recycle them is significantly less
expensive, with transportation costing a mere $18. This
cost difference is indicative of the high price of treating,
transporting, and reporting the bulbs as hazardous waste.
Through the recycling process, according to Kirschner,
lamps are crushed, components are separated, and the
mercury is extracted through a retort process. The mercury
powder is heated until it transforms into a vapor which
is pulled by vacuum through distillation coils and cooled.
The liquid mercury is then filtered to purify. “They’ve
made it so easy to recycle, it would be silly not to,”
How do T12, T10, T8, and T5 fluorescent lamps differ?
These four lamps vary in diameter (ranging from 1.5 inches
to 0.625 or five-eighths of an inch in diameter). Efficacy is
another area which distinguishes one from another. T8 lamps
offer a 5-percent increase in efficacy over 34-watt T12 lamps,
and have become the most popular choice for new installations.
Choosing Light Sources for General Lighting, published in 1998
by the Illuminating Engineering Society of North America (IESNA),
New York City, states that although they are available in lengths
similar to the T12, T8s require a different ballast. For retrofit,
the T10 is compatible with T12 ballasts. The T10 also uses a
higher-efficiency phosphor and has a greater efficacy than the
T5s are straight tube lamps with a high efficacy. Due to their
unique sizes (available only in “metric” lengths)
and special ballast requirements, the T5 is not a favorable
choice for many retrofits. It is important that the proper fixtures
are used during T5 installations in order to reduce glare.
How can a lighting upgrade improve a facility’s return
Subject to final rulemaking, the U.S. Department of Energy
(DOE), Washington, D.C., efficiency advocates, and lighting
manufacturers have reached an agreement that magnetic ballasts
will no longer be manufactured after April 1, 2005. “Magnetic
ballasts typically operate at 60 hertz, which is the common
operating frequency for electrical systems. Electronic ballasts
operate at 20 kilohertz, so they operate at a higher frequency.
[This] enables them to be more efficient at operating the lamp,
so they use less power,” says Dorene Maniccia, manager
of LRC partners program, Lighting Research Center (LRC).
Low-wattage lamps are often the first consideration when it
comes to cutting lighting costs. However, choosing energy-efficient
ballasts can substantially contribute to energy savings. The
evolution of ballast technology is also lessening the price
gap between magnetic and electronic ballasts.
“The big drivers for facilities professionals are the need
for flexibility and ease with maintenance,” says Janice
Rewers, marketing communications manager, lighting products,
Magnetek, Nashville. Facilitating maintenance and reducing the
need to purchase a range of products also affects overall costs.
Multi-functional, universal input voltage ballast products can
deliver those effects while reducing facilities headaches.
The other side of the energy-savings equation is reducing energy
consumption through lighting controls. Two types of occupancy
sensors — ultrasonic and passive infrared — are available.
Ultrasonic sensors generate sound waves that bounce off objects.
Occupancy detection occurs when the device senses that movement
in a certain area has interfered with these waves. Passive infrared
sensors (PIR) sense the difference in heat from a person vs.
general room radiation. PIR sensors are passive, while ultrasonic
are considered active.
Choosing the proper sensor depends on a given area’s configuration
and conditions. Choosing the proper sensor also affects the
bottom line. PIR sensors are available as wall-switch, wall-mount,
ceiling-mount, and outdoor commercial-grade units. Wall-switch
PIR sensors, used to replace traditional wall switches, are
best suited for private offices, copier rooms, and storage spaces.
Wall-mount units, that are typically mounted high on a wall,
are best suited for rooms with high ceilings, conference rooms,
hallways, classrooms, and stairwells. Ceiling-mount sensors,
best suited for open office spaces, lobbies, and cafeterias,
provide coverage for areas needing an overhead view. Outdoor
commercial units are available for perimeter and loading dock
According to the LRC, the effectiveness and energy-saving potential
of occupancy sensors is greatly influenced by proper installation.
Start with determining the amount of time lighting is left on
when a space is unoccupied. Additionally, facilities managers
need to monitor patterns of light usage to determine true savings.
Used correctly, occupancy sensors can lengthen lamp life and
reduce wattage and operating hours. When paired with a lighting
upgrade, savings can be significant.
Preheat, rapid-start, or instant-start — what ballast
is the best?
How long does it take a fluorescent lamp to turn on after
the switch is flipped? For ballasts that employ the preheat
system, it may take a few seconds. Rapid-start and instant-start
provide immediate starting. Traditional thought has been that
by providing a higher starting voltage across the lamp in an
instant-start system, lamp life may be significantly reduced.
However, research from the LRC, published in the Guide to Selecting
Frequently Switched T8 Fluorescent Lamp-Ballast Systems (1998),
found “no evidence to support the common belief that, when
operating cycles are short, rapid-start electronic ballasts
for T8 lamps provide longer lamp life than instant-start electronic
ballasts.” In areas where occupancy sensors are employed,
and lamps are switched on and off more frequently than every
three hours, both the instant-start and rapid-start systems
demonstrate comparable lamp life.
What is group relamping and how can it reduce maintenance
“In almost all cases, the cost of replacing the bulb
is more than the bulb,” says John Bachner, communications
director, National Lighting Bureau (NLB), Silver Spring, MD.
This principle is the basis of a practice called group relamping,
something Bachner says may seem counter-intuitive to some. The
idea is that all lamps are installed, cleaned, and replaced
at the same time, regardless of whether they have expired. This
practice is a money saver and cuts the average cost per lamp
replacement; allows work crews to spend less time on spot replacement
and more time on other duties; and enables new lamps to be purchased
in bulk — many times at volume-discount rates.
Interruptions for spot replacement are eliminated, building
occupants can be made aware of a pre-scheduled time when the
process will take place, and lamps can be ordered in advance.
“Group relamping significantly reduces expenses in the
short term, and big time in the long term,” Bachner concludes.
What can be done to prevent glare?
That light spot on the computer screen, the brightness “hole”
on a glossy sheet of paper, and the light bouncing off a glass-framed
piece of art are all examples of glare. Eyestrain, physical
fatigue, an inability to concentrate, headaches, and muscle
aches in the neck and shoulders are the results of this lighting
nemesis. According to the NLB, “a 1-percent productivity
loss among a $1 million/year workforce will cost a company $10,000
Strategies are available to eliminate and prevent glare. Rule
number one, according to Dr. Peter Boyce, head of the human
factors program, LRC, is “you don’t want a direct
view of the lamp from any normal viewing position.” Boyce
explains that a “bright thing out in the edge of the field
of view, [is] very distracting because the visual system is
designed to turn your attention toward it.” The NLB recommends
relocating items on the wall, reframing graphics with non-glare
glass, reorienting workstation or computer screens, and replacing
the lens or louver grid on overhead lighting as less expensive
alternatives to replacing the overhead lighting altogether.
Parabolic louvers for ceiling-recessed parabolic luminaires
will help reduce glare to surfaces, says the LRC’s Maniccia.
Because the parabolic luminaire directs light downward, caution
should be observed to ensure that a cave-like effect does not
result, because vertical surfaces may appear dark and gloomy.
Specular reflectors and diffusers are useful accessories to
direct the light of fluorescent (and compact fluorescent) lamps.
Boyce explains that smaller fluorescents need to be controlled
carefully. “The T5 has a much smaller surface area than
the T12 or T8. To get the same light output, the luminance of
the lamp is going to be a lot higher, [resulting in] a much
higher brightness,” he says. Reflectors minimize wasted
light by reflecting and redirecting it down and out of the luminaire.
However, illuminance uniformity may be affected.
What’s the story with daylighting?
Daylighting is defined as the sky’s contribution to
illuminating indoor spaces, excluding direct sunlight. Natural
sunlight has long been touted for its benefits to the work environment.
At the same time, glare from windows is the bane of people working
on computers. The secret to the daylight dilemma is diffused
natural lighting. While direct lighting can impair vision and
heat up a space, diffused sunlight connects end-users with the
external environment and creates a comfortable environment to
perform many tasks. “In a lot of open office environments,
the wall partitions are placed really high. All the advantages
of daylight in an open environment are taken away, because people
are essentially in windowless spaces,” says Heerwagon.
Facilities managers, architects, and interior designers need
to work together to create spaces that achieve the maximum advantage
of natural light.
The lighting environment includes window treatments and panel
systems. Adds Heerwagon, “Better integration of interior
design and facilities management with architectural solutions
has to happen.” In some applications, giving end-users
the ability to adjust window shading devices or using panel
systems with windows can curtail complaints. Manual dimming
controls, especially on the desktop, facilitates the use of
natural light. “Lighting is sexy; it’s intimate. Lighting,
unlike other systems, is something we are accustomed to interacting
with,” says Rewers of MagneTek.
The use of photosensors to dim lighting can also prevent excessive
brightness and reduce energy usage. Photosensors, unlike occupancy
sensors, are electronic control devices that adjust the light
output of a lighting system because of the detected illuminance
in the area. Proper installation and placement, according to
the LRC, have a tremendous impact on operation, energy savings,
and end-users’ complaints. Testing sensors and following
manufacturers’ guidelines translates into better performance.
In combination with occupancy sensors, energy-efficient luminaires,
and manual dimming controls, photosensors improve savings and
the general environment.
Lamp technology innovation has issued forth a tremendous improvement
in the quality of color and light. However, luminaires have
also had a tremendous impact on the quality of lighting. Instead
of static basic fixtures attached to office furniture, some
furniture manufacturers are creating diffused light fixtures
that work in concert with their workstations. The proper combination
of task lighting and general or ambient indirect lighting can
create a quality lighting environment. A Cornell University
department of design and environmental analysis case study on
the benefits of two-component lighting showed how task and indirect
ambient lighting improved end-users’ perception of their
A quality lighting environment is one where the end-users are
satisfied and there is an absence of lighting-related health
symptoms. The study also showed the importance end-users place
on flexibility and the desire to control the brightness of their
light environment. In open office space, this is usually achieved
with task lighting. Conversely, in private offices, ambient
and task lighting need to be adjustable. “I believe the
industry is really listening to the voice of the customer; we’re
giving the flexibility they need,” says Rewers.
How can a higher-quality lighting system save money?
Small improvements equal big savings. Bachner explains that
if, in a 40-hour work week, employees are losing 26 seconds
per hour due to the effects of poor lighting, a 1-percent improvement
in productivity, due to a high-quality lighting system, will
equal a 500-percent savings each year. This figure assumes an
employee’s yearly salary of $25,000, including fringe benefits.
What’s on the horizon in lighting?
Ever since the first firefly was captured, there has been
a search for light without heat. This promise of cool light
is coming true with research on LEDs (light-emitting diodes),
and their usage in signage, dim switches, and backlighting.
Adds Rewers, “The industry needs to prepare the buyers
for all the revolutionary changes that are coming.” Improvements
in glass and plastic fiber-optics and LEPs (light-emitting polymers)
are enabling light in challenging applications.
Computer and tabletop controls are also changing the face of
commercial interiors. An industry initiative to increase awareness
of lighting controls and fluorescent dimming products, the Rosemont,
IL-based National Dimming Initiative (NDI), is striving to educate
lighting professionals and building design firms. Through education,
the NDI is promoting possibilities about the latest technologies.
At the same time, facilities professionals are recognizing how
quality lighting in conjunction with overall good design redefines
their buildings. Perhaps it’s no coincidence that the symbol
for a bright idea is a lit light bulb — enlightened thinking
about lighting is one of the brightest ideas there is.
Regina Raiford firstname.lastname@example.org
is senior editor at Buildings magazine.
Jana J. Smith email@example.com
is senior associate editor at Buildings Magazine.
Illustration by Rowan Enterprises.
Color rendering index (CRI) —
a method for describing the effect of a light source
on the color appearance of objects being illuminated,
with a CRI of 100 representing the reference condition
(and the maximum CRI possible). In general, a lower
CRI indicates that some colors may appear unnatural
when illuminated by a lamp.
Color temperature — see correlated color
Constant-wattage autotransformer (CWA) —
the most common type of ballast used for HID lamps,
it maintains a constant power (wattage) supply to the
lamp when system input voltage fluctuates.
Correlated color temperature (CCT) — a description
of the color appearance of a light source in terms of
warmth or coolness, as measured on the Kelvin scale
(K). As the temperature rises, the color appearance
shifts from yellow to blue. Thus, lamps with a low CCT
(3000K or less) have a yellow-white color appearance
and are described as “warm”; lamps with a
high CCT (4000K and higher) have a blue-white color
appearance and are described as “cool.”
Ballast factor (BF) — the ratio of the light
output of a lamp operated by a given ballast to the
light output of the same lamp when operated by a reference
ballast. Lamps operated by a ballast with a BF of 0.90
will provide 90 percent of their rated light output
(lumens). BFs between 0.85 and 1.0 are the most common.
Disability glare — light that is relatively
bright compared to the background, making vision measurably
worse. The inability to see clearly as a result of the
brightness of headlights from an oncoming car at night
is an example.
Discomfort glare — the type of glare that
is uncomfortable and distracting, yet less obvious than
disability glare. A bright light source in an individual’s
peripheral vision is an example.
Efficacy — the ratio of light output (lumens)
to input power (watts), expressed in lumens per watt
High-pressure sodium (HPS) — a high-intensity
discharge lamp that uses sodium under high pressure
as the primary light-producing element.
Illuminance — The amount of light that reaches
a surface. Illuminance is measured in footcandles (lumens/square
foot) or lux (lumens/square meter). One footcandle equals
10.76 lux, although for convenience the IESNA uses 10
lux as the equivalent.
Instant-start — a method of starting fluorescent
lamps in which the voltage that is applied across the
electrodes to strike the
electric arc is up to twice as high as it is with other
starting methods. The higher voltage is necessary because
the electrodes are not heated prior to starting.
Lamp life — the median life span of a very
large number of lamps. Half of the lamps in a sample
are likely to fail before the rated lamp life, and half
are likely to survive beyond the rated lamp life.
Lamp lumen depreciation (LLD) — the reduction
in lamp light output that progressively occurs during
Lumen (lm) — a unit measurement of the rate
at which a lamp produces light. A lamp’s light
output rating expresses the total amount of light emitted
in all directions per unit time. Ratings of initial
light output provided by manufacturers express the total
light output after 100 hours of operation.
Luminance — the photometric quantity most
closely associated with the perception of brightness,
measured in units of luminous intensity (candelas) per
unit area (feet squared or meters squared).
Luminaire efficiency — the ratio of the
light emitted by a luminaire to the light emitted by
the lamp or lamps within it. A highly efficient luminaire
emits most of the light that the lamp(s) emits.
Mercury vapor (MV) — a high-intensity discharge
lamp type that uses mercury as the primary light-producing
Metal halide (MH) — a high-intensity discharge
lamp type that uses mercury and several halide additives
as light-producing elements.
Open-circuit voltage — the voltage applied
across the output terminals of a ballast when no load
is connected. This is the voltage applied across a lamp
circuit to start a lamp. After starting, the voltage
rapidly decreases and stabilizes at the operating voltage.
Preheat — a method of starting fluorescent
lamps in which the electrodes are heated before a switch
opens to allow a starting voltage to be applied across
the lamp. With preheat starting, the lamp flashes on
and off for a few seconds before staying lit.
Power factor — a measure of how effectively
a ballast converts current and voltage into usable power
to operate the lamps. A power factor of 0.9 or greater
indicates a high-power-factor ballast.
Prismatic lens — an optical component of
a luminaire that is used to distribute the emitted light.
It is usually a sheet of plastic with a pattern of pyramid-shaped
refracting prisms on one side. Most ceiling-mounted
luminaires in commercial buildings use prismatic lenses.
Rapid-start — a method of starting fluorescent
lamps in which the ballast supplies voltage to heat
the lamp electrodes for one to two seconds prior to
starting and, in most cases, during lamp operation.
A rapid-start system starts smoothly, without flashing.
Reflected glare — often called veiling reflections,
glare that results from light shining off polished or
Restrike time — the time required for a
lamp to restrike, or start, after the lamp is extinguished.
Normally, HID lamps need to cool before they can be
Visual comfort probability (VCP) — a system
for estimating discomfort glare that predicts the percentage
of people who are likely to find the lighting comfortable,
against the percentage that find it uncomfortable.
GLOSSARY SOURCE: LIGHTING RESEARCH CENTER, TROY, NY