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Commercial Lighting Design Guide Appendix E
Doc 4775A 100
L
LAMP CURRENT CREST FACTOR (LCCF): The peak lamp current divided
by the RMS (average) lamp current. Lamp manufacturers require <1.7
for best lamp life. An LCCF of 1.414 is a perfect sine wave
LAMP LUMEN DEPRECIATION FACTOR (LLDF): A factor that represents
the reduction of lumen output over time. The factor is commonly used as
a multiplier to the initial lumen rating in illumination calculations, which
compensates for the lumen depreciation. The LLD factor is a
dimensionless value between 0 and 1
LAY-IN-TROFFER: A fluorescent fixture; usually a 2' x 4' fixture that sets
or "lays" into a specific ceiling grid
LED: Abbreviation for light emitting diode. An illumination technology
used for exit signs. Consumes low wattage and has a rated life of
greater than 80 years
LENS: Transparent or translucent medium that alters the directional
characteristics of light passing through it. Usually made of glass or
acrylic
LIGHT LOSS FACTOR (LLF): Factors that allow for a lighting system's
operation at less than initial conditions. These factors are used to
calculate maintained light levels. LLFs are divided into two categories,
recoverable and non-recoverable. Examples are lamp lumen
depreciation and luminaire surface depreciation
LIFE-CYCLE COST: The total costs associated with purchasing,
operating, and maintaining a system over the life of that system
LOUVER: Grid type of optical assembly used to control light distribution
from a fixture. Can range from small-cell plastic to the large-cell
anodized aluminum louvers used in parabolic fluorescent fixtures
LOW POWER FACTOR: Essentially, an uncorrected ballast power factor of
less than 0.9 (SEE NPF)
LOW-PRESSURE SODIUM: A low-pressure discharge lamp in which light
is produced by radiation from sodium vapor. Considered a
monochromatic light source (most colors are rendered as gray)
LOW-VOLTAGE LAMP: A lamp (typically compact halogen) that provides
both intensity and good color rendition. Lamp operates at 12V and
requires the use of a transformer. Common lamps are MR11, MR16, and
PAR36
LOW-VOLTAGE SWITCH: A relay (magnetically-operated switch) that
allows local and remote control of lights, including centralized time clock
or computer control
LUMEN: A unit of light flow, or luminous flux. The lumen rating of a lamp
is a measure of the total light output of the lamp
LUMINAIRE: A complete lighting unit consisting of a lamp or lamps, along
with the parts designed to distribute the light, hold the lamps, and
connect the lamps to a power source. Also called a fixture
LUMINAIRE EFFICIENCY: The ratio of total lumen output of a luminaire
and the lumen output of the lamps, expressed as a percentage. For
example, if two luminaires use the same lamps, more light will be
emitted from the fixture with the higher efficiency.
LUMINANCE: A photometric term that quantifies brightness of a light
source or of an illuminated surface that reflects light. It is expressed as
footlamberts (English units) or candelas per square meter (Metric units)
LUX (LX): The metric unit of measure for illuminance of a surface. One
lux is equal to one lumen per square meter. One lux equals 0.093
footcandles
M
MAINTAINED ILLUMINANCE: Refers to light levels of a space at other
than initial or rated conditions. This term considers light loss factors
such as lamp lumen depreciation, luminaire dirt depreciation, and room
surface dirt depreciation
MAGNETIC LOW-VOLTAGE (MLV): Magnetic low-voltage lighting uses a
magnetic (core and coil technology) transformer to convert line voltage
(120 VAC) to low voltage (typically 12 VAC). This lower voltage is then
used to power an incandescent low-voltage lamp. Recessed lights are
most often magnetic low-voltage. Magnetic low-voltage lights tend to be
larger and heavier than electronic low-voltage
MERCURY VAPOR LAMP: A type of high intensity discharge (HID) lamp in
which most of the light is produced by radiation from mercury vapor.
Emits a blue-green cast of light. Available in clear and phosphor-coated
lamps
METAL HALIDE: A type of high intensity discharge (HID) lamp in which
most of the light is produced by radiation of metal halide and mercury
vapors in the arc tube. Available in clear and phosphor-coated lamps
MR-16: A low-voltage quartz reflector lamp, only 2" in diameter.
Typically the lamp and reflector is one unit, which directs a sharp,
precise beam of light
N
NADIR: A reference direction directly below a luminaire, or "straight
down" (0 degree angle
NEMA: Abbreviation for National Electrical Manufacturers Association
NEON/COLD CATHODE: Highly inductive boost transformer for neon/cold
cathode lighting
NIST: Abbreviation for National Institute of Standards and Technology
NPF (NORMAL POWER FACTOR): A ballast/lamp combination in which no
components (e.g., capacitors) have been added to correct the power
factor, making it normal (essentially low, typically 0.5 or 50%)
O
OCCUPANCY SENSOR: Control device that turns lights off after the space
becomes unoccupied. May be ultrasonic, infrared or other type
OPTICS: A term referring to the components of a light fixture (such as
reflectors, refractors, lenses, louvers) or to the light emitting or light-
controlling performance of a fixture
P
PAR LAMP: A parabolic aluminized reflector lamp. An incandescent,
metal halide, or compact fluorescent lamp used to redirect light from the
source using a parabolic reflector. Lamps are available with flood or spot
distributions
PAR 36: A PAR lamp that is 36 one-eighths of an inch in diameter with a
parabolic shaped reflector (SEE PAR LAMP)
PARABOLIC LUMINAIRE: A popular type of fluorescent fixture that has a
louver composed of aluminum baffles curved in a parabolic shape. The