BU 3: Lighting and Acoustics (AUSAT)

Luminaire

Complete LIGHTING UNIT consisting of one or more lamps.

Luminaire Efficiency

ratio of LUMINOUS FLUX EMITTED to TOTAL FLUX EMITTED.

Luminous Efficacy

Measure of EFFECTIVENESS where light source converts electric power to luminous flux

Luminous Intensity

Luminous flux per unit solid angle; Measured in CANDELA or CANDLE POWER

Intensity

Luminous flux per unit solid angle expressed in LUMENS PER STERADIANS

Luminous Flux

RATE OF FLOW of light through a surface; Quantity of light; in LUMENS

Luminance Meter

Visual instrument used to MEASURE LUMINANCE.

Brightness

Attribute of visual perception to which a surface appears to emit MORE or LESS light

Brilliance

CLARITY, STRENGTH, and BRIGHTNESS of color

Contrast

DIFFERENCE IN BRIGHTNESS of an object and its background

Glare

sensation produced by luminance within the visual field that is sufficiently GREATER than which the EYES ARE ADAPTED.

Direct Glare

Glare resulting from HIGH LUMINANCE

Discomfort Glare

Glare producing DISCOMFORT

Emissivity

Ratio of RADIANT ENERGY EMITTED to that emitted by a perfect black body.

Infrared Radiation

NON VISIBLE LIGHT characterized by its relation to HEAT.

Ultraviolet Radiation

Non- visible light that can have both HARMFUL and BENEFICIAL effects.

Visible Light

COMBINATION of the colors of the visible spectrum. ROYGBIV

Coefficient of Utilization

RATIO of the LUMINOUS FLUX to the LUMINOUS FLUX EMITTED by luminaire lamp

Lamp Lumen Depreciation

Multiplicative factor in REDUCTION in light output over a PERIOD OF TIME.

Light Loss Factor

Factor used in calculating ILLUMINANCE after a given period. Also known as Maintenance Factor

Luminaire Dirt Depreciation

Multiplicative factor in REDUCTION in light output due to COLLECTION OF DIRT.

Room Cavity Ratio

Number indicating the proportions of the room. VOLUME OF THE ROOM.

Visual Comfort Probability

RATING of lighting system when viewing from a SPECIFIED LOCATION.

Point Source

A source where light RADIATES in ALL DIRECTION

Beam Angle

Angle between two directions where the intensity is 50 PERCENT of the maximum intensity

Critical Angle

Angle at which light undergoes total INTERNAL REFLECTION.

Nadir

VERTICALLY DOWNWARD directly below the luminaire or lamp

Specular Reflection

Mirror-like reflection

Polarization

Process by which the TRANSVERSE VIBRATION of light waves are oriented in a SPECIFIC PLANE.

Ambiant Lighting

Lighting throughout an area the produces GENERAL ILLUMINATION.

Light

Artificial source of illumination

Photoluminescence or Gaseous Discharge

Is light emission from any form of matter after the ABSORPTION of photons (electromagnetic radiation).

Fluorescence

The visible or invisible radiation emitted by certain substances as a result of incident radiation of a shorter wavelength such as X-rays or ultraviolet light.

Phosphorescence

Light emitted by a substance WITHOUT COMBUSTION or perceptible heat.

Electroluminescence

Luminescence produced ELECTRICALLY, especially in a phosphor by the application of a voltage.

Absorption (Laws of light)

Component colors are ABSORBED

Absorptance

Ratio of LIGHT ABSORBED by a material to the light falling upon it

Reflection (Laws of light)

Property of being able to REFLECT light when hitting a surface.

Diffuse Reflection

When reflection is SPREAD to different directions

Reflectance

RATIO of REFLECTED TO INCIDENT LIGHT

Transmission (Laws of light)

Property of being able to TRANSMIT light from one surface to another

Diffuse Transmission

Emerging light spreads in all direction

Diffusion(Laws of light)

Property of being to DIFFUSE light in all directions.

Refraction (Laws of light)

Property of being able to CHANGE DIRECTION of light at the interface between two materials.

Polarization (Laws of light)

Phenomenon where the waves vibrate only in ONE PLANE.

Illumination

LUMINOUS POWER PER UNIT AREA; E= F/A; Lux or Foot Candle

Inverse Square Law

A law stating that the intensity of an effect such as illumination or gravitational force changes in inverse proportion to the square of the distance from the source.

Cosine Law

Illuminance on any surface varies with the COSINE of the angle of incidence

Illuminance

The amount of luminous flux per unit area.

Incandescent Lamp

Lamp where it employs the principle of converting ELECTRICAL ENERGY into HEAT.

Fluorescent Lamp

Lamp where electric ARC is produced between the opposing electrodes.

High Intensity Discharge Lamp

Produces HIGH INTENSITY light within an arc tube contained in an outer bulb.

Short Arc Lamp

Produces light in a SMALL TUBE and are the closest thing to a TRUE POINT SOURCE of high Luminance.

Low Pressure Sodium Lamps

Monochromatic lamps in the yellow region of the spectrum

Electroluminescent Lamp

Emit light by direct excitation of phosphor from an alternating current

Electrodeless lamp

Gaseous Lamps excited by means of electromagnetic or microwave energy.

Initial Lumens

INITIAL rated light power output.

Average Lumens

AVERAGE of the initial lumens output

Mean Lumens

Lumens output at 40% of the rated life

Beam Lumens

Initial lumens output within the central beam

Rated Lamp Life

Time elapsed when 50 percent of LAMPS remain BURNING.

Lumen Depreciation

LOSS OF LIGHT output as it DEPRECIATES with time.

Filament (Parts of a bulb)

It may be straight coil or a coiled coil.

Bulb (Parts of a bulb)

A soft glass used to encase the filaments

Lead in Wires (Parts of a bulb)

Made from base to stem press and nickel from press to filament

Support Wires

Molybdenum wire support the filament

Button Glass

Heated during the manufacturing and support wires stuck into it.

Button Rod

Glass rod support button

General Service Type (Types of Incandescent Lamp)

For GENERAL use in buildings

Rough and Vibration Services (Types of Incandescent Lamp)

Used in location subjects such as on MACHINERY or in mechanical equipment

Extended Life Service (Types of Incandescent Lamp)

Designed with HEAVY FILAMENTS to operate at lower than 3800 degrees F.

Dichroic Reflector Lamps

Lamps TRANSMIT COLOR selectively through a molecular layer of chemical coating. Used to reduce infrared wavelength

Krypton Lamps (Types of Incandescent Lamp)

Lamps are filled with KRYPTION gas.

Tungsten Halogen Lamps (Types of Incandescent Lamp)

Makes use of HALOGEN regenerative cycle to reduce blackening by depositing evaporated tungsten atoms on filaments

Miniature Reflector Lamps (Types of Incandescent Lamp)

Popular in interior and accent lighting application

Preheat Lamp (Type of Fluorescent Lamp)

Manual or automatic STARTER SWITCH is required for this type of fluorescent lamp

Instant Start Lamp (Type of Fluorescent Lamp)

These lamps operate WITHOUT STARTERS

Rapid-Start Lamps

These lamps start in less than one second, INSTANTANEOUSLY.

SL Lamps

These lamps are specifically designed to FIT DIRECTLY in an INCANDESCENT LAMP FIXTURE.

Black Lamps

Produce energy in the near ULTRA VIOLET RANGE

UV Lamps

Produce ULTRA VIOLET energy for germicidal use

Plant Growth Lamp

Designed to simulate PHOTOSYNTHESIS

Cold Cathode Lamp

Phosphor coated lamp filled with MERCURY VAPOR and ARGON gas, used for DECORATIVE LIGHTING.

Neon Lamps

Emits different COLORS due to different gases.

Mercury Lamps

Containg MERCURY VAPOR and produces bluish white light

General Lighting

Designed to give uniform and generally diffuse lighting throughout the area under consideration

Local and Supplementary Lighting

Provides small high level area of lighting without contributing to the general lighting

Supplementary Lighting

Provides restricted area of high intensity light

Combined General and Local Lighting

Used in spaces where the general visual task is low but supplementary lighting is required.

Indirect Lighting

90 to 100 percent of the light is directed to the ceiling.

Semi indirect Lighting

60 to 90 percent light is directed to the ceiling

Direct-Indirect and General Diffuse Lighting

Provides approximately equal distribution of light UPWARD and DOWNWARD

Semi-Direct Lighting

60 to 90 percent of the lamp output is directed DOWNWARD and the remaining serves to illuminate the ceiling

Direct Lighting

ALL light is directed downward.

Zonal Cavity Method

Method used for general lighting design when the average illuminance in a horizontal work surface is to be estimated

Absorbing Materials

Materials that DISSIPATE acoustic energy as HEAT.

Absorption

Ability of a material to ABSORB acoustical energy.

Absorption Coefficient

FRACTION of sound energy on a surface that is ABSORBED by the surface

Acoustics

SCIENCE OF SOUND including Generation, transmission and effects of sound waves

Acoustical Analysis

Detailed STUDY of all pertinent sound sources in a context of a particular acoustic problem.