LAMPS (Chapter 3)

Lamp efficacy, life, and color Incandescent

Incandescence (Additional information) Light emitted from a heated object Uses a tungsten filament enclosed in a glass bulb, usually filled with a mixture of

nitrogen and argon gases Operates at 4800oF

Tungsten has the highest melting point of all metals (6170° F) and has a high conductivity Efficacy (some additional information)

Efficacy = Lumens/Watt Life Color Special lamps Lamp Shape and size

LAMPS (Chapter 3) Fluorescent lamps

Fluorescence (Additional information) Conversion of ultra-violet light into visible energy

Efficacy Life CRI Color Operation Lamp types and bases

Preheat Instant start Rapid start High and very high output

Lamp designations Ballasts Special fluorescent lamps

Compact Energy efficient fluorescent lamps Cold cathode Neon

LAMPS (Chapter 3)

High intensity discharge (HID) What is it?

Production of light by passing an electric arc through a conductive vapor HID efficacy and life

Mercury Color Efficacy Life

Sodium High pressure Low pressure Color Efficacy Life

Metal Halide Color Efficacy Life

CRI Comparisons

Other types E-lamp

A compact high-tech induction reflector lamp LED

Special semi-conductor chips (diodes) that emit light when connected in a circuit

LIGHTING NUMBERS (Chapter 7)

Terms and accents How much light? Luminaire photometrics

Luminaire (Additional information) Complete lighting unit consisting of lamps, parts that position and protect lamp, and means of connection to power supply. Also

referred to as a fixture S/MH (spacing-to-mounting height ratio [spacing between two adjacent luminaires/mounting height of the luminaire); also called

spacing criteria (SC)] Coefficient of utilization (CU)

CU values are influenced by (Additional information): Room surface reflectances Size and shape of a room Location of luminaires Design of luminaires

Light loss factor (LLF) (Additional information) Ratio of illumination of a given area after a period of time to the initial illumination on the same area Usually two main factor are taken into consideration for calculating LLF (additional information):

Lamp lumen depreciation (LLD): A factor used to account for reduced lumen output due to aging of lamp sources. Luminaire dirt depreciation (LDD): A factor used to account for reduced illumination due accumulation of dirt on luminaires. May be obtained

by consulting the Maintenance Category of the luminaires. LLF = LLD*LDD

Cavity ratio (CR) (Additional information) A number that indicates the proportions of a cavity (space) calculated from its length, width, and height. Room, floor, and ceiling cavity

ratio have to be determined. RCR FCR CCR

LIGHTING NUMBERS (Chapter 7)

Footcandle calculations Example calculations Reflectances

Coefficient of utilization CU values are influenced by (Additional information):

Room surface reflectances Size and shape of a room Location of luminaires Design of luminaires

Lighting quality numbers VCP ESI CRF VDT

W

L

Perimeter = 2x(L+W)

LIGHTING DESIGN (Additional information)

Determination of CU Divide the space into cavities: (1) Ceiling cavity (2) Room cavity (3) Floor

cavity Determine cavity ratio: CR = 2.5*cavity ht.*cavity perimeter/cavity area Example:

Room cavity ratio = [2.5*5.5*(29.33+14+29.33+14)]/410.62 = 2.9 Reflectances

Find out wall, ceiling, and floor reflectances based on surface colors Find out effective ceiling and floor cavity reflectances Effective ceiling cavity reflectance: Combined reflectance effect of all

surface areas above plane of luminaire Effective floor cavity reflectance: Combined reflectance effect of all surface

areas below work plane Use actual reflectances when CR = 0 Adjust CU if effective floor cavity reflectance is more than 30% or less than

10%

Mean reflectance values of some common colored surfaces

Surface color ReflectanceWhite 80Light gray 50Dark gray 20Ivory white 80Ivory 70Fawn 50Buff 50Tan 40Brown 30Cream 50Green 40Olive 20Azure blue 50Sky blue 40Pink 60Red 20

LIGHTING DESIGN (Additional information)

Choosing a luminaire Choose one that has a CU table available Use lamps with high efficacy

Determine number of lamps and find out initial lumens, life, and replacement protocol

Spacing criteria (SC or S/MH) Fixture spacing should have an acceptable uniformity of

illumination. Use recommended SC factor to determine both across (side-to-side) and along (end-to-end) spacing.

Formula to be used for lighting design Illuminance = (No. of luminaires*lamps per luminaire*lumens per

lamp*CU*LLF)/Area No. of luminaires = (Illuminance*Area)/(Lamps per luminaire*lumens

per lamp*CU*LLF)