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LAMPS (Chapter 3) Lamp efficacy, life, and color Incandescent Incandescence (Additional information) Light emitted from a heated object Uses a tungsten.

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Presentation on theme: "LAMPS (Chapter 3) Lamp efficacy, life, and color Incandescent Incandescence (Additional information) Light emitted from a heated object Uses a tungsten."— Presentation transcript:

1 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 4800 o F 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

2 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

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4 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

5 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

6 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

7 W L Perimeter = 2x(L+W)

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11 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*( )]/ = 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%

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13 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)


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