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# Lighting Efficiency Measures

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This chapter describes the different lighting efficiency measures in lieu with the application of architecture, design and planning.

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### Lighting Efficiency Measures

1. 1. LightingIntroductionTypes of lighting systemsAssessment of lighting systemsEnergy efficiency opportunities 1
2. 2. IntroductionBackground• Lighting energy consumption • 20-45% in commercial buildings • 3-10% in industrial plants• Significant energy savings can be realized with a minimal capital investment 2
3. 3. IntroductionBasic Theory• Light: electromagnetic waves in space• Light is emitted through: a) Incandescence b) Electric discharge c) Electro luminescence d) Photoluminescence 3
4. 4. IntroductionDefinitions and Common Terms Lumen • 1 lumen = the photometric equivalent of the watt • 1 lumen = luminous flux per m2 of a sphere with 1 m radius and a 1 candela isotropic light source at the centre • 1 watt = 683 lumens at 555 nm wavelength Lux • metric unit of measure for illuminance on a surface: 1 lux = 1 lumen / m2 4
5. 5. IntroductionDefinitions and Common Terms Luminous intensity (I) • measured in Candela (cd) Luminous flux (lm) • 4 x luminous intensity 5
6. 6. IntroductionDefinitions and Common Terms Installed load efficacy • Average maintained illuminance on a working plane: lux/W/m2 Installed load efficiency ratio • Target load efficacy / Installed load Rated luminous efficacy • Rated lumen output of the lamp / rated power consumption • Lumens per watt 6
7. 7. IntroductionDefinitions and Common Terms Room index • Ratio for the plan dimensions of the room Target load efficiency • Installed load efficacy considered achievable under best efficiency • Lux/W/m² Utilization factor • A measure of the effectiveness of the lighting scheme 7
8. 8. IntroductionDefinitions and Common Terms The inverse square law • Defines the relationship between illuminance from a point source and distance E = Iluminance E=I/ d2 I = Luminous intensity E1 d12 = E2 d22 d = distance 8
9. 9. IntroductionDefinitions and Common Terms Color temperature • Color appearance of a lamp and the light it produces • Measured in Kelvin (K) • Incandescent lamps: “true value” color temperature • Fluorescent and high intensity discharge (HID) lamps: correlated color temperature 9
10. 10. IntroductionDefinitions and Common Terms Color rendering index (CRI) Color CIE general color Typical application rendering rendering Index(Ra) groups 1A Ra > 90 Wherever accurate color rendering is required e.g. color printing inspection 1B 80 < Ra < 90 Wherever accurate color judgments are necessary or good color rendering is required for reasons of appearance e.g. display lighting 2 60 < Ra < 80 Wherever moderate color rendering is required 3 40 < Ra < 60 Wherever color rendering is of little significance but marked distortion of color is unacceptable 4 20 < Ra < 40 Wherever color rendering is of no importance at all and marked distortion of colour is acceptable Table 1. Applications of color rendering groups (Bureau of 10 Energy Efficiency, 2005)
11. 11. Training Agenda: ElectricityIntroductionTypes of lighting systemsAssessment of lighting systemsEnergy efficiency opportunities 11
12. 12. Types of Lighting Systems• Incandescent lamps• Tungsten Halogen Lamps• Fluorescent lamps• High pressure sodium lamps• Low pressure sodium lamps HID lamps• Mercury vapour• Metal halide• Blended• LED lamps 12
13. 13. Types of Lighting Systems Incandescent Lamps• Emit radiation mainly in the visible region• Bulb contains vacuum or gas filling• Efficacy: 12 lumen / Watt• Color rendering index: 1A• Color temperature: 2500 – 2700 K• Lamp life <2000 hrs (BEE India, 2005) 13
14. 14. Types of Lighting Systems Tungsten-Halogen Lamps• Tungsten filament and a halogen gas filled bulb• Tungsten atoms evaporate from the hot filament and move to cooler wall of bulb • Advantages:• Efficacy: 18 lumens/Watt • More compact • Longer life• Color rendering index: 1A • More and whiter light• Color temperature: warm • Disadvantages: • Cost more• Lamp life < 4000 hrs • Increased IR and UV • Handling problems Tungsten halogen lamps 14 (BEE India, 2005)
15. 15. Types of Lighting Systems Fluorescent Lamps• 3 – 5 times as efficient as standard incandescent lamps and last 10 – 20 times longer• Electricity passes through a gas or metallic vapor and causes radiation• Fluorescent tubes are hot cathode lamps 15 © UNEP 2006
16. 16. Types of Lighting Systems Fluorescent Lamps Features: Halo-phosphate • Efficacy – 80 lumens/Watt (HF gear increases this by 10%)• Different types (T12, • Color Rendering Index –2-3 T10, T8 and T5) • Color Temperature – Any differing in diameter • Lamp Life – 7-15,000 hours Tri-phosphor and efficiency • Efficacy – 90 lumens/Watt • Color Rendering Index –1A-1B• Most efficient at • Color Temperature – Any ambient temperature • Lamp Life – 7-15,000 hours of 20-30 oC,• Compact fluorescent lamps (CFL) have much smaller luminaries Compact fluorescent lamp (CFL) 16 (BEE India, 2005)
17. 17. Types of Lighting Systems High Pressure Sodium (HPS) Lamps• Used in outdoor and industrial applications• Consist of: ballast, high- voltage electronic starter, ceramic arc tube, xenon gas filling, sodium, mercury• No starting electrodes• High efficacy: 60 – 80 lumen/Watt• Color rendering index: 1 - 2• Color temperature: warm• Lamp life < 24,000 hrs 17 BEE India, 2005
18. 18. Types of Lighting SystemsLow Pressure Sodium (LPS) Lamps• Commonly included in the HID family• Highest efficacy: 100 - 200 lumen/Watt• Poorest quality light: colors appear black, white or grey shades• Limited to outdoor applications• Efficacy: Color rendering index: 3• Color temperature: yellow• Lamp life < 16,000 hours 18
19. 19. Types of Lighting Systems Mercury Vapor Lamps• Oldest HID lamp• Consists of: arc tube with mercury and argon gas and quartz envelope, third electrode, outer phosphor coated bulb, outer glass envelope• Long life and low initial costs• Very poor efficacy: 30 – 65 lumens/Watt• Color rendering index: 3• Color temperature: intermediate• Lamp life: 16000 – 24000 hours 19
20. 20. Types of Lighting Systems Metal Halide Lamps• Works similar to tungsten halogen lamps• Largest choice of color, size and rating• Better efficacy than other HID lamps: 80 lumen/Watt• Require high voltage ignition pulse but some have third electrode for starting• Color rendering index: 1A – 2 BEE India, 2005• Color temperature: 3000 – 6000 K• Lamp life: 6000 – 20,000 hours 20 © UNEP 2006
21. 21. Types of Lighting SystemsBlended Lamps• “Two-in-one”: 2 light sources in 1 gas filled bulb • Quartz mercury discharge tube • Tungsten filament• Suitable for flame proof areas• Fit into incandescent lamps fixtures• Efficacy: 20 – 30 lumen/Watt• Lamp life < 8000 hours• High power factor: 0.95 BEE India, 2005• Typical rating: 160 W 21
22. 22. Types of Lighting SystemsLED Lamps• Newest type of energy efficient lamp• Two types: • red-blue-green array • phosphor-coated blue lamp• Emit visible light in a very narrow spectrum and can produce “white light”• Used in exit signs, traffic signals, and the technology is rapidly progressing• Significant energy savings: 82 – 93%• Longest lamp life: 40,000 – 100,000 hours 22
23. 23. Types of Lighting Systems Reflectors• Impact how much light reaches area and distribution pattern• Diffuse reflectors: • 70-80% reflectance but declining in time BEE India, 2005 • painted or powder coated white finish• Specular reflectors: • 85-96% reflectance and less decline in time • Polished or mirror-like • Not suitable for industrial open-type strip fixtures 23
24. 24. Types of Lighting SystemsGear• Ballast • Current limiting device • Helps voltage build-up in fluorescent lights• Ignitors • Start metal halide and sodium vapor lamps 24
25. 25. Types of Lighting SystemsComparing lamps Lum / Color Watt Life Type of Lamp Rendering Typical Application Rang Av (Hours) Index e g.Incandescent 8-18 14 Excellent Homes, restaurants, general 1000 lighting, emergency lightingFluorescent Lamps 46-60 50 Good w.r.t. Offices, shops, hospitals, 5000 coating homesCompact fluorescent lamps 40-70 60 Very good Hotels, shops, homes, 8000-10000(CFL) officesHigh pressure mercury 44-57 50 Fair General lighting in factories, 5000(HPMV) garages, car parking, flood lightingHalogen lamps 18-24 20 Excellent Display, flood lighting, 2000-4000 stadium exhibition grounds, construction areasHigh pressure sodium 67- 90 Fair General lighting in factories, 6000-12000(HPSV) SON 121 ware houses, street lightingLow pressure sodium (LPSV) 101- 150 Poor Roadways, tunnels, canals, 6000-12000SOX 175 street lighting 25
26. 26. Training Agenda: ElectricityIntroductionTypes of lighting systemsAssessment of lighting systemsEnergy efficiency opportunities 26
27. 27. Assessment of Lighting SystemsDesigning with Light• Better lighting: increased productivity• Two main questions for designer: • Choose correct lighting level • Choose quality of light (color rendering) 27
28. 28. Assessment of Lighting Systems Designing with LightRecommended light levels for different tasks (BEE India, 2005) Illuminance Examples of Area of Activity level (lux)General Lighting for rooms 20 Minimum service illuminance in exterior circulating areas,and areas used either outdoor stores , stockyardsinfrequentlyand/or casual or simple 50 Exterior walkways & platforms.visual tasks 70 Boiler house. 100 Transformer yards, furnace rooms etc. 150 Circulation areas in industry, stores and stock rooms. 200 Minimum service illuminance on the task 300 Medium bench & machine work, general process in chemical and food industries, casual reading and filing activities.General lighting for 450 Hangers, inspection, drawing offices, fine bench and machineinteriors assembly, colour work, critical drawing tasks. 1500 Very fine bench and machine work, instrument & small precision mechanism assembly; electronic components, gauging & inspection of small intricate parts (may be partly provided by local task lighting)Additional localized lighting 3000 Minutely detailed and precise work, e.g. Very smallfor visually exacting tasks parts of instruments, watch making, engraving. 28
29. 29. Assessment of Lighting SystemsRecommended Illuminance Levels Scale of illuminance • Illuminance for all non-working interiors > 20 Lux • Factor 1.5 is the smallest significant difference in effect of illuminance • Therefore the following scale is recommended: 20–30–50–75–100–150–200–300–500–750–1000 –1500–2000, …Lux 29
30. 30. Assessment of Lighting SystemsRecommended Illuminance Levels Illuminance ranges recommended for interior or activity • Middle value (R) for working interiors • Higher value (H) for visual work • Lower value (L) where accuracy is non- important 30
31. 31. Assessment of Lighting SystemsMethodology for Efficiency Study• Step 1: Make inventory of lighting system elements and transformers Table: Device rating, population and use profile S. Plant Lighting Rating in Population Use / Shifts as I / N Locati Device & Watts Lamp Numbers II / III shifts / Day o. on Ballast Type & Ballast Table: Lighting transformer/rating and population profile S. Plant Lighting Measurement Provisions Numbers N Locatio Transformer Rating Available Volts / Amps / Installed o. n (kVA) kW/ Energy 31
32. 32. Assessment of Lighting SystemsMethodology for Efficiency Study• Step 2: Measure and document the Lux levels• Step 3: Measure and document the voltage and power consumption at input points• Step 4: Compare the measured Lux values with standard values as reference• Step 5: Analyze the failure rates of lamps, ballasts and the actual life expectancy levels 32
33. 33. Assessment of Lighting SystemsMethodology for Efficiency StudyStep-6 : identify improvement options, for example:• Maximum sunlight use options through transparent roof sheets• Replacements of lamps and ballasts to more energy efficient types• Selecting interior colors for light reflection• Modifying layout as per needs• Providing individual / group controls for lighting 33
34. 34. Training Agenda: ElectricityIntroductionTypes of lighting systemsAssessment of lighting systemsEnergy efficiency opportunities 34
35. 35. Energy Efficiency OpportunitiesUse Natural Day Lighting• North lighting• Glass strips across the roof• Sky lights with fiber reinforced plastic (FRP)• Atrium with FRP dome• Natural light from windows 35
36. 36. Energy Efficiency OpportunitiesDe-lamping to Reduce ExcessLighting• Effective method to reduce energy consumption• Reducing lamp height combined with de-lamping: illuminance hardly affected• Complicated for series wired ballasts• Less problematic with parallel wired ballast 36
37. 37. Energy Efficiency Opportunities Task Lighting• Low wattage lamps at task• General illuminance at lower level• Benefits: • Reduce number of lighting fixtures • Reduce lamp wattage • Save considerable energy • Better illuminance • Aesthetically pleasing ambience 37
38. 38. Energy Efficiency OpportunitiesHigh Efficiency Lamps & Luminaries Examples (9 – 75% savings): • Metal halide lamps to replace mercury / sodium vapor lamps • HPSV lamps where color rendering is not critical • LED panel indicator lamps to replace filament lamps • Luminaries with mirror optics instead of conventional painted ones 38
39. 39. Energy Efficiency OpportunitiesReduction of PercentageLighting Feeder 1 2Voltage 3 Supply voltage percentage 5 4 6• Can save 4 6 energy 3 5• Provided drop 2 1 in light output 1) Lamp current 2) Circuit power, 3) Lamp power, is acceptable 4) Lamp output 5) lamp voltage 6) lamp efficiency Effect of voltage variation of fluorescent tube light parameters (BEE India, 2005) 39
40. 40. Energy Efficiency Opportunities Electronic Ballasts instead of Electromagnetic Ballasts• Oscillators that convert supply frequency to about 20,000 – 30,000 Hz• Available for fluorescent tube lights, LPSV and HPSV lamps• Benefits in fluorescent tube lights: • Reduced power loss: 1 Watt instead of 10-15 Watt • Improved efficacy at higher frequencies • Elimination of starter: no flickering 40
41. 41. Energy Efficiency OpportunitiesLow Loss Electromagnetic Ballastsfor Tube LightsLoss per tube lights:• Standard ballasts: 10 – 15 Watts• Low loss ballasts: 8 - 10 Watts 41
42. 42. Energy Efficiency Opportunities Timers, Twilight Switches & Occupancy Sensors• Timers: switching of unnecessary lights• Twilight switches: depending on availability of daylight• Occupancy sensors: depending on presence of people• Applicable for general areas, conference rooms, cubicles, restrooms, exteriors 42
43. 43. Energy Efficiency OpportunitiesT5 Fluorescent Tube Light• Slimmer tubes than T12 and T8 tubes• Improved luminaire efficiencies by 7%, and with super-reflective aluminum luminaire by 11-30%• Mercury reduction: 3 mg instead of 15 mg per lamp• Can only be operated with electronic ballasts and not existing luminaries 43
44. 44. Energy Efficiency OpportunitiesLighting Maintenance• Light levels decrease >50% due to aging lamps and dirt on fixtures, lamps and room surfaces• Maintenance options: • Clean equipment • Replace lenses • Keep spaces bright and clean • Re-lamping 44