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Efficient Lighting

Efficient Lighting. Energy for Lighting. We spend about one-quarter of our electricity budget on lighting, or more than $37 billion annually

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Efficient Lighting

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  1. Efficient Lighting

  2. Energy for Lighting • We spend about one-quarter of our electricity budget on lighting, or more than $37 billion annually • Technologies developed during the past 10 years can help us cut lighting costs 30% to 60% while enhancing lighting quality and reducing environmental impacts.

  3. Objectives • Lighting principles and definitions • Types of lighting and how each works • Energy-efficient lighting options, including daylighting, for new or retrofit applications.

  4. Lighting and Energy Savings • Lighting principles and definitions • Types of lighting and how each works • Energy-efficient lighting options, including daylighting, for new or retrofit applications.

  5. How lighting is measured? • The most common measure of light output (or luminous flux) is the lumen . All lamps are rated in lumens • The distribution of light on a horizontal surface is called its illumination. • Illumination is measured in footcandles. A footcandle of illumination is a lumen of light distributed over a 1-square-foot (0.09-square-meter) area

  6. How much light do we need? • The task(s) being performed (contrast, size, etc.) • Ambient • Task • Accent • The ages of the occupants • The importance of speed and accuracy

  7. Factors Affecting the Quantity of Lamps Required • Fixture efficiency • Lamp lumen output • The reflectance of surrounding surfaces • The effects of light losses from lamp lumen depreciation and dirt accumulation • Room size and shape • Availability of natural light (daylight)

  8. How Much Light? • In the past, spaces were designed for as much as 200 footcandles in places where 50 footcandles may not only be adequate, but superior. • Not only does over lighting waste energy, but it can also reduce lighting quality • 30 fc of ambient lighting for computer room • 50 fc for reading and writing

  9. Color Rendition Index • The ability to see colors properly is another aspect of lighting quality • The color rendering index (CRI) scale is used to compare the effect of a light source on the color appearance of its surroundings. A scale of 0 to 100 defines the CRI. • A higher CRI means better color rendering, or less color shift

  10. Types of Lighting • There are four basic types of lighting: • Incandescent, • Fluorescent, • High-intensity discharge, and • Low-pressure sodium

  11. Incandescent Light • Light is produced by a tiny coil of tungsten wire that glows when it is heated by an electrical current. • shortest lives • Inefficient Filament

  12. Types of Incandescent Bulbs • Standard incandescent • Most common yet the most inefficient • Larger wattage bulbs have a higher efficacy than smaller wattage bulbs • Tungsten halogen • It has a gas filling and an inner coating that reflect heat • Better energy efficiency than the standard A-type bulb • Reflector lamps • Reflector lamps (Type R) are designed to spread light over specific areas • floodlighting, spotlighting, and downlighting

  13. Fluorescent Bulbs • filled with an argon or argon-krypton gas and a small amount of mercury • coated on the inside with phosphors • equipped with an electrode at both ends 3 to 4 times as efficient as incandescent lighting • Fluorescent lamps provide light by the following process: • An electric discharge (current) is maintained between the electrodes through the mercury vapor and inert gas. • This current excites the mercury atoms, causing them to emit non-visible ultraviolet (UV)radiation. • This UV radiation is converted into visible light by the phosphors lining the tube

  14. Fluorescent Bulbs • Fluorescent lamps last about 10 times longer than incandescent bulbs • Fluorescent lights need ballasts (i.e., devices that control the electricity used by the unit) for starting and circuit protection

  15. Types of Fluorescents Compact fluorescent • Tube fluorescent

  16. CFLs • CFLs can replace incandescents that are roughly 3 to 4 times their wattage • They last 10 to 15 times as long. • Cost from 10 to 20 times more than comparable incandescent bulbs • One of the best energy efficiency investments available.

  17. High Intensity Discharge (HID) Lamp • High-intensity discharge (HID) lamps provide the highest efficacy and longest service life of any lighting type • mercury vapor • metal halide, and high-pressure sodium They also require ballasts, and they take a few seconds to produce light when first turned on because the ballast needs time to establish the electric arc

  18. Efficacy • This is the ratio of light output from a lamp to the electric power it consumes and is measured in lumens per watt (LPW).

  19. Improved Lighting Controls • Snap Switches • Photocells • Timers • Occupancy sensors • Dimmers

  20. Resources • http://www.eren.doe.gov/erec/factsheets/eelight.html • http://www.misty.com/~don/dschlamp.html • LIGHTING FUNDAMENTALS

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