12. efficient lighting

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12. Efficient Lighting

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  • Energy for LightingWe 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.

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

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

  • 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

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

  • Factors Affecting the Quantity of Lamps RequiredFixture 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)

  • 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 room50 fc for reading and writing

  • Color Rendition IndexThe 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

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

  • Incandescent LightLight is produced by a tiny coil of tungsten wire that glows when it is heated by an electrical current. shortest lives InefficientFilament

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

  • Fluorescent Bulbsfilled 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 lightingFluorescent 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

  • Fluorescent BulbsFluorescent 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

  • Types of Fluorescents

    Compact fluorescent Tube fluorescent

  • CFLsCFLs 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.

  • High Intensity Discharge (HID) LampHigh-intensity discharge (HID) lamps provide the highest efficacy and longest service life of any lighting type mercury vapormetal 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

  • 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).

  • Improved Lighting ControlsSnap SwitchesPhotocellsTimersOccupancy sensorsDimmers

  • Resourceshttp://www.eren.doe.gov/erec/factsheets/eelight.htmlhttp://www.misty.com/~don/dschlamp.htmlLIGHTING FUNDAMENTALS

    Incandescent lighting is the most common type of lighting used in residences. Fluorescent lighting is used primarily in commercial indoor lighting systems, while high-intensity discharge lighting is used only for outdoor lighting applications. Low-pressure sodium lighting is used where color rendering is not important, such as highway and security lighting. These lighting types vary widely in their construction, efficiency, color characteristics, and lamp life. Fluorescent lights need ballasts (i.e., devices that control the electricity used by the unit) for starting and circuit protection. Ballasts consume energy. You can increase the energy savings for existing fluorescent lighting by relamping (e.g., replacing an existing lamp with one of a lower wattage), replacing ballasts, and replacing fixtures with more efficient models.CFLs are one of the best energy efficiency investments available. When introduced in the early- to mid-1980s, CFLs were bulky, heavy, and too big for many incandescent fixtures. However, newer models with lighter electronic ballasts are only slightly larger than the incandescent lamps they replace. CFLs come in integral and modular designs. Integral CFLs have a ballast and a lamp in a single disposable unit. Modular designs feature a separate ballast that serves about five lamp replacements before it wears out.