EGEE 102 – Energy Conservation And Environmental Protection

Energy Efficient Lighting

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.

Objectives

• Lighting principles and definitions • Types of lighting and how each

works • Energy-efficient lighting options,

including daylighting, for new or retrofit applications.

Lighting and Energy Savings

• Lighting 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.) • Ambient• Task• Accent

• The ages of the occupants • The importance of speed and

accuracy

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)

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

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

Types of Lighting

• There are four basic types of lighting:

1. Incandescent, 2. Fluorescent, 3. High-intensity discharge, and 4. Low-pressure sodium

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

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

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

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

Types of Fluorescents

Compact fluorescent•Tube fluorescent

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.

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

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 Controls

• Snap Switches• Photocells• Timers• Occupancy sensors• Dimmers

Resources

• http://www.eren.doe.gov/erec/factsheets/eelight.html

• http://www.misty.com/~don/dschlamp.html

• LIGHTING FUNDAMENTALS