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/facts

heets/eelight.html• http://www.misty.com/~don/dschla

mp.html• LIGHTING FUNDAMENTALS