Transcript EGEE 102 – Energy Conservation And Environmental Protection Energy Efficient Lighting Energy for Lighting • We spend about one-quarter of our electricity budget on.

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.
2.
3.
4.
Incandescent,
Fluorescent,
High-intensity discharge, and
Low-pressure sodium
Incandescent Light
Filament
• Light is produced
by a tiny coil of
tungsten wire that
glows when it is
heated by an
electrical current.
• shortest lives
• Inefficient
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 Atype 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
•Tube fluorescent
Compact 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
They also require ballasts, and they take a few seconds to
sodium
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/factsh
eets/eelight.html
• http://www.misty.com/~don/dschlam
p.html
• LIGHTING FUNDAMENTALS