L I G H T I N G

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L I G H T I N G
the jewelry of architecture
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V O C A B U L A R Y
COLOR RENDERING INDEX (CRI) Describes the
quality of light on a scale of 0 (horrible) to
100 (perfect). COLOR TEMPERATURE Describes
whether the light appears warm (reddish) neutral,
or cool (bluish). The term temperature relates to
the light emitted from a metal object heated to
the point of incandescence. DIMMING Process by
which lamps are operated at less than full
light. ENERGY EFFICIENCY Called efficacy and
is measured in lumens per watt. Like miles per
gallon, the higher the number the better.
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II N C A N D E S C E N T L I G H T

• Generates warm-colored white light when current
  heats lamps filament
• Incandescence A metal is heated until it glows
• Among the least energy-efficient sources
  available. (20 lumens/watt)
• Inexpensive
• When dimmed, incandescent lamps are the only type
  that shifts color toward red as intensity
  decreases.
• Trade off for low energy efficiency and short
  life for warm color and low cost.

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F L O U R E S C E N T L I G H T I N G

• Considered the workhorse light source for
  commercial and institutional buildings.
• Uses the principle of flourescence in which
  minerals exposed to ultraviolet light are caused
  to glow.
• Requires a ballast in order to work properly
• Ballast An auxiliary electric device
• Considered a cool white or blue white light
• Most common flourescent lights are straight tubes
  but can also be bent. Most common length is 4
  feet the shortest length is 4 inches.
• Good energy efficiency, good to excellent color,
  dimming. (100 lumens/watt)

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H I G H - I N T E N S I T Y D I S C H A R G E
(HID) lamps

• Emits a great deal of light from a compact,
  long-life light source
• Most often used for street and parking lot
  lighting and large indoor spaces (I.e.,
  gymnasiums)
• Uses a point source of light, making an excellent
  source for spot lighting as stadium lights do
• Uses a ballast as flourescent lights do
• Requires time to warm up they get progressively
  brighter over several minutes until reaching full
  light output. Full color is often not reached
  for 2-5 min.
• Types of HID lamps Halide (white light 100
  lumens/watt)
• Sodium (yellow 180 lumens/watt)
  Mercury Vapor

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I N D U C T I O N L I G H T I N G

• Sometimes called the electronic light bulb
• Uses radio waves rather than an electric arc to
  cause the gas in the lamp to give off ultraviolet
  energy.
• Has most characteristics of flourescent lamps
  (70-80 lumens/watt, color and CRI
• Because induction lamps have no electrodes, the
  lamps are rated to 60,000 to 100,000 hours. An
  induction lamp used every day for 12 hours will
  last more than 20 y ears.
• Typical applications include street lighting and
  lighting in hard-to-maintain locations.

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L I G H T - E M I T T I N G D I O D E S
(LEDs)

• Used in specialty applications, including signs
  and display lighting
• Costly
• Most common usage EXIT signs
• Since the writing of Lighting Design Basics,
  LEDs are used in residential decorative fixtures
  because of their energy effifciency and
  long-life. Cost of LEDs is still high.

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L U M I N A I R E S
DIRECT LUMINAIRES Emits light downward At
least 90 of light goes downward Distributes
light directly to task area Typically used in
lobbies, offices, restaurants and other spaces
where designer wishes to create drama. Dramatic
spaces can be tiring, so direct lighting is
generally not recommended for workspaces. Example
Can lights, track lighting
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I N D I R E C T L U M I N A I R E S Tend to
create comfortable, low-contrast soft light that
psychologically enlarges space. At least 90 of
light goes upward Many people that experience
totally indirect lighting without direct lighting
as well feel the lighting is bland and liken it
to a cloudy day. Task lighting or other direct
lighting is recommended with indirect
lighting. Example Recessed indirect troffers,
Torchiers
D I F F U S E L U M I N A I R E S Creates broad
general light that is often considered glaring
due to lack of side shielding. Light is
distributed in all directions Most diffuse
luminaires are chosen for ornamental
reasons. When used carefully, as in a chandelier,
diffuse luminaires can create sparkle and
interest, but other lighting must also be
present. Example Chandeliers, sconces.
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D I R E C T / I N D I R E C T L U M I N A I R E
Considered a good compromise between the
efficiency of direct lighting and the comfort of
indirect lighting. Gives balance (direct) and
comfort (indirect) Gives 40 uplight 60
downlight Semi-indirect 40-60 uplight 60-40
down or
10-40 uplight 90-60 down Example Some
sconces, floor lamps
A S Y M M E T R I C L U M I N A I R E Chosen
when accent lighting of objects or surfaces is
desired. Lighting distributions vary Also
referred to as aimable lighting Example Wall
washer, accent light
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B A S I C T H E O R Y O F L I G H T
The science of lighting was invented over 300
years ago and was, of course, based on
candlelight. The foot-candle is the amount of
light striking a surface 1 foot away from a
candle. The intensity of light is 1 candela. We
measure light sources in 2 distinct ways. Most
lamps are measured according to the total amount
of light they radiate, while luminaires and
directional lamps are measured by the intensity
of the emitted light. Lamps Lumens (A candle
generates 12.5 lumens of light) Luminaires
Measured according to intensity and direction
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L U M I N A I R E S T Y L E S
DOWN
DOWNLIGHT
TROFFER
FLOURESCENT
ACCENT
WALLWASHER
WALL GRAZING
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L U M I N A I R E S T Y L E S, continued
Undercabinet
Pendant
Task
Torchier
Lantern
Sconce
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S W I T C H I N G V O C A B U L A R Y
SWITCHING Controlling operating time Codes
National Electric Code, Energy Codes
(ASHRAE/IESNA 90.1) Preset Dimmers Permit
light level from each dimmer to be set and
memorized Time Control Controlled
automatically by time Motion Sensing Detect
presence of people and respond by automatically
turning lights on. Daylighting Controls Turn
lights off or dim them when daylight is
sufficient Lumen Maintenance Controls Designed
to take advantage of the overdesign of lighting
systems so that as lamps age and luminaires
become dirty, designed lighting levels are
maintained. Switches Turn lights on and off
Switch types Toggle and decora
(paddle) Dimmers Control devices that vary
light level and power to lights. Timer Switch
that turns lights off automatically
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D A Y L I G H T I N G
DAYLIGHTING Defined as the complete process
of designing buildings to utilize natural
light to its fullest. Maximum amount of
daylight is about 10,000 footcandles on a sunny
summer day. DAYLIGHTING TERMS Siting the
building Orienting it for optimum solar
exposure. Massing the building Present the
optimum building surfaces toward the sun Chosing
fenestration to permit the proper amount of light
into the building, taking into account seasons,
weather and daily solar cycles. Shading the
façade and fenestration from unwanted solar
radiation. Operable shading devices such as
blinds and cutains to permit occupant control
over daylight admission. Designing electric
lighting controls that permit full realization of
the energy savings benefit of daylighting.
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D A Y L I G H T I N G F A C T S

• For energy efficiency in buildings, only about 5
  of the daylight, or a peak of about 500
  footcandles should be allowed into a building
  more will generate so much heat that energy will
  be wasted in air conditioning.
• Color of daylight varies. Pay attention to
  orientation. The cold blue light from the winter
  north sky is over 10,000K. Color quality (CRI)
  is excellent however the ultraviolet light
  content is high.
• Consider fading of interiors when daylighting.
  Photodegradation causes bleaching of pigments and
  other harm to irreplaceable art and antiquities.
• At least 2.5 times as much a/c is needed to cool
  the heating effect of the most efficient electric
  light producing the same lighting level as
  daylight.

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T O P L I G H T I N G To harvest the
energy-saving benefits of daylighting, electric
lights must be switched off or dimmed. One of the
most common ways to introduce daylight is through
skylights and other means of toplighting. Here
are other ways Skylights Single clerestory (high
windows above ceiling line Sawtooth single
clerestory (Angled ceiling, shown right) Monitor
or double clerestory
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S I D E L I G H T I N G Side lighting employs
vertical fenestration (usually windows) to
introduce natural light. Unlike top lighting,
side lighting tends to introduce light that can
be too bright relative to the room surfaces,
sometimes causing glare. Using low-e glazing on
windows can help to reduce this when a desirable
view is wanted but glare is not. Overhang
soffits, awnings or other extended shades offer
additional protection.