L I G H T I N G

“the jewelry of architecture”

V O C A B U L A R YCOLOR 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.

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 lamp’s 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.

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)

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

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.

L I G H T - E M I T T I N G D I O D E S (LED’s)

• Used in specialty applications, including signs and display lighting

•Costly

•Most common usage: EXIT signs

•Since the writing of Lighting Design Basics, LED’s are used in residential decorative fixtures because of their energy effifciency and long-life. Cost of LED’s is still high.

L U M I N A I R E S

DIRECT LUMINAIRESEmits 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

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.

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

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

L U M I N A I R E S T Y L E S

DOWNLIGHTFLOURESCENT

DOWN

TROFFER

ACCENT WALLWASHER WALL GRAZING

L U M I N A I R E S T Y L E S, continued

PendantTask

Undercabinet

Torchier

LanternSconce

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

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.

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.

T O P L I G H T I N GTo 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

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.