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Lighting Systems and Luminaires
Lighting Systems and Luminaires
LIGHTING SYSTEMS
• Defined as one or more luminaire with one or more lamps having a characteristic lighting distribution.
• Several types of luminaires with lamps can be combined to make up a lighting system.
LIGHTING SYSTEMS
• The lighting system with the corresponding choice of luminaires that constitute the system depends technical and artistic considerations.
• Technical refers to the purpose of the space that is to be illuminated together with the minimum about of lux required for that particular space.
LUMINAIRES
An electrical device used to create artificial light by use of an electric lamp.
LAMP
The use of the word "lamp" to describe light fixtures is common slang for an all-in-one luminary unit (it can be used also to describe portable fixtures such as desk lamps, and permanent / semi-permanent fixtures).
In technical terminology, a lamp is the light source, what is typically called the light bulb.
LUMINAIRES
Luminaire is a lighting unit consisting of the following components:
1) optical devices to distribute the light,
2) sockets to position and protect the lamps and to connect the lamps to a supply of electric power,
3) ballast of the lamp, if separate from the lamp,
4) mechanical components required to support or attach the luminaire.
5) other features such as reflectors to direct light and housing for physical protection
Functions of Luminaires
• The main function is to efficiently direct light to appropriate locations without causing glare or discomfort.
• Ideally, its function is to direct the lamp output to where it is needed while shielding the light from the eyes at normal angle of view.
How to select the proper lamp type?
Consider several criteria:
1. Efficacy, Life, Lumen Depreciation
If a lamp's lumen output declines rapidly during its life, the prudent designer initially provides more lumens than is required so that as the lamp declines with age, a sufficient amount of light is still available.
2. Amount of Diffusion Desired
It is sometimes desirable to have diffuse light rather than highly directional light since the latter may cause harsh shadows.
How to select the proper lamp type?
3. Controllability
One must consider if simple on/off control is acceptable, if inexpensive dimming is desired, or if it is reasonable to incur the larger expenditures to get higher quality dimming.
4. Color Rendition
One of the key areas of concern for the architect, interior designer and lighting engineer is the lighted appearance of the space.
How to select the proper lamp type?
5. Distribution Control
Light distribution from a small lamp can be controlled more easily than light emitted from a large lamp.
6. Air Conditioning Load
All artificial lighting adds an additional heat load to a building.
How to select the proper lamp type?
7. Consistency and Reliability of Supply Voltage
High-pressure gaseous discharge lamps are more sensitive to voltage variation than low-pressure lamps.
8. Ambient Temperature and Humidity
Some lamps, notably fluorescents, are very sensitive to temperature and humidity.
How to select the proper lamp type?
9. Cost
One must consider not only the initial cost, but the cost to operate the system over its entire life, including energy costs and the requirement to pay a worker to change the burned-out lamps frequently.
Artificial lighting
• Other sources of light developed to compensate for or assist the natural light.
• Have different frequencies and wavelengths that determine the light color.
• Forms: 1) Indoor Lighting and 2) Outdoor Lighting
Indoor Lighting
• Indoor lighting is usually accomplished using light fixtures, and is a key part of interior design
Types of Indoor Luminaires
Light fixtures are classified according to the following:
1) Lamp type
2) The light function.
3) Installation method.
4) The percentage of light output above and below the horizontal.
Types of Light fixtures according to light function
1) Ambient (general lighting).
2) Task.
3) Accent.
4) Informational lighting/Guidance Lighting.
5) Decorative lighting.
Ambient lighting
• Provides an area with overall illumination.
• Radiates a comfortable level of brightness without glare and allows you to see and walk about safely.
Ambient lighting
• Often provided by traditional pendant type fixtures, down lights, chandeliers, or ceiling mounted fixtures etc.
• The general decor and aspect of the room will affect the amount of general lighting required.
• Having a central source of ambient light in all rooms is fundamental to a good lighting plan
Task Lighting
• Also known as directional lighting
• Aimed at a specific task
• A way to provide more light on a specific area to perform a task that requires more light than the ambient fixtures can give.
Task Lighting
• Can be provided by recessed and track lighting, pendant lighting and undercabinet lighting, as well as by portable floor and desk lamps.
• Should be free of distracting glare and shadows and should be bright enough to prevent eye strain.
Accent lighting
• A sort of a directional lighting that adds drama to a place by creating visual interest.
• As part of an interior design scheme, it is used to draw the eye to houseplants, paintings, sculptures and other prized possessions.
Accent lighting
• It can also be used to highlight the texture of a brick or stone wall, window treatments or outdoor landscaping.
• To be effective, accent lighting requires as least three times as much light on the focal point as the general lighting surrounding it.
• Usually provided by recessed and track lighting or wall-mounted picture lights
Informational lighting
• It is designed to help us see our way safely.
• Examples are the light in your closet, the light by your doorbell, and night lights, as well as path lighting and motion lights
Informational lighting
• Informational lighting can be beautiful as well as functional, and can create dramatic statements.
• Lights inset on stairs can create pathways that enhance architecture, while outdoor informational lighting can create
Decorative lighting
• Light fixtures that draw attention to themselves and add character to the place being lighted.
• Examples are light strips, pendants, chandeliers, and sconces
• Many are also used for general lighting.
Types of Light fixtures according to installation method
Free standing or Portable
Examples are the typical table, office or standard lamp fixtures
Fixed
1- Recessed light :
Protective housing is concealed behind a ceiling or wall, leaving only the fixture itself exposed. The ceiling-mounted version is often called a downlight.
Cans, downlighting , uplights placed on the floor, Troffer light (recessed fluorescent lights ), Cove light ( recessed into the ceiling in a long box against a wall), Torch lamp (floor lamp).
2- Surface-mounted light : the finished housing is exposed, not flush with surface.
3- Pendant light : suspended from the ceiling with a chain or pipe.
4- Sconce : provide up or down lights; can be used to illuminate artwork, architectural details; commonly used in hallways or as an alternative to overhead lighting.
5- Track lighting fixture: individual fixtures can be positioned anywhere along the track, which provides electric power.
6- Under-cabinet light : mounted below kitchen wall cabinets.
7- Emergency lighting or exit light : connected to a battery backup or to an electric circuit that has emergency power if the mains power fails.
8- High- and low-bay lighting : typically used for general lighting for industrial buildings and often big-box stores.
High for ceilings greater than 6 meters, Low for less than 6 m
9- Strip lights or industrial lighting : often long lines of fluorescent lamps used in a warehouse or factory.
10- Soffit : can be general or a decorative wall-wash, sometimes used to bring out texture on a wall, though this may also show its defects as well. The effect depends heavily on the exact type of lighting source used.
Outdoor / Landscape lighting
used to illuminate walkways, parking lots, roadways, building exteriors and architectural details, gardens, and parks
Special Purpose Lighting
- accent light - strobe light
- background light - traffic light
- flood light - theatrical
- safe light (dark rooms) - wall washer
- safety light (coal mines) - search light
SUMMARY
Types of Light fixtures according to the percentage of light output above and below the horizontal
Direct Lighting
• Luminaires direct 90 to 100% of their output downward.
Direct Lighting
• The distribution may vary from widespread to highly concentrated, depending on the reflector material, finish and contour, and on the shielding or control media employed.
• Troffers and downlights are two forms of direct luminaires.
Direct Lighting
• Can have the highest utilization of all types, but this utilization may be reduced in varying degrees by brightness-control media required to minimize direct glare.
• Reflected glare and shadows may be a problem with direct lighting unless close spacings are employed.
Semi-direct Lighting
• The distribution is predominantly downward (60 to 90%) but with a small upward component to illuminate the ceiling and upper walls.
Semi-direct Lighting
• The same as for direct lighting except that the upward component will tend to soften shadows and improve room brightness relationships.
• Care should be exercised with close-to-ceiling mounting of some types to prevent overly bright ceilings directly above the luminaire.
Semi-direct Lighting
• Such systems are best suited to rooms with high ceilings where a high level of uniformly-distributed illumination is desirable. Semi-direct lighting
• Glare is minimized by the use of diffusing globes and shields, which also improve the brightness at eye level and efficiency of the system with reference to the working plane.
General Diffuse Lighting
• When downward and upward components of light from luminaires are about equal (each 40 to 60% of total luminaire output).
General Diffuse Lighting
• Very suited for rooms with high reflectance surfaces.
• Brightness-relationships throughout the room are generally good and the upward light reflected from the ceilings soften the shadows from the direct illumination.
General Diffuse Lighting:
• General-diffuse units combine the characteristics of direct lighting and those of indirect lighting.
• Brightness relationships throughout the room are generally good and the upward light reflected from the ceiling softens shadows from the direct component.
General Diffuse Lighting:
• Pendant-mounted luminaires designed to provide a general-diffuse or direct-indirect distribution are frequently installed on or very close to the ceiling.
• Such mountings change the distribution to direct or semidirect since the ceiling acts as a top reflector redirecting the upward light back through the luminaire.
Semi- Indirect Lighting
• Lighting systems that emit 60 to 90% of their output upward.
Semi- Indirect Lighting
• The characteristics are similar to those of indirect systems except that the downward component usually produces a luminaire luminance that closely matches that of the ceiling.
• However, if the downward component becomes too great and is not properly controlled, direct or reflected glare may result.
• Light is partially received by diffuse reflection and partly direct from the source
Indirect Lighting
• Lighting systems which direct 90 to 100% of the light upward to the ceiling and upper sidewalls.
Indirect Lighting
• In a well-designed installation, the entire ceiling becomes the primary source of illumination, and shadows will be virtually eliminated.
• Also, since the luminaires direct very little light downward, both direct and reflected glare will be minimized if the installation is well planned.
Indirect Lighting
• It is also important to suspend the luminaires a sufficient distance below the ceiling to obtain reasonable uniformity of ceiling luminance
• Since the indirect lighting the ceiling and upper walls must reflect light to the work plane, it is essential that these surfaces have high reflectances. Care is needed to prevent overall ceiling luminance from becoming too high and thus glaring.
Direct-indirect Lighting:
• Direct-indirect is a special category within this classification for luminaires that emit very little light at angles near the horizontal.
• Since this characteristic result in lower luminances in the directglaze zone, direct-indirect luminaires are usually more suitable than general-diffuse luminaires that distribute the light about equally in all directions.
SUMMARY BY LIGHT OUTPUT
