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NCIDQ - IDFX > Chapter 15: Lighting > Flashcards

Chapter 15: Lighting Flashcards

1
Q

What is visible light?

A

A form of electromagnetic radiation with wavelengths that range from about 400 nm for violet light to about 700 nm for red light.

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2
Q

When is white light produced?

A

When a source emits approximately equal quantities of energy over the entire visible spectrum.

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3
Q

What is candlepower (cp)?

A

The unit of luminous intensity approximately equal to the horizontal light output from an ordinary wax candle. This unit is the candela (cd).

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4
Q

What is a lumen (lm)?

A

The unit of luminous flux equal to the flux in a unit solid angle of one steradian (1 sr) from a uniform point source of one candlepower (1 cp).

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5
Q

What is illuminance?

A

The density of luminous flux incident on a surface in lumens per unit area.

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6
Q

What is luminance?

A

The luminous flux per unit of projected (apparent) are and unit solid angle leaving a surface, either reflected or transmitted. Takes into account the reflectance and transmittance properties of materials and the direction in which they are viewed. Sometimes called brightness.

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7
Q

What factors can cause direct glare?

A

Brightness of the source, its position, the background illumination, and the adaptation of the eye to the environment

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8
Q

What is the visual comfort probability (VCP) factor?

A

This factor is the percentage of people who, when viewing from a specified location and in a specified direction, will find the situation acceptable in terms of discomfort glare.

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9
Q

What is the critical zone for direct glare?

A

In the area above 45 degrees

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10
Q

What is reflected glare?

A

Occurs when a light source is reflected from a viewed surface into the eye. If the reflected glare interferes with the viewing task, it is also called a veiling reflection.

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11
Q

How can you mitigate veiling reflection?

A

Move either the task or the light source so as to change their relationship. Or you can avoid it altogether by providing general background illumination and specific task lighting that can be moved around by the user.

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12
Q

What should the brightness ratio be between the task and immediate surroundings?

A

3:1

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13
Q

What should the the brightness ratio be between the task and general surroundings?

A

5:1

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14
Q

What should the brightness ratio be between the task and more remote surroundings?

A

10:1

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15
Q

What is efficacy?

A

The ratio of luminous flux emitted to the total power input of the source and is measured in lumens per watt.

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16
Q

What is an incandescent lamp?

A

Consists of a tungsten filament placed within a sealed bulb containing an inert gas.

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17
Q

What are the various incandescent lamp shapes?

A

(R) - Standard reflector lamp - has a wide beam spread
(ER) - Elliptical reflector lamp - provides a more efficient throw of light form a fixture. Spread is slightly smaller than that of the R lamp
(PAR) - Parabolic aluminized reflector lamp. Focuses light in a tighter spread, with the light rays more parallel because its reflector is a parabola with the filament at the focus of the parabola.
(MR-16) - Multifaceted mirror refector. Have narrowest beam spread.

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18
Q

What are the advantages of an incandescent lamp?

A

Inexpensive
Compact
Easy to dim
Can be repeatedly start without a crease in lamp life
Have a warm color rendition
Light output can be easily controlled with reflectors and lenses

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19
Q

What are the disadvantages of an incandescent lamp?

A

Low efficacy, short lamp life, and high heat output.

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20
Q

What is a fluorescent lamp?

A

Contain a mixture of an inert gas and low-pressure mercury vapor. When the lamp is energized, a mercury arc is formed that creates ultraviolet light. This invisible light in turn strikes the phosphor-coated bulb, causing it to fluoresce and produce visible light.

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21
Q

How is size denoted in a fluorescent lamp?

A

Size is designated in eighths of an inch, so a T8 lamp has a 1” diameter.

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22
Q

What are the advantages of fluorescent lamps ?

A

High efficacy, relatively low initial cost, long life, available in variety of color temperatures

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23
Q

What are the disadvantages of fluorescent lamps?

A

Difficult to control precisely

24
Q

What is a high-intensity discharge (HID) lamp?

A

They produce light by passing an electric current through a gas or vapor under high pressure. Include mercury-vapor, metal-halide, and high-pressure sodium. Require time to restart after being shut off or in case of power failure.

25
Q

What is a mercury-vapor lamp?

A

A type of HID where an electric arc is passed through high-pressure mercury vapor, which causes the lamp to produce both ultraviolet light and visible light.
Long lamp life but poor color rendering.
Limited to outdoor lighting and industrial applications.

26
Q

What are metal halide lamps?

A

A type of HID where an electric arc is passed through halides of metals in the arc tube. Best combination of features of HID lamps - increases efficacy and improves color rendition (60-90 CRI)

27
Q

What is a high-pressure sodium lamp?

A

Type of HID that produces light by passing an electric arc through hot sodium vapor. Arc tube must be made a special ceramic material to resist attack by the hot sodium. Among most efficient lamps available.
Produce a very yellow light.

28
Q

What is a light-emitting diode (LED)?

A

It’s a semiconductor device that used solid-state electronics to create light.

29
Q

What are the advantages of LED lighting?

A

Brightness, long life, and low power consumption, product no heat, can be manufactured to produce a number of colors or white light.

30
Q

What are the disadvantages of LED lighting?

A

Cost more and have relatively lumen output than traditional sources (this has been improved as the technology develops).

31
Q

What is a direct lighting systems?

A

Provide all light output on the task ie. recessed lighting

32
Q

What is a semidirect system?

A

Put a majority of the light down and a small percentage torward the ceiling ie. surface mounted or suspended fixtures

33
Q

What is a direct-indirect systems?

A

Distribute light up and down about equally.

34
Q

What is an indirect system?

A

Direct all the light toward a reflective ceiling, where the light illuminates the room by reflection.

35
Q

What is a task-ambient system?

A

Common commercial lighting system - provides general background illumination level with separate light fixtures used at individual workstations or wherever light is needed. Done with desk lamps or directed spotlights, or by locating more fixtures near the tasks requiring more illumination.

36
Q

What is a surface mounted fixture?

A

Directly attached to ceiling surface, among most commonly used types of fixture.

37
Q

What is a recessed fixture?

A

Widely used in both residential and commercial; can be for general illumination or wallwashing

38
Q

What is a suspended fixture?

A

Luminaires dropped below the level of the ceiling; used when lighting is needed closer to the task area.

39
Q

What is a wall-mounted fixture?

A

Can provide indirect, direct-indirect, and direct lighting.

40
Q

What is furniture-mounted lighting?

A

Individual lights are built into the furniture above the work surface to provide sufficient task illumination.

41
Q

What is a characteristic spectral energy distribution?

A

Measure of the energy output at different wavelengths, or colors.

42
Q

What is color rendering index (CRI)?

A

Measure of how well one source renders the color of an object when compared with the same object lighted with a reference source of similar chromacity whose CRI is 100 (scale of 1-100).

43
Q

What is the range of color temperatures in most interior applications?

A

2700K-5000K

44
Q

Describe the design process for lighting a space.

A
  1. Determine function of space - determining light levels, single/multi-use, any special conditions, ceiling heights, daylighting, ceiling construction, size of the room
  2. Lamp types are selected - concurrently, luminaires are selected
  3. Number and location of luminaires are determined
45
Q

What is the coefficient of utilization (CU)?

A

How efficiently the luminaire distributes the light from the lamps under various degrees of finish reflectivity of the floor, walls, and ceiling.

46
Q

What is the lamp lumen depreciation factor?

A

The gradual loss of light output of the lamps over time.

47
Q

In addition to lighting, what else can be shown on an RCP?

A

Locations of air diffusers, smoke detectors, switching may be indicated.

48
Q

What is a “three-way switch?”

A

A three-way switch requires three conductors (not including the ground) to make it possible to control a light from two different switches. The number refers to the number of conductors required to make the switching possible.

49
Q

What factors should be considered in daylighting?

A

Window coverings, compass orientation, area of the glass, window height, obstructions, reflectance of surfaces, partitions in room

50
Q

What is a light shelf?

A

A horizontal surface placed above eye level that reflects direct daylight onto the ceiling while shading the lower portions of the window and the interior of the room.

51
Q

What is a daylight factor?

A

Expressed as a percentage, is the ratio of the indoor illuminance at a point on a horizontal surface to the unobstructed exterior horizontal illuminance. Direct sunlight is excluded.

52
Q

How can LEED credits be obtained with daylighting?

A

By provided a daylight factor of 2% for 75% of all space occupied for critical visual tasks.

53
Q

How can an interior designer design an energy efficient lighting scheme?

A

Daylighting, selecting high-efficacy lamps, using efficient luminaires, minimizing unneeded ambient illumination, providing task lighting only where it is needed, and selecting high-reflectance ceiling, wall, and floor surfaces to reduce the total number of fixtures required to light a space.

54
Q

What is lighting system tuning?

A

Measure of energy conservation - lamps are replaced with lower wattage units, adjustable luminaires aimed for their optimal position, ballasts are adjusted for maximum efficiency, and switches are replaced with dimmer controls or time-out units.

55
Q

Where does emergency illumination need to be provided?

A
  • Exit access corridors and aisles in rooms and spaces required to have two or more exits
  • Exit access corridors and exit stairways in buildings required to have two or more exits
  • Interior exit discharge elements when permitted, such as building lobbies where 50% of the exit capacity may egress through the ground-floor lobby.

NCIDQ - IDFX (22 decks)

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