Determining Special Systems Flashcards
Evaluating and selecting the best lighting for a building depends on 8 factors:
- Required light levels for a specific task
- Age of users
- Glare
- Contrast
- Light uniformity
- Color
- Available light sources
- Efficacy
Required light levels for a specific task are determined by 4 factors:
- Nature of the task
- Age of the person performing the task
- Surface reflectance
- Speed and accuracy needed for completing the task
What is VCP (Visual Comfort Probability)?
VCP (Visual comfort probability) = metric used in evaluating the problem of direct glare, defined as the percentage of normal observers who may be expected to experience visual comfort in a particular environment with a particular lighting situation
What is the glare zone for direct glare?
Glare zone for reflected glare?
direct glare = above 45 deg angle from the light source
indirect glare = below 45 deg angle from the light source
What is a veiling reflection? How can it be solved?
Veiling reflection = when reflected glare interferes with the viewing task
Can solve by moving lighting source or task or providing general background illumination/specific task lighting
What are 4 primary types of artificial light sources?
- Incandescent Lamps
- Fluorescent Lamps
- High-intensity discharge (HID) lamps
- Light-emitted diodes (LED)
What is an incandescent lamp?
What are 4 pros? 3 cons?
Typical designation?
A tungsten filament is placed within a sealed glass bulb containing an inert gas. When electricity passes through the lamp, the filament glows and produces light.
Pros:
- Inexpensive
- Easy to install
- Compact
- Warm color rendition
Cons:
- Low efficacy
- High heat output
- Short lamp life
Nomenclature: ex A-21 where letter = shape and number = diameter at widest point in ⅛”
What is a Tungsten halogen lamp?
A type of incandescent lamp that has whiter light, longer lamp life, and higher efficacy, but operates at higher temperatures so needs to be enclosed in a second layer
What is a reflector lamp (R lamps) and parabolic aluminized reflector lamps (PAR lamps)
Types of incandescent lamps that contain a reflective coating built into the lamp which increases efficiency and allows more precise beam control. Suitable for outdoor use.
What is an elliptical reflector lamp? (ER lamps)
an incandescent lamp that is an improved version of R lamps by providing a more efficient throw of light from a fixture by focusing the light beam slightly in front of the lamp before it spreads out. Used for downlights with deep baffles or small openings
What are low-voltage miniature reflector lamps (MR lamps)?
a small tungsten halogen (incandescent) lamps that are available in a variety of voltages and beam spreads.
Consistently high output and lamp life and color temperatures that are whiter than standard incandescent.
What is a fluorescent lamp?
What are 4 pros?
contain a mixture of an inert gas and low-pressure mercury vapor. When energized, a mercury arc is formed that creates ultraviolet light that causes the bulb to produce visible light.
- high efficacy (about 80lm/W)
- relative low initial cost
- long life
- range in color temperature from cool to warm
What is the typical use for incandescent bulbs? Fluorescent bulbs?
Incandescent bulbs are generally smaller (except for CFL), and so are better suited for downlights. Larger fluorescent lamps are better suited for general illuminatio.
What are 3 types of fluorescent lamps?
- preheat lamps = need time to warm up
- rapid-start lamps = start within 2 seconds
- instant-start lamps = carry constant charge for instant start
What is the ballast?
part of the light bulb that supplies and regulates proper voltage. Part of every gaseous discharge lamp.
What are 4 types of ballasts?
- magnetic = obsolete
- electronic = use less power, operate without noise/flicker, generate less heat, and allow dimming
- multilevel = used to change lighting levels evenly to conserve energy
- energy saving = reduces total lamp/ballast wattage by using a lower current, efficient ballast design, and disconnecting filaments after the lamps starts
What are High-intensity discharge (HID) lamps?
produce ultraviolet light and visible light. Need extra casing to protect from ultraviolet light. HID lamps need time to restart after shutting down to avoid failure.
What are 3 ways to rate efficiency of ballasts?
- ballast factor (BF) = ratio of the lamp’s light output when operated on a tested ballast to the lamp’s light output when operated by a standard refence “perfect) ballast. Helps determine which ballast is best for a particular lamp to reduce energy usage.
- ballast efficacy factor (BEF) = the ratio of BFx100 to the power in watts. Helps compare the efficacy of different ballasts with the same kind and number of lamps.
- power factor = measures how effectively the ballast converts supplied power into usable power (watts) for the lamps. a power factor of 0.90 or greater is considered high.
How are ballasts rated for noise?
A-F, where A is suitable for quiet environments and F is suitable for noisy environments.
What are High-intensity discharge (HID) lamps?
Where are they most often used?
produce ultraviolet light and visible light. Need extra casing to protect from ultraviolet light. HID lamps need time to restart after shutting down to avoid failure.
typically used when high levels of light are needed over large areas, such as gymnasiums, warehouses, roadways, parking lots, football stadiums, etc.
What are 4 types of HID lamps?
- mercury vapor
- metal halide
- ceramic metal halide (CMH)
- high-pressure sodium
What is a mercury vapor lamp?
How does it work?
Efficiency?
How long does it take to restart after being shut off?
A type of HID lamp in which electric arc passed through mercury vapor.
Moderately high efficiency.
3 min to 10 min to relight
What is a metal halide lamp?
How does it work?
Efficiency?
How long does it take to restart after being shut off?
A type of HID lamp in which electric arc passed through mercury vapor and a combination of metal halides.
Increases efficiency and color rendition, but shortens life.
10 min to 20 min to relight
What is a ceramic metal halide (CMH) lamp?
How does it work?
Efficiency?
How long does it take to restart after being shut off?
A type of HID lamp in which ceramic allows it to operate at higher temperatures and improves color rendition and light control. But higher cost and needs a ballast.
10 min to 20 min to relight
What is a high-pressure sodium (HPS) lamp?
How does it work?
Efficiency?
How long does it take to restart after being shut off?
A type of HID lamp in which electric arc passed through hot sodium vapor.
Extremely efficient and long life, needs to be made with color correction to offset its natural yellow light.
1 min to relight
What are 3 types of outer bulbs a HID lamp may use to protect people from ultraviolet light?
- clear bulb = optical control
- phosphor-coated bulbs = better color rendition
- diffuse bulbs = recessed downlight fixtures
What is an alternate to a high-pressure sodium (HPS) lamp?
low-pressure sodium (LPS) lamp = even higher efficacies, but even yellower light. Good for street lamps.
What are 5 advantages of LEDs?
2 disadvantages?
- long life
- brightness
- lack of heat production
- low power consumption
- variety in color or white light
- low efficacy (lumens per watt)
- high cost
What is efficacy in lighting?
ratio of lumens per watt = measures the energy efficiency of a light source.
What are neon lamp?
glass tubes filled with gas that can be formed into an unlimited number of shapes. Variety of colors can be produced by varying the gas. Often used for signs and specialty accent lighting.
What are cold-cathode lamps?
Similar to neon lamps in that they can be produced in long runs of thin tubing and bent to shape.
Higher efficacy and slightly larger.
What are fiber optic luminaires?
carries light from a remote light source to another area. Bundled optical fibers deliver light to the ends of the fibers.
What is a direct lighting system?
90-100% light directed down
What is a semi-direct lighting system?
60-90% light down, 10-40% up
What is a direct-indirect lighting system?
50% up, 50% down
What is a diffuse lighting system?
40-60% up, 40-60% down
What is a semi-indirect lighting system?
10-40% down, 60-90% up
What is an indirect lighting system?
90-100% up
What is a task-ambient lighting system?
When it is inefficient to light an entire space, provide a general background level of illumination and then separate light fixtures with individual controls at task/work stations.
What is the spectral energy distribution (SED) of a lamp?
The measure of energy output at different wavelengths/colors.
What is color temperature?
the temperature in kelvins to which a black body radiator would have to be heated to produce light of the same dominant color.
lower color temperature = warm colors
high color temperatures = cool colors
What is CRI index? What is considered an excellent CRI?
Color rendering Index = a measure of how closely the perceived colors of an object illuminated with a test light source match the colors of the object when it is illuminated with daylight of the same color temperature.
A CRI of 85 is excellent
What is IES TM-30-18?
new method for evaluating color rendition. helps find the preferred light source for a given application based on efficacy and color rendering.
What are the 3 basic qualities of sound?
- velocity
- frequency
- power
Which factors impact the velocity of sound?
depends on the medium in which the sound is traveling and the temperature of the medium.
What is the frequency of sound?
A high-pitched sound has _____ frequency.
A low-pitched sound has _____ frequency.
What is the range of sound frequencies that a healthy young person can hear?
the number of cycles completed per second, measured in hertz (Hz) where 1 Hz = 1 cycle/second.
higher
lower
20 - 20,000 Hz
What is the power of sound?
the amount of acoustic energy as measured in watts. This is what people perceive as “loudness”.
What is the threshold of hearing in dB?
0 dB