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