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Flashcards by Kara Biczykowski, updated more than 1 year ago
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Created by Kara Biczykowski
almost 2 years ago
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| Question | Answer |
| Nomenclature see p19-2 | tbc |
| 1) what is "transmittance?" 2) what is clear glass transmittance 3) how does light pass thru clear mat.'s? 4) what is the "reflectance" or "reflectance coefficient?" | 1) the ratio of the total transmitted light to the total incident light expressed as a %, aka "coefficient of transmission" 2) 85%, frosted is 70-85% 3) it's "refracted" or bent slightly 4) the ratio of the total reflected light to total incident light |
| 1) what is "specular reflection?" 2) what is "diffuse reflection?" 3) what is "combined specular & diffuse reflection?" | 1) results from a smooth, polished surface like a mirror & angle of incidence equals the angle of reflection Fig19.1 2) results from a uniformly rough surface, appears bright, but no image seen 3) makes surfaces appear brighter at pt of light source contact than surroundings |
| *be familiar w/ relationships 1) "candlepower" is the unit of luminous intensity approx. equal to: 2) "illuminance" is the density of luminous flux incident on a: 3) "lumen" (lm) is the unit of luminous flux equal to the: | 1) the horiz. light output from an ordinary wax candle, in SI system of measurement = "candela" unit 2) surface, expressed in lumens per unit area, 1 lumen on 1ft2 area = illuminance of 1 foot-candle (fc) 3) flux in a unit solid angle of 1 steradian from a uniform pt source of 1 candlepower Fig19.3 |
| 1) on a sphere, 1ft radius (an area of 1sqf) will subtend an angle of: 2) b/c area of a sphere is 4 π, a source of 1 candlepower produces: 3) "luminance" is the luminous flux per unit of projected (apparent) area &: | 1) 1 steradian 2) 12.57lm (lumen) 3) unit solid angle leaving a surface, reflected or transmitted, SI unit = candela per sq meter aka "the nit" *^ in the US the unit is the footlambert (fL) where 1fL is 1/π candlepower per sqft |
| 1) luminance takes into acct what properties of mat.'s as well as: 2) ^so, 100fc striking a surface w/ 50% reflectance would result in: *in metric: 100 lux striking a 1 sq m surface w/ 50% reflectance would result in: | 1) reflectance & transmittance & directions in which they're viewed 2) a luminance of 50fL * a luminance of 50 candelas per sq m |
| 1) "luminous intensity" is the solid angular flux density in a: 2) illuminance target for population btwn ages 25-65 is std, but when 50% abv 65 : 4) 50% blw 25: 3) what does ASHRAE/IESNA Std. 90.1 set a max on? | 1) given direction measured in candlepower or candelas 2) recommended illuminance is doubled 3) recommended is halved 4) along w/ energy conservation codes, max limit on total power for lighting a bldg |
| 1) what is considered "direct glare?" 2) what is "visual comfort probability" (VCP)? | 1) when a light source in the field of vision causes discomfort & interference w/ the visual task 2) a metric used in evaluating the problem of direct glare; % of observers who may exp. visual comfort in specific enviro w/ specific lighting situation |
| 1) what is the critical zone for direct glare? 2) how can direct glare problems be solved 3) "reflected glare" occurs when a light source is: | 1) 45deg angle from light source Fig19.4 b/c field of vision includes an area 45deg abv a horiz. line 2) using a luminaire w/ a 45deg cutoff angle or moving light from field of view 3) reflected from a viewed surface into the eye, contrast btwn task & its background is reduced |
| 1) what is "veiling reflection?" 2) how can it ^ be corrected? 3) contrast ratio for task & adj surrounds: 4) task & more remote darker surfaces: 5) task & more remote lighter surfaces: | 1) if reflected glare interferes w/ viewing task 2) adjust position of task or light source, but b/c angle of incidence = to angle of reflection, this can be calc'd to prevent 3) 3:1 4) 5:1 5) 1:10 |
| 1) oth than daylight, what are the 4 primary types of light sources? 2) "efficacy" is the ratio of luminous flux emitted to the: 3) efficacy is a measure of a light's: 4) why is the amt of heat generated by a light source important? | 1) incandescent lamps, fluorescent lamps, high-intensity discharge (HID) lamps, light-emitting diodes (LED) 2) total power input to the sources, measured in lumens per watt 3) efficiency 4) it generates waste heat that needs to be removed, typ w/ A/C system which adds to total energy load of bldg |
| *see table19.1 for light characteristics 1) how does an incandescent lamp produce light? 2) what does the code A-21 mean? 3) advg's of incandescent lamps: | 1) a tungsten filament w/in a sealed glass bulb full of inert gas glows when electricity pass thru lamp 2) A = designated lamp code, # = bulb diameter (21 is 21/8" or 2-5/8") 3) inexpensive, compact, easy to dim, on/ off w/out life decrease, warm color, output easily ctrl'd w/ reflectors & lenses |
| 1) disadvg's of incandescent lamps: 2) how does the tungsten halogen incandescent lamp differ from the typ? | 1) low efficacy, short lamp life, high heat output; so not good for energy-efficient installations 2) includes a small amt of halogen (iodine or bromine) in bulb w/ inert gas but here as filament burns off it mixes w/ halogen & is redeposited on filament = longer bulb life, even color, whiter light from higher burning temp, better efficacy |
| 1) what is unique about the halogen bulb? 2) reflector (R) & parabolic aluminized reflector (PAR) lamps contain a: 3) elliptical reflector lamps (ER) are improved R lamp version & prvd a more efficient: | 1) made of quartz due to high operating temp & pressure, but failures are explosive, so often encased in glass 2) reflective coating to increase efficiency & allow precise beam ctrl 3) throw of light from a fixture by focusing the light beam at a pt slightly in front of the lamp before it spreads out |
| 1) low-voltage miniature reflector lamps (MR) are small: 2) "fluorescent lamps" contain a mix of inert gas & low-pressure mercury vapor, & when energized light is produced by: | 1) tungsten-halogen lamps, w/ consistent high output & lamp life, whiter color, in many watts & beam spread options 2) a mercury arc forms that creates ultraviolet light, the invisible light strikes the phosphor-coated bulb causing it to fluoresce & make visible light |
| 1) advg's of fluorescent lamps: 2) what new fluorescent is smaller & brighter & now has downlights w/ reflector designs? 3) what are the 3 types of fluorescent lamps? | 1) high efficacy (80lm/W), lowish initial cost, long life, wide color temp range from cool to warm, be dimmed for more $ 2) compact fluorescent lamp (CFL) 3) preheat, rapid-start, instant-start lamps |
| 1) preheat-lamps don't carry current unless in operation & don't begin: 2) rapid-start lamps maintain a constant low current in the cathode that: 3) instant-start lamps maintain a constant voltage high enough to: | 1) luminescing until the cathode has reached operating temp 2) allows them to start w/in 2 sec.'s 3) start the arc in the tube directly w/out preheating the cathode |
| 1) every gaseous discharge lamp (including fluorescents) has a ballast, what is it? 2) "magnetic ballasts" are constructed from laminated steel plates wrapped w/ 3) "electronic ballasts" are solid-state electronics that operate at: | 1) device that supplies proper starting & operating voltages to the lamp & limits the current once the lamp has started 2) copper windings, operate at 60Hz, but mostly obsolete except for old lights 3) 25-60kHz & use less power, no noise or flicker, generate less heat, can dim |
| 1) "multilevel ballasts" 2 or 3 level are used: 2) "energy-saving ballasts" reduce the total wattage of the lamp-ballast combo by: 3) what are 2 oth types of ballast? | 1) to change lighting levels evenly to conserve energy 2) using lower current + efficient ballast design & disconnecting lamp filaments after lamp starts 3) low-current & high-current for specific lamp types |
| BALLAST EFFICIENCY RATINGS 1) a "ballast factor" (BF) is the ratio of light output of a lamp when operated on: 2) "ballast efficacy factor" (BEF) is the ratio of the ballast factor is: 3) BEF compares efficacy of diff. ballasts when used w/ the same kind & # of: 4) "power factor" is how effectively ballast converts: | 1) a tested ballast to the light output of a lamp according to a std. testing procedure 2) multiplied by 100 to the power in watts 3) lamps, even when the wattages used by diff. lamp-ballast combos are diff. 4) supplied power into usable power (watts) for the lamps, high factor like 0.90 = more energy efficient |
| 1) noise for ballast is rated in letters A-F, which is loudest? 2) F40T12WW / RS describes a fluorescent lamp, what does it mean? 3) Energy Star program req.'s not using a st.d Edison screw based, but a: | 1) F, & A is quietest 2) (F) fluorescent, (40) 40W, (T) tubular, (12) 12/8" diameter, (WW) warm white color, (RS) rapid start circuit 3) GU-24 lamp w/ a two-pin base & it's impossible to use any oth type of lamp; becoming the most common energy-efficient lamp (it's the spiral CFL shape) |
| 1) "high-intensity discharge lamps (HID)" include: 2) in a HID mercury vapor lamp, an electric arc is passed thru: 3) how can color be altered in mercury lamp? 4) are HID mercury lamps good in efficacy? | 1) mercury vapor, mtl halide, high & low-pressure sodium 2) high-pressure mercury vapor to make ultraviolet & visible light in blue-green band 3) phosphors can be applied inside lamp to produce more in yellow-red bands 4) moderately high w/ 30-50 lm/W |
| 1) "metal halid lamps" are sim. to mercury ones except what has been added to tube? 2) what are their advg's? 3) & the disadvg's? 4) what are the 3 types of outer bulbs used to protect ppl from ultraviolet light on HIDs | 1) a combination of metal halides has been added to the arc tube 2) increased efficacy & color rendition 3) life lamp shorter, & color temp shifts over life of lamp 4) clear bulbs for optical ctrl, phosphor-coated bulbs for color rendition, diffuse bulbs for recessed downlight fixtures in low ceilings |
| 1) a new type, "ceramic metal halide lamps (CMH)" use a: 2) what are the disadvg's? 3) & the advg's? | 1) ceramic arc tube rather than quartz to burn at higher temps which improves color rendition & light ctrl 2) higher initial cost, difficulty dimming, need for a ballast 3) efficacy better, esp to mtl halides, better color over life |
| 1) a "high-pressure sodium lamp" produces light by: 2) advg's of HPS lamps include: 3) & the disadvg's? 4) a "low-pressure sodium lamp" is better or worse than a HPS lamp? | 1) passing an electric arc thru hot sodium vapor 2) one of most efficient lamps available at efficacy of 80-140 lm/W & very long lives 3) produce very yellow light 4) has even higher efficacy at 150 lm/W, but produce monochromatic light of deep yellow, so can't use if color's important |
| 1) all HID lamps need time to cool & warm up again after shut off, mercury-vapor needs: 2) metal halide lamps need: 3) HPS lamps need: | 1) 3 min - 10 min to relight 2) 10 - 20 min 3) 1 min |
| 1) a "light-emitting diode (LED)" is a: 2) what is the basic unit of an LED? 3) 2 other types of LEDs include: 4) advg's of an LED include: | 1) semiconductor device that uses solid-state electronics to create light 2) an LED "package", combined w/ oth's they make up a LED luminaire 3) organic-LEDs & polymer-LEDs 4) brightness, long life, lack of heat production, low power consumption, ctrl'd by digital interface, can be made to produce many colors or white light |
| 1) what are the disadvg's of LEDs? 2) LEDs are replacing which type of light? 3) besides 4 common types of lamps, what are the 3 others? 4) neon & cold-cathode use a glass tube filled w/: 5) fiber-optics carry light from a remote light source to area to be illuminated, used typ when: | 1) low efficacy (lumens per watt) & high cost, but technology improvements is changing this so efficacy avg 80-100lm/W 2) CFLs & many types of incandescent 3) neon, cold-cathode, fiber optic luminaire 4) gases, varying them makes colors 5) ultraviolet radiation & heat must be kept away, ex delicate objects in museum |
| FUNDAMENTALS OF ACOUSTICS *study definitions p19-11 1) (IIC) "impact insulation class" is a single-# rating of a: 2) (STC) "sound transmission class" is a barrier's abililty to reduce sound over: 3) (TL) "transmission loss" is the difference in decibels btwn the: | 1) floor-clg assembly's impact sound transmission performance at various frequencies 2) several frequency bands, higher rating = better ability to ctrl sound transmission 3) sound power incident on a barrier in source room & sound power radiated into receiving room on opp. side, loss varies w/ frequency |
| 1) the velocity of sound depends on the: 2) in air at sea level velocity = 3) frequency if the number of: 4) how are frequency (f), velocity (c), & wavelength (w) related? what is the equation? | 1) medium in which it's traveling & the temp of the medium 2) 1130 ft/sec 3) cycles completed per sec, in Hz, one Hz = one cycle per sec. 4) 3 basic qualities of sound: f = c / w |
| 1) power (P) is the quantity of: 2) in free space, a pt source emits waves in: 3) ^so sound intensity (I) at given pt at a distance of "r" from the source is = to: | 1) acoustical energy, measured in watts 2) all directions equally 3) the power divided by the area of a sphere of radius r I = P / 4?r² |
| 1) if sound intensity is wanted in watts per sq cm & radius is given in feet, use equation: | 1) I = P / (930 cm²/ft²) 4?r² |
| 1) "inverse square law" says the intensity of a force or energy (like a sound wave) at a given pt is inversely proportional to the square of the distance from the source of that energy, what is equation? | I₁ / I₂ = r₂² / r₁² |
| 1) hearing is proportional to the: 2) sound intensity is measured in: 3) how do humans exp. 0 dB vs 130 dB 4) what is the equation that expresses this relationship ^? *see table19.2 for common sound intensities | 1) logarithm of the source intensity 2) decibels (dB) 3) 0 = threshold of human hearing (hardly audible) & 130 = threshold of pain 4) intensity level = 10log I / I₀ |
| LOUDNESS table 19.3 change in intensity level: 1) 1dB = 2) 3dB = 3) 5dB = 4) 6dB = 5) 10dB = 6) 18dB = 7) 20dB = | change in apparent loudness: 1) 1dB = almost imperceptible 2) 3dB = just perceptible 3) 5dB = clearly noticeable 4) 6dB = change when distance to source in a free field is doubled or halved 5) 10dB = twice or half as loud 6) 18dB = very much louder or quieter 7) 20dB = 4x or 1/4 as loud |
| *table19.4: guideline of addition of decibels to w/in 1% accuracy b/c decibels are logarithmic they can't be added directly -diff btwn 2 values is: 1) 0 or 1 dB 2) 2 or 3 dB 3) 4 to 8 dB 4) 9 or more dB | - add this value to the higher value: 1) 3 dB 2) 2 dB 3) 1 dB 4) 0 dB *for 3 or more sources, add the first 2, then add the result to the 3rd # & so on |
| *for the addition of an arbitrary # "?" of sources of identical value, use equation: | IL total = IL source + 10log ? *IL (intensity level) |
| 1) for a normal young healthy human ear, audible sounds range from: 2) in what range is sound of speech? 3) human ear is less sensitive to what type of frequencies? 4) for measurement & analysis, frequency range is divided into a scale of: | 1) 20Hz - 20,000Hz & is most sensitive to frequencies 3000Hz to 4000Hz range 2) 125Hz to 8000Hz & most energy in range of 100Hz to 600Hz 3) low less than 500Hz, then middle 500-2000Hz, then high abv 2000Hz 4) 8 octave bands, they are one octave wide when its highest frequency is 2x its lowest frequency |
| 1) bands are identified by their center frequencies which are: 2) b/c the human ear is less sensitive to low frequencies, which modified decibel scale is used? 3) what are 2 important factors in transmission of sound? | 1) 63, 125, 250, 500, 1000, 2000, 4000, & 8000Hz 2) the dBA scale to predict human response to sounds & for acoustical design when low frequencies are part of sound 3) stiffness of barrier (less is better) & mass |
| 1) 1st important concept in noise reduction is transmission loss which is the: 2) noise reduction is 2nd, it is the: | 1) diff. in dB btwn the sound power incident on a barrier in a source rm & the sound power radiated into receiving rm 2) arithmetic diff. in dB btwn the intensity levels in 2 rooms separated by a barrier of a given transmission loss, which it's dependent on as well as barrier area & absorption of surfaces in receiving rm |
| 1) noise reduction is calc'd using which equation? | 1) NR = TL + 10log A/S *1 sq m = 10.76 english sabins TL = transmission loss S = surface area in sq m A = total acoustical absorption in metric sabins |
| 1) noise reduction can be increased by increasing: 2) in critical situations, transmission loss & barrier selection should be calc'd using values for: | 1) the transmission loss of barrier, more absorption in receiving rm, decreasing area of barrier separating 2 rooms, per equation 2) specific frequencies rather than an STC avg value |
| 1) when a partition includes 2 or more types of const., the combined transmission loss is found using equation: 2) if the value of the transmission loss of the individual mat.'s is known, to find value of "t" use equation: | TL composite = 10log A total / ∑ t S t = 10 ^superscript - (TL/10) *t = coefficient of transmission S = surface area A = total acoustical absorption TL = transmission loss |
| 1) noise criteria curves can be used o specify the max amt of: *see associated noise criteria table19.5 2) NC for concert halls 3) for bedrooms, apts, hospitals 4) for private offices, sm conf. rm's 5) large offices, retail stores, restaurants 6) lobbies, drafting rm, lab work space 7) kitchens, comp. rm, maintenance | 1) cont. background noise allowable in a space to est. a min amt of noise desired to help mask sounds & eval. exist. cond.'s 2) 15-20 dB 3) 20-30 dB 4) 30-35 dB 5) 35-40 dB 6) 40-45 dB 7) 45-55 dB |
| TRANSMISSION LOSS GUIDELINES 1) typ loss thru barrier increases w/ frequency of sound 2) a wall w/ 0.1% open area (cracks, holes, door undercuts) will have max loss of 30dB & w/ 1% open area 20dB 3) to determine req.'d STC barrier rating, guidelines in table19.6 can be used | 4) a hairline crack will decrease a partition's loss by 6dB, a 1sqin opening in 100sqft gyp board can transmit almost as much sound as if the entire partition didn't exist 5) placing fibrous insulation in a wall cavity increases STC rating, but the density of insulation isn't significant |
| *19.6 EFFECT OF STC ON HEARING 1) STC 25 2) STC 30 3) STC 35 4) STC 42-45 5) STC 45-50 | 1) normal speech can be clearly heard 2) loud speech clearly heard, normal heard but hardly understood 3) loud speech not intelligible but heard 4) loud speech faintly heard, but not normal speech 5) loud speech not audible & oth loud sounds only heard faintly, if at all |
| 1) sound intensity levels decrease ~6dB for ea. doubling of distance from source but: 2) sound absorption is used to ctrl 3) absorption of a mat. is defined by coefficient of absorption "a" which is the ratio of the sound intensity absorbed by mat. to: | 1) only in free space, not in a room or semi-enclosed outdoor area, b/c sound begins to reflect 2) unwanted sound reflections, improve speech privacy, decrease or enhance reverberation 3) the total intensity reaching the mat. |
| 1) when is an absorption coefficient considered reflective vs absorbing? 2) absorption coefficient varies w/: 3) noise reduction coefficient is the avg of: 4) sound absorption avg (SAA) has been superseding NRC, it's the avg of absorption coefficients for: | 1) reflective = 0.2, absorptive = abv to 1.0 2) frequency of the sound, type of mat. 3) a mat.'s absorption coefficients at 250, 500, 1000, 2000Hz rounded to nearest .05 4) the 12 one-third-octave bands from 200-2500Hz when tested w/ ASTM C423 |
| 1) the total absorption of a mat. is dependent on the area of the mat. & the mat.'s coefficient of absorption per equation: | A = S a a = absorption coefficient S = surface area *b/c most rooms contain diff. mat.'s, total absorption is the sum of individual mat. absorptions |
| 1) increasing sound absorption w/in a space will result in noise reduction per equation: | NR = 10 log A₂ / A₁ A₁ = the original total room absorption in sabins A₂ = total room absorption after the increase |
| SOUND ABSORPTION GUIDELINES 1) the avg absorption coefficient should be 2) a coefficient abv 0.5 is considered: 3) mat.'s w/ higher values are suitable for 4) ea. doubling of the amt of absorption in a room results in: | 1) at least 0.2 2) not desirable or economically justified 3) small noisy rooms, & opp. for a large rm 4) noise reduction of only 3dB |
| 1) if add.'l absorptive mat. is being added to a room, total absorption should be: 2) when adding extra absorption, an increase of 10x is approx. practical limit b/c 3) ea. doubling of absorption in a room reduces reverberation time by: | 1) increased at least 3x 2) more results in a decreasing amt of noise reduction as practical limit of 0.5 total avg absorption coefficient is near 3) one half |
| 1) where is absorptive mat. more effective in large vs small rooms? 2) typ absorption increases w/ an increase in: 3) amt of absorption of a porous sound absorber (mineral wool ex) depends on: | 1) in large on clg, in small on walls 2) thickness of a porous absorber (low frequency noise may req. xtra treatment) 3) mat. thkns, mat. density, mat. porosity, orientation of mat.'s fibers; best to be open, interconnected voids |
| 1) "reverberation time" (T in sec.'s) is the time it takes sound levels to: 2) what is the equation? | 1) decrease 60dB after the source has stopped producing the sound T = 0.05 (V / A) = 0.05 (V / a S) V = volume of room in cubic ft (use 0.16 not 0.05 if cubic meters is used) |
| 1) reverberation time that is shorter is better for spaces that are: *see table 19.7 2) ex time for auditoriums (speech & music) & opera halls: 3) ex time for offices, small rooms for speech: | 1) smaller, & opp. for large spaces which req. longer times 2) 1.5 - 1.8 3) 0.3 - 0.6 |
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