arch 4521 final exam

luminous flux

luminous flux

the time rate of light flow, unit of measure is the lumen

ex: rate of water from sprinkler head

luminous efficiency

-how much energy is being converted into usable light

-a measure of lumens/watt

-the power or rate at which lamps emit light is measure in lumens

-because of large differences in efficiency, lamps of equal wattage can emit very different amounts of light

luminous intensity

-the amount of luminous flux in a given direction measures in lumens per solid angle (candelas or candelpower)

-water per minute sprayed with a cone of a given angle

color reflectance

ratio of reflected flux to incident flux

color absorbance

ratio of absorbed flux to incident flux

color transmittance

ration of transmitted flux to incident flux

illuminance

-the density/amount of luminous flux a given surface

-ex: gallons of water sprayed per minute in a specific area

luminance

-brightness

-the measure of reflected light that is governed by illuminance and reflectance

footcandles

unit for the amount of light reaching an object

lumens

the unit of light output from a light source or luminaire

candlepower distribution curve

-photometric measurements representing the total light intensity pattern produced by a source

specular reflection

-a mirror is a specular reflector

-changes the direction of a beam of light without otherwise appreciably altering the nature of the beam

diffuse reflection

reflection of light from a rough surface in many directions

cosine effect

a beam of sunlight will illuminate a larger area as the sky

opacity

refers to the transparency of a tool or layer

inverse square effect

(be able to calculate

i1/i2=(d2/d1)^2

illuminance from a point light source is inversely proportional to the distance squared

light reflectance

the percentage of light hitting a surface, that is reflected and not absorbed into the surface

light absorption

the percentage of light hitting a surface, that is absorbed and not reflected off of the surface

light transmission

the passing of light or sound waves through a material

colorimetry

hue- range

value- shade

chroma- intensity

sensitivity of the human eye

light enters pupil, focused onto light sensitive retina in back of eye - eye adapts to brightness levels by making the pupil larger using the iris

issues with light trespass

-decreased sleep quality

-glare

-loss of night sky darkness

-spill light affecting neighbors

frit

-painted on exterior of glass to make it semi transparent

-small pieces of glass

color perception

distinguishing the difference between wavelengths of light

characteristics of the field of vision

detail: we only see at high resolution in a small area at the center of our vision

color: we don't see much color outside of the center of our vision

blind spots: we have a blind spot on the left and right side of our vision

factors that affect performance of visual task

-the task: size/proximity (exposure angle) exposure time, brightness, contrast, familiarity

-light condition: illumination level, brightness ratios, glare

-the observers: condition of eyes, adaption, fatigue, health, drunkenness (or sobriety)

light quantity

a space has more than enough lighting horizontally, it may still appear dark if there is a low brightness vertically

light quality

additional illumination vertically will improve the light

contrast ratios

rates of the luminance of the brightest color (white) to that of the darkest color (black) that the system is capable of producing

glare

types

1. direct (discomfort)

2. disability

3. reflected (or veiling)

location of field of vision

all the area a person can see while looking straight ahead

-foveal surround

-foveal vision

-center of vision

how daylight enters a building

-reflection

-direct

what design strategies can optimize daylight penetration

-shading and light shelves

-aperture design

-skylights

-top lighting

-side lighting

-configuring and massing

daylighting rules of thumb

orientation: east/west

room depth: make the depth no more than 2 to 2.5 times the window head height

15/30 rule: sufficient daylight will be delivered at a 15 ft distance from the window wall

daylight capture: varies with aperture slop and orientation

top lighting: for uniform lighting, make the spacing of the skylights 1 to 1.5 times the ceiling height

overcast

illumination of 500-2000 fc (still 10 to 50 times greater than what is needed indoors)

clear skies

illumination of 6,000-10,000 fc (100 to 200 times greater than requirements for good indoor illumination)

daylighting factor

the ratio of daylight indoors as compared to the overall amount available outdoors

daylight opportunities

-micro climate and site

-configuring and massing

-daylight zoning

-room proportion and shape

-aperture quntity and location

-shading and light shelves

-glazing type

-finishes

-furnishings

-light control

-operation

relationship of window head height to daylight penetration

make the depth of the room more than 2 to 2.5 times the window head height

concept of overcast sky

the challenge is quantity of light in the space while quality is good.

ex: a skylight would be a lot bigger/floor area for an overcast sky to let in more light while a skylight would be much smaller/floor area for clear sky to reduce direct glare. The brightness distribution of an overcast sky is typically 3 times greater at the zenith than at the horizon

visible transmittance

amount of light allowed through a window

solar heat gain coefficients

amount of heat allowed through a window

15/30 rule

sufficient daylight will be delivered at a 15ft distance from the window wall

basic lamp types and application

-incandescent

-fluorescent

-HID

-LED

-other/specialty

inverse square law

intensity is inversely proportional to the square of distance from the source

i1/i2=d1^2/d2^2

color temperature

color appearance of light sources can be defined in terms of "degree" kelvin

color rendering index

-measures how faithfully a light source reveals the colors of objects

-ranges from 0-100

-the higher the CRI number, the better color rendering ability of the lamp

basic components of a luminaire and what they do

What is it:

an entire fixture assembly including the instrument, lamp and mounting device

Components:

-source/ballast

-reflector

-shield/diffusor -housing

types:

-direct

-indirect

-semi-direct

-semi-indirect

-general diffuse

how light level varies from a source with distance

the intensity of light is inversely proportional to the square of the distance. This means that as the distance from a light source increase, the intensity of light is equal to the value multiplied by 1/d^2

primary factors that determine coefficient of untilization

-room surface reflection (ceiling, wall, floor)

-room size and proportion (room cavity ratio)

-luminaire characteristics (efficiency and intensity distribution)

light pollution

brightening of the night sky caused by street lights and other man-made sources, which has a disruptive effect on natural cycles and inhibits the observation of stars and planets.

light trespass

-decreased sleep quality

-glare

-loss of night sky darkness

-spill light affecting neighbors

sound absorption

The process of dissipating sound energy by converting it to heat.

sound transmission

the passing of sound waves through a material

acoustic properties of openings

the properties of a material to absorb or reflect sound acoustically

area effect

acoustical materials spaced apart can have greater absorption than the same amount of material butted together.

The increase in efficiency is due to absorption by soft exposed edges and also diffraction of sound energy around panel perimeters

articulation index

a tool used to predict the amount of speech that is audible to a patient with a specific hearing loss. The AI figure for a given patient can range from zero to one, representing the proportion of the average speech signal that is audible

ceiling attenuation class

indicates the ceiling's ability to prevent airborne sound from traveling between adjacent rooms when the dividing wall does not connect with the structural ceiling

considerations for sound reduction of mechanical equipment

-how high does the barrier have to be

-how close should the barrier be

-how much sound attenuation will we get from the barrier

considerations for sound reductions in doors and windows

-keyhole consideration

-airtight seals

decibel level for human hearing

0-barely audible

20- whisper

130- painful

200- damage

diffuse sound field

an acoustic field where sound waves reach the observer from all directions. The reflected sound is of similar magnitude to the direct sound when it reaches the observer, and as a result, does not appear to have a single source.

direct sound

any sound recorded directly from the event

early sound

Sound that reaches the listener within a short time (50 to 80 ms) after the direct sound

reverberation field

a component of the response associated with reflections from boundaries of the subsystem and blocked connections and is statistical

directivity of sound and variation with frequency

-high frequencies are very directional

-low frequencies are effectively non directional

echo

a sound or series of sounds caused by the reflection of sound waves from a surface back to the listener

factors that influence environmental noise

-day/night average sound levels as a function of population density

-warm/cool air

-site/site specific qualities

flutter echo

an energy that's trapped between two surfaces and the angle that the sound enters between the two surfaces

free sound field

there are no reflections; sound waves reach an observer directly from a sound emitting object. The sound waves passes the observer exactly once, and never returns

noise reduction

the difference between the intensity levels of two rooms separated by a barrier of a given transmission loss

noise criterion curves

-a set of curves that weight the dB scale to reflect human hearing

-low frequencies are more tolerable than high frequencies

-they are intended to quantify the differing perception of loudness across different frequencies

dB scale

Scale used to measure sound intensity. 0dB is the faintest noise we can detect. 120dB is the threshold of pain.

impact insulation class

an integer-number rating of how well a building floor attenuates impact sounds, such as footsteps

what happens whens doubling the distance in open field

6 dB reduction for a doubling distance in free field conditions from point source, 1/4 of the old intensity

how to add and subtract sources of various SPL dB amounts

dB are not additive to add two or more noise levels, if the difference between the highest and next highest noise level is

ex: 0-1 dB then add 3 dB to the higher level to give the total noise level

doubling power of sound sources, halving power of sound sources

-every time you double the number of identical sound sources, you can add 3dB

-halving the number of identical sound sources, you can subtract 3dB

multiplying sound power

to determine the SPL dB level of N sound producers add 10log(N)-for example-for 865dB sound sources = 65dB + 10log(8) = 74

methods of noise reduction

source: proper selection and installation of equipment

path: from point to point by proper selection of construction materials and appropriate construction techniques

receiver: location through acoustical treatment of the relevant spaces

noise reduction coefficient

a scalar representation of the amount of sound energy absorbed upon striking a particular surface. An NRC of 0 indicates perfect reflection; an NRC of 1 indicates perfect absorption

octave band

a frequency band where the highest frequency is twice the lowest frequency

phon

a rating system that takes into account the different perceptions of loudness at different frequencies

pinna

the external part of an ear in humans and mammals: the auricle

pitch

the sensation of a frequency is commonly referred to as this of sound

propagation of sound for curved/flat surfaces

sound concentration caused on curved surfaces

properties of "noise"

-frequency

-sound pressure

-sound power

properties of human hearing

-variation in sensitivity with respect to frequency

-phon

-increased annoyance with increased frequency

properties of waves

-frequency

-wavelength

-amplitude

-speed of sound

- wave form (simple vs complex)

pure tones vs. complex sounds

pure: one frequency

complex: multiple frequency components

range of comfortable sound levels

perceptible sound levels

sound reflection

occurs when sound bounces off hard, rigid, and flat surfaces such as concrete, brick, stone, or glass.

sound diffusion

process of random movement toward equilibrium

sound diffraction

waves bend when they encounter an obstacle

general relationship of absorptive to frequency and thickness

the thicker an absorbent material, the better its low frequency absorption characteristics

relationship between change in dB scale and apparent loudness change

change in 1 dB=imperceptible (except for tones)change in 3 dB = just barely perceptible,change in 6 dB=clearly noticeable, change in 10 dB = about twice (or half) as loud, change in 20 dB = about 4 times (or one-fourth) as loud.

resonant panels

-absorbs low frequencies

-they work by vibrating at these low frequencies and turning sound into heat

reverberation time

a collection of time-delayed versions of a sound that have decayed in intensity over time as they arrive at the listener

reverberations

Multiple or continuous reflections of sound that prolong(distort) the existence of the sound within a confined space

sound

A disturbance that travels through a medium as a longitudinal wave

sound directivity

-projection of sound from source

-the voice sounds natural

-mega horn greatly enhances this