DEFINITION OF ACOUSTICS
the following are the various definitions of
"acoustics" depending on its context
- The science of sound phenomena in buildings dealing
with the production, transmission, and absorption of
sound in order to secure the distinct conditions in every
part of the building or room.
- The science of sound and vibration which refers to the
stress fluctuations as well as waves in a material medium.
- An environmental technology on sound and noise
control in a man-made surrounding conducive to a clear
understanding of speech, better appreciation of music,
and minimal noise interference.
- The art and science of designing a room or building
which insures both comfort and communication, and
provides special features as the purpose and use of the
structure requires.
TYPES OF ACOUSTICS
1. Psycho Acoustics
deals with the reaction of human beings to audible
sound
2. Environmental Acoustics
deals with the effects of the environment upon audible
sound waves; may be broken down to Architectural
Acoustics and Landscape Acoustics
3. Electro Acoustics
deals with the generation and detection of audible
sound waves
4. Sonics
deals with the technical application of mechanical
waves in basic scientific research, industry, and
medicine.
DEFINITION OF SOUND
- Any vibratory motion of bodies, the transmission of
these vibrations in a medium, ad the sensation produced
on the human auditory mechanism.
- An alteration in pressure (particle displacement in
velocity) projected and propagated in an elastic
material.
- Form of energy propagated in waves which continue to
subsist until filtered through a material turning into heat
by friction.
SOURCES OF SOUND
Speech – produced by the human voice
Music – produced by an instrument
Noise – produced by impact, by vibrating bodies, even by
speech or music
TYPES OF SOUND
Wanted – sound heard as perfectly as possible at the right
level or loudness without pain or strain Unwanted – sound
which entails an annoyance factor
PROPERTIES OF SOUND
•
•
Sound must always have a source, a
path, and a receiver. (see F1)
Speed – sound travels at 1130 ft. per
second or 344 m. per second at normal
•
•
•
•
•
•
•
•
•
•
•
•
room temperature (68°F); sound travels
faster in denser media.
Intensity – rate at which sound energy is
being transmitted, measured at any point in
the medium; intensity diminishes inversely
as the square of the distance.
decibel – the unit in which sound intensity is
defined for architectural purposes
decibel-meter – instrument by which
sound intensity is measured
Sound Pressure – the fluctuation in the
atmospheric pressure caused by the
vibration of air particles due to a sound
wave.
Loudness – subjective attribute of an
auditory sensation in terms of which sounds
may be ordered on a scale of soft to loud.
Threshold of Audibility – minimum
intensity that is capable of evoking an
auditory sensation in the ear.
Threshold of Pain – minimum sound pressure
level which stimulates the ear to a point
which is painful
Frequency – the number of
displacements or oscillations that a
particle undergoes in 1 second.
o hertz – unit of frequency;
numerically equal to cycles
per second
Pitch – the attribute of an auditory system
which enables us to pinpoint sounds on a
scale extending from high to low frequency.
Tone – sound sensation having pitch.
Wavelength – the distance a sound wave
travels during each complete cycle of
vibration measured in meters or feet.
Directional of Sound Sources – sound sources
radiate sound waves in all directions; radiation
pattern varies with the frequency; high
frequency sounds are more pronounced along
the longitudinal axis of the sound source.
NATURAL ELEMENTS THAT AFFECT SOUND
•
•
•
•
Temperature – particles of sound tend to
follow cold air
Clouds – if heavy, clouds can act as a
reflecting surface
Wind – may change the direction of sound
Bodies of Water – can also act as a
reflecting surface
CHARACTERISTICS OF SOUND
1.
2.
Sound Reflection – sound reflected off a
surface, usually one which is hard, rigid
and/or flat.
Sound Absorption – sound waves absorbed
into a material upon contact; change of
sound energy into some other form
3.
4.
5.
6.
7.
> Sound Absorption Coefficient (α) –
fraction of energy of the incident sound
absorbed by the surface; rates the efficiency
of sound absorption of a material at a
specified frequency (0-1)
> Noise Reduction Coefficient (NRC)
–arithmetic average of sound absorption
coefficients at the frequencies 250, 500,
1000 and 2000 Hz, expressed to the nearest
multiple of 0.05
> Surface
Absorption
–
sound
absorption of a surface obtained by
multiplying the area of the surface by its
sound absorption coefficient
Sound Diffusion – occurs when sound
waves are dispersed equally in a room
Sound Diffraction – acoustical phenomenon
which causes sound waves to be bent or
scattered around such obstacles as corners,
columns, walls, beams, etc.
Sound Refraction – change of sound
wave direction as it moves from one
medium to another of different density
Sound Transmission – sound which
penetrates through a surface
Reverberation – the prolongation of sound as
a result of successive reflections in an
enclosed space after the source of sound is
turned off
1.3 Acoustical Defects
Echo – sound waves which have been reflected to a
listener with sufficient magnitude and time delay so as to
be perceived separately from those communicated
directly from the source to the listener.
Long-Delayed Reflection – similar to echo except that
the time delay between the perception of direct and
reflected sounds is somewhat less.
Flutter Echo – a rapid succession of noticeable small
echoes observed when a short burst of sound is produced
between parallel sound reflective surfaces. Sound
Concentration – sound reflections from concave surfaces
concentrating in an area sometimes referred to as hot
spots. The intensity of sound at hot
spots are always at the expense of dead spots. Coupled
Spaces – two rooms adjacent to each
other by means of open doorways, with at least one
space being highly reverberant.
Distortion – an undesirable change in the quality of
musical sound due to the uneven and excessive sound
absorption of the boundary surfaces at different
frequencies.
Room Resonance – also called Coloration. Occurs when
certain sounds within a narrow band of frequencies tend to
sound louder than other frequencies.
Sound Shadow – occurs when an area does not
receive an adequate amount of direct and reflected
sound.
Whispering Gallery – high frequency sounds
creeping along large concave surfaces such as a
hemispherical dome.
Architectural Contributions to Auditorium Design
•
•
•
•
•
•
Room Shape
Volume and Dimensions
Layout of Boundary Surfaces
Surface Treatment
Audience Capacity
Seating Arrangement
Acoustical Requirements in Auditorium Design
+ There should be adequate loudness in every part of the
auditorium, particularly the remote seats.
GOAL : REDUCE SOUND ENERGY LOSS
1. The auditorium should be shaped so that the audience
is as close to the sound source as possible, thereby
reducing the distance the sound must travel.
> inclusive angle must be less than 140°
> fan-shaped plans gives lesser distance from
speaker to seats/centroid
2. The sound source must be raised as much as feasible
in order to secure a free flow of direct sound waves to
every listener.
3. The floor where the audience is seated should
be properly ramped or raked, because sound is more
readily absorbed when it travels over the audience at
grazing incidence.
> gradient along the aisles of sloped floors should not
exceed 1:8
> other methods to improve sight lines and direct
sound paths:
- low-stepped aisles
- two-row vision
4. The sound source should be closely and abundantly
surrounded with large sound reflective surfaces in order
to supply additional reflected sound energy to every
portion of the audience.
5. The floor area and volume of the auditorium should be
kept at a reasonable minimum, shortening the distance
that direct and reflected sound must travel.
6. Parallelism between opposite sound reflective
boundary surfaces should be avoided, to eliminate
undesirable back reflections.
7. The audience should occupy those parts of the seating
area which are advantageous both for viewing and for
hearing.
8. If besides the primary sound source, which is normally
located at the front part of an auditorium, additional
sound sources exists in other parts of the room, these
sound sources must also be surrounded by sound
reflecting surfaces.
+ Sound energy within the room must be diffused. That is,
there must be a uniform distribution of sound.
BEST METHODS TO PROVIDE DIFFUSION include:
1. providing surface irregularities
2. a random or alternating application of absorptive
and reflective materials
3. providing diffusers
+ The room must maintain optimum reverberation
characteristics. The Reverberation Time must allow
+ The room should be free from acoustical defects
such as echo, long-delayed reflection, sound
concentration, coupled spaces, etc.
THE GENERAL RULE OF THUMB FOR WALL
SURFACES:
1. Reflective near sound source
2. Diffusive at the main audience area (i.e., at the
middle)
3. Absorptive at the rear
favorable reception and efficient presentation.
•
problems, even if rear wall is not treated
acoustically.
For such rectangular lecture rooms with a
modest capacity, a diagonal seating layout
is recommended as it eliminates
parallelism between walls and utilizes
splayed front walls as sound reflectors.
ROOMS FOR MUSIC
Acoustical attributes that affect the Quality of Music:
+ Noise and vibration which would interfere with
listening or performing should be excluded, or at least
reasonably reduced to a minimum.
Acoustical Intimacy : music giving the impression of being
performed in a small intimate hall
3.2 Acoustical Requirements for Various
Auditorium Types
Warmth : felt when the room has a relatively long RT at
low frequencies (250 hz and below)
Recommended Volume per Seat Values
Fullness of Tone : noticed when there is a controlled RT
over the entire audio frequency range
TYPE OF
AUDITORIUM
VOLUME PER AUDIENCE SEAT
(cu. m.)
MINIMUM
OPTIMUM
Ensemble : orchestra performing in unison as a wellcoordinated unit
MAXIMUM
Good Blend : musical sound well-mixed before they reach
the listener (perceived as harmonious)
Rooms for
2.3
3.1
4.3
Speech
Concert Halls
Definition : possessed by a room where the sound of
different musical instruments played simultaneously are
easily distinguishable
6.2
7.8
10.8
5.7
8.5
12.0
5.1
7.1
8.5
Live Hall : an auditorium with a large volume relative to its
audience capacity, with predominantly sound reflective
enclosures
2.8
3.5
5.1
Dead Hall : a hall with a relatively small volume
compared to its audience capacity, with enclosures
which are highly sound absorptive
Roman Catholic
Churches
Balance : created by numerous reflective and diffusive
surfaces around the sound source to strengthen and
improve the balance between various sections of the
orchestra
Multipurpose
Auditoriums
Motion Picture
Theaters
3.2.1 Lecture Halls and Classrooms
LECTURE HALLS and CLASSROOMS
• The most important requirement for
lecture halls and classrooms is noise
control.
• The Optimum Reverberation Time in lecture
halls and classrooms is 0.4 to 0.7 seconds.
• Lecture halls with volumes of 425 – 570 cu.
m. or an audience of 150–200 persons
does not require a Sound Amplification
System.
• However, non-amplified speech, directly
from sound source to receiver is hardly
understandable beyond 9-12 meters.
• Classrooms with rectangular shapes, level
floors, and floor areas normally between 59–
93 sq. m. seldom create any acoustical
•
•
•
•
•
Investigations show that music requires a
longer RT than speech basically because
musical sounds last longer than the syllables
of speech.
No music hall is built for one specific type or
style of music; the RT therefore, must always
be a meticulously established compromise.
The frequency range for music is much
wider than that for speech.
Floor shapes of typical music halls:
o rectangular
o fan-shaped o
horseshoe
o
irregular
Balconies should not protrude too deeply. As
much as possible the height should be
roughly equal to the depth.
CONCERT HALLS
• The floor area of the orchestra platform should
be based on the space requirements of the
musicians, their instruments, the conductor,
and soloists.
• Platform should be neither too deep nor too
wide; a maximum depth of 9 m. and a width
of 18 m. is recommended.
• If chorus space is necessary, 3 m. on either
side or at the back can be added.
• Surrounding enclosures should
have reflective treatment.
• The level of the platform should
be elevated high enough above the audience
floor level to provide ample direct sound to
the audience, and to have a resonant space
underneath to enhance instrumental bass
radiation and reduce overpowering sounds
of percussion instruments.
THEATERS and OPERA HOUSES
• An opera house is defined as a
combination of a theater and a concert
hall.
• As opposed to orchestra platforms, theaters
and opera houses use orchestra pits, located
at least 2.50 m. below the stage.
• Stages of theaters and opera houses
include:
o proscenium o
open / thrust o
arena
o adaptable
• Performances in opera houses rely heavily
upon colorful settings and scenery,
thus proscenium stages are
recommended.
3.2.3 Churches, Synagogues, Multipurpose
Auditoriums, and Community Halls
CHURCHES and SYNAGOGUES
• One of the most difficult aspects in the
acoustical consideration of churches is RT
control.
• A long RT is preferred to enhance organ
sounds, chorus singing, and even the
chanting of words. However, speech
intelligibility suffers.
• The Chancel and Pulpit, as well as the organ
and choir, should be well elevated and
surrounded by reflective enclosures.
• Churches usually consist of several
coupled spaces (e.g., nave, chapel,
baptistery, confessionals, etc.).
• Coupled spaces must be provided with
certain acoustical requirements and need
individual reverberation control.
MULTI-PURPOSE AUDITORIUMS and COMMUNITY HALLS
• The problem with most multi-purpose
auditoriums is the unraked or level floor.
•
Each musician requires a floor area of
1.10–1.40 sq. m., while each member of the
chorus requires 0.30–0.40 sq. m.
•
Level floors introduce the following:
o difficulty in providing direct
sound
o flutter echoes between level
ceiling and floor
lack of absorptive treatment
Community halls and auditoriums found at
the basement of large churches offer a lot of
acoustical problems, primarily the existence of
an excessively long RT (5–8 seconds).
o
•
3.2.4 Motion Pictures Theaters and Recording Studios
MOTION PICTURE THEATERS
• Motion picture theaters represent an
exclusively single purpose auditorium.
• The original sound source is not present but
is a mere reproduction, reflecting the
acoustical character of the motion picture
studio in which the film scenes was shot.
• Motion picture theaters should have a
relatively short RT.
• Boundary surfaces should be treated in a
manner which is favorable to sound
diffusion.
• The room should be raked and fanshaped, with the room length not
exceeding 50 m.
• Heavily upholstered seats should be used to
counteract detrimental defects caused by
fluctuating attendance.
• The front wall behind the screen is treated
with absorptive material to avoid back
reflections from the speakers.
• The size of the screen depends on the
theater area.
• The projection room, acoustically treated
because of the noise it produces, should be
located at the center.
MOTION PICTURE STUDIOS
• Economy in construction and efficiency of
operation suggest that several large-sized
motion picture studios be grouped together.
• Motion picture studios are usually built as
large halls with highly absorbent enclosures
so that the sets can contribute their own
acoustical characteristics as required.
• Provision for the required short RT and for a
high degree of noise and vibration isolation
within these studios is the main acoustical
objective.
RECORDING STUDIOS
• Of all spaces which require acoustical
attention, recording studios are the most
complex.
•
•
•
•
The receiver of sound in studios is
microphones, which can easily detect long RTs,
inadequate diffusion, all acoustical defects,
and even the faintest noise or vibration.
(H:W:L):
- for small studios the recommended ratio is
1:1.25:1.6
> e.g., 2.70 m x 3.375 m x 4.32 m
- for medium-sized studios the
recommended ratio is 1:1.5:2.5
> e.g., 3.00 m x 4.50 m x 7.50 m
The apparent RT in a studio, as eventually
perceived by the listener, depends on the
microphone pick up technology.
Different required RTs cannot be avoided so
variable absorbers and electronically
controlled RT devices are used.
To avoid noise and vibration detection,
studios make use of structural isolation,
sound locks, multi-leaf panels, and other
acoustical technology.
RADIO STUDIOS
There are several types of studios for broadcasting:
• Announcer's Booth : The smallest studio
normally associated with a larger one. The
floor area is only about 14 sq. m.
• Talk Studio : Used for newscasts, panel
discussions, addresses, and even recitals, the floor
area is about 47 sq. m.
• Drama Studio : Floor area is from 56 to 140 sq.
m.
• Versatile Studio : Used for either speech or
musical presentations, floor area varies between
140 and 370 sq. m.
• Audience Studio : Used for broadcasting
choral and orchestral programs
TELEVISION STUDIOS
• Acoustical conditions are not as critical as for
radio studios because the settings, scenery,
and properties will change the acoustical
environment.
• RT in TV studios are usually short. If longer
RTs are required the performance moves to
a Satellite Audio Studio.
• There are several types of television
studios:
o audience studios with permanent
audience seating
o general-purpose studios for all
types of programs
o small interview studios o
dubbing suites
• Television studios normally have most of the
following auxiliary rooms, all with short RTs:
o production control room o
sound control room
o lighting control room o
announcer's booth o
storage areas
• The control rooms are often located one
storey higher than the studio floor.
•
•
The frequency range considered in the
acoustical design of studios is from 32–
8000 Hz.
For rectangular studios certain room
proportions are generally advocated
CONTROL ROOMS
• Every radio, television, or recording studio is
linked with a control room, where the control
desk is located.
•• aVisual contact between the studio and
• window.
control room is provided by a wide control
• The size and shape of the control room
depend on how many people and how
much equipment it will accommodate.
3.3 Sound Amplification Systems
CHECKLIST FOR EFFECTIVE USE OF
AMPLIFICATION/REINFORCING SYSTEMS
SOUND
1. A well-designed sound-reinforcing system should
augment the natural transmission of sound from source to
listener. It should be properly integrated with the room
acoustics design to provide adequate loudness and good
distribution of sound. It should never be used in lieu of good
room acoustics design because it will rarely overcome or
correct serious deficiencies, rather, it will likely amplify and
exaggerate deficiencies.
2. Spaces seating less than 500 will seldom need a soundreinforcing system. Spaces seating 500-1000 may need a
sound system, depending on the use of space. Spaces
seating more than 1000 will normally need a sound
system although it may not be used all the time.
3. The preferred type of sound-reinforcing system always is
the central system, in which a loudspeaker or cluster of
speakers are located directly above the source of sound to
give maximum realism as well as intelligibility.
4. The other principal type of sound-reinforcing system is
the distributed system in which a large number of
loudspeakers, each supplying low-level amplified signals to
a small area, are located overhead. The distributed system
should be used only when the ceiling height is inadequate
to use a central system or when not all listeners can have a
line of sight to a central loudspeaker.
5. Avoid feedback of sound energy from loudspeaker to
microphone by careful location of microphones out of
coverage pattern of the loudspeakers. Feedback is the
regeneration of a signal between loudspeaker and
microphone which is heard as "howling" or "screeching".
6. A sound-reinforcing system used only for speech need
not reproduce sound down to 63 Hz so avoid the "bass
costs only a little more" sales presentation.
SOUND SYSTEMS CRITERIA
1.
SAS should properly transmit a wide range
of frequencies (32-12000 Hz) to maintain a
2.
3.
4.
5.
correct balance between fundamentals and
harmonics to achieve perfect tone color for
SAS should provide a wide dynamic range,
i.e., a pianissimo sound must be clearly
audible, and a fortissimo must be
reproduced without distortion.
SAS should be free from disturbing
echoes or feedback.
SAS should create a sufficiently low room
reverberation.
SAS should remain undetected. The illusion
should be preserved that amplified sound
comes from the natural sound source.
SYSTEM COMPONENTS
• Microphone - picks up the sound energy
radiated by the source, converts it into
electric energy and feeds it into the amplifier
• Amplifier - increases the magnitude of the
electric signal and delivers it to the
loudspeaker
• Loudspeaker - converts the electric signal into
airborne sound waves for distribution to the
listeners
LOUDSPEAKER SYSTEMS
• Central System - uses a single cluster of
loudspeakers over the sound source. The
preferred type because it gives maximum
realism
• Distributed System - uses a number of
overhead loudspeakers located throughout
the auditorium. Realism cannot be expected
from this type of system but it does provide
high intelligibility if the room is not too
reverberant.
o loudspeaker spacing (S) ideally
should be about equal to room
height (H); however S
= square root of 2H is the
practical spacing limit for
uniform coverage
• Stereophonic System - employs 2 or more
microphones adequately spaced in front of
the performing area and connected through
separate amplifying channels to 2 or more
corresponding loudspeakers which must be
placed in the listening area in same pattern as
their corresponding microphones
each musical instrument and to provide
clear, non-distorted sound.
4.1 Structural Acoustics
FUNDAMENTALS OF NOISE CONTROL
• Noise : All sounds that are distracting,
annoying, or harmful to everyday activities
• Airborne Noise : sound transmitted through
the air only, usually through continuous air
paths, doors, windows, vents, air shafts, etc.
These pathways are called Acoustical Short
Circuits.
• Structure-borne Noise : radiated sound
setting into vibration of solid parts of the
building
• The fundamental objective of noise control is
to provide an acceptable acoustical
environment
Recommended Background Noise Criteria for Rooms
ROOM
NOISE CRITERION
Concert Hall, Opera House
20
TV / Movie Studio
25
Classroom, Lecture Hall
25
Assembly Hall, Courtroom
30
Hospital
30
Hotel
35
Library
35
Business Office
40
Restaurant
45
Coliseum, Gymnasium
50
LOUDSPEAKER CLASSIFICATION
• High Level - raises the level of reproduced
sound very high; central systems usually
belong to this group
• Low Level - raises the level of reproduced
sound just slightly; distributed
systems usually belong to this group
STRUCTURAL METHODS TO OVERCOME NOISE AND
VIBRATION
TYPE OF LOUDSPEAKER
• Line or Column - concentrates most of the
sound in a narrow angular spread in
the vertical plane and a semi-narrow
spread in the horizontal plane
Walls
•
Foundation and Frame
•
•
•
•
isolate the foundation from the frame
use resilient members (mounts, clips, and
hangers)
suspend walls using resilient hangers, clips, or
mounts
use multiple leaf lightweight constructions
use thicker, high density material
•
•
•
•
•
•
•
use different material for multiple layers
increase spacing of studs, stagger placement, or
eliminate studs altogether
increase air space within walls
introduce acoustical blankets into the air space
make use of perimeter caulking and other
sealants
extend walls to floor slab above
for adjacent dwellings, the partition wall should
consist of two separate layers extending from the
bottom of the foundation to the roof
Floors, Ceilings, and Roofs
• use floated floor constructions with isolation
blankets
• install floor carpets
• isolate floors and ceilings from adjacent walls
• suspend ceiling with resilient attachments
• use multiple layered floor to ceiling
connections
• use furred plaster ceilings
• apply fiberglass thermal insulation
• use sound insulating roof construction
Doors and Windows
• use door stops and window fittings
• improve door and window layouts
• provide sound locks
Machinery
• isolate the machines from the foundation
• introduce air plenum chambers
• choose proper locations for machine rooms
4.2 Outdoor Acoustics
AFFECTING
OUTDOOR
ACOUSTICS
Temperature
•
downwind from the source, sound is normally
bent towards the ground, increasing its sound
level
upwind from the source, sound is normally directed
upwards causing a shadow zone where the sound level
will be reduced
Clouds and Rain
• if heavy with impending rain, clouds can act as a
reflective surface
• light, cloudy skies can act as an absorptive
surface
Bodies of Water
• when calm, can also act as a reflective surface
LANDSCAPE ELEMENTS FOR NOISE CONTROL Vegetation
•
•
Ducts, Pipes, Chases, and Conduits
• lag or wrap ducts with absorbent materials
• separate ducts from walls and floors by
suspension or packing
• line ducts with absorbent material and divide
paths into several branches
• introduce noise attenuators
• provide different ducts per space
• increase number of bends and turns
• use heavy gauge metal
• use flexible coupling elements for ducts and
conduits
• use resilient mounts
FACTORS
Wind
•
sound tends to bend towards the cooler
temperature
• on a clear, calm day when warmer air is near the
ground, sound tends to bend upwards
• on a clear, calm night when cooler air is near the
ground, sound bends downwards
LAND USE PLANNING FOR NOISE CONTROL Zoning
•
•
•
Trees and vegetation are normally NOT effective as
noise control barriers. It is because attenuation
from trees is mainly due to branches and leaves,
which is why sound energy near the ground will
not be significantly reduced.
Deciduous trees will provide almost no
attenuation during the months when their
leaves have fallen.
A single row of trees has no value as an
acoustical barrier. Thin planting of trees can
provide visual, but not acoustical shielding.
Many rows of trees have some value as an
acoustical barrier.
Addition of shrubs on the ground will provide
better attenuation.
Earth Berms
• Earth berms are effective isolators if
completely covered by sound-absorbing
material, such as plant.
• If there are reflective surfaces along their tops or
deciduous trees, the effectiveness is reduced
because it can scatter sound energy.
Thin Wall Barriers
• Elevated roadbed plus shielding of grass-covered
earth berm and thin-wall barrier can provide useful
attenuation. However, elevated highways more
than 500 ft. away can produce almost the same
noise levels as highways at grade level because the
line of sight will not be blocked.
• Roadbeds below grade can interrupt the direct
sound path from source to receiver even further,
thereby providing greater attenuation by
diffraction. Roadbed depressions of 12 ft. or more
are usually needed to control highway noise.
• Attenuation from thin-wall barrier is more
effective where there is greater angle of
diffraction.
•
•
Industrial and commercial areas may act as
barriers of noise for the benefit of residential
occupancies.
Light industry may be completely surrounded by
office and research park buildings so that the
residential areas are protected from industrial
and vehicular traffic noise.
Site Planning
• Use of concentrated external parking
• Use of cuttings
• Use of landscape embankments
Building Orientation
• Orient the buildings such that the building will be
shielded from traffic noise. Openings and
sensitive areas should be located away from
source of noise or near shielded areas.
• By angling or staggering the buildings, noise
build up from courtyards can be reduced.
Perception and the Eyes
- Matter is perceived through 3 steps: reception,
extraction, and inference.
- The human eye does not respond to the quantities of light
falling on surfaces; rather, the eye sees color and
brightness contrasts.
Lens, Iris, and Retina
Lens
> elastic and transparent; focuses one's view onto the
fovea in a process called accommodation
> a structural defect in the lens can cause objects or
scenes to appear out of focus
> if the lens is a bit too round, then the focal length is too
short and objects are focused in front of the retina, in a
condition called myopia or nearsightedness because only
nearer objects can be seen clearly
> if the lens is a bit too flat, then the focal length is too
long and objects are focused behind the retina, in a
condition called hypermetropia or farsightedness
> another structural difficulty usually associated with
aging is presbyopia, in which the lens become less elastic,
reducing accommodation; bifocal corrective lenses are
usually required for this condition because the lens cannot
focus well on either near or distant objects
Iris
> a membrane covering that dilates (opens) to allow more
light to enter the eye during darkened conditions, and
constricts (closes) to minimize light entry during brightened
conditions, in a process of adjustment known as adaptation
Retina
> contains receptors responsible for transmitting an
"image" to the brain for analysis
2 basic categories of receptors:
1.) cones
Luminous Energy
- unit : lumen-second
- constant flow
- nheavily concentrated in the fovea, providing sharp,
distinct detail vision
- perceives color
2.) rods
- respond to very low light levels and occur over the
entire retina except in the area of the fovea
- do not provide distinct, detailed vision, nor do they
provide color stimulus to the brain
- peripheral vision is supplied by the rods
Color and EM Spectrum
Ultraviolet
- electromagnetic radiation having wavelengths from about
370 nanometer (immediately beyond the violet in the visible
spectrum) to 10 nanometer (on the border of the x-ray
region)
Visible Light
- electromagnetic radiation that the unaided human
eye can perceive
- having a wavelength in the range from about 300 - 800
nm, and propagating at a speed of 186,281 miles per
second
- violet, blue, green, yellow, orange, red
Infrared
- electromagnetic radiation having wavelengths from
about 800 nm (contiguous to the red end of the visible
spectrum) to 1 mm (on the border of the microwave
region)
Nature of Light
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Reflection
Diffusion
Absorption
Refraction
Transmittance
Diffraction
Color Temperature and Color Rendering Index Color
Temperature
- the temperature at which a blackbody emits light of a
specified spectral distribution
- used to specify the color of a light source
Color Rendering Index
- a measure of the ability of an electric lamp to render
color accurately when compared with a reference light
source of similar color temperature
Units of Measure
Solid Angle / Steradian
- Solid Angle: an angle formed by 3 or more planes
intersecting at a common point
- Steradian: a solid angle at the center of a sphere
subtending an area on the surface equal to the square of
the radius of the sphere
Luminous Flux
- SI unit : lumen/s (lm)
- the rate of flow of visible light per unit time
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Luminous Intensity
- SI unit : candela (cd)
- the luminous flux emitted per solid angle by a light
source
Illuminance
- SI unit : lux (lx) equal to one lumen per square meter
- unit : footcandle (fc) equal to one lumen per square foot
- the intensity of light falling at any given place on a
lighted surface, equal to the luminous flux incidence per
unit area
Cloud Sky - a sky having between 30% - 70%
cloud cover with the solar disk obstructed
Overcast Sky - a sky having 100% cloud
cover
Daylighting Techniques
• Sidelighting - e.g., windows and
clerestories
• Toplighting - e.g., skylight
• Shades and Reflectors
• Building Shapes and Orientation
Types of Artificial Lighting
Exitance and Luminance
- unit : lambert (l); footlambert (fl)
- light energy leaving a surface
- the quantitative measure of brightness of a light source or
an illuminated surface, equal to the luminous intensity per
unit projected area of the source or surface viewed from a
given direction
Task or Functional Lighting
lighting designed to provide strong illumination for a
visually demanding activity
Brightness
- the sensation by which an observer is able to
distinguish between differences in luminance
Accent or Decorative Lighting
lighting that calls attention to a particular object or
feature in the visual field or that forms a decorative
pattern on a surface
Contrast
- relative difference of adjacent luminances
General or Ambient Lighting
lighting designed to provide a uniform level of
illumination throughout an area
Path or Information Lighting
lighting designed for wayfinding
Inverse Square Law
- the farther away it is, the less energy arrives
Daylighting
- The science, theory, or method of providing
illumination through the use of light of day
- To provide an interior space with daylight from both
direct and indirect sources
Sky Luminance Distribution
• Sunlight - direct light of the sun
• Skylight - the light from the sky, reflected
and diffused by air molecules
• Clear Sky - a sky having less than 30%
cloud cover with the solar disk
unobstructed
Fluorescent Lamps
- electric energy excites the gas inside the lamp, which
generates ultraviolet light that excites the phosphors
painted onto the inside of the bulb
- requires a ballast in order to work properly
- T-8 (4' long with 1" dia.) is the most commonly used
general purpose lamp
- compact fluorescent lamps (CFLs) come with either a
screw base (to replace incandescent lamps) or a plug-in
base
High Intensity Discharge (HID) Lamps
- designed to emit a great deal of light from a compact,
long-life light source
- most often used for street and parking lot lighting
Types of Lamps
Incandescent and Halogen Lamps
- generally light when electric current heats the lamp's
filament
- start and warm up almost instantly and can be
extinguished and restarted at will
- preferred for their color and versatility
- drawbacks of this type of lamp is inefficiency and
short life
- requires time to warm up; true light output and color is
often not reached for 2-5 minutes
- requires a cool-off period (restrike time) before it can be
restarted once turned off
- types of HID lamps:
> Metal Halide Lamps
> Sodium Lamps
> Mercury Vapor Lamps
Neon and Cold Cathode Lamps
- closely-related to fluorescent lamps in operating
principles
- primary applications are signs and specialty lighting
- tubular lighting that can be formed into any shape and
be made to create any color of light
- cold cathode lamps are generally larger in diameter than
neon lamps and comes with a plug-in base while neon
tubing usually terminates in base wire connections
- includes track lights, floodlights, and accent lights
Computation Guide
Fiber-Optics
- generally uses a thin, flexible, transparent fiber as a
"light pipe" to transmit light between the 2 ends of the
fiber
Light-Emitting Diodes (LED)
- light output produced by an individual diode often
used together
- small compared to incandescent and CFL
Types of Luminaires
Direct Luminaires
- emits light downwards
- includes most types of recessed lighting, including
downlights and troffers
Guidelines
- Methods discussed below are merely for rough
calculations or architects and interior designers for basic
ambient lighting and should follow the conditions below:
- Apply only to relatively ordinary spaces with white
ceilings, medium tone to light walls, and a reasonable
number of windows and other details. This does not work
well for dark-colored spaces or spaces with unusual
shapes.
- Use common, everyday lighting equipment intended for
the space being designed. Avoid custom designs and
clever uses of lighting equipment.
- Make sure you understand the different effects of
point sources like incandescent or halogen and
fluorescent lamps
WATTS-PER-SQUARE-FOOT METHOD
Indirect Luminaires
- emits light upwards, bouncing light from the ceiling
into a space
- includes many styles of suspended luminaires,
scones, and some portable lamps
Diffuse Luminaires
- emits light in all directions uniformly
- includes most types of bare lamps, globes,
chandeliers, and some table and floor lamps
Direct-Indirect Luminaires
- emits light upward and downward but not to the sides
- includes many types of suspended luminaires as well as
some table and floor lamps
- can be semi-direct or semi-indirect according to the
proportions of up and down light
Asymmetric Luminaires
- usually designed for special applications
- may be direct-indirect luminaires with a stronger
distribution in one direction
Adjustable Luminaires
- generally direct luminaires that can be adjusted to
throw light in directions other than down
- Number of Lighting Fixtures Needed = Total Required
Lumens ÷ Lumens per Lighting Fixture
Sample Computation:
- Compute for the number of lighting fixtures needed for an
800 s sq.ft. classroom if the desired lighting level for a
classroom is about 50 footcandles, and the lighting fixture
to be used is a luminaire containing 2 lamps, each of which
produces 2850 lumens.
- Multiply the desired lighting level by two (2) = 50 fc x
2 = 100 footcandles
- Total Lumens Required in the Room = 800 sq.ft. x 100
fc = 80,000 lumens
Computation Guide:
- Use the table above as a guide
- Total Light or Watts Needed in a Space = Area x
Prescribed Watts per sq.ft.
- Number of Lighting Fixtures Needed = Total Required
Watts ÷ Watts per Lighting Fixture
Sample Computation:
- Compute for the number of lighting fixtures needed for an
800 s sq.ft. classroom if the desired lighting level for a
classroom is about 50 footcandles, and the lighting fixture to
be used is a luminaire containing 2 lamps of 32 watts each.
- Total Light or Watts Needed in the Classroom =
800sq.ft. x 1.2 watts per sq.ft. = 960 watts
- Number of Lighting Fixtures Needed = 960 watts ÷ (2 x 32
watts per lighting fixture) = 15 lighting fixtures
LUMEN METHOD
Computation Guide:
- Use the table above as a guide
- Multiply the desired lighting level by two (2)
- Total Lumens Required in the Room = Area x Total
Desired Lighting Level
- Number of Lighting Fixtures Needed = 80,000 lumens ÷ (2
x 2850 lumens per lighting fixture) = 14.04 fixtures = 14 or
15 lighting fixtures
Average Light Level
Desired and Typical
Application
Watts per Square Foot of
Fluorescent, CFL, or HID
Lamps
Watts per Square Foot of
Incandescent or Halogen
Lamps
2.5 - 5.0 fc
Hotel Corridors
Stair Towers
0.1 - 0.2
0.3 - 0.7
0.2 - 0.4
0.7 - 1.0
10.0 - 20.0 fc
Building Lobbies
Waiting Areas
Elevator Lobbies
Malls
Hotel Function Spaces
School Corridors
0.4 - 0.8
1.0 - 2.0
20.0 - 50.0 fc
Office Areas
Classrooms
Hold Rooms
Lecture Halls
Conference Rooms
Ambient Retail Lighting
Industrial Workshops
Gyms
0.8 - 1.2
not recommended
50.0 - 100.0 fc
Grocery Stores
Big Box Retail Stores
Laboratories
Work Areas
Sports Courts (not
professional)
1.2 - 2.0
not recommended
5.0 - 10.0 fc
Office Corridors
Parking Garages
Theaters (house lights)