Room acoustical quality

Transkript

Czech Technical University in Prague
Faculty of Civil Engineering
Department of Microenvironmental and Building Services Engineering
125 YMCB
MICROENVIRONMENT and Architecture
6th Lecture
Light and sound
prof. Ing. Karel Kabele, CSc.
A227b
[email protected]
Visual Comfort
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Light
• electromagnetic radiation that is visible to the
human eye
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http://en.wikipedia.org/wiki/Light
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The human eye
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The Human Eye
The function of the eye is to translate the light into patterns of
nerve impulses that are transmitted to the brain.
The actual process of seeing is performed by the brain (visual
cortex) rather than the eye.
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Human Eye - Retina
• Photoreceptors
– rods
– cones
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http://en.wikipedia.org
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Scotopic and Fotopic Vision
Scotopic vision
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• Vision scotopiq
Fotopic vision
prof. Karel Kabele
http://en.wikipedia.org/wiki/Luminosity_function
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Adaptation
• operates via the contraction of the iris
(muscle), which allows to see well in different
lighting conditions: 0,25 – 100 000 lx
• In rapidly changing lighting conditions
temporarily we can not see or can see poorly
– To light – several seconds
– To dark – up to several minutes
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Accomodation
The eye focuses on a given object by changing the shape of the eye
lens through accommodation.
Healthy human eye: change power of 12-15 diopters
accommodation from "infinity" to a distance of 7 cm.
http://simple.wikipedia.org/wiki/Accommodation_(eye)
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Accomodation Depending on Age
range of accommodation
in diopters
the minimum
distance
for sharp vision in cm.
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Vision Disorders
• myopia
• hypermetropia
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Vision Disorders
Normal Vision
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Macular Degeneration
Glaucoma
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From National Eye Institute, USA
Diabetic Retinopathy
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Cataract
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Vision Disorders
• Colourblidness (daltonism)
= disturbance of color vision. Colorblindness has several types depending on
what color a person does not perceive. Color blindness rarely occurs in all
colors (black and white vision).
http://cs.wikipedia.org/wiki
Sample test of
color
blindness.
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What do we see?
The resulting image = image on the retina +
brain image adjustments based on past
experience
 We see what we "want to" see.
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http://michaelbach.de/ot/index.html
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Quantitative Characteristics of
Lighting
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Measures and units of light
http://new-learn.info/learn/packages/mulcom/
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Measures and units of light
http://cs.wikipedia.org/wiki/Steradian
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Luminous Flux
Symbol: F
Unit:
lm
SOX 70 W – 6000 lm
100 W GLS – 1400 lm
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Luminous Intensity
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Candle - 1 cd
Symbol: I
Unit:
cd
100 W GLS – 110 cd
Sun 3 x 1027 cd
Fitting and its corresponding luminous intensity distribution
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Illuminance
Symbol: E
Unit:
lx =lm/m²
Sunlight 100 000lx
Office 500lx
Corridor 100lx
Dusk 50lx
Moon 0.5lx
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Luminance
prof. Karel Kabele
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VDU - 100
Candle – 8,000
Symbol: L
Unit:
cd/m2
Fluorescent 10,000
Sun 1,6 x 109
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Percieved brightness
There is no linear relationship between the luminance
and the perceived brightness.
How we perceive the brightness of an object depends
on the luminance of the object and the state of the
adaptation of the eyes.
•
http://new-learn.info/learn/packages/mulcom/comfort/visual/vision/box1.html
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Percieved Brightness
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Percieved Brightness
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Qualitative Characteristics of
Lighting
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Quality of Light
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Modelling Ability
• ability to recognize 3-dimensional
objects
• background of similar brightness
• Too diffuse light
• Too direct light
• Sport arenas,
• public places
• distinguishing faces
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Directionality
Diffusely and directly lit wall
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Directionality
Direct, indirect, and direct-indirect luminaires
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Colour temperature
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Light Sources
and Colour
Temperature
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Colour Rendering
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Colour Rendering
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Colour Rendering
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Contrast
•
Narrow beam angles create high contrasts in
the visual environment. If the ceiling and walls
are not lit at all, a cavern effect can be created
which will create an unpleasant feeling.
•
Broader distributions of the fittings will create a
visually interesting scalloping pattern on the
walls while still casting shadows which result in
a good contrast
•
Very diffuse light creates uniformly lit surfaces.
Since no shadows are cast, it can be difficult to
recognise objects.
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Simple contrast:
Contrast
Weber contrast:
Michelson contrast:
[source : Lechner (2001) Heating, Cooling, Lighting, fig. 12.8d, p. 341 + http://www.liden.cc/Visionary/Vision.frame.c.html]
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Glare
• Too large differencies
in contrast
• Light source is close
to the task area
• Windows
• impairs the visibility of objects
disability
glare
• creates unpleasentness
discomfort glare
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Glare and reflections
VDT reflection
Discomfort Glare
Veiling reflection
Disability Glare
[source : Guy Newsham, National Research Council of Canada, IRC, Cope]
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Glare - assessment
• UGR (unified glare rating) – glare index
Lz – luminance of light source of glare
Ώ – solid angle of the light source seen from the observer
Lp – average background illuminance (addaptation illuminance)
n - number of sources of glare
P – coefficient characterizing the effect of the position of glare source
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Glare
Measures that avoid discomfort glare
Dark surfaces and heavy furnishing reduce daylight, especially at the back of
the room. In deep room, select light colours and cautious plan of furnishing.
[source: Jens Christoffersen, Sbi, Denmark]
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Glare
Interior finishes with light colours
EN-12464 (2002):
reflectances:
ceiling 0,6-0,9
walls 0,3-0,8
working planes 0,2-0,6
floor 0,1-0,5
[source: Public Works and Government Services, 2002, Daylight Guide for Canadian Commercial Buildings, Brown & Dekay, 2001,
Sun Wind Light, Standard, 2002 EN 12464-1]
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Glare
Recommended values for interior surface reflectance:
Ceiling > 0,7 Walls > 0,5 - 0,7 Floor > 0,2 - 0,4
[source: Jens Christoffersen, Sbi, Denmark]
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Glare
• Direct glare
• Glare from a luminous object located in the same
direction as the object which is looked at, or in a
neighbouring direction.
• Reflected or indirect glare
• Glare caused by a luminous object not located in the
direction of the object which is looked at.
prof.
Karel
125
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Kabel
e
Direct and reflected glare
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Glare
Direct glare
Reflected or
indirect glare
[source: Steven Holl]
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Criteria for good lighting
– Adequate illuminance level in the room and
task
– Luminance distribution within field of view
(e.g. contrast, luminance ratio between
horizontal and vertical surfaces ….)
– ‘Preventing’ glare
– Light distribution in the room and task (e.g.
direct/diffuse, daylight/artificial light)
– Colour properties of the light
[source : Jens Christoffersen, Sbi, Denmark]
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Lighting Requirements
EN 15251, EN 12464-1.
Specify requirements for illuminance, glare and color rendering.
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Acoustic Comfort
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Is environmental component made up of
acoustic flows in the atmosphere, that act
on body and so help to create its overall
condition. (prof. M.Jokl)
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ACOUSTIC FLOW
is created by oscillation of air molecules or other liquid by a
sound source, giving rise to acoustic waves of different lengths
or frequency

c
m
f
λ- wavelength[m]
c – sound velocity [m.s-1]
in air 15°C = 340 m.s-1
in water 25 °C = 1500 m.s-1
in seawater 13°C =1500 m.s-1
in ice -4°C = 3250 m.s-1
in steel při 20 °C = 5000m.s-1
f – frequency [s-1] [Hz]
75
SOUND =
is a mechanical wave that is an oscillation
of pressure transmitted through a solid,
liquid, or gas, composed of frequencies
within the range of hearing
THE SOUND is every ACOUSTIC
FLOW.
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SOUNDS
TONES = music sounds
regular (periodic)
oscillation
NOISE = non-musical
sounds - irregular
(aperiodic) oscillations
flute
Sound „s“
Sound „o“
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THE EFFECT OF SOUND ON THE HUMAN
Sound is received by the ear,
that consists of three parts
1. OUTER EAR (auricle, the
ear canal, tympanic
membrane)
2. MIDDLE EAR (the malleus
(hammer), incus (anvil), and
stapes (stirrup), oval window)
3. INNER EAR (cochlea, basilar
membrane, thousands of hair
cells, nerve impulses to the
brain, interpretation of
sounds)
http://en.wikipedia.org/wiki/Ear
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Zdroj : http://www.audified.com
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SOUND
Basic Properties
PHYSICAL INTENSITY
FREQUENCY
COURSE OF VIBRATION
physical quantity
SOUND
PRESSURE
LEVEL[dB]
physical quantity
FREQUENCY
[s-1,Hz]
physiological
value
VOLUME
physiological
value
THE TONE PITCH
physical quantity
COURSE OF
VIBRATION
physiological value
THE COLOR OF
SOUND
79
???
FREQUENCY OF SOUND WAVES
5 Hz
100 kHz
12 Hz
175 kHz
5 000
http://www.zubrno.cz/studie/kap06.htm
v tomto rozmezí je lidské ucho nejcitlivější
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STRENGTH OF SOUND WAVE
perceives intensity of sound waves on the
basis of SOUND PRESSURE, which creates
sound
http://tattoo-a-pierc.blog.cz/
HEARING
sound pressure from 20
µPa do 100 000 000 µPa
𝒑𝟎 = 20 µPa = 0dB
THRESHOLD OF HEARING
logarithm of these values
so-called
SOUND PRESSURE LEVEL
[dB]
𝑳𝒑 = 𝟐𝟎 𝒍𝒐𝒈
𝒑
𝒑𝟎
THRESHOLD OF PAIN = 100 Pa =130 dB
81
SOUND
PRESSURE
LEVEL
> 35 dB – negative
impact on the psyche
> 65 db – autonomic
nervous system
> 85 db – danger to
the auditory system
> 120 db – may
permanently damage
the cells and tissues
Sound at 155 decibels can burn the skin.
Sound at 180 decibels can kill
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http://www.audified.com/projekt
mu/page58/page69/page69.html
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NOISE
SOUND
BASED ON THE EFFECTS ON
HUMANS!
(person x sound x situation)
PLEASANT
UNPLEASANT
ACOUSTIC
ACOUSTIC
MICROCLIMATE
MICROCLIMATE
84
NOISE
= unwanted sound (regardless of volume)
which adversely affects human well-being
- INTERRUPT, ANNOY, THREATEN THE HEALTH
in general
Noise is each sound / sounds
that are harmful to the human body.
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SOURCES OF NOISE IN A BUILDING
•
•
•
•
•
•
From outside:
traffic
meteorological events
industry
agriculture
Ventilation and cooling
systems on walls and
roofs
show-business (cultural
and social facilities,
sporting equipment)
Zdroj: http://skrt.kam.vutbr.cz/?p=klid
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SOURCES OF NOISE IN A BUILDING
From inside:
• building services
• normal activity of persons in dwelling
• noise from neighbors
http://www.youtube.com/watch?v=hvQfkEXl5_Q&feature=related
Respect your neighborough !!!
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BIGGEST SOURCE OF NOISE
in the CR is ROAD TRANSPORT (over 95%)
Noise mapping showed noise annoyance of almost
300 000 inhabitants of the Czech Republic.
(not mapped the entire country!)
In Prague - 36 schools and 14 health facilities are exposed
to noise levels that exceed the maximum limits for all-day
nuisance (70 dB).
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Velká Británie – zpěvný pták červenka ustoupil konkurenci hluku
velkoměsta !!!
Noise map – Prague Airport
http://hlukovemapy.mzcr.cz/
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Noise map – Prague Airport
• Prague airport annoys by noise
( ˃ Ld =60 dB a Ln = 50 dB)
1600 inhabitants all day
1900 inhabitants in the night
• Airport troubles mostly inhabitants of
Horoměřice (1452 inhabitants)
Jeneč (325 inhabitants)
Kněževes (66 inhabitants)
r. 2008
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NIGHT
Noise map
Praha
Barrandov
http://hlukovemapy.mzcr.cz/
DAY
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Noise Map Praha Barrandov
• From the 22 656 residents living near the street K
Barrandovu is 51.44% permanently (day and night!) hit
by unsafe levels of traffic noise
• In the area of risk there are primary and nursery
schools
ZŠ Slivenec – day 78,5 dB a night 74 dB
MŠ Kurandova na sídlišti Barrandov - day 74,1dB
r.200492
The
alarm
signal
http://www.guardian.co.uk/football/2009/dec
/22/vuvuzela-ownership-row
Hearing =
a warning system
http://health.howstuffworks.com/human
-body/systems/nervous-system/brainpictures.htm
heart rhythm
increase
respiratory rhythm
increase
blood pressure
increase
Increase of
levels of stress
hormones
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STRESS
RESPONSE OF
THE ORGANISM
Increase of
brain activity
THREAT
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-> reverberation time
The time necessary, after switching off
the source, for the sound pressure level
to drop 60 dB.
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-> reverberation time
Sound absorbing
space
Sound reflecting
space
Short reverberation
time
Long reverberation
time
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-> reverberation time: target values
Type of room
Reverberation time
Furnished room
Office space
Landscape office
Classroom
Music room
Theatre
Chamber music hall
Opera
Concerthall
Church (organ music)
T = ca. 0,5 s
T = 0,5 – 0,7 s
T = 0,7 – 0,9 s
T = 0,6 – 0,8 s
T = 0,8 – 1,2 s
T = 0,9 – 1,3 s
T = 1,2 – 1,5 s
T = 1,2 – 1,6 s
T = 1,7 – 2,3 s
T = 1,5 – 2,5 s
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-> reverberation time in seconds
Room volume in m3
T= 1/6 x (V/A)
Total absorption in the room
in m2
The larger the room, the longer the reverberation time!
The more absorbing materials present in the room, the shorter
the reverberation time!
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-> total absorption in m2
Surface area in m2 of the material
A = α1 x S1 + α2 x S2 + α3 x S3 + …
Absorption coefficient of the material 0 < α < 1
totally reflecting
totally absorbing
An open window has an absorption coefficient α equal to 1 (all of the sound will
disappear outside through the open window). If the surface area of the open
window equals 1 m2, then the total absorption of this window is equal to
A = 1 x 1 = 1 m2
98
-> sound absorbing materials
= acoustically ‘soft + open’ materials or perforated materials with
an acoustically ‘soft + open’ material behind the perforations
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-> sound absorbing materials
= acoustically ‘soft + open’ materials or perforated materials with
an acoustically ‘soft + open’ material behind the perforations
[Source: Schallschutz +
Raumakustik in der Praxis –
Planungsbeispiele und konstruktive
Lösungen, W. Fasold / E. Veres,
Verlag für Bauwesen – Berlin, 1998]
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-> calculation of reverberation time
3.0m
3.0m
3.0m
Surface
S [m2]
0<α<1
α x S [m2]
Ceiling
Floor
Window
Door
Walls
9
9
1
2
33
0,79
0,04
0,03
0,08
0,02
7,11
0,36
0,03
0,16
0,66
Total
A [m2]
8,32
A = a1 x S1 + a2 x S2 + a3 x S3+…. [m2]
T= 1/6 x (V/A) = 0,167 x (27/8,32) = 0,54 s
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-> problem:
classroom 15 x 8 x 3 m3, door 2 m2, window 12 m2
target value reverberation time T = 0,7 seconds
Surface
0<α<1
Floor
Window
Door
Walls
0,04
0,03
0,08
0,02
[Source: Schallschutz +
Raumakustik in der Praxis –
Planungsbeispiele und konstruktive
Lösungen, W. Fasold / E. Veres,
Verlag für Bauwesen – Berlin, 1998]
Which absorption coefficient is necessary for the ceiling to achieve
a reverberation time equal to 0,7 seconds?
102
-> solution: T= 1/6 x (V/A)
A = 1/6 x (V/T)
= 0,167 x (360/0,7) = 86 m2
Surface
S [m2]
0<α<1
α x S [m2]
Ceiling
Floor
Window
Door
Walls
120
120
12
2
124
?
0,04
0,03
0,08
0,02
?
4,8
0,36
0,16
2,48
Total
A [m2]
? + 7,8
86 – 7,8 = 78,2 m2
α = A/S = 78,2/120 = 0,65
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-> Regular office room with concrete core activition
target value reverberation time T < 0,8 s
Solution: Add sound absorbing materials to the upper
part of the walls
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-> Landscape office with concrete core activition
target value reverberation time T < 0,5 s (furnished room)
upper part of the walls = not sufficient
Alternative solutions
Ceiling islands or baffles
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-> undesirable echo’s and reflections -> reflectogram!
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Sound insulation between rooms
air-borne
sound insulation
structure-borne
sound insulation
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-> air-borne sound insulation
Sound transmission
-1 direct
-2 flanking
-3 circulation
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-> circulation sound = sound that reaches the destination room
through an adjacent space or room, for example a plenum
Solution? Sound barriers
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-> flanking sound = sound that reaches the destination room
through adjacent constructions
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-> sound leaks, for example with pore seam sealing, through cable
trays, duct transits, etc.
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-> structure-borne sound insulation
• sliding chairs
• walking sounds
• falling objects
•…
Direct <<excitation>>
of the building
Lots of energy injected into
the buidling structure!
FLOOR MASS = UNSUFFICIENT
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-> improving structure-borne sound insulation
floating floors structures!
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-> floating floors structures = very sensitive to construction details on site
- levelling ducts
- border strips
- flexibel layer
- covering foil
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Background noise levels
-> Installation noise = background noise coming from the operation of
all the necessary technical installations in a building such as airconditioning units, elevators, sanitary installations, etc.
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-> technical installations
Energy efficiency / Comfort
Ventilation system (incl. cooling)
Technical installations larger and larger
Project enough technical rooms
Where??
118
-> building design
• Technical rooms not directly adjacent to work or living
spaces
• Installations not on the roof, noise disturbance for the
environment
• Sanitary blocks, elevators, traffic zones not
directly adjacent to work or living spaces
• Installation noise can also be useful for
preserving speech privacy in a landscape office
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-> building design
Office or
living space
Office or Office or
living space living space
Office or Office or Office or
living space living space living space
Office or
living space
Target value background
noise
max. 30 à 35 dB(A)
[Source: Bouwakoestiek, G.
Vermeir, Uitgeverij Acco Leuven,
1999]
Target value background
noise
max. 30 à 35 dB(A)
120
Noise radiation
-> air-conditioning unit on roof top: - 3 dB with doubling of the
distance
Sound power level
Sound pressure
level
80 à 100 dB(A)
40 à 60 dB(A)
30 m
Mesures necessary!! Enclosures, silencers, …
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-> Environmental noise = background noise coming from sound
sources outside such as traffic (cars, trains, airplanes), industry,
bars, etc.
[Source: Bouwakoestiek, G.
Vermeir, Uitgeverij Acco Leuven,
1999]
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-> High environmental noise levels
solutions through building site layout
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solutions through building design
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solutions through facade design
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-> Facade sound insulation = composed sound insulation
126
-> Weak link in facade sound insulation = seam sealing
- ‘deaf’ facade = completely ‘closed’ facade -> windows cannot be
opened -> to be used with high sound pressure levels from
environmental noise
- ventilation through facade
openings not possible
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-> Weak link in facade sound insulation = ventilation openings
- mechanical balanced ventilation system
- ventilation through sound muffled ventilation unit
sound absorbing
material
128
Standards on acoustics
•
•
•
•
•
•
•
EN 12354 Building acoustics: estimation of acoustic performance of
buildings from the performance of elements
EN ISO 14257 Acoustics: measurements and parametric description of
spatial sound distribution curves in workrooms for evaluating acoustical
performance
EN ISO 140 Acoustics. Measurement of sound insulation in buildings and
of building elements
EN ISO 10052 Acoustics: field measurement of airborne and impact
sound insulation and of service equipment noise; survey method
ISO 9921 Ergonomics. Assesment of speech comunication
EN ISO 18233 Acoustics: application of new measurement methods in
building and room acoustics
ISO 6897, ISO 2631-1, ISO 2631-2
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Literature
•
L. CREMER, M. HECKL, E. UNGAR, Structure-Borne Sound, Springer Verlag, 1973
•
L. CREMER, H. MÜLLER, T. SCHULTZ, Principles and Applications of Room
Acoustics, Volume 1, Volume 2, Applied Science Publishers, 1982
L.L. Beranek (ed.), Noise and vibration control, Institute of Noise Control
Engineering, 1988
W. Fasold, H. Winkler, Bau- und raumakustik, Verlag für Bauwesen, VEB, Berlin,
1987
Bluyssen Philomena M.: The Indoor Environment Handbook, How to Make Buildings
Healthy and Comfortable, Earthscan Ltd (United Kingdom), 2009, ISBN-13:
9781844077878
http://educypedia.karadimov.info/electronics/dataaudio.htm
http://www.abqenvironmentalstory.org/city/energy-pollution/s5noise.html
http://www.freewebs.com/soundwaves-/introduction.htm
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130
125 YMCB
55

Room acoustical quality

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