Download - The Sound of Silence - BECOR · 2011-02-01 · 1-800-838-8183 BECOR Brag Session …Problem Solved. December 8, 2009 The Problem The easy bit: •The owners of a 13 storey, 1970s

1-800-838-8183BECOR Brag Session

December 8, 2009…Problem Solved.

The Sound of SilenceSolving Noise Problems with Windows

(Apologies to Theodore Geisel and Chuck Jones)

George TorokNational Capital Region Manager

& Technical Specialist

BUILDING CONSULTANTS INC.

Building Science SpecialistsContract AdministratorsReserve Fund PlannersConsulting Engineers

Newmarket 1-800-838-8183 Ottawa



The Problem

The easy bit:•The owners of a 13 storey, 1970svintage apartment building wanted to replace windows to address convenience, comfort and aestheticissues, justified by reduced energy bills.



The Problem

The tricky bit:•The building was located next to a busy commuter and regional train station.

•The train line was also used frequently by freight trains.

•Nearby was a level crossing.



The Problem

The hidden trap:•noise,



The Problem

The hidden trap:•noise, noise,



The Problem

The hidden trap:•noise, noise, NOISE!



The Problem

The hidden trap:•noise, noise, NOISE!•Typical resident response: “You get used to it.”



The Problem

Why it’s a trap:•Existing windows were typical 1970s vintage high-rise type, fixed-over-slider:• Thermally broken, open-back, 4 ½ in. aluminum frame.• Fixed glazed section consisted of fixed exterior pane and

removable interior sash, about 3 in. between, no weatherstrip, cavity drains to sliding section below.

• Operable section consisted of double-run of single-glazed sashes, 3 – 4 in. cavity between, drained to exterior, worn pile weatherstrip.



The ProblemRemovable inner sash panel

Fixed outer sash panel ~ 3 in.



The Problem

Why it’s a trap:•Typical new replacement windows have similar frame, layout and sliding sash arrangement, but:• Fixed glazing consists of sealed, double glazed, insulating

glass units with 1/2 in. wide cavity.• Reduction of cavity width from 3 in. to 1/2 in. would

increase sound transmission (reduce transmission loss), causing more train noise to enter the apartments.

• A “typical” off-the-shelf replacement window would degrade acoustical performance!



Soun

d Tr

ansm

issi

on L

oss (

dB)

60

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40

30

20

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0 125 250 500 1,000 2,000 4,000 8,000Frequency (Hz)

The ProblemBest Guess for Existing Condition:• both panes 4.76 mm glass,• 100 mm unsealed air filled cavity.

Female voice range

Male voice range

Train noise range



Soun

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dB)

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0 125 250 500 1,000 2,000 4,000 8,000Frequency (Hz)


The Usual Solution:• both panes 3 mm glass,• 13mm sealed air-filled cavity.



Soun

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dB)

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0 125 250 500 1,000 2,000 4,000 8,000Frequency (Hz)



Train noise, human voice, and weak acoustic performance of glass coincide.



Other Problems

What we couldn’t do:•Change the configurationof the windows:• 13 mm cavity width for

insulating glass units desirable for optimum thermal performance.

• 22 mm typical overall insulating glass unit thickness to suit available frames (typical for GTA high-rise at the time).

• Retain double-run of single-glazed sashes for operable portion (too costly to change to hinged vent).



Other Problems

What we could do:•Maintain or improve acousticperformance of sliding sashes:• Air gap between sashes spaced

about the same as existing to maintain existing acoustic performance.

• Specify high level of air leakage resistance (A3) to improve acoustic performance, at least in the short term(an air leak is a sound leak).



Other Problems

What we could do:•Maintain or improve acoustic performance of insulating glassunits, but:• Sound transmission loss data not available for 4 mm thick

glass required for wind load resistance (CGSB-12.20).• Use available data (IGMA, NRCC, etc.) and interpolate:

• for 3 mm and 6 mm thick glass.• for monolithic and laminated glass. • for various types of windows.



Principles

At very low frequencies:•Sound transmission through glass is controlled by the shape (aspect ratio) of glass, which affects its flexibility (stiffness).

•Control by:• Change window shape.• Increase glass thickness (makes glass stiffer when size

is not changed).



Principles

At low frequencies:•Parallel glass panes, separated by an air space, will vibrate together and transmit some sounds very efficiently (‘mass-spring-mass resonance’).

•Control by:• Change the stiffness of the spring between the panes

(width of the cavity).• Change the vibration frequency of one pane of glass

(use one pane at least 30% thinner than the other and/or one pane of laminated glass).



Principles

At middle and through high frequencies:•Sound transmission is controlled by the weight (mass) of glass.

•Control by:• Increase weight (thickness) of the glass.



Principles

At high frequencies:•Vibration of the air (sound) parallel to glass surfaces, matches the vibration pattern in the glass, transmitting sound very efficiently (‘coincidence dip’).

•Control by:• Use double glazing to introduce a “spring” (cavity)

to absorb vibration energy.• Make one pane of glass at least 30% thinner so that

vibrations are not synchronized and thus, sound transfer is less efficient.



Frequency (Hz)

Soun

d R

educ

tion

Inde

x(I

ncid

ent /

Tra

nsm

itted

, dB

)

ResonanceControlled

Mass ControlledStiffnessControlled

CoincidenceControlled

“CoincidenceDip”

Increase mass(thickness)

Increase damping

Increasedamping

Increasestiffness

(thickness)

Sound Reduction by Windows – Fixed GlazingFrom “Measurements in Building Acoustics” by Bruel & Kjaer, January 1988

Damping Methods:• Double glazing• Unequal pane thickness• Laminated glass• Change cavity width

Principles



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0 125 250 500 1,000 2,000 4,000 8,000Frequency (Hz)

The Usual Solution


Best Guess for Existing Condition:• both panes 4.76 mm glass,• 100 mm unsealed air filled cavity.

Female voice range

Male voice range

Train noise range



Soun

d Tr

ansm

issi

on L

oss (

dB)

60

50

40

30

20

0

0 125 250 500 1,000 2,000 4,000 8,000Frequency (Hz)


ResonanceControlled





Increase damping

Increasedamping

Increasestiffness

(thickness)


ResonanceControlled





Increase damping

Increasedamping

Increasestiffness

(thickness)




Soun

d Tr

ansm

issi

on L

oss (

dB)

60

50

40

30

20

0

0 125 250 500 1,000 2,000 4,000 8,000Frequency (Hz)0 125 250 500 1,000 2,000 4,000 8,000


ResonanceControlled





Increase damping

Increasedamping

Increasestiffness

(thickness)


ResonanceControlled





Increase damping

Increasedamping

Increasestiffness

(thickness)


Train noise, human voice, and weak acoustic performance of glass coincide.



Soun

d Tr

ansm

issi

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dB)

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0 125 250 500 1,000 2,000 4,000 8,000Frequency (Hz)

A Better Solution

One Step Better (correct depth):one pane 3 mm glass,• 13mm sealed air-filled cavity,• one pane 6 mm glass.




Soun

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ansm

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oss (

dB)

60

50

40

30

20

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0 125 250 500 1,000 2,000 4,000 8,000Frequency (Hz)0 125 250 500 1,000 2,000 4,000 8,000

ResonanceControlled





Increase damping

Increasedamping

Increasestiffness

(thickness)


ResonanceControlled





Increase damping

Increasedamping

Increasestiffness

(thickness)






Soun

d Tr

ansm

issi

on L

oss (

dB)

60

50

40

30

20

0

0 125 250 500 1,000 2,000 4,000 8,000Frequency (Hz)

ResonanceControlled





Increase damping

Increasedamping

Increasestiffness

(thickness)


ResonanceControlled





Increase damping

Increasedamping

Increasestiffness

(thickness)


Better noise isolation except at very low and high frequencies.





Soun

d Tr

ansm

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dB)

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0 125 250 500 1,000 2,000 4,000 8,000Frequency (Hz)

An even Better SolutionTwo steps better (but too thick):• one pane 6 mm monolithic glass,• 13 mm unsealed air filled cavity,• one pane 6 mm laminated glass.





Soun

d Tr

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dB)

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0 125 250 500 1,000 2,000 4,000 8,000Frequency (Hz)

Two steps better (but too thick):• one pane 6 mm monolithic glass,• 13 mm unsealed air filled cavity,• one pane 6 mm laminated glass.


R e so n a n c eC o n tr o lle d

M a ss C o n tr o lle dS tiffn e ssC o n tr o lled

C o in c id e n c eC o n tr o lle d

“ C o in c id e n c eD ip ”

In c re a se m a ss( th ic k n e ss )

In c re a se d a m p in g

In c re a sed a m p in g

In c re a ses tif fn ess

( th ic k n e ss )

D a m p in g M e th o d s :• D o u b le g la z in g• U n e q u a l p a n e th ic k n e ss• L a m in a te d g la ss• C h an g e c a v ity w id th









( th ic k n e ss )





Soun

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dB)

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0 125 250 500 1,000 2,000 4,000 8,000Frequency (Hz)

Two steps better (but too thick):• one pane 6 mm monolithic glass,• 13 mm unsealed air filled cavity,• one pane 6 mm laminated glass.










( th ic k n e ss )










( th ic k n e ss )


Much better noise isolation except at very high frequencies.




Soun

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The GRG Solution

The GRG Solution (compromise):• one pane 4mm glass• 13 mm sealed, argon filled cavity• one pane 6 mm laminated glass.

Best Guess for Existing Condition:• both panes 4.76 mm glass,• 100 mm unsealed air filled cavity.


Expected range of compromise similar to estimated original performance (likely lower than blue line).



What did the Client Hear?

Less is more:•Residents in mock-up apartments reported a decrease in train noise.

•General installation proceeded with modified windows.

•As project proceeded, other residents also reported reduced train noise levels.



Questions?1-800-838-8183…Problem Solved.

BECOR Brag SessionDecember 8, 2009



The Sound of SilenceSolving Noise Problems with Windows

George TorokNational Capital Region Manager

& Technical Specialist

BUILDING CONSULTANTS INC.

Building Science SpecialistsContract AdministratorsReserve Fund PlannersConsulting Engineers

Newmarket 1-800-838-8183 Ottawa

Download - The Sound of Silence - BECOR · 2011-02-01 · 1-800-838-8183 BECOR Brag Session …Problem Solved. December 8, 2009 The Problem The easy bit: •The owners of a 13 storey, 1970s

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