Sound
& Noise Reduction
Please - Bear With Us - this Section is necessarily
lengthy - Good Noise Insulation is a complicated subject - even for us!
If you would prefer to have a chat with someone, feel free to give us a call.
For Quick Navigation of this section
We
live in an increasingly Noisy Society.
Not only in the Major Cities,
but across the Country in Towns & Villages everywhere - Intrusive, Irritating,
Stressful and Sleep Disturbing - Noise is coming at us from All Directions.
Road Noise from Cars & Motorbikes, Buses, Lorries & Taxis - Railway Station
& Train Noise - Aircraft & Airport Noise - Pubs, Clubs & Discos - Ambulance, Police
& Fire Engine Sirens - People Shouting & Talking Loudly in the streets at All
Hours - Car & Burglar Alarms - Dogs Barking - Noisy Neighbours.
The
List is Endless & Seems to be Growing Longer by The Day.
For many people,
a Good Nights' Sleep is a Thing of The Past & the Simple Pleasure of a Quiet Evening
At Home no Longer Exists.
Why Secondary
Glazing?
The Majority of Intrusive Noise enters a building through
its' Most Vulnerable Point - the Windows & Doors.
Effective Noise Insulation
is achieved by creating an Additional Barrier - a Second Layer of Glass.
However, Noise is not So Easily Defeated!
Other Factors play a
Significant Part in Effectively Eliminating or Reducing Noise To a Tolerable Level:
Secondary
Glazing, despite what your friendly neighbourhood Double Glazing Representative
may tell you, is by far & away the Most Effective Solution for Combating Noise,
for the following reasons: The gap between
the two layers of glass when installing Secondary Glazing inside the Existing
Window is always greater than when fitting Sealed Unit Replacement Double Glazing
- and the gap plays a crucial part in effective Noise Reduction - for 4mm Glass
each increase in the gap of 25mm (1 inch) approximates to an increase in Noise
Insulation of 0.75dB Rw - for 6mm Glass each increase in the gap of 25mm (1 inch)
approximates to an increase in Noise Insulation of 1.25dB Rw (See explanation
in the next section for dB Rw)
It
is important to Correctly Specify the Glass - in general, the thicker the better
- but it is also relevant, dependant upon the Type and Frequency of the Noise,
to use Different Thicknesses of Glass for the two layers of glazing in order to
tackle Acoustic Resonance which results in Vibration - nobody wants to cut out
the Noise of a Passing Lorry only to have to Listen to the Glass Vibrating! Laminating
either one of the Glass Layers further reduces Sound Transmission.
Both the Glass & the Framing are Helping to Control the Noise - if a Solid Timber
Framed Window is removed & Replaced with a Hollow Framed PVC-U Replacement Window,
the New Frame will be a Less Effective Barrier - so you end up Gaining a Bit by
having the Sealed Unit and Losing a Bit because of the Less Effective Frame.
Government (or other similar work such as Airport Sound Insulation Schemes) Funded
Noise Insulation work around New Roads, etc, is always Secondary Glazing, never
Replacement Windows.
A large proportion
of our work involves fitting Secondary Glazing inside Replacement Sealed Unit
Double Glazing.
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The Facts & Figures
- An Explanation of Noise & Its' Measurement - With Sources & Links
-
What is noise? Noise is 'sound which is undesired
by the recipient'. In other words noise can be any sound that intrudes or disturbs
or annoys.
-
How is it measured?
- Sound levels are measured in decibels (dB) However, the human ear is
not equally sensitive to all frequencies or types of sound.
-
A-Weighting [dB(A)] - An electronic filter that approximates
the frequency response of the human ear. A-weighting is used to measure average
noise levels. A-weighting is usually referred to simply as dB.
-
Rw Weighted Sound Reduction Index - R-values are measured
in tests of octave or 1/3rd octave bands. The resultant curve is adjusted so that
any shortfall of the actual measurements below the standard curve, averaged over
all the octave or 1/3 octave bands, is not greater than 2dB. The resultant value
of the curve at 500Hz is the Rw. General Sound Reduction is expressed as
dB Rw General Rated Reduction [Rw].
-
dB
Rt - Measurement used for the Interior Noise Levels coming from Outside Typical
Road Traffic Noise in City & Town Centres. Rtra (Reduction of road traffic
noise) is expressed as dB Rt. This is an Index used for measuring a
windows' specific performance in Reducing Road Traffic Noise from Outside.
-
The three-decibel rule The decibel is a logarithmic
measurement; sound intensity doubles with every 3 dB increase. Thus sounds
at 88 dB are actually twice as intense as they are at 85 dB and 115 dB
is 1000 times as intense as 85 dB. Conversely, a 3 dB decrease in sound
intensity represents a halving of the noise.
-
An
average single glazed window - Achieves around a 25 dB Rw Noise Reduction
over & above just having a hole in the wall!
-
dB
Rw & dB Rt - Are always expressed as the Combined Noise Reduction of
the Glazing System - so a typical single glazed Primary Window + standard Secondary
Glazing = a Combined Noise Reduction of 37 dB Rw.
-
A comfortable (inside) sound level is around 35dB in daytime and
30dB at night.
Information
from ENCAMS - an Environmental Charity
Best Known for their Keep Britain Tidy Campaign, which has been running for over
50 years. ENCAMS also Campaign on issues such as graffiti, fly posting,
abandoned vehicles and gum dropping. They are partly grant funded by the Government
through DEFRA (the Department for Environment, Food & Rural Affairs) so are also
asked to campaign on or develop ways of tackling problems such as dog fouling,
fly-tipping and nuisance noise. ENCAMS also work very closely with the
Home Office & DCLG (the Department for Communities & Local Government) to address
these issues and other types of anti-social behaviour. http://www.morton-hanthorpe.org.uk/PDF/noise_sq.pdf
Neighbour Noise - A Guide for the Public - Includes Useful Information
on Problem Resolution, Associated Government Agencies & Environmental Groups &
Information for Scotland, Wales & Northern Ireland http://www.encams.org/aboutus/index.asp
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The Solution
At
Granada we have been dealing with both Residential & Commercial Noise Reduction
for many years & it is the fastest increasing sector of our business.
Standard
Secondary Glazing primarily designed for Thermal Insulation will as standard give
Excellent Noise Insulation.
To put this into perspective,
A Granada Secondary Glazing Unit with 4mm Low E Glass and 85mm cavity inside a
putty glazed timber window with a single pane of 4mm Float Glass achieves a 37
dB Rw General weighted reduction & a 31 dB Rt Traffic Noise Reduction.
A Granada Secondary Glazing Unit with 6mm Float Glass, a 150mm cavity and fitted
inside a 4mm single glazed primary window achieves a 45 dB Rw General weighted
reduction.
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Page
See Test Reports
http://www.1st-4-secondary-double-glazing.co.uk/test_certificates.html
Things have now moved on even further at Granada since we started Importing Stadip
Silence ® laminated glass from Saint-Gobain Glass in France.
This Exceptional
Glass has been developed Specifically for Noise Reduction.
Using this glass
we are able to achieve in the region of a 48 dB Rw Noise Reduction with a 150mm
cavity & a 45 dB Rw Noise Reduction with a smaller, 75mm cavity.
This means
that we can now carry out Noise Reduction Installations that are both More Effective
and much more Aesthetically Pleasing.
Test
Report
Currently awaiting test report
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Ventilation
When opening Primary & Secondary Windows for Ventilation ensure that you open
them in the staggered position, i.e., if the Left Hand side of a Casement Window
is opened, then open the Right Hand side of the Secondary Unit - this will improve
Sound Reduction by 15 - 25 dB Rw depending upon the Noise Source/s, window size
& exact configuration.
http://www.teachernet.gov.uk/_doc/4075/Section%203%20-%20Sound%20Insulation.pdf
(Pages 4 & 5)
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Road,
Rail & Aircraft/Airport Noise
Our Secondary Glazing Systems are effective
for all types of noise. However, applications differ slightly & other factors
also play a part: -
Road & Rail Noise -
It is important to use an Asymmetrical Glazing System, i.e., 1 pane of 4mm glass
coupled with 1 pane of 6mm glass - this is effective in Reducing the Resonance
& Vibration caused by the Lower Frequencies produced by Diesel Engines & Trains.
-
Aircraft & Airport Noise - The same Principles apply
but dependant upon the Direction & Altitude that the Noise is coming from you
should also consider Improving Your Loft Insulation.
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News
16/05/2008
People
in 23 urban areas can now see a snapshot of noise levels in their neighbourhoods.
A new Defra (Department for Environment, Food & Rural Affairs) website launched
today, provides maps showing the level of environmental noise from major industries,
road and rail networks & airports in 23 urban areas in England. The information,
covering 80,000 km of roads within urban areas, 28,000 km of major road networks,
major airports and almost 5,000 km of railways, will be used to draw up action
plans to reduce unreasonable levels of noise, where practical. In urban areas
these will also include measures to protect designated quiet areas.
Users
are able to search by postcode to access maps that show noise levels over an average
24 hour period, as well as during night time hours only. The site also includes
information on the number of people exposed to these levels of noise. All member
states have to produce maps under the EU Environmental Noise Directive.
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Useful
Links
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