Säker på Osäkerhet i Byggakustik
NAS årsmöte
Trondheim
2013-10-25
Christian Simmons
Simmons akustik & utveckling ab, Chalmers Teknikpark, SE-412 88 Göteborg
Telefon/Mobil: +46 (0) 31 27 66 00 [email protected] www.simmons.se
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f
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Säker på Osäkerhet
NAS Trondheim 25 okt 2013
Christian Simmons
Expectations !
•
•
•
High demands for sound
insulation
Lifestyle, expectations
Need for quitness
•
Costs vs. Performance 
•
Safety margins based on
statistical considerations
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Sound requirements for residential houses are based on
performance (dimensions). Unique designs…difficult…
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Who takes the responsibility for the sound properties of the building?
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
The EN 12354 standards convert element data into building
performance  requirements
NS 8175
ISO 16283
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Safety: Which element data are reliable?
3 types of data source may be considered:
•
A. “Laboratory measurements” –
they only reflect the real performance of
- 1 sample product in
- 1 sample laboratory
- under idealized circumstances
- are feasible for small elements
(windows, doors, air inlets etc)
•
To be useful (reliable) for complex
elements, there must be
- a series of tests,
- under non-idealized conditions,
- performed in several laboratories
•
At least, apply margins from round robin
tests of reproducibilities

NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
New products – laboratory data variations
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Missing data for old or generic constructions:
”tune” calculated input data to the best fit
1.
2.
3.
4.
5.
6.
Take lab data of similar
constructions, (2-3 labs)
Calculate the sound insulation
for each case
Compare calc-lab data
Average & Std Dev 
empirical correction
Calculate the real
constructions and add these
corrections
Compare to field data
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Luleå-bjälklaget (timber joist floors constructed in situ)
Results from 170 field measurements in similar 2-storey houses, floating floor & susp. ceiling
….BASTIAN database has 3 series of timber floors meas in lab, 3 dB ”penalty” added
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
3.15kHz
2.5kHz
2kHz
1.6kHz
1.25kHz
1kHz
800Hz
630Hz
500Hz
400Hz
315Hz
250Hz
200Hz
160Hz
125Hz
100Hz
70
65
60
55
50
45
40
35
30
25
20
Ii dB
dB
170 timber floors
Simmons akustik & utveckling
Room acoustics affect quality of life (not just a comfort aspect)
BBR 2006 - Boverkets handbok
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Ljuddagen 2008
: 2007221
/ 2008-11-20
© 2008 S.A.U.
Simmons akustik & utveckling
Sound absorption, round robin
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
…so, are there better sources of input data for walls, floors?
•
B. “Field measurements” (in situ, in the building or in the field) –
– performance of an assembly of elements, under realistic but unknown
circumstances
– the Robust Details system in the UK quires 30 field measurements to
document a ”construction”, i.e. an element
– Large random errors but small systematic errors, i.e. chaotic data sets
result from field data if they are not ”normalized” to reflect performance of
the element only
•
C. “Theoretical calculations” –
– estimates the performance of an element with assumed properties,
its accuracy being limited by the theoretical model and underlying
assumptions
– logical, structured data follows (low random error, possibly high systematic
error)
– Suitable for old, generic constructions (without manufacturers support)
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Learn from field meas’s
only – is not practical
•
•
•
•
•
4 buildings of ”same”
construction:
Airborne insulation
of HC floor + parquet
Different consultants
made the measurements
Floor direct transmission
dominated
Good agreement
with calculations on the
average, but individual
variations because of
unforeseen effects of
workmanship and meas
errors
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
…so, are there better sources of input data for walls, floors?
•
B. “Field measurements” (in situ, in the building or in the field) –
– performance of an assembly of elements, under realistic but unknown
circumstances
– the Robust Details system in the UK quires 30 field measurements to
document a ”construction”, i.e. an element
– Large random errors but small systematic errors, i.e. chaotic data sets
result from field data if they are not ”normalized” to reflect performance of
the element only
•
C. “Theoretical calculations” –
– estimates the performance of an element with assumed properties,
its accuracy being limited by the theoretical model and underlying
assumptions
– logical, structured data follows (low random error, possibly high systematic
error)
– Suitable for old, generic constructions (without manufacturers support)
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Use exact tools? FEM-tools validated vs analytical methods
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Simmons akustik & utveckling
Vibration reduction at junctions by FEM analyses
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Different boundary conditions, but…
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Which model for the
vibration reduction index ?
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Ex 1: with random differences only between the
calculated – measured sound insulation
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Ex 2: systematic and random differences
calculated – measured sound insulation
Needtoincreasemarginby1dB
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Si
m
mo
ns
Student’s t-distr, k-factors
single sided conf.interval
23
Simmons akustik & utveckling
Uncertainty of field measurements (only)
•
Situation B in ISO/WD 140-2:2009,
(c.f. ISO/FDIS 12999-1:2013)
– same test objects and test rooms, but
– different operators, routines and equipments
•
aimed to test reproducibility of measurement methods under field conditions
(rather than the properties of a test object)
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Differences calculated – measured insulations
•
•
•
Field cases collected (not perfectly documentedassumptions)
Both random and systematic influences discussed …
Results appear reasonably like other authors results…more data
3 dB margin – EN 12354 is acceptable (heavy floors)
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Reverberation times
in classrooms
•
44 classrooms, calc’s compared to
field meas’s
•
23 ”simple” rooms, i.e. diffusing
furnitures etc.
•
0,2/0,1 s agreed tolerances
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Uncertainty budget helps focus improvements
•
•
Ruff/Fischer, Hall and others..measured Ri, Rj, Kij and η
Example from Wittstock, uncertainty of each parameter estimated & added to
global uncertainty of a calculation
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Design goals & tolerances:
– uncertainties ”built-in” the SS 25267/68
•
Results of field measurements must meet each type of requirement on the
average within each dwelling.
•
The maximum unfavourable deviations from the requirements
– 1 dB for the single weighted numbers of sound reduction (ISO 717, 100-3150
Hz)
– 2 dB when spectrum adaptation terms for low frequencies (50-3150 Hz) are
included
– 2 dB for service equipment sound pressure levels in third octave bands 31-200
Hz.
– 0,1 second for the reverberation time in octave bands 250-4000 Hz,
0,2 s in the 125 Hz octave band
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
A procedure to find input data & margins that suit consultants:
compare calculations with field data, systematically
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Simmons akustik & utveckling
I analyzed impact data of
40 well documented field cases
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Simmons akustik & utveckling
Idea: combine all sources !
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
New methods for sound pressure level measurements at low
frequencies
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Systematic deviations from true room average
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Simmons akustik & utveckling
Random deviations 24 measurement methods
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Simmons akustik & utveckling
prEN ISO 16283-1
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Simmons akustik & utveckling
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
prEN ISO 16283-1 test in a furnished living room 25 m2
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
prEN ISO 16283-1 test in a furnished living room 25 m2
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Practical considerations
•
Some practical problems with moving microphone
techniques (manual scanning) emerged during the
measurements.
• It is difficult to fit wide circles of various shapes into
the narrow spaces typical for small and densely
furnished rooms.
• If parts of the microphone path come close, the
result approximates one single fixed position taken
in this part of the room and obtains an unknown
weigt in the average.
• The manual moving microphone methods were
somewhat prone to causing noise from body and
clothes, which may cause errors in the receiving
room if the loudspeaker sound level is not high
enough.
• The fixed positions method was easier to perform
than anticipated, where the operator may pay
attention to the data acqusition, S/N etc instead of
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
focus on the mic movement
Questionnaire vs Measurements
Annoyance - Impact Sound
8
6
4
2
0
51
54
57
60
63
Lnw+CI,AkuLite,20-2500
66
69
Applied Acoustics: Correlation between sound insulation and occupants’ perception
– Proposal of alternative single number rating of impact sound
Fredrik Ljunggren1 Christian Simmons2 Klas Hagberg3
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Simmons akustik & utveckling
Structure borne
sounds
En
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Simmons akustik & utveckling
Structure borne sound from service equipmentsubstitution method (force sources) – round robin
Need to make complementary analyses, e.g. point
mobilites of source and floor,
statistics of each machine case etc…
Ynormal
NAS Årsmöte 2013-10-25 Trondheim Säker på Osäkerhet
Ylow
Yhigh
Unbalance
weight 1,5 kg
Simmons akustik & utveckling
Average – 1 StdDev
Test object – TM vibration level difference, dB
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Simmons akustik & utveckling