PROCEEDINGS of the23rd International Congress on Acoustics
9 to 13 September 2019 in Aachen, Germany

Requirements for the façade sound insulation
for different types of outdoor noise
Steffen KÖRPER
German Environment Agency, Germany

ABSTRACT
Buildings are exposed to a wide variety of external noise situations. The time course of the sound pressurelevel and the frequency response of external noise can vary greatly between the vicinity of roads comparedto the vicinity of airports or railways.
The sound insulation of facades protect the indoor spaces and the residents against external noise day andnight. The German standard DIN 4109 "Sound insulation in building construction” contains the minimum
requirements for sound insulation for all new buildings in Germany. All requirements are based on a singlenumber-value, the equivalent sound pressure level, without adequate respecting to the particularities of thefrequency response and time structure of a sound source.
The presentation shows the German standard values in building acoustics and the subject of external noise.
The results of measurements of different sound sources will be shown. A new approach and an outlook forfurther possibilities to protect inhabitants appropriately to the noise situation will be discussed.
Keywords: façade sound insulation, building acoustics, outdoor noise

1. INTRODUCTION
In most countries, the façade sound insulation of residential buildings is determined as a functionof the calculated external noise. External noise is calculated using the average traffic d ensity of thenearby roads and railways as a single number value. In most cases annual average traffic volumes areused. Seasonal and daily fluctuations are not taken into account. Level fluctuations or maximum level
during a single vehicle pass by or frequency characteristics are also not considered.
However, since the change of DIN 4109 (1) outside noise levels in the nighttime must be respectedin Germany. This leads on average to an improvement of the façade sound insulation against externalnoise.
1.1 German standard DIN 4109
DIN 4109 "Sound insulation in building construction" (1) includes minimum requirements for thesound insulation for new building construction. In 2016, the standard was reissued. Since then, thestandard consists of 4 parts dealing with various aspects of sound insulation. DIN 4109-1 "Minimumrequirements" and 4109-2 "Computational proofs of compliance" have already been revised andrepublished in 2018.
A major deficit of the old DIN 4109 from 1989 was the inadequate protection in b uildings fromnocturnal noise. Since 2016 the outside noise levels in the nighttime must be taken into account inorder to determine the façade sound insulation of buildings. As a result the requirements slightlyincreased for the majority of the construction projects in Germany.

2. PROTECTION OF INDOOR SPACES AGAINST OUTDOOR NOISE2.1 Indoor sound level and protection level
For the maintenance of the psychomotor efficiency and health undisturbed sleep in sufficientduration is of central importance. Therefore the outdoor noise level must be considered, whenconstructing residential buildings in Germany. The calculation method of the façade sound insulationof DIN 4109 leads to an average indoor noise level of 35 dB during the daytime and 25 dB during thenighttime.

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2.2 Day and night level differences
The level differences between day- and nighttime depend on the fluctuation of the traffic density.
The Data of the noise mapping in Germany consists the calculated day-, evening- and nighttime level
for a large number of streets and railways in Germany. For an assessment of the day and night level
differences a data set of the noise mapping of 5 metropolitan areas in the federal state of Hessen wasevaluated, which covers a total of approximately 1,600 kilometers of road and approximately 750
kilometers of railway. Figure 1 shows the day-night level differences of the roads. The day night-level
differences for railway are shown in figure 2. Both figures are displayed as histogram with theinvestigated length of roads or railway.
500
450
400
350

km

300
highway

250

district road

200

national road150

federal roadmunicipal road

100
50
0
12345678

910

11121314

15

day-night sound level difference [dB]

Figure 1 – Day and night level differences for road traffic
100
90
80
70

km

60
50
railway

40
30
20
100-12 -10 -8 -6 -4 -20246810 12 14 16 18 20 22 24 26 28 30

day-night sound level difference [dB]

Figure 2 – Day and night level differences for rail traffic

3529The investigated day-night level differences strongly depend on the street category. The
investigated highways show a much smaller day-night level difference than roads with usually lesstraffic like district roads or municipal roads.
The investigated railway lines show a much wider range and on average lower day-night level
differences than the examined roads. The day-night level differences of the railway lines are mainlyin the range -8 to 10 dB. On numerous railways, the nighttime period is even louder than the daytime
period. This is mainly caused by the night freight train traffic. Very few of the investigated railway
lines have no or very little rail traffic at night. These railway lines are summarized in Figure 2 with acalculated day-night level difference of 26 dB.

Sound pressure level in dB(A)

2.3 Seasonal and daily level fluctuation
The daily level fluctuation of traffic mainly depends on the street category and with it the task ofthe street in the surrounding street network. The sound level does not only depend on the amount ofvehicles, but as well on the traffic mix of trucks, cars and motorcycles.
For an investigation of a road in the city of Karlsruhe in Germany the daily sound levels had beenmeasured by the State Office for the Environment, Measurements and Nature Conservation of theFederal State of Baden-Württemberg (LUBW) over three years (2). The average sound levels for theweekday are displayed in Figure 3. As Figure 3 shows the measured sound pressure level beside theroad vary during the daytime between 67 and 68 dB(A) in 2018. Average sound pressure levels on
Saturdays and Sundays are lower than the sound pressure levels during the workdays from Monday toFriday, even when the differences are small.

MondayTuesday

Wednesday Thursday

FridaySaturday

SundayFigure 3 – Average Weekday fluctuation of the sound level at Reinhold-Frank-Straßein Karlsruhe (2) - modified
Figure 4 shows the results of the measurements of the LUBW (2) for the fluctuation of sound levels
for the whole year period. Figure 4 shows the Lm,T - the average sound pressure level for the daytime(6 am to 10 pm) - and the LDEN - the average sound pressure level for the 24 h of a whole day, including
day-, evening-, and nighttime.
During summertime the noise level measured beside the roads are slightly lower than during thewintertime. For example in 2018 the LDEN varies between 66 dB(A) and 68 dB(A), while the L DEN
varies between 69 dB(A) and 71 dB(A).

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Sound pressure level in dB(A)Figure 4 – Average yearly fluctuation of the sound level at Reinhold-Frank-Straßein Karlsruhe (2) - modified
2.4 Maximum sound pressure level during a vehicle pass by
The outdoor noise to which buildings a subjected is not an average year-, week- or day sound level.
The outdoor noise underlies fluctuations within every vehicle pass by. Especially trains got in thefocus of public discussion in Germany and a study of the Hessian Ministry of the Environment,
Climate Protection, Agriculture and Consumer Protection (3) shows that fluctuating sound pressurelevel can lead to interruption of sleep and impair sleep quality. The indoor noise level can become
sleep disturbing, especially when the façade sound insulation is determined to an average soundpressure level.
One way to describe the fluctuation of sounds is the comparison between the maximum sound level
and the average sound level during a measurement period. The difference between maximum leveland average level only depend on the sound source, but as well on the dista nce to the source. In
Germany exist a large number of railway noise measurement stations. As an example in table 1 themeasurement results of a measurement station based in the Hessian city Assmannshausen in theMiddle Rhine Valley from 2018 (4) is shown. The measurement station is placed very close to thetrack in about 7 m distance. Data was provided by the Hessian Agency for Nature Conservation,Environment and Geology (HLNUG).
Table 1 – Average and maximum railway sound levels of the measurement station in Assmannshausen (4)DayNight

MonthLAeq

LAF,max

LAeq

LAF,max

Jun 1871,998,874,699,3Jul 18

72,099,074,498,7

Aug 18*71,699,174,299,6Sep 18

72,099,674,399,5

Oct 1872,299,774,299,1Nov 18

71,599,572,798,2Dec 18

70,398,972,397,73531

2.5 Frequency response
Beside the differences in time structure the frequency response of outdoor noise can vary widely.
In conjunction with the frequency spectrum of façade components, as windows, the indoor level canbe influenced because of the frequency signature of different sound sources.
The German standard DIN 4109 includes a 5 dB reduction to railway noise because railway traffic
consists less low frequency noise than road traffic noise. In the last few years in Germany several
investigations dealt with the topic of "spectrum corrections" and "spectrum adjustment values" (e .g.
Schedl (5), Leupoldt (6) and Fischer (7)). Additionally the German standard VDI 2719 “Sound
insulation of windows and their auxiliary facilities” of 1987 (8) contains spectrum adjustment values
for façade sound insulation. The VDI 2719 shall be revised soon.
Schedl (5) investigated the spectral properties of more than 1,000 windows and summarized andcategorized their frequency-related noise reduction measures. Leupoldt (6) determined the pass-by
spectrum of about 500 trains at 9 locations and evaluated 140 overflights. Fischer (7) determined thespectrum of various road traffic situations at 8 measuring locations with approximately 60 20-minutemeasurements each. The results are summarized in Table 2 and divided according to the categories ofVDI 2719 (8).
Table 2 – K-values and spectrum adjustment values comparison between VDI 2719 (8) and Fischer (7)VDI 2719
KImmission points near…

Fischertyp ofaveragemaximum

window(rounded)

value

in dB

in dB

0

2,5

single4

6box type

68,5

single12box type

2

3

7

11,3

in dB
railway lines with predominantPassenger transport0other railway lines

3

inner-city roads

6other roads

3airports

6

singlebox type
singlebox typesinglebox type

The comparison of the K-values for railway lines (all) and inner-city roads show, that there is adifference on average for single and box type windows of approximately 5 dB.
Other roads have only about 1 dB difference compared to rail lines. There is thus a difference ofapproximately 4 dB between inner-city roads and other roads. The reason given by Fischer is inparticular the faster out-of-town speeds, which lead to a low proportion of low-frequency noise in theoverall noise.
According to the results of Leupoldt, the spectral differences between freight traffic and passenger
traffic are low on average. Routes with a train mix of freight and passenger traffic can thus be
combined with routes with predominat passenger traffic.

3. CONCLUSIONSThe committee of the DIN 4109 has set up a working group, which deals intensively with thequestions around the topic outdoor noise. The main task is the development of the existing regulations
on façade sound insulation. Outdoor noise underlies a wide variation. Depending of the sources,3532

distances or obstacles in the transmission path, the time and frequency structure of the outdoor noise
influences the indoor noise.
In first investigations the night and daytime sound level differences could be determina ted fordifferent road types and trains. They show that the day-nighttime level differences often stay below
10 dB. With the goal of an average indoor sound pressure level of 35 dB daytime and 25 dB nighttime
it is important to consider the night time noise levels to determine the necessary façade soundinsulation.
A three year continuous measurement of road traffic noise of the LUBW (2) show that the daily,
weekly and yearly fluctuations of noise have a negligible impact on the outdoor noise sound pressurelevel. The average fluctuation of the investigated sound level stays under 1 to 2 dB so the yearly
average traffic intensity seems to be a good predictor for the calculation of outdoor noise soundpressure levels.
Measurements of railway noise of the HLUNG (4) show that the maximum sound pressure level
and the equivalent average sound pressure level deviate largely in the vicinity of railway tracks.
The investigations by Schedl (5), Leupoldt (6) and Fischer (7) show that traffic noise can be much
more differentiated in the determination of spectrum correction terms than currently specified in DIN
4109 or in VDI 2719. The consideration of a 5 dB correction sum due to the spectral composition ofrail traffic is on average justified on the basis of the available studies on spectral characteristics oftraffic noise sources in Germany.
However, this general consideration leads to a strong under- and over-dimensioning in theconstruction practice, because it is a strong simplification and summary of the actual spectral
properties of the traffic noise and the sound insulation of the exterior components . A more detailed
model could effectively reduce the under- or over-dimensioning of the sound insulation of the externalfaçade.
Further research on the spectral and time related properties of various external noise situations isnecessary as well as further investigations on the maximum sound pressure level.

ACKNOWLEDGEMENTS
The data used for the comparison of the day and night level differences come from the noise
mapping "Plus" of the HLNUG. The data were provided kindly by the Hessian State Office for Nature
Conservation, Environment and Geology (HLNUG) and the Federal Railway Office (EBA )REFERENCES
1. Deutsches Institut für Normung, DIN 4109:2018-01, Schallschutz im Hochbau - Teil 1 bis 4 Berlin:Beuth-Verlag, Januar 2018.
2. Ministerium für Verkehr Baden-Württemberg, Landesanstalt für Umwelt Baden-Württemberg (LUBW):
Messung von Straßenverkehrslärm 2018, Messergebnisse für die stationären Verkehrslärm-Messstationen
Karlsruhe Reinhold-Frank-Straße und Reutlingen Lederstraße-Ost. April 2019.
3. Hessisches Ministerium für Umwelt, Klimaschutz, Landwirtschaft und Verbraucherschutz: Gutachten zur
Berücksichtigung eines Maximalpegelkriteriums bei der Beurteilung von Schienenverkehrslärm in derNacht, durchgeführt von: Möhler + Partner Ingenieure AG, ZEUS GmbH, Deutsches Zentrum für Luftund Raumfahrt e.V. Oktober 2017.
4. Hessisches Landesamt für Naturschutz Umwelt und Geologie (HLNUG): Messbericht über die
Geräuschmessung in Assmannshausen an der Bahntrasse im Mittelrheintal (2018)
5. Schedl K. et al.: Untersuchung des Bemessungsansatzes der VDI 2719 für den Schallschutz von Fenstern
unter Berücksichtigung unterschiedlicher Außenlärmspektren, Berlin, Bauphysik 39 (2017), Heft 4.
6. Leupoldt P. et al.: Untersuchung des Bemessungsansatzes der VDI 2719 für den Schallschutz vonFenstern unter Berücksichtigung aktueller Außenlärmspektren des Bahn- und Fluglärms, Berlin,Bauphysik 39 (2017), Heft 5.
7. Fischer I. et al.: Ermittlung und Vergleich von Straßenverkehrslärmspektren – Zur Überprüfung derKorrektursummanden der VDI 2719 hinsichtlich des Schallschutzes von Fenstern, TU München,
15.11.2018.
8. Verein Deutscher Ingenieure, VDI 2719:1987-08, Schalldämmung von Fenstern und deren Zusatzeinrichtungen. Berlin: Beuth-Verlag, August 1987.

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