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

New Finnish building acoustic regulation
Mikko KYLLIÄINEN1; Ari SAARINEN212

Tampere University, Finland

Ministry of the Environment, Finland

ABSTRACT
New building acoustic regulation and related guidelines took eﬀect in Finland recently. The statutes include
provisions concerning sound insulation, noise and vibration abatement and acoustic conditions necessary forthe construction of a new building, repair and alteration of a building and the changing of the intended use ofa building. The essential technical characteristics enacted concern health and wellbeing in the mannerrequired by the intended use of the building. The purpose of the guidelines is to clarify and facilitate
compliance with the requirements as the statute directs. The guidelines provide instructions on theprocedures for design and veriﬁcation. The statutes apply to buildings with dwellings or accommodation orpatient rooms, facilities for teaching, meeting, eating, treatment, recreation or physical exercise, or oﬃce
spaces.
Keywords: sound insulation, noise control, room acoustics

1. INTRODUCTIONIn Finland, guidelines and recommendations for acoustics of different buildings has existed since
the year 1955. The first guidelines revised in 1960 and 1967 were not official, even though building
inspectors usually required them to be followed. Regulation came into effect when The National
Building Code of Finland was first published in 1975. One part of the Building Code concerned
acoustics of buildings. This part was the revised in 1985 and 1998 (1).
New building acoustic regulation and related guidelines took eﬀect in Finland recently. In the endof the year 2017, the regulation was revised as the Decree of the Ministry of the Environment on theAcoustic Environment of Buildings was given (2). The decree came into force in the beginning of theyear 2018. The purpose of this paper is to describe the main revisions of the new regulation.
The revision of the regulation was preceded by extensive scientific research and evaluation of thecost and other effects of suggested changes in the regulation (3–4). The scientific studies were carriedout as a research project “User-oriented development of sound insulation in buildings ÄKK” (2012–2014). The project was funded by Tekes – the Funding Agency for Technology and Innovation,
Ministry of Environment and eight companies of building industry. This paper also describes thescientific background for the revisions as well as the evaluation of the effects of the revised regulation.

2. PURVIEW OF THE REGULATIONThe structure of the Finnish regulation is shown in Figure 1. There are three levels: first level isformed by the decree which is mandatory. The revised decree includes (2) provisions concerningsound insulation, noise and vibration abatement and acoustic conditions necessary for the constructionof a new building, repair and alteration of a building and the changing of the intended use of a building.
The essential technical characteristics enacted concern health and wellbeing in the manner required by
the intended use of the building. The statutes apply to buildings with dwellings or accommodation or
patient rooms, facilities for teaching, meeting, eating, treatment, recreation or physical exercise, oroﬃce spaces.

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mikko.kylliainen@tuni.fi
ari.saarinen@ym.fi

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Figure 1 – Levels of the Finnish regulation.
The second level is the guidelines (5) concerning the decree. The purpose of the guidelines (3) is toclarify and facilitate compliance with the requirements as the statute directs. The gu idelines provide
instructions on the procedures for design and veriﬁcation. The guidelines are not mandatory. However,they describe the good way of building. The decree nevertheless defines that there is a possibility todesign and construct using structures and methods not prescribed in the decree or in the guidelines, if
the building still fulfills the essential technical requirements defined in the Land Use and Building Act
from the year 2000 (6).
The third level is formed by different guidebooks which give either design methods for different
engineering problems or guidance for acoustical engineering of certain building types . For example,
one of the guidelines concerns interpretation of single-number quantities for sound insulation definedin the earlier regulation as well as repair and alteration of a building and the changing of the intended
use of a building (7).

3. MAIN REVISIONS AND THEIR BACKGROUND
3.1 Standardized single-number quantities for rating the sound insulation
In Finland, the single-number quantity for rating the airborne sound insulation has been theweighted apparent sound reduction index R’ w since the year 1967. The impact sound insulation hasbeen rated by the weighted normalized impact sound pressure level L’ n,w. Earlier, the single-number
quantities standardized to a reference reverberation time of 0,5 s were used. The revision of theregulation has returned the standardized values. Table 1 shows the requirements for the soundinsulation of a new building given in the decree (2). The guidelines (5) give also requirements forschools, office buildings, hospitals etc.
Table 1 – Requirements for the sound insulation of a new building (2).
Room
Between dwellings or accommodation orpatient rooms
From the exit route to a residential,accommodation or patient room

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Permitted DnT,w

Permitted L’nT,w + CI,50-2500≥ 55 dB≤ 53 dB≥ 39 dB≤ 63 dB

The change of definition of the single-number quantities is justified on the bases of the references(8) and (9). In the reference (8), a study on the agreement between the transmission of living sounds
from a neighboring dwelling expressed as the A-weighted equivalent sound level L A,eq and different
single-number quantities like R’ w and D nT,w is described. Measurement results of airborne soundinsulation was collected from 100 field measurements. Six sound types were studied: guitar playing,
two kinds of music, baby cry, loud speech and dog bark. In all cases, the single-number quantity DnT,w
resulted in a better correlation with the transmitted sound than R’ w. Figure 2 describes the situation
when the transmitted sound is loud speech. Similar results concerning the rating of impact soundinsulation have been reported in the reference (9).

Figure 2 – Sound levels LA,eq of transmitted loud speech in receiving room asfunction of the R’w (left) and DnT,w.
In the referred study (8), it was also shown that the reverberation times of Finnish furnished rooms
are typically 0,5 s which agrees with the reference absorption area used in the definition of thesingle-number quantities DnT,w and L’ nT,w. The absorption areas of the Finnish rooms do not correspondto the reference absorption area of 10 m2 . This indicates that the revision concerning the single-number
quantities defined in the regulation has been justified.
3.2 Rating the impact sound insulation
The measured frequency range for rating airborne and impact sound insulation has been 100–
3150 Hz in the Finnish regulation earlier. The airborne sound insulation is also in the revised
regulation defined to be measured at this frequency range. This is because the measurement
uncertainty is considered to become too large in the widened frequency range reaching to 50 Hz (10).
In the Finnish research prescribed in the introduction, no significant benefit was not found in rating ofairborne sound insulation if the rated frequency range was enlarged down to 50 Hz (11).
In rating the impact sound insulation, the revised regulation enlarges the measured frequency range
down to 50 Hz as was already shown on chapter 3.1. In the reference (12), it was found that enlarging
the frequency range slightly improves the correlation between the subjective rating and thesingle-number quantity. In the case of impact sound insulation, the measurement uncertainty does notraise unacceptably large (13). However, it can be stated that present single-number quantities for
rating the impact sound insulation are not the possible as the correlation between them and thesubjective rating by the people is relatively low. There are also possibilities to find new better rating
methods (14).
An interesting question is the effect of the revision on the structur al types of the floors. In thereference (3), a study on a sample of 214 field measurement results on impact sound insulation wascarried out. From the measurement results, both the weighted normalized impact sound pressure level6979

L’ n,w and weighted standardized impact sound pressure level L’ nT,w + CI,50-2500 were calculated. The
calculated values were compared to the largest permitted value given in the previous and present
regulation. The result was that 7 % of the results fulfilling the requirements of the previous regulation
would not fulfill the revised requirements. This amount can be considered small, but the 7 % of themeasurement results are from such situations where people have expressed their unsatisfaction
towards the impact sound insulation. The results have been shown in Table 2.
Table 2 – Amount of measurement results fulfilling the previous requirement but
not fulfilling the present requirements (3).
Material of the bearing structure

AmountProportion (%)

Concrete

136,7 %

Lightweight

1

7,7 %

Other

1

11,1 %In total

15

7,0 %

3.3 Room acoustics
The requirements for room acoustics for different roomtypes and spaces are given in the guidelines(5). Examples of the room acoustical requirements are shown in Table 3. In addition to the traditional
reverberation time, the requirement has been given also as speech transmission index STI for some ofthe room and space types. This is done in order to ensure the acoustic quality for the rooms. For
example, the reverberation time is not a sufficient measure for rating the room acoustics in anopen-plan office.
Table 3 – Examples of requirements for room acoustics (2).
Reverberation time

Speech transmission index

TSTI

Classroom or meeting room0,5–0,7 s≥ 0,7Canteen, sports hall (≤1500 m3)≤ 1,2 s

≥ 0,6Patient room

≤ 0,8 s

≥ 0,6Open-plan office≤ 0,6 s

≤ 0,5Office room≤ 0,8 s–

Day care centre≤ 0,6 s–Exit route to a residential building≤ 1,3 s–Room

Concerning room acoustics, cost effects were studied. These calculations concerned both building
costs and costs which usually are not considered at all, i.e. costs for the user of the space depending on
insufficient acoustic conditions (4). An example of this is classroom where poor acoustic may cause
problems in voice formation of the teachers, which often results in a long rehabilitation period and sickleave. Another example is open-plan office studied in the reference (4).
In an open-plan office, the loss of working time is known to be connected with speech transmission
index STI as speech is considered a source of disturbance (15). In the study reported in the reference(4), an open-plan office with 170 workstations was studied in two cases; when it was planned to be
acoustically functional and when it was planned to meet only the minimum requirements. For bothcases the building costs resulting from the acoustic design were determined as well as the costs
resulting from the loss of working time. Assuming there was constantly at least one speakersomewhere in the space, STI value and a model presented in the reference (15) was used to calculate
the resulted costs. To determine the loss of working time it was assumed that 90 % of office work time
is work that can be charged and price of one hour of work is 60 €/h (VAT 0 %). Figure 3 shows the6980

cumulative costs of both versions of the open-plan office during a period of five years. On the bases of
the results it was obviously justified and profitable to set room acoustical criteria for open-plan officesin the revised regulation.

Figure 3 – Sound levels LA,eq of loud speech in receiving room as function of the R’w (left) and DnT,w.

4. CONCLUSIONSThis paper presents the main revisions of the new Finnish regulation on acoustical environment ofbuildings as well as the scientific background of the regulation. The Finnish regulation is based on athorough national research project and utilizing the international scientific literature. The
requirements given in the regulation are scientifically justified. The cost effects of the regulations havealso been studied beforehand which also supported the revisions made by the Ministry of theEnvironment.

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