Add5_Acoustical study_BEL.pdf

ADDENDUM 5 : Acoustical study

100% FOR CONSTRUCTION

Shape Belgian School

S.H.A.P.E., Belgium

PN 328030

October 31, 2023

ABETEC nv Architects & Engineers

Acoustical study for the Shape Belgian School in Mons

Ankara Lane 7000 Mons

23rd of October 2023

To the attention of Mr. Christophe Vermeiren, Abetec by

Jeroen Laureys Pierre De Fonseca

Bureau De Fonseca bvba Krogstraat 106, 1860 Meise Kalkhoevestraat 1, 8790 Waregem

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RPR Brussel

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Ref :

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Contents

Contents Version history

1. Objective and scope of the acoustical study

2. Fundamentals in the study: typology and use of the rooms

3. Impact sound insulation HS

3.1 Requirements for impact sound insulation

3.2 Floor construction

3.3 Key points in the execution of works

3.4 Stairs

3.5 Terrace

4. Airborne sound insulation

4.1 Requirements for airborne sound insulation

4.2 Floors

4.3 Walls

4.3.1 Wall composition

4.3.2 Elements in the partition walls

4.4 Crosstalk through the ventilation system

4.5 Construction Details

4.5.1 Junction between the walls and the floor

4.5.2 Junction between walls and the ceiling

4.5.3 Junction between two walls

4.5.4 Electrical outlets in light weight walls

4.5.5 Installation of cable trays

5. Installation noise and background noise levels

5.1 Requirements

5.2 Ventilation noise

5.3 Shafts

5.3.1 Wall composition

5.3.2 Perforations of the shaft walls

5.4 Technical installations

6. Sound insulation of the façade

6.1 Noise level on site

6.2 Requirements according to the Belgian standard

6.3 Applied to the building

6.3.1 Windows

6.3.2 Junction between the windows and the façade

7. The reverberation time

7.1 Requirements

7.1.1 NBN S01-400-2 (2012)

7.2 Calculation of the reverberation time

7.2.1 Corridors

7.2.2 Other rooms

8. Noise pollution to the surroundings

Version history

Version Date Modifications

23/01/2017 First version of the report a 12/05/2017 Adaptation of the report after the meeting of 29 of January b 23/10/2023 Minor adaptation + update measurement standards

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1. Objective and scope of the acoustical study

The goal of this study is to verify that a good acoustic climate is achieved in the new Belgian School of the Shape High International School in Mons. Therefore the following aspects of the building’s acoustics are evaluated:

Airborne sound insulation between rooms Impact sound insulation between rooms Installation noise Façade insulation Reverberation time Radiated noise to the environment

For this evaluation the plans of 23 January 2016 were used.

The following standards are taken into account:

NBN S01-400-2 (2012): Acoustical criteria for school buildings Walloon environmental legislation: Code Wallon de l'urbanisme, de l'aménagement du territoire, du Patrimoine et de l’énergie

For the verification of the requirements the following standards are applicable:

NBN EN ISO 16283-1

NBN EN ISO 16283-2

NBN EN ISO 16283-3

NBN EN ISO 10052

2. Fundamentals in the study: typology and use of the rooms

The performance requirements for a room according to the standard NBN S01-400-2 (2012) are determined by its function and use. As such, it is important that this typology and the use of the rooms is specified. When determining the applicable performance requirements for the rooms following interpretations and intended use of the rooms are applied:

Persons with hearing or communication limitations can be present in de school.

However, it is assumed that this is normally not the case. As such, the demands for higher acoustic comfort according to the standard NBN S01-400-2 (2012) should not be met.

The hallways and staircases will not be used during the lessons. They are regarded as circulation areas for temporary use.

The primary staff room, the secondary staffroom, the secondary principal room, the primary/secondary meeting room, the secondary secretary, the secondary Bursar and the Secondary Supervisor room are considered to be offices/staff rooms.

The computer Centre is considered to be a classroom.

The Tele-room, Electric-room and Janitor room are considered to be storage rooms.

The playground will be used while the classrooms are in use.

These interpretations are to be confirmed by the architect and the client.

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3. Impact sound insulation HS

3.1 Requirements for impact sound insulation

Impact sound insulation relates to the reduction of footstep noise or of sound from moving furniture. It is determined by measuring the sound level L, in the receiver room, when the floor in the source room is being impacted by a standard tapping machine (according to ISO 16283-2). The measured sound level is corrected for reverberation time, L'nT, and weighted to give a single number value for standardized impact sound insulation L'nT,w (according to ISO 717-2). The lower the measured level L'nT,w the better the impact sound insulation.

The applicable Belgian standard NBN S 01-400-2 (2012) specifies maximal admitted weighted impact sound levels between two rooms, corrected for specific source spectrum for running noise L’i. The requirements are determined by the function of the rooms.

The requirements are to be met in vertical direction as well as the horizontal direction.

The parameter L’i does not only depend on the material of the separate floor-ceiling assembly but also on its surface, the volume of the receiving room, and the properties of the flanking walls.

The following table is an excerpt from the Belgian standard. The applicable requirements for this project are indicated in the red rectangles:

L’i=L’nTw+Ci [dB] Source room

Receiving room

C la s s ro o m s

T e a c h e rs r o o m

R s tr o o

K in d e rg a rt n

M u s ic r o

S tu d y r o s e a rc h r o o

G y m n a s iu w rk r o

C ir c u la ti o n a re a

(s h o rt

-t e rm u s e

C ir c u la ti o n a re

(c n ti n u o u s u s e

M e e ti n g r o

Music room – study room

55 50 60 55 45 60 55 50

Classroom (Kindergarten, middle school)

60 55 65 60 45 65 60 55

Research room – Teachers room

60 55 65 60 55 65 60 55

Gymnasium 65 65 n.r. n.r. 60 n.r. 65 60

Work room – restroom – circulation area – meeting room n.r. n.r. n.r. n.r. 65 n.r. n.r. n.r.

n.r.: no requirement

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3.2 Floor construction

The plans give following floor constructions.

Basement floor

Component Specification Thickness

Finishing - 2 cm

Screed ≥ 150 kg/m² 8 cm

Thermal insulation - 6 cm

Concrete base floor ≥ 840 kg/m² Min. 35 cm

At this moment there is no floating floor present in the basement floor. To prevent impact noise from being transferred from the basement floor onto the walls of the sound sensitive rooms above, a floating floor is needed in following rooms:

- Water room

- High Tension room

- MEP-room

All technical installations are to be decoupled from the rest of the building. This is done as discussed in section 5.5.

Ground floor

Finishing: linoleum or acoustic vinyl tiles - 1 cm

Screed ≥ 115 kg/m² 6 cm

Thermal insulation - 6 cm

Concrete bubble deck floor ≥ 610 kg/m³ 34 cm

The floor finishing that will be placed has a ΔLw ≥ 5 dB to 15 dB. This will not suffice to meet the predetermined performance requirements.

An extra impact sound insulation layer is to be placed above the thermal insulation. The insulation layer must have a ΔLw ≥ 21 dB (ISO 717-2). The layer should be placed in all rooms, except in the storage rooms.

First and second floor

Finishing: linoleum or acoustic vinyl tiles - 1 cm

Screed ≥ 115 kg/m² 6 cm

Concrete bubble deck floor ≥ 610 kg/m³ 34 cm

In order to meet the performance requirements with this floor composition, an impact sound insulation layer should be placed above the concrete floor. Any unevenness should be limited to 0,5 cm. The insulation layer must have a ΔLw ≥ 21 dB, it is to be placed in every room.

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3.3 Key points in the execution of works

The buildup of the floor on the ground floor will look like this:

The thermal insulation is to provide a perfect even surface. To ensure the good functioning of the impact insulation foil, the surface must be completely level. Any unevenness should be limited to 0,5 cm.

The buildup of the floor on the first and second floor will look like this:

Screed

Impact insulation layer

Each perforating tube or cable is fully enveloped with an anti-vibrating material during the whole passage through the floor

Thermal insulation with piping

Elastic joint between the plinth and the floor finishing

Screed

Impact insulation layer

Each perforating tube or cable is fully enveloped with an anti-vibrating material during the whole passage through the floor

Piping beneath the floor

Elastic joint between the plinth and the floor finishing

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This floor composition does not have a thermal insulation layer, in which the piping can be placed. This means it is not possible to place draining pipes on these floors. If draining pipes are needed, the pipes are placed above the suspended ceiling of the floor below. In this case the remarks mentioned in section 5.3 are followed.

Piping for electricity and heating can be installed directly onto the concrete slab. When this piping is placed, the irregularities are larger than the authorized maximum of 5 mm.

In order to prevent contact bridge or local perforations, sand or mortar is placed on both sides of the piping as to obtain a soft slope on both sides. Preferably, an additional strip of sound insulation foil is here provided above the conduit. The figure below illustrates the situation.

Placing a floating floor requires a persistent attention to detail in order to avoid any contact points between the floating screed and other parts of the building structure (floor, façade or walls). The edge insulation must be placed correctly and sufficiently high. The foil must not be perforated during placement. These two aspects are critical.

Radiator pipes should best be placed in grinding slots in the walls, as such the edge insulation is a continuous layer. If not, the piping shall be fully enveloped with an anti-vibrating material, such as the impact insulation foil. This avoids rigid contacts, and therefore, contact sounds between the pipes and the base floor.

In order to meet the requirement for impact sound insulation between the corridors and classes, an acoustic cut should be made in the floating screed. This cut shall be made under all light (movable) walls and under all acoustic entrance-doors (see section 4.4.3).

3.4 Stairs

Two stair cases are present in the building. In some situations, these stairs are next to noise sensitive rooms (classrooms, staff rooms, …). The stairs are indicated on the plan below.

Impact insulation layer

Concrete slab

Sand/mortar

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As mentioned in section 2 it is presumed that the stairs won’t be used during the classes.

As consequence, no sound disturbance is to be expected and no extra measures are to be taken.

3.5 Terrace

Two terraces will be placed on the second floor. If these terraces are used while the classes below are in use the following measures should be taken:

- The tiles are placed on tile supports

- A rubber strip with a thickness of at least 1 cm is placed between the roof covering and the tile supports. The rubbers have a ΔLw ≥ 28 dB.

4. Airborne sound insulation

4.1 Requirements for airborne sound insulation

Airborne sound is the sound produced by voices, multimedia devices, musical instruments etc. The noise source sets the air into vibration. This vibration is passed on to the walls, floor and the ceiling whereby the sound is radiated in the nearby rooms.

In the Belgian standard airborne sound insulation is expressed as a single number value:

‘weighted standardized level difference’ (according to ISO 717-1), corrected for the specific source spectrum for sounds of a human voice, DA. The higher the DA the better the airborne sound insulation.

The applicable Belgian standard NBN S01-400-2 (2012) specifies minimum airborne sound insulation levels between two rooms depending on the function of both rooms. The following table is an excerpt of the standard. The applicable situations are indicated in red.

DA=DnTw+C [dB] Source room

Receiving room

C la s s ro

K in d e rg a rt u s ic

R o

S tu d y r o o m r e s e a rc h ro

G y m n a s iu m w rk ro

In d o o r p la y g ro u d

T a c h e rs r o s tr o o c u la ti o n a re a s h o rt te rm u c u la ti re a (c o n ti n u o u s u s e ti n g r o

Classroom 44 48 56 (1) 56 56 48 48 32 36 44(5)

Kindergarten (1) 44 52 (1) 32 52 44 44 32 36 44(5)

Music room (1) (1) 52 (1) 56 56 (1) 48 32 36(3) 44(5)

Study room – research room

48 52 60(3) 40 60 60 52 52 32 36 44(5)

Gymnasium – indoor playground – work room

(1) (1) (1) (1) 32 32 (1) 32 n.r. n.r. n.r.

Teachers room (1) 44 52(3) (1) 52 52 44 44 (1) (1) (1)

Restrooms (1) (1) (1) (1) 32 32 (1) 32 n.r. n.r. n.r.

Circulation area – meeting room

(1) (1) (1) (1) n.r. n.r.

(3) n.r. n.r. n.r. n.r.

(1) A requirement is valid in the other direction.

(2) n.r.: no requirement

(3) Only valid if a higher privacy is demanded.

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The parameter DnT,w does not only depend on the material of the separating wall or floor-ceiling assembly but also on its surface, the volume of the receiving room, and the properties of the flanking walls. There also can be a great influence of doors, windows, … in the separating wall. The sound reduction of the different materials in the separating wall is given by the parameter Rw+C, where the ‘C’ indicates the correction for the specific source spectrum for the sound of a human voice. In the following paragraphs requirements will be given for the Rw+C of the different walls and elements in the walls in order to meet the requirements set by the standards.

4.2 Floors

The performance requirements in the vertical direction are achieved with the floor composition as discussed in paragraph 3.2.

4.3 Walls

The following paragraphs give a description of the materials needed for walls, doors, … in order to meet the specifications.

4.3.1 Wall composition

To meet the performance requirements for airborne sound insulation imposed on the partition wall, solid walls in perforated bricks, hollow or full concrete blocks are used.

The table below indicates the specifications of the different types of building blocks.

Type Surface mass Rw+C Abbreviation

Perforated bricks of 19 cm

≥ 215 kg/m² 44 dB 19 PB

Hollow concrete blocks of 19 cm

≥ 260 kg/m² 48 dB 19 HC

Full concrete blocks of 14 cm

≥ 265 kg/m² 48 dB 14 FC

Full concrete blocks of 19 cm

≥ 360 kg/m² 53 dB 19 FC

In general, following placement rules apply:

If the required sound insulation is higher than 32 dB, the walls in hollow concrete blocks are finished with a layer of plaster on at least one side of the wall.

The joint between the top of the wall and the concrete ceiling is sealed airtight.

The acoustic requirements for door assemblies are specified for each situation. A detailed plan with the indication of the acoustical doors is given in section 4.3.2.

When a window is next to the door, the requirement applies to the combination of door, window and frame.

The performance requirements for the glass parts in the walls are specified for each situation.

Perforation of the walls for ventilation ducts is carried out as described in paragraph 4.4 Crosstalk through the ventilation system

The placement of electrical outlets in lightweight walls is performed as discussed in Section 4.5.5.

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Between all technical rooms (requirement DA ≥ 32 dB) The intended wall composition of 19 PB will suffice.

Between the technical rooms and the corridor (requirement DA ≥ 32 dB) The intended wall composition of 19 PB will suffice.

The door in the partition wall: Rw+C ≥ 29 dB

Ground floor Between a classroom and a storage room (requirement DA ≥ 32 dB) The intended wall composition of 19 PB will suffice.

Between a classroom and a corridor (requirement DA ≥ 32 dB) The intended wall composition of 19 PB will suffice.

The door in the partition wall: Rw+C ≥ 27 dB The glass in the partition wall: Rw+C ≥ 30 dB

Between two classrooms (requirement DA ≥ 44 dB) The intended wall composition of 19 PB will not suffice.

A wall composition that can be used is 19 HC or 14 FC.

Between a classroom and a restroom (requirement DA ≥ 48 dB) The intended wall composition of 19 PB will not suffice.

A wall composition that can be used is 19 FC.

Between a classroom and a staff room (requirement DA ≥ 48 dB) The intended wall composition of 19 PB will not suffice.

A wall composition that can be used is 19 FC.

Between a corridor and a staff room (requirement DA ≥ 32 dB) The intended wall composition of 19 PB will suffice.

The door in the partition wall: Rw+C ≥ 29 dB

Between a study room and a corridor (requirement DA ≥ 32 dB) The intended wall composition of 19 PB will suffice.

The door in the partition wall: Rw+C ≥ 27 dB The glass in the partition wall: Rw+C ≥ 30 dB

Between the secretary and the principal office (requirement DA ≥ 40 dB) The intended wall composition of 19 PB will suffice.

Between the secretary and the corridor (requirement DA ≥ 32 dB) The intended wall composition of 19 PB will suffice.

The door in the partition wall: Rw+C ≥ 29 dB

Between the principal office and the corridor (requirement DA ≥ 38 dB) The intended wall composition of 19 PB will suffice.

The door in the partition wall: Rw+C ≥ 36 dB.

First floor Between the secondary staff room, meeting room and a corridor (requirement DA ≥ 32 dB) The intended wall composition of 19 PB will suffice.

The door in the partition wall: Rw+C ≥ 27 dB The glass in the partition wall: Rw+C ≥ 30 dB

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Between the secondary supervisor and the corridor (requirement DA ≥ 32 dB) The intended wall composition of 19 PB will suffice.

The door in the partition wall: Rw+C ≥ 29 dB The glass in the partition wall: Rw+C ≥ 36 dB

Between the secondary principal and the corridor (requirement DA ≥ 38 dB) The intended wall composition of 19 PB will suffice.

The door in the partition wall: Rw+C ≥ 36 dB The glass in the partition wall: Rw+C ≥ 36 dB

Between the supervisor and the secondary staffroom (requirement DA ≥ 40 dB) The intended wall composition of 19 PB will not suffice.

A wall composition that can be used is 19 HC or 14 FC.

Between the secondary principal and the meeting room (requirement DA ≥ 40 dB) The intended wall composition of 19 PB will not suffice.

A wall composition that can be used is 19 HC or 14 FC.

Between the secondary secretary/ Bursar and the corridor (requirement DA ≥ 32 dB) The intended wall composition of 19 PB will suffice.

The door in the partition wall: Rw+C ≥ 32 dB The glass in the partition wall: Rw+C ≥ 36 dB

Between the secondary secretary and the Secondary Bursar (requirement DA ≥ 40 dB) The intended wall composition of 19 PB will not suffice.

A wall composition that can be used is 19 HC or 14 FC.

Between the secondary secretary and the meeting room (requirement DA ≥ 40 dB) The intended wall composition of 19 PB will not suffice.

A wall composition that can be used is 19 HC or 14 FC.

Between the restroom and the Secondary Bursar (requirement DA ≥ 44 dB) The intended wall composition of 19 PB will not suffice.

A wall composition that can be used is 19 FC.

Between the restroom and a Classroom (requirement DA ≥ 48 dB) The intended wall composition of 19 PB will not suffice.

A wall composition that can be used is 19 FC.

Between a classroom and a corridor (requirement DA ≥ 32 dB) The intended wall composition of 19 PB will suffice.

The door in the partition wall: Rw+C ≥ 27 dB The glass in the partition wall: Rw+C ≥ 30 dB

Between two classrooms (requirement DA ≥ 44 dB) The intended wall composition of 19 PB will not suffice.

A wall composition that can be used is 19 HC or 14 FC.

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The second floor Between a big classroom and a corridor (requirement DA ≥ 32 dB) The intended wall composition of 19 PB will suffice.

The door in the partition wall: Rw+C ≥ 27 dB The glass in the partition wall: Rw+C ≥ 30 dB

Between a small classroom and a corridor (requirement DA ≥ 32 dB) The intended wall composition of 19 PB will suffice.

The door in the partition wall: Rw+C ≥ 29 dB The glass in the partition wall: Rw+C ≥ 30 dB

4.3.2 Elements in the partition walls

The final insulation of a separating wall (Rw) is determined by the various elements in the wall: the base wall (solid or light), the windows and the doors. The windows and doors are usually the weak elements in the chain.

Glass elements The windows are fixed. The sound reduction index Rw of the window is determined by the composition of the glass pane, the window profile, and the junction to the wall. The junction should always be airtight: the gap between the window profile and the wall is limited to 1 cm. The gap is filled completely with mineral wool or an elastic sealant (for narrow gaps <0.5 cm). The table below gives the requirements for the windows in this project and gives an example of products that can be used.

Rw+C [dB] Example

30 Single glass blade of 6 mm in a wooden frame

36 Laminated glass 55.1A in a wooden frame

Acoustic doors A door can be opened and closed, which makes it more difficult to realize the complete airtightness. The junction between the door frame and the wall is executed in the same way as for a window. Depending on the acoustical requirement of the door, a suitable junction between the door and the frame and floor is needed. The figure below illustrates the connection between the door and the frame (source: CSTC).

Floor

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Frame:

A flexible joint is provided between the floating screed from the corridors and from the class- and staffrooms. This prevents the screed from passing on impact sounds from the hall way floor onto the floors from the class- and staffrooms. An L- of T-profile is mounted onto the thermal insulation or the concrete slab just underneath the door. The impact insulation is placed on both sides of the profile. The situation is presented in the figure below.

The following plans indicate the minimum sound reduction index for the doors in the building. If no indication is applied, no requirement is demanded.

The table below gives an overview of types of doors used in this project:

Rw+C [dB] Description Example

27, 29 Light acoustical door, with rubber sealing strip all around and an automatic dropseal

De Coene DCA 2

32, 36 Heavy acoustical door, with rubber sealing strip all around and an automatic dropseal

De Coene DCA 5

Impact insulation

Thermal insulation

Floating screed

Concrete floor

Elastic coupling piece L-Profile

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Legend:

Rw+C ≥ 27 dB Rw+C ≥ 29 dB

Rw+C ≥ 36 dB

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Ground floor

Rw+C ≥ 29 dB

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First floor

Rw+C ≥ 29 dB

Rw+C ≥ 32 dB

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Second floor

Rw+C ≥ 29 dB

Rw+C ≥ 32 dB

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4.4 Crosstalk through the ventilation system

Mechanical ventilation (intake and exhaust) is foreseen in all rooms. Each room will have at least one intake and one exhaust vent. No flow openings are foreseen below or in the entrance doors of the rooms.

In order to avoid crosstalk between rooms, at least 1 m of acoustic flexible duct is placed in front of each ventilation grille. The duct can be placed in the plenum of the false ceiling. The duct has at least following attenuation values (in dB) per octave band per meter:

125 Hz 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz

17 26 33 38 28 17

When perforating a wall with ventilation ducts, following points are to be taken into account:

- The diameter of the perforation should be at maximum 1 cm larger than that of the air duct.

- Only hard ducts are used at the perforations (no flexible ducts).

- No rigid contacts between the duct and the wall are allowed. The gap between de duct and the wall is filled with mineral wool or flexible PU-foam. To ensure the airtightness the connection is sealed with airtight aluminum tape.

The figure below illustrates a correct connection:

Ventilation ducts are suspended using flexible connections (with an attenuation efficiency of at least 90%) to eliminate the transmission of vibrations to the structure. This can be done by working with a vibration-decoupled suspension system or by placing a rubber strip in the (standard) suspension system. The figure below illustrates this.

Flexible PU foam

Aluminum tape

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Rubber strip in a standard suspension system (source: Airquality) vibration-decoupling suspension system

(Source: abcgeluid)

4.5 Construction Details

4.5.1 Junction between the walls and the floor

Solid walls are placed directly on the concrete floor. The edge insulation prevents rigid contact between the floating screed and the walls. The image below illustrates the implementation.

4.5.2 Junction between walls and the ceiling

The bearing walls continue into the structural ceiling. The non-bearing walls stop at 1 to 2 cm of the structural ceiling. The joint is filled with mineral wool over the total thickness of the wall.

4.5.3 Junction between two walls

The gap between two walls is limited to 1 cm. It is filled with an elastic sealant over the total height of the wall.

Legende:

Solid wall

Impact insulation

Floating screed

Concrete floor

Concrete ceiling

Mineral wool max 1 à 2 cm

Solid partition wall

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4.5.4 Electrical outlets in light weight walls

In lightweight partitions between noise sensitive areas (offices, classrooms, ...) an electrical outlet is never placed opposite on both sides of the wall. There is always at least one vertical division (metal profile) between 2 sockets and a distance of 60 cm. Two outlets on different sides of the wall should never be in the same stud space. When it is not possible to avoid this is, a soundproof socket should be used of the type Econ 64 Helia or an equivalent. The figure below illustrates this product.

4.5.5 Installation of cable trays

It is possible that cable ducts will be installed in some places. Where they perforate the partition walls the correct measures should be taken. These differ depending on the situation.

Between sound sensitive rooms (airborne sound insulation required of at least 40 dB) :

The perforation is carried out as described below:

- The hole in the partition wall is carried out in the same way as for ventilation ducts (see section 4.4). The hole is a maximum of 1 cm bigger than the dimensions of the cable duct.

- The cable duct is filled with well-pressed mineral wool (30-40 kg / m³) over a length of at least 10 cm, on both sides of the partition wall.

- On top of the duct an OSB or MDF board of at least 18 mm is mounted. The connections are finished airtight.

- The gap of 1 cm around the duct is filled with mineral wool or an elastic sealant

- U-shaped closed cable ducts are used. If open ducts are used, an OSB or MDF board should also be placed on the sides and bottom of the duct.

The figure below illustrates the execution.

Note: If it is not necessary for the cable duct to perforate the wall, a simpler execution is possible:

- The duct is stopped at about ten centimeters of the partition wall

- All cables are properly bundled

- A hole is made in the wall, a maximum of 1 cm is bigger than the bundle of cables.

10 cm

Elastic sealant

OSB/MDF board

Mineral wool

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- The perforation is filled elastically and airtight with mineral wool or an elastic sealant.

Between a corridor and a sound sensitive room (airborne sound insulation required of 32 dB or less)

- The hole in the partition wall is carried out in the same way as for ventilation ducts (see section 4.4). The hole is a maximum of 1 cm bigger than the dimensions of the cable duct.

- The hole, as well as the cable duct, is filled completely with a sound barrier made out of high density mineral wool (70 kg/m²).

- The sound barrier is covered with an airtight paste on both sides

5. Installation noise and background noise levels

Following paragraph gives criteria for the maximum allowed noise levels from installations as well as some guidelines for achieving those criteria. As the installation noise levels depend on the selection of the installation components and the detailed design of the systems, it is the responsibility of the contractor to respect these criteria.

5.1 Requirements

The Belgian standard imposes a maximum permitted sound level LAeq,nT,stat. This parameter is defined as the upper limit of the measured sound level of the combined installation of noise (all installations operating simultaneously. The sound level is measured as the A-weighted equivalent sound pressure level in a room with a reference reverberation time (as discussed in paragraph 7). The table below gives the upper limit for several room types.

Room LAeq, nT, stat [dB]

Corridor 45

Technical room 75

Restroom 65

Classroom 35

Computer class 40

Laboratory 40

Offices/staff room 40

5.2 Ventilation noise

In order to respect these performance requirements following measures are recommended:

- Just behind each ventilation unit and each VAV box a silencer (or acoustic flexible) is placed.

- An acoustic flexible of at least 1 m (see section 4.4 is placed in front of each air grille or extraction mound.

- Care is taken that no local velocity increases occur in constrictions or valves.

- The air diffusers should have a plenum depth of at least three to four times the diameters of the ducts leading to the diffuser.

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Centrifugal fans with airfoil-shaped blades should be used in most cases in order to achieve the background sound levels required for the learning spaces. Centrifugal fans with forward curved blades should be avoided.

The air velocity in the ventilation ducts is limited to the following values:

LAinst,nT [dB] In the main duct In side ducts In end ducts

35 5.0 m/s 4.5 m/s 2.5 m/s

37 6.5 m/s 5.5 m/s 3.5 m/s

42 7.5 m/s 6 m/s 4 m/s

All ventilation units, supply air and exhaust, must be equipped with the proper silencers to respect the proposed noise levels.

5.3 Shafts

5.3.1 Wall composition

To prevent noise nuisance from the installation ducts, the walls of the shafts should have one of the following compositions:

- 14 cm hollow concrete blocks (195 kg/m²)

- 19 cm perforated bricks (210 kg/m²)

- Lightweight gypsum board wall:

o Gypsum board : 2x12,5 mm o Metal profile 5 cm, cavity filled with 4 cm of mineral wool o Gypsum board : 2x12,5 mm o Metal profile 5 cm, cavity filled with 4 cm of mineral wool

The shaft walls are plastered on the outer side. The drain pipes, plumbing pipes or ventilation ducts may not be fixed to walls adjacent to a noise-sensitive area (classroom, office, ...). In this way, the vibrations of the pipes cannot be transmitted to these walls.

The pipes are preferably mounted only in heavy walls or in the concrete floor slabs. Al brackets mounting the drain and water pipes to the shaft walls are fitted with rubber inlay.

Where drains pass in the ceiling in noise-sensitive rooms, an enclosure is to be foreseen.

These enclosures isolate the sound coming out of the pipes and prevent unwanted noise in the noise-sensitive rooms. The enclosure consists of a double gypsum plasterboard (12,5 mm) on a metal structure. At least one wide side of the box is lined with mineral wool of 4 cm (≥ 30 kg/m³). All joints are finished airtight. The figure below indicates this enclosure.

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5.3.2 Perforations of the shaft walls

Openings in the shaft walls for the conduits may have a diameter of maximum 1 cm larger than the conduit itself. These openings must be filled completely airtight with elastic sealant. The conducts do not make any rigid contact with the shaft walls. See also section 5.4.

5.4 Technical installations

Technical installations are foreseen in the basement and on the roof of the building. To respect the mentioned performance requirements following recommendations apply:

- The choice of the equipment will take into account the maximum noise levels as shown in section 5.1.

- The technical installations are placed on vibration isolators with a critical frequency below 12 Hz.

- The required wall compositions and acoustic doors as discussed under the section

"Airborne sound insulation” are followed.

- The installation and piping of the installation has no rigid contact with the rest of the building. Flexible connections are to be used.

- The maximum permitted sound power level of the ventilation groups on the roof, as mentioned in section 8, are respected.

- The maximum sound pressure level in front of the door of the high-voltage room is limited to 60 dB(A). The sound should not be tonal.

6. Sound insulation of the façade

6.1 Noise level on site

The noise level on site was estimated using annex D of the Belgian Standard NBN S01- 400-2 (2012). The building is located on the site of the Shape School in Mons. The noise level to be expected on the façade is only due to local traffic. For this situation the standard indicates the minimal sound level of 60 dB(A).

6.2 Requirements according to the Belgian standard

The performance requirements for the façade insulation are determined by this noise level and the maximum background noise level in the receiving room. The façade insulation will be dimensioned such that this maximum background noise level is respected.

The calculations will be performed according to the standard NBN EN 12354-3 (2000):

‘Building acoustics – Estimation of acoustic performance of building from the performance of elements – Part 3: Airborne sound insulation against outdoor sound’. The standard uses the design parameter LA,ref. In this situation LA,ref equals 60 dB(A).

The following table shows the minimum façade sound insulation of every type of room according to the Belgian Standard.

Type of room DAtr [dB]

Classroom 26

Laboratory 26

Office (ancillary learning space)

Hallway -

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6.3 Applied to the building

6.3.1 Windows

Outdoor noise from traffic contains much energy in the low frequencies, therefore the Ctr-correction is always applied. For example: a window with a sound reduction index Rw (C;

Ctr) of 33 (-1, -3) dB, has an Rw+Ctr-value of 30 dB. Keep this in mind when selecting the products.

The façade has the following composition:

- Perforated bricks of 19 cm (210 kg/m²)

- Thermal insulation

- Air cavity

- Brick 9 cm

This results in an Rw+Ctr of at least 42 dB.

The roof has the following composition:

- Concrete floor slab of 28 cm (640 kg/m²)

- Thermal insulation

- Mineral wool 20 cm

- Waterproof coating

This composition gives an Rw+Ctr of at least 54 dB.

Because the windows are acoustically the weakest elements in the façade, an explicit requirement for the sound attenuation (Rw+Ctr) is imposed on them.

The calculations indicate that windows with an Rw+Ctr ≥ 30 dB will suffice to respect the requirements set by the Belgian standard. An indicative glass composition for the requested Rw+Ctr-value is 4-16-6. The contractor however has to provide a laboratory measurement report for the combination window-glazing that proves that the performance requirements are met.

6.3.2 Junction between the windows and the façade

When installing the windows following installation instructions are advised:

The window profile is placed against the outer façade wall Junction on the sides: An airtight screen is stuck to the framework of the window and integrated into the finish of the reveal sides (plasterboard or plaster). The picture below illustrates the correct positioning of the screen.

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The cavity between the frame and the masonry is on all sides completely filled with well-pressed mineral wool or filled with permanently flexible PU foam (type Soudal Flexifoam or an equivalent).

The junction between the window frame and the window sill is sealed airtight with the aid of a base rubber. This rubber is placed over the entire length of the window frame in wet silicone. This avoids sound leakage between the rubber and the window sill.

The use of solid, heavy window sills is preferred over light aluminum window sills.

Light window sills are significantly more error-prone to a failing airtight junction between the different elements. Later adjustments are often difficult and expensive.

7. The reverberation time

7.1 Requirements

The acoustical properties of a room have an important influence on the general comfort for the users. Functionality, aesthetic properties and acoustical comfort have to be in balance with each other.

One of the most important parameters in room acoustics is the reverberation time. When a sound needs more time to die away in a room, the reverberation time will be higher. A (too) long reverberation time leads to reduced speech intelligibility. The reverberation time is defined as the time (in seconds) it takes for a noise to decrease with 60 dB.

The reverberation time in a room can be decreased by adding sound absorbing material in the room. The absorption properties of a product are expressed by the absorption coefficient (αw). This parameter indicates the percentage of the incident sound that is absorbed by the material, and needs to be proven by the manufacturer of the product.

The sound absorption is measured according to the standard NBN EN ISO 354, and converted to the one-number indication (αw) according to the standard NBN EN ISO 11654.

The optimum reverberation time of a room (in all the octave bands from 500 to 2000 Hz, which are the most important in speech) depends on the volume and the use of the room. It is measured according to the standards NBN ISO 3382-1 or NBN ISO 3382-2.

7.1.1 NBN S01-400-2 (2012)

The Belgian standard gives a maximum permitted reverberation time Tnom or a minimum average absorbing surface per type of room. These requirements are determined by the use and function of the rooms. This reverberation time is measured in a finished room without furniture or people.

Room type minimum average absorbing surface αw

Tnom [s]

Classroom w ≥ 0,2 0,7 - 0,8

Corridor - Absorbing surface ≥ 40% ceiling

Laboratory w ≥ 0,2 0,8

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Office / Staff Collaboration

- 1,0

7.2 Calculation of the reverberation time

The calculations are based on the Sabine model. This model has an accuracy of 20%. The results should be interpreted in this context.

7.2.1 Corridors

The standard indicates a minimal absorbing surface of 40 % of the total ceiling surface. A lowered acoustic ceiling is foreseen in all corridors. If the chosen material has an absorption coefficient (αw) of minimum of 0,4, the requirements of the standard are met.

7.2.2 Other rooms

In these rooms a lowered acoustic ceiling is foreseen. The table below indicates the minimal absorption coefficient (αw) at a 100% ceiling coverage.

Room type Tnom [s] αw

Big classroom 0,8 0,80

Small classroom 0,7 0,85

Staffroom 1,0 0,60

Laboratory 0,8 0,80

The table below gives some examples of products that can be used.

w Example Type

0,75 Rigitone 8/18 or 15/30 or 12/25 or 10/23 + 20cm plenum with 5cm mineral wool

Perforated gypsum board

0,85 Rigitone 8/18 Q (19,8% perforations) + 20cm plenum with 5cm mineral wool

Perforated gypsum board

0,85 Heradesign Superfine 2,5 cm with mineral wool of 2,5 cm on top of it, plenum of at least 2,5 cm

Wood wool panels

0,9 – 1,0 Rockfon Mono Acoustic Jointless mineral wool ceiling

1,0 Rockfon Color all Mineral wool tiles

1,0 Rockfon Fibral White Mineral wool tiles

1,0 Heradesign Superfine 3,5 cm with mineral wool of 4 cm on top of it, plenum of 20 cm

Wood wool panels

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8. Noise pollution to the surroundings

The permissible noise level caused by the school to the surroundings is determined by the Walloon Law, CWATUP, its position on the regional zoning plan and that of the nearest dwellings. The location of the school is marked with a yellow arrow on the excerpt of the zoning plan below.

The building is located in an area for ‘community facilities and public utilities’. The nearest houses are located in 'residential area (the red zones on the map) and at less than 500 m from this area for community facilities and public utilities’. The table below shows the limiting values that are valid in this area.

Day (7h – 19h)

Evening (19h – 22h)

Night (22h – 7h)

50 dB(A) 45 dB(A) 40 dB(A)

These values are valid in a residential area and for noises produced by a classified establishment according to the Walloon environmental legislation. If the school proves not to be a classified establishment, it is still appropriate to use these values as a guide to prevent discomfort in the area.

The closest location where noise nuisance is possible are the houses on the other side of the Ankara Lane. They are located at a minimum of 20 m of the school building.

The technical installations are located in the basement of the building and on the roof.

The exhaust grilles of the technical rooms in the basement are preferably directed away from the houses and the windows of the classrooms.

It is possible that the installations will function day and night, therefore the requirement for the night is decisive. In order to prevent any possible nuisance for the neighbors, the technical installations should comply with the maximum sound pressure level of 40 dB (A). This requirement is to be met at the boundary with the nearest neighboring house.

For the installations on the roof of the building should then be limited to a sound power level of 70 dB(A). This sound pressure level is also to be respected by the exhaust and intake of the ventilation groups, silencers are thus to be foreseen. The sound must not be tonal. The contractor takes these performance requirements into account when choosing the installations.