Lecture-NOISE CONTROL IN A BUILDING Lecture-NOISE CONTROL IN A BUILDING Lecture-NOISE CONTROL IN A BUILDING Lecture-NOISE CONTROL IN A BUILDING.pptx

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1. NOISE CONTROL IN A BUILDING

2. Noise and Noise Sources Noise: is an annoyance caused by undesirable sound. It depends on: Level of the sound Time of occurrence and duration Masking effect: presence or absence of background noise level activity noise level. Age Its effect is both psychological and physiological. i.e. Causing annoyance or dissatisfaction Affecting communication Causing damage to hearing Affecting performance of tasks Causing permanent changes in the normal functioning of the human organism, resulting in deterioration in mental and/ or physical health. We should be able to measure/ quantify noise to reduce or control it.

3. Noise Classification Noise exists in various forms, such as, Speech, music (amplified), machinery noise, plumbing noise, traffic noise etc. But generally noise can be categorized as: Environmental noise – ambient noise Indoor / outdoor: Household noise – radiator equipment, Speech, music, etc Traffic noise [Aircraft, Road traffic] Construction noise, Industrial premises noise, Entertainment noise Air borne / Dynamic or Impact noise (structure borne): vibrations caused by walking/ foot falls, Dropped objects, Slamming doors, Shuffled furniture, Vibrating machines/ causing resonance Continuous / non continuous

4. Quantifying the noise When approaching noise measurement, the various features of the noise that are likely to affect the subjective reaction must be considered. These include: 1. The type of noise: for example, is it continuous at a constant level, or continuous but fluctuating in level; or is it intermittent? 2. The frequency content of the noise: is it broad band; or has it a prominent frequency (i.e., a tonal quality)? 3. The time of day it occurs The relevant combination of these features will lead to a parameter and unit to use and from that the noise exposure can be quantified.

5. Noise Sensitive Functions Examples: at building level: - Medical facilities, schools - Recording and Broadcasting studios - Control Cabins (specially in factories) - Libraries - Residence (sleeping zone) - Telephone stands At environmental level: - Residential areas [ against aircraft and other environmental noise] - Schools [in relation to traffic noise]

6. Noise Protection Stages Principles of noise control There are three basic components in any noise control system, as illustrated in the figure below: 1. The source of the sound 2. The path through which the sound travels 3. The receiver of the sound (Faulkner, 1976). In many situations, of course, there are several sources of sound, various paths for the sound, and more than one receiver, but the basic principles of noise control would be the same as for the more simple case. The objective of most noise control programs is to reduce the noise at the receiver . This may be accomplished by making modifications to the source, the path, or the receiver, or to any combination of these elements.

7. 7 Noise Control Strategies Source controls Replace the sound source with a quieter one. Path controls Block the sound with a solid, heavy material that resists the transmission of sound waves. Sound barriers that reflect and diffuse noise Buffer zones Receiver Absorb the sound with a light, porous material that soaks up sound waves.

8. Preventive ‛Prevention is better than cure.‛ Control the source – the first measure Isolation Mechanical / silencer

9. Control the source Preventing noise before it started . Any additional cost involved in the reduction of noise at the source is likely to be far less than the expense of sound insulation once the noise is produced.

10. Isolation Complete enclosure of the noise-producing element, together with its’ acoustic isolation from any supporting structure. For example, a noisy machine may be enclosed and mounted so that all or sufficient of the noise and vibration is prevented from reaching the surrounding air and structure. Typical Applications; Cinemas, Recording & broadcast studios, Music practice rooms, Dance studios etc… mechanism - Floating floor

11. With regard to the built environment, three basic noise protection stages can be identified: Planning level, Building level, and Building element level.

12. I. Noise Control at Planning Level Planning (Macro/ Micro Planning) Functional Zoning with Sound Contour Screening Surface covering Reflecting objects Building-street proportion / volume proportion

13. Planning (Macro/ Micro Planning) Macro planning Large scale planning: At neighborhood/ city level Considering environmental conditions [ Natural features like hills and valleys can either amplify or reduce noise levels.Climatological Factors: Wind direction, temperature inversions, and humidity can affect how sound travels, altering its intensity and reach] Depending on principles of distance Zoning of land use considering noise and other factors

14. Planning (Macro/ Micro Planning) Macro planning At macro planning level the following two noise protection planning approaches can be considered: Zoning refers to grouping and placing functions as residential, industrial, commercial, etc. It means that to avoid placing noise-sensitive buildings on noisy sites . Clear zoning is good for acoustical solutions but creates social segregation . 2 . Mixed use planning: to plan specified zones for different land use. Here acoustical problems are tackled by design solutions in which Sound insulation is at focal level. It’s expensive, on top of this, the need for natural ventilation and light contradicts with good sound insulation. To reduce the impact of exterior noise, therefore, noise control solutions at all levels have to be considered.

15. Radial Road pattern More concentration of sound Grid Iron pattern Less concentration of sound

16. Traffic Management Rubber/ PVC speed Breakers

17. Site Planning

18. Micro planning Small scale planning focusing on site level functional zoning with Sound contour [principle of distance] Screening Grasse cover – reduction by surface/ layout design Volume proportion [building street relation]

19. Functional Zoning with Sound Contour In micro planning, functional zoning with sound contours takes in to consideration the principle of distance to place functions with respect to their degree of noise sensitivity and the sound contour.

20. Screening Screening is one means of reducing the loudness of the noise heard. When sound wave bends at the edge of a barrier it will diffract. Diffracted sound fall in to the shadow zone and will have less intensity. Screening is usually effective for higher frequencies. Since the ear is more sensitive to high frequencies than low, the characteristic is an advantage in the reduction of the loudness of the noise heard. This is because more diffraction occurs at low frequencies.

21. Screening . Screening is possible by: Fence, walls, trees, ground level (form), buildings which are not vulnerable to noise disturbance can be used to screen more sensitive accommodation. Examples of screening

22. Surface covering/ Grass cover This is noise reduction by grassed surface and planting. The effectiveness of the vegetation is greatest closest to the noise source like road traffic. Planting the surface has more effect in reducing noise by absorption than hard surfaces.

23. When the street width to building height ratio is narrow a noise buildup will occur. A counter measure to this is either reducing the building height to reduce multiple reflection and buildup or increasing the street width to widen the reflection angle and hence reduce the buildup. Building-street proportion / volume proportion

24. Street width (the spacing between the building facades on both sides of the street ) is the most important spatial morphological parameter for studies on urban street sound propagation . street canyon, urban design studies have suggested ideal height-to-width ratios (H/W ). In addition, H/W was found to directly affect the urban microclimate such thermal comfort and temperature at street level. A "canyon street" or "urban canyon" is a street that is surrounded by tall buildings on both sides, creating a canyon-like environment

25. An ideal aspect ratio typically falls between 1:1 and 3:1, depending on specific urban characteristics and traffic conditions. Urban planners must integrate these findings into their designs to foster environments that are both aesthetically pleasing and acoustically comfortable.

26. Screening/ Sound Diffraction Screening Road traffic Noise Grass covered Surface reducing Sound reflection Building- Street proportion

27. Design principles at building level Layout typology Functional Zoning Screening structures Designing sound lobbies Volume separation/ buffer Structural separation Noise Control at Building Level

28. Layout typology A ‘u’ shaped layout typology with relatively compact court will create a noise build up while wide angled and inverted typology reduces the impact.

29. Orientation of Buildings on Sites

30. Functional zoning Lateral zoning – the different areas within the building envelope should be categorized according to proposed usage; residential accommodation, common parts, service areas storage and so forth. Proper layout of rooms and spaces should be used to optimize the effectiveness of the sound insulation. Vertical zoning – stacking of rooms types can also be used to minimize the likelihood of noise problems. The most severe noise problems usually result from improperly stacked rooms, such as living rooms above bedrooms, or bathrooms above living rooms.

31. Screening Structures Screening structures like balconies, vertical fins, and parapet walls are of great help in reducing the external noise before it reaches the envelope. See the examples below referring to the source position(s) and the listener position (L).

32. Designing sound lobbies Sound lobby refers to a transition space especially at entrance where the intruding noise through the gate is protected. The protection mechanism includes the introduction of staggering two doors where the one to the noise source side is made heavy and internal absorptive lining is applied to the walls.

33. Volume separation/ buffer: Space layout considerations: When designing a plan based on a programmed number and type of spaces, consider the relationship between noise-producing spaces and sound-critical spaces sensitive to intruding sound. These requirements can be reduced by separating the two spaces with acoustical buffer spaces. These include: buffer spaces corridors lobbies storage rooms stairwells electrical/janitorial closets offices not requiring sound privacy

34. The figure bellow illustrates the effect of locating a mechanical equipment room adjacent to several private offices and the positive benefits of rearranging the spaces to include a buffer zone between the offices and equipment room. In addition to zoning Volume separation and creating buffer zones is also another design solution. Volume separation/ buffer

35. Structural separation Structural separation means complete structural break in case of impact and flanking noise transmission. For instance, separating workshops from office buildings/ factory. This can be done in two ways; either use of isolating mounting or discontinuous construction system.

36. Noise Control at Building element level Group assignment Openings & external walls Floors & Roofs Partitions Joints & connections ……… add more building elements Delivering Time: December 19,2024 up to 10:00 Lt Mode of delivery: Via telegram