Page 119 - GRIHA Manual Volume IV - Introduction to National Rating System
P. 119
110 Griha Manual: Volume 4
The following are two fundamental ways in which noise can be controlled.
1. Keeping the noise source away from the occupant/building user
2. Screening/blocking excess noise
In general, the best control method is to reduce noise levels at the source. The outdoor noise levels
should be measured at a distance of at least 1 metre from the façade.
outdoor noise control strategies
1. Control noise at source: Noise can be controlled at source by either modifying the architecture
by adding high sound absorbing materials around the source to reduce its decibel level or by
refining the equipment to reduce the level of noise produced. For example, as per the NBC
2005 the minimum recommended distance between a train track and a building is about 50–
70 m.
2. Increase the length of the path: Increasing the distance between the source and receiver reduces
the intensity of sound received at the receiver’s end. Doubling the distance of the receiver
from a point source and/or line source have significant impacts on the reduction in sound
levels at the receiver’s end.
3. Block the length of the path: There are various factors, which affect the sound reduction potential
of the sound barriers.
• Position of the barrier: The barrier should ideally be placed either close to the receiver or the
source. This has the maximum impact on the acoustical performance of the sound barrier.
• Height of the barrier: The height of the barrier should be such that it is able to block the direct
line of sound movement between the source of noise and the receiver. Thus, depending
upon the location of the sound barrier (close to source or receiver), the height of the barrier
may vary for effective sound reduction.
• Continuity: The sound barrier will be most effective if there are no gaps or weak points in
the barrier. The sound barrier should be continuous without any breaks.
• Barrier length: The barrier should run for a length, which is greater than the distance
between the source and the receiver.
• Material of the barrier: The barrier should be made of a high density material to cause
significant reduction in sound transmission through it.
• Texture of the barrier: Barriers with very fine and smooth textures tend to cause reflections in
sound instead of absorbing them. Barriers with rough texture tend to absorb more sound.
• Vegetation and earth berms: Design of earth berms and use of vegetation with dense
foliage can also help in reducing sound transmission between the source and the receiver.
The earth berms and vegetation covers can be used in combination with sound barriers as
well. Dense planting of trees with an understory of shrubs can result in reduction of 3–5 dB
9
per 30 m of the depth from the source of the sound . Plantation of less than 30 metre depth
does not sufficiently reduce sound levels.
9 Harris Charles W/& Dines Nicholas T, Time-saver standards for Landscape Architecture, McGraw Hill, 1997 Page: 660-7.
The following are two fundamental ways in which noise can be controlled.
1. Keeping the noise source away from the occupant/building user
2. Screening/blocking excess noise
In general, the best control method is to reduce noise levels at the source. The outdoor noise levels
should be measured at a distance of at least 1 metre from the façade.
outdoor noise control strategies
1. Control noise at source: Noise can be controlled at source by either modifying the architecture
by adding high sound absorbing materials around the source to reduce its decibel level or by
refining the equipment to reduce the level of noise produced. For example, as per the NBC
2005 the minimum recommended distance between a train track and a building is about 50–
70 m.
2. Increase the length of the path: Increasing the distance between the source and receiver reduces
the intensity of sound received at the receiver’s end. Doubling the distance of the receiver
from a point source and/or line source have significant impacts on the reduction in sound
levels at the receiver’s end.
3. Block the length of the path: There are various factors, which affect the sound reduction potential
of the sound barriers.
• Position of the barrier: The barrier should ideally be placed either close to the receiver or the
source. This has the maximum impact on the acoustical performance of the sound barrier.
• Height of the barrier: The height of the barrier should be such that it is able to block the direct
line of sound movement between the source of noise and the receiver. Thus, depending
upon the location of the sound barrier (close to source or receiver), the height of the barrier
may vary for effective sound reduction.
• Continuity: The sound barrier will be most effective if there are no gaps or weak points in
the barrier. The sound barrier should be continuous without any breaks.
• Barrier length: The barrier should run for a length, which is greater than the distance
between the source and the receiver.
• Material of the barrier: The barrier should be made of a high density material to cause
significant reduction in sound transmission through it.
• Texture of the barrier: Barriers with very fine and smooth textures tend to cause reflections in
sound instead of absorbing them. Barriers with rough texture tend to absorb more sound.
• Vegetation and earth berms: Design of earth berms and use of vegetation with dense
foliage can also help in reducing sound transmission between the source and the receiver.
The earth berms and vegetation covers can be used in combination with sound barriers as
well. Dense planting of trees with an understory of shrubs can result in reduction of 3–5 dB
9
per 30 m of the depth from the source of the sound . Plantation of less than 30 metre depth
does not sufficiently reduce sound levels.
9 Harris Charles W/& Dines Nicholas T, Time-saver standards for Landscape Architecture, McGraw Hill, 1997 Page: 660-7.
