Building Acoustics: Noise Aspects of Ventilation Coursework Assignment

This report provides a comprehensive analysis of building acoustics, specifically focusing on the noise aspects of ventilation in residential buildings. The assignment addresses the necessity of the Acoustic, Ventilation and Overheating Guide (AVOG), summarizing its scope and application in managing noise levels, ventilation, and overheating. It explores the importance of limiting noise from mechanical ventilation in habitable rooms, outlining acceptable noise level limits for bedrooms, living rooms, kitchens, and bathrooms. The report also delves into the noise level standards for different ventilation conditions, including ADF-whole dwelling, ADF Extract, and ADP-Purge Ventilation. Furthermore, it evaluates the effectiveness of trickle vents as a ventilation method and examines the impact of open windows on indoor noise levels, referencing the AVO guidelines and providing specific noise level calculations for various scenarios. The report offers insights into the practical implications of these concepts, supporting the importance of effective noise management in residential building design.

Running head: BUILDING ACOUSTICS
Building Acoustics
Name of the Student
Name of the University
Author note

1BUILDING ACOUSTICS
Question 1:
(a)Answer:
Here noise implies the noise level of the indoor environment due to the exposure to the
external noisy environment such as road traffic, gathering induced noise, natural noise and
other indoor noise from mechanical equipment. The number of openings such as door,
windows, open balcony and other construction related technical and mechanical equipment
and their positions in the building regulates how much external noise can influence the indoor
ambiance (Kapsalaki, 2017). These openings are also responsible for the air flow of the
buildings as well as the ventilation systems that allows extracting the polluted, high moisture
level air to the external environment with the exchange of in-taking the fresh are in the house
from the external environment. The air flow also controls the heat level of the indoor. Apart
from the airflow, the positions of the openings to the sunlight, positions and energy efficiency
of residential mechanical equipment, the heat absorption level regulates temperature
generation in indoor environment.
Therefore from the above discussion it can be found that the three of the major factors that
significantly influence comfort and healthy ambiance of an indoor environment are the noise
level, ventilation level and temperature. In the process of designing residential buildings or
dwelling the architect, designers and contractors have a significant value when it comes to the
health, safety and comfort level. In traditional approach noise level, ventilation and indoor
head were considered independent factors of a residential constructional design (Torresin et
al. 2019). The Acoustic, Ventilation, Overheating guidance allows these stakeholders
responsible for developing and designing a residential building to make a healthy and
comforting indoor environment for the residents.
(b)Answer:

2BUILDING ACOUSTICS
The Acoustic, Ventilation and Overheating Guideline is intended for the constructional
development of residential buildings, flat apartments and other dwellings. The scope of the
AVO guide for the noise level is intended for the airborne sound from transport sources and
the sound from mechanical equipment of the dwelling. However, noise from industrial,
commercial or entertainment premises and any kind of ground borne noise and vibrations are
excluded from the scope of AVOG (Association-of-noise-consultants.co.uk. 2019).
The AVO guidance encourages for assessment of noise and the effectiveness of the noise
minimization procedures that interdependent to the ventilation system of the dwelling and the
overheating conditions. It includes the measurement procedures, the instrumental
investigation approach, analysis, and evaluation method for the AVO assessment. AVO
guidance provides the assessment methods to satisfy the needs for acoustic, ventilation and
overheating at the very beginning of the planning stage (Association-of-noise-
consultants.co.uk. 2019). It allows the designers to make the AVO consideration integrated to
the blue print of the building structure resulting more effective and associative designing
procedures as per the AVO guidelines. AVOG assists to educate the environmental health
and planning officers, the client and other stakeholder for the design and development of the
building.
The AVO policy coverage is limited to England. However, the approach can be acceptable in
other parts of the United Kingdom. The documentation of AVO guidelines has been
developed by assuming that the user has general knowledge of acoustics and standard
terminology. At the same time, the AVO assists the reader by providing a glossary of
terminology used throughout this document (Association-of-noise-consultants.co.uk. 2019).
The subjective benefits such as inletting external windows by occasional opening windows,
its impact on the ventilation strategies, and location of the external air inlets apart from the
ventilation procedures are excluded from the scopes of this AVOG documentation.

3BUILDING ACOUSTICS
Question 2:
(a)Answer:
In habitable rooms such as bedrooms and living rooms the residents usually spend their
maximum time. The living rooms are mainly used for leisure purposes where the residents
usually spent a larger amount of time in their residential stay. Therefore, the levitated noise
level because of mechanical ventilation can not only disrupt their level of comfort, but also
can cause long term noise related health issues such as hearing loss, agitation, anxiety,
restlessness, elevated blood pressure and others (Murphy and King 2014). Since, living room
is also used for socialisation and welcoming guest elevated noise level can disrupt the
socialisation ability of the residents. Therefore, it is very important for the health condition
and social life of the resident to limit the noise from mechanical ventilation.
Bedroom is the most sensitive room in their entire building in terms staying duration of the
residents and the purpose of usage. Bedroom is for resting where the residents can relax and
sleep and develop enough energy for their body and mind. However, elevated noise level in
bedroom due to mechanical ventilation system can cause disturbance in sleep (Varfolomeeva
et al. 2014). Disturbance in sleep can cause fatigue and tiredness in the residents while
leading to disrupted personal, professional and social life. Long-time exposure to a noisy
environment while in bedroom can cause several health issues such as Insomnia, cardiac
issues, neurological disorders and other major problems. Therefore, it is very important for
the entire quality of life of the resident to limit the noise in bedroom from mechanical
ventilation.
(b)Answer:
The noise tolerance level of human being depends on the magnitude level of sound measured
by decibel. 0 decibel the threshold level of hearing where zero perceivable sound is present.

4BUILDING ACOUSTICS
Human ear can tolerate up to 120 decibel. More than that can cause immediate hearing
impairment. Usually the outdoor traffic noise ranged from 70 to 80 decibels. More than 50
decibel of noise can cause disturbance. Therefore, the noise level of overall indoor should be
less than 50 decibel (Bies, Hansen and Howard, 2017). However, for different habitable
rooms this level should be changed according to their purpose of utilisation.
There are usually four habitable rooms in a typical apartment namely bedroom, living room,
kitchen, and bathroom. As discussed earlier the bed room should be the most noise free room
because, it is used as a place of peaceful relaxation and rest. Therefore, the noise level of
bedroom should be around 30 to 35 decibel. Living rooms are usually used for comparatively
more sound developing purposes through TV, music system, welcoming guests and others.
Therefore. The noise level of living room should be 35 to 40 decibel. Kitchen and dining
room are used for comparatively noisy purposes associated with cooking. Therefore, the
noise level of kitchen and dining room should be within 40 to 45 decibel. Bathroom is also
used for short time and where slight noise level cannot interrupt the habitability of the
residents. Therefore, for bathroom the noise level should be within 40 to 45 decibel.
(c)Answer:
As per the guideline of the AVO the mechanical room noise level depends on ventilation
conditions. According to the guideline the mechanical noise limit can varies based on three
types of ventilation conditions namely ADF-whole dwelling ventilation, ADF Extract
Ventilation and ADP-Purge Ventilation. As standardised in the guideline the for ADF-whole
dwelling ventilation system the desirable internal and ambient noise levels from mechanical
services should be within 30 decibel. For bedroom it should be lower than 26 to 30 decibel
and for living room it should be lower than 30 decibel. To enforce this measures Continuous
mechanical extract or MEV will be required where the ventilation rate will be minimal low
(Association-of-noise-consultants.co.uk. 2019). Apart from that the continuous mechanical

5BUILDING ACOUSTICS
supply cha extract heat recovery or MVHR will be required with minimum low ventilation
rate.
For ADF Extract Ventilation the desirable internal and ambient noise levels from mechanical
services should be within 45 decibel. For bedroom it should be lower than 26 to 30 decibel.
For living room and dining room it should be lower than 35 decibel. For Bathroom and
Kitchen the desirable mechanical noise level should be lower than 45 decibel. To maintain
this standardisation the intermittent extract fans will be required along with Continuous
mechanical extract or MEV continuous mechanical supply cha extract heat recovery or
MVHR with minimum low ventilation rate. For ADP-Purge Ventilation there is no desirable
noise level because currently there is no specific guideline about it due to lack of evidences
(Association-of-noise-consultants.co.uk. 2019). To maintain the standardisation the manually
controlled fan exchanging minim 4 air change per hour will be required.
Question 3:
(a)Answer:
Trickle vent can be acceptable as one of the ventilation method for ADF-whole dwelling
ventilation. However, only the trickle vents cannot serve all the purpose of ventilation.
Trickle bents are used as a background ventilations with intermittent extract fans for whole
dwelling ventilation. It can be also used with a passive stack as a natural background
ventilation process. However, the major disadvantage of the trickle vent is that it does not
enable sufficient airflow to have a significant cooling effect. For this same reason it can be
used as a passive ventilation cooling for ADF-whole dwelling ventilation system. When it
comes to the consideration of noise level two trickle vents can provide an equivalent area of
5000 squire millimetre (Harvie, 2013). For this same reason, trickle vents are sized based on

6BUILDING ACOUSTICS
the winter conditions. To work effectively as a noise management equipment it requires a
partially open window.
Two high acoustic performance trickle vents can provide approximately 2500 squire
millimetre effective area for making 31 decibel as a lower noise limit of ADF-whole dwelling
ventilation system. In this case the total equivalent area of a ventilators required to comply
with a criteria where more than two trickle vents are required in some rooms. When it used
with proper external noise minimization process with standard double glazing along with two
trickle vents it yields average 56 decibel noise at day and 51 decibel at night when the
maximum limit is 67 decibel. Therefore, from the above discussion it can be found that even
the acoustic trickle vents cannot provide very high quality air ventilation and noise protection
at the same time (Harvie-Clark et al. 2019). To work it as a perfect ventilator some conditions
are required that can cause more noise level and to act as a noise minimizer it cause poor air
flow quality. Therefore, using only trickle vents for ADF-whole dwelling ventilation system
is not very effective like other ventilation systems.
(b)Answer:
(i)
As per the AVO guidelines open window can cause imitate hike of noise level by 10 to 20
decibel of the immediate room. Depending on the position of the other room the noise level
across the other habitable room varies. Let assume that in a perfect AVO system for a whole
dwelling ventilation the noise level of bedroom is below 30 decibel, the noise level of
bathroom is 35 decibel, noise level of living room is 35 decibel and noise level of kitchen is
40 decibel. Now, after opening the window of the bedroom the noise level of the bathroom
can rapidly raise to 40 to 50 decibel. Based on the material used in the indoor designing as
per the AVO guidelines the noise of other rooms of the house can raise by 0.5 to 0.2 times of

7BUILDING ACOUSTICS
the noise elevation occurs in the bathroom. Therefore, if the noise elevation of the bed room
ranged from n1 to n2, where the n1 is the lower limit and the n2 is higher limit in decibel.
The noise elevation of other room will ranged from the lowest value 0.2 x n1 to 0.5x n2.
Therefore the noise level hike of the indoor can ranged from (0.2x 10)= 2 decibel to (0.5 x
20)= 10 decibels.
At the same time depending on the ventilation type and the duration of opening this range can
be varied. According to the AVO guidelines for windows opening during the day time the
noise hike will be 20 decibel and the night time the noise hike will be 6 decibel and the
average hike will be 13 decibel. Therefore the noise range of the bedroom has measured and
presented in the following table for all types of ventilation
Type of ventilation Closed
windows
noise level
Noise level of
bedroom during
day time
Noise level of
bedroom during
night time
Average noise
level of
bedroom
Continuous
mechanical extract
(MEV), minimum
low ventilation rates
26 dB 26 + 20 = 36 dB 26 + 6 = 32 dB 26 + 13 = 39
dB
Intermittent extract
fans extract
ventilation
30 dB 30 + 20 = 50 dB 30 + 6 = 36 dB 30 + 13 = 43
dB
Manually controlled
fan exchanging a
minimum
4 air changes per
hour, purge
ventilation
35 dB 35 + 20 = 55 dB 35 + 6 = 41 dB 35 + 13 = 48
dB
(ii)

8BUILDING ACOUSTICS
As per the AVO guidelines depending on the overheating the duration of the opening window
varies. Room with no elevation condition and standardized ventilation technique the low risk
of overheating can lead to occasional day time windows opening causing 53dB noise level at
day time and 45 dB at night time. However, in case of overheating the windows can open
much longer time and the maximum noise exposure level equivalence or LAFmax will be 72 dB.
Room with north east elevation condition and standardized ventilation technique the medium
level risk of overheating can lead to occasional day time windows opening causing 59 dB
noise level at day time and 52 dB at night time. However, in case of overheating the
windows can open much longer time and the maximum noise exposure level equivalence or
LAFmax will be 77 dB.
Figure: Day time and night time noise level from open window
Source: (Association-of-noise-consultants.co.uk. 2019)
Room with south west elevation condition and standardized ventilation technique the high
level risk of overheating can lead to occasional day time windows opening causing 64 dB
noise level at day time and 59 dB at night time. However, in case of overheating the
windows can open much longer time and the maximum noise exposure level equivalence or
LAFmax will be 87 dB.

9BUILDING ACOUSTICS
Hence, from the above discussion it can be said for zero elevation or north-elevation the open
window can be considered as acceptable for the controlling overheating and while keeping
the noise level as per the AVO standardization.
(c)Answer:
In a situation where the open window cannot be used as a solution of the overheating there
are more than one strategies that can be applied to mitigate the necessity of overheating. The
target of minimizing the overheating process should be to minimize the heat produced for the
mechanical equipment. For a north east elevation house with moderate overheat risk, the
Continuous mechanical extract (MEV), and minimum low ventilation rates will be most
effective (Torresin et al. 2019). For a south west elevation house with high overheat risk
Continuous mechanical supply and extract with heat recovery (MVHR), minimum high
ventilation rates will be required. None of these cases trickle vents can be applied because it
requires at least one windows opening. Apart from that, for long term effective ventilation
quality with minimum heat level the ventilation motor will be assessed for energy efficiency.
Replacing that with energy efficient motors will be helpful to reduce heat emission.
Furthermore, heat emission from other mechanical equipment such as refrigerator, sound
system, and computer system should be assessed to take necessary actions to reduce heat
emission (Harvie 2014).

10BUILDING ACOUSTICS
References:
Association-of-noise-consultants.co.uk. 2019. ACOUSTICS VENTILATION AND
OVERHEATING GUIDELINE. [online] Available at: <https://www.association-of-noise-
consultants.co.uk/wp-content/uploads/2019/12/ANC-AVO-Residential-Design-Guide-
January-2020-v-1.1.pdf> [Accessed 16 April 2020].
Bies, D.A., Hansen, C. and Howard, C., 2017. Engineering noise control. CRC press.
Conlan, N. and Harvie-Clark, J., 2017. Methods of controlling noise levels and overheating in
residential buildings. ICSV24, July.
Harvie, J., 2013. Problems in residential design for ventilation and noise. Acoustics Bulletin,
p.37.
Harvie, J., 2014. Problems in residential design for ventilation and noise part 2: mechanical
ventilation. Acoustics Bulletin, p.33.
Harvie-Clark, J., Chilton, A., Conlan, N. and Trew, D., 2019, September. Adaptive acoustic
comfort: Assessing noise with provisions for ventilation and overheating in dwellings.
In Proceedings of the 23rd International Conference of Acoustics, Aachen, North Rhine-
Westphalia, Germany (pp. 9-13).
Kapsalaki, M., 2017. Challenges of using passive ventilation to control the overheating of
dwellings in noisy environments.
Murphy, E. and King, E., 2014. Environmental noise pollution: Noise mapping, public
health, and policy. Newnes.
Torresin, S., Albatici, R., Aletta, F., Babich, F., Oberman, T. and Kang, J., 2019. Acoustic
design criteria in naturally ventilated residential buildings: new research perspectives by
applying the indoor soundscape approach. Applied Sciences, 9(24), p.5401.

11BUILDING ACOUSTICS
Varfolomeeva, A.V., Bezjazychny, A.V., Popkov, S.V. and Popov, A.V., 2014. Review of
noise control and regulation methods in habitable rooms of ships and off-shore
facilities. Technical Acoustics/Tekhnicheskaya Akustika, (5).