SCHOOL OF ARCHITECTURE, BUILDING & DESIGN Bachelor of Science (Honors) (Architecture)
BUILDING SCIENCE 2 [ARC 3414] PROJECT 2 : INTEGRATION WITH DESIGN STDUIO
MAHI ABDUL MUHSIN
0314421 TUTOR : MR EDWIN
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TABLE OF CONTENT 1.0
Introduction
2.0
Lighting Proposal
2 03 - 14
2.1 Natural Daylighting 2.1.1 Space 1 : Multipurpose reading courtyard 2.1.2 Space 2 : Child care/ children’s reading room
03 - 05 6
2.2 Artificial Lighting 2.2.1 Space 1 : ICT/ multimedia room
07 - 09
2.3 ( PSALI ) 2.3.1 Space 1 : book café’
10 - 12
3.0
Acoustic Proposal
13 - 24
3.1
External Noise Calculations
15 - 16
3.2 Reverberation Time ( calculations & solutions ) : 3.2.1 Space 1: creative studio 3.2.2 Space 2: ICT/ multimedia room
16 - 17 18 - 20
3.3 Transmission Loss 3.3.1 space 1: childcare/ children reading room 3.3.2 space 2 : quiet reading room
21 - 22 23 - 24
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1.0
DESIGN INTRODUCTION
Integrated with Architectural Design Studio 5, this project required us to calculate the optimum lighting and acoustic proposal for the spaces in the building. Studio 5 centres around a community library located in Jalan Haji Salleh, Sentul, which is an urban infill project giving students a throrough insight into urban design and further enhancing our understanding about practical building solutions. For this project, we are required to do a thorough analysis on the lighting and acoustics. Artificial lighting, daylighting as well as PSALI is covered under lighting. For each category, at least two spaces are chosen. Reverberation time (RT) and transmission loss (TL) is calculated for acoustics.. My library is designed with sustainability and permeability in mind, to provide tranparency within the process of learning and sharing knowledge as well as to overcome the boundaries of insecurity in the area, creating a more peaceful and user oriented environment, where everyone can enjoy reading in a renowened nexus of knowledge. ETFE retractable skylight, vertical louvers, curtain wall and the usage of carefully picked materials are some design strategies adopted to tackle the issues of lighting and acoustics.
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2.0
Lighting Proposal 2.1
Zone Very Bright Bright Average Dark
– Natural Lighting DF (%) >6 3–6 1–3 0-1
Distribution Very large with thermal and glare problem Good Fair Poor
Table 1 Daylight factors and distribution (Department of Standards Malaysia, 2007)
2.1.1
Space 1 : Reading courtyard The public courtyard on the ground floor receives an amount of daylight factor as much as 8.4%. Based on the requirement of MS1525, the courtyard probably receives more light than it should have since the requirement for courtyard is 2-6%. The reason why the courtyard receives extra daylight is probably due to the fact that it is wrapped by glass windows on the ground floor which is the public realm of the building. To reduce the amount of daylight from the façade, the ground floor is recessed in 3 m from the 5 foot walkway, and is shaded by the first and upper floors, which eliminates direct sunlight passing through the windows. The skylight is made out of ETFE and aluminium panels which are retractable, so only about 30% of the skylight being transparent etfe, allowing light through. Since the daylight factor is still above the requirement, causing glare and thermal problems, The skylight ETFE sections will be proposed as translucent ETFE
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instead of transparent.
Formula : Daylight Factor (DF) = (Ei / Eo) x 100% Area of Space (m2) Area of Curtain Wall (m2) Area of skylight allowing light through Daylight Factor (%)
(8.2m x 16m ) = 131 m2 (9.8m x 4.5)+(8.2m x 4.5m )=81m2 30.2m2 (111 / 131) x 100% = 84.7 % x 0.1 = 8.4 %
MS 1525 ILLUMINANCE REQUIREMENT FOR TYPICAL SPACES Task
Illuminance Example of Application (Lux)
Lighting for infrequently used area
20 100 100 100 100 150 100 100 100 300 200
Lighting for working interiors
200 300 – 400 300 – 400 150 200 150 – 300 150 150 100 100 300 – 500 200 – 750 300
Localized lighting for exacting 500 task 1000 2000
Minimum service illuminance Interior walkway and car-park Hotel bedroom Lift Interior Corridor, passageway, stairs Escalator. Travellator Entrance and exit Staff changing room, locker and cleaner room Entrance hall, lobbies, waiting room Inquiry desk Gate house Infrequent reading and writing General offices, shops, and stores, reading and writing Drawing office Restroom Restaurant, Canteen, Cafeteria Kitchen Lounge Bathroom Toilet Bedroom Classroom, Library Shop, Supermarket, Department store Museum and gallery Proof reading Exacting drawing Detailed and precise work
Table 2 Recommended Average Illuminance Levels
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NATURAL ILLUMINATION CALCULATION illuminance 110, 000 lux 20,000 lux 1000- 2000 lux 400 lux 40 lux
description Bright sunlight Shade illuminated by entire clear blue sky, midday Typical overcast day Sunrise or sunset on a clear day ( ambient illumination) Fully overcast sunset/sunrise
Illuminance level : 20000, ( DF = ( E internal/ 20,000 ) x 100 8.4 = ( E internal / 20000 ) x 100 = ( 8.4 x 20000 ) / 100 = 1680 lux The general illuminance level of the courtyard is 1680 lux with a daylight factor of 8.4%. The This proves that the hall itself receives too much daylight during the day time. Thus, transclucent ETFE will be used to overcome the glare and thermal problems for the courtyard. The diagram below shows a part of the proposed skylight with translucent ETFE panels.
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NATURAL LIGHTING : 2.1.2 CHILDREN READING ROOM DAYLIGHT FACTOR CALCULATION: Area of Space (m2) Area of Curtain Wall (m2) Daylight Factor (%)
(4.4m x 17.3m ) = 76.12 m2 46.55 m2 (46.55 / 76.12) x 100% = 61.15% x 0.1 = 6.1 %
ILLUMINANCE CALCULATION: illuminance 110, 000 lux 32,000 lux 1000- 2000 lux 400 lux 40 lux
description Bright sunlight Unobstructed sky of malaysia Typical overcast day Sunrise or sunset on a clear day ( ambient illumination) Fully overcast sunset/sunrise
Illuminance level : 32000 DF = ( E internal/ 32,000 ) x 100 6.1 = ( E internal / 32000 ) x 100 = ( 6.1 x 32000 ) / 100 = 1952 lux The children reading room receives a daylight factor of 6% which is considered bright, with possible glare and thermal problems during midday. Based on the requirements as stated in MS1525, this area has an optimum natural daylighting as it is slightly more than 3 – 6%. This is probably due to the zoning of the room right adjacent to the south opening curtain wall. The general illuminance level for a reading and leisure room is 300- 400 lux. The final calculation of daylighting is 1952 lux, which is over the requirement range. This explains that the childcare reading room itself receives too much daylight during the day time. The solution proposed in order to eliminate any glare problems and to control the daylighting is installation of rotating sun tracking timber louvers which are used on the façade, which opens up and closes as necessary for the user during different times of the day.
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2.2 ARTIFICIAL LIGHTING 2.2.1 – ICT/MULTIMEDIA ROOM The multimedia room is a combination of computer lab, printing services as well as gaming and e learning room. The aid from artificial light is needed to provide sufficient amount of illuminance throughout the day as computers must be used in brightly lit spaces in order to prevent harm to eyes. Artificial light is important in order to deliver a suitable reading environment for the users and can be used to complement in the area where the natural daylight is not sufficient. RIO LDL downlight is chosen to light up this space.
Lamp Type
LED downlight
Material of fixture Product brand and code Nominal life ( hours ) Wattage range ( W) CRI Colour temperature Colour designation lumens
aluminium RIO LDL 801 50, 000 44 -50 80 3000 Warm white 3753
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Calculations Location
Discussion and IT Hall
Dimension (m)
Length (L) Width (W) Height of the ceiling
Total floor area, A (m2)
13.4 x 9.5 = 127.3
Standard Illuminance Required (lux) according to MS1525, E Lumen of lighting fixtures, lm
300
Height of luminaire (m)
3.0m
Work level (m)
0.8
Mounting Height, Hm (m)
2.5m
Assumption of reflective value
Ceiling : 0.7
3753
Room Index, RI (K) �=
�  �  � � + � ��
Floor : 0.2
= 2.22 0.54
Maintenance Factor, MF
0.8
Lumen Calculation đ?‘Ź  đ?’™  đ?‘¨ đ?‘  đ?’™  đ?‘źđ?‘  đ?’™  đ?‘´đ?‘
Wall : 0.5
13.4  x  9.5  16 +  9.5  2.5
=
Utilization Factor, UF
đ?‘ľ = Â
= 13.4 = 9.5 = 3.5 m
=
300  x  127.3 3753  �  0.54  �  0.8
= 23.55 Â lights (take 24) 24 lights are needed to reach the minimum requirement of MS 1525 = 300 lux
Number of luminaires across = đ?‘ł Â đ?’™ Â đ?‘ľ đ?‘ž
13.4 Â đ?‘Ľ Â 24 9.5
= 5.81 (take 6) Therefore, each spacing would be 13.4 á 6 = 2.2  đ?‘š Â
Â
8 Â
Number of luminaires along đ?‘ž Â đ?’™ Â đ?‘ľ đ?‘ł
=
9.5 Â đ?‘Ľ Â 24 13.4
= 4.12 (take 4) Therefore, each spacing would be 9.5 á 4 = 2.3đ?‘š Â
LIGHTING DIAGRAM
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2.3 PSALI – Permanent Supplementary Artificial Lighting of Interiors 2.4.1 BOOK CAFÉ. PSALI is a system of combined artificial lighting and daylighting, where the two are blended together to provide an even illumination. Parts of the room are permanently lit by artificial light. The principle of PSALI is to provide illumination that appears to be of good
daylight character even though most of the working illumination may be from artificial light The book cafe is located at the ground floor. It is a multi purpose space with a mini kitchen, a bar and a performance platform, partly illuminated by daylight from the skylight and façade, and deeper sides illuminated by artificial lighting. Lamp Type
COB LED TRUNK DOWN LIGHT
Material of fixture
Aluminium
Product brand and 25W COB LED code Nominal life ( hours ) 50, 000 Wattage range ( W)
25W
CRI
80
Colour temperature
3000
Colour designation lumens
Warm white 2000
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Location
BOOK CAFÉ WITH BAR
Dimension (m)
Length (L) Width (W) Height of the ceiling
Total floor area, A (m2)
19.2 x 6.0 = 115.2m2
Standard Illuminance Required (lux) according to MS1525, E Lumen of lighting fixtures, lm
200
Height of luminaire (m)
4.0m
Work level (m)
0.8
Mounting Height, Hm (m)
3.0m
Assumption of reflective value
Ceiling : 0.7
2000
Room Index, RI (K) �  �  � �= � + � ��
Wall : 0.5
Floor : 0.2
19.2  x  6.0 19.2 +  6.0  3.0
=
= 1.52
Utilization Factor, UF
0.54
Maintenance Factor, MF
0.8
Lumen Calculation đ?‘Ź  đ?’™  đ?‘¨ đ?‘ľ =  đ?‘  đ?’™  đ?‘źđ?‘  đ?’™  đ?‘´đ?‘
= 19.2 = 6.0 = 4.5 m
=
200  x  115.2 2000  �  0.54  �  0.8
= 26.6 Â lights (take 26) 26 lights are needed to reach the minimum requirement of MS 1525 = 200 lux
Number of luminaires across = đ?‘ł Â đ?’™ Â đ?‘ľ đ?‘ž
19.2 Â đ?‘Ľ Â 26 6.0
= 9.12 (take 9) Therefore, each spacing would be 19.2 á 9 = 2.1  đ?‘š Â
Â
11 Â
Number of luminaires along đ?‘ž Â đ?’™ Â đ?‘ľ đ?‘ł
=
6.0 Â đ?‘Ľ Â 26 19.2
= 2.8 (take 3) Therefore, each spacing would be 6.0 á 3 = 2.0  đ?‘š Â
26 downlights are used to illuminate the book cafĂŠ to achieve a minimum of 200 lux as stated in MS 1525.
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ACOUSTICS Understanding sound pressure level: SOUND PRESSURE LEVEL 90 dBA 80 dBA 75 dBA 70 dBA
DESCRIPTION Noisy workshop area Very loud traffic noise of passing lorries at 7.5 m distance, Passing car at 7.5 m distance, un-silenced wood shredder at 10 m distance Level close to a main road by day, quiet hair dryer at 1 m distance to ear
45 dBA
Noise of normal living; talking, or radio in the background
40 dBA
Quiet library - Distraction when learning or concentration is possible Very quiet room fan at low speed at 1 m distance Rustling leaves in the distance
35 dBA 10 dBA
The table below provides acceptable sound levels for various room types
3.0 ACOUSTICS
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3.1 External Noise Calculation ( Peak hours ) the external noises recorded during the site visit are as follows, Traffic Noise along Jalan Haji Salleb
: 80dB
Activity Noise from 5 foot path
: 50dB
Back Lane with park
: 70 dB
Intensity for Traffic Noise
Intensity for Activity Noise
Intensity for Back Lane Noise
80 = 10 log (Itraffic/ Io) Antilog 8.0 = Itraffic/ 1 x 10-12 Itraffic = 1 x 10-4
50 = 10 log (Itraffic/ Io) Antilog 5.0 = Itraffic/ 1 x 10-12 Itraffic = 1 x 10-7
70 = 10 log (Itraffic/ Io) Antilog 7.0 = Itraffic/ 1 x 10-12 Itraffic = 1 x 10-5
Total Intensities, ITotal
Combined SPL,
= 1 x 10-4 + 1 x 10-7 + 1 x 10-5
= 10 log (ITotal/ Io)
= 1.1 x 10-4
= 10 log (1.1 x 10 -4 / 1 x 10-12) = 80 dB
The external noises which have a combined SPL of 80dB generated from traffic noise along Jalan Haji salleh, street activity noises along the 6 foot walkway and noises from the back lane travels into the library compound without passing through walls that will cause transmission loss. Therefore, the combined SPL of the external noise is approximately the total sound pressure level in the library. Conclusion: The required sound pressure level for a library for a sufficient reading environment is 35dB but the sound pressure level calculated has extremely exceeded at 80dB during peak hours. The zoning of the spaces and the levels of space usage are divided accordingly to counter this problem.
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External Noise Calculation ( NON Peak hours )
the external noises recorded during the site visit are as follows, Traffic Noise along Jalan Haji Salleb
: 70dB
Activity Noise from 5 foot path
: 30dB
Back Lane with park
: 60 dB
Intensity for Traffic Noise
Intensity for Activity Noise
Intensity for Back Lane Noise
70 = 10 log (Itraffic/ Io) Antilog 7.0 = Itraffic/ 1 x 10-12 Itraffic = 1 x 10-5
30 = 10 log (Itraffic/ Io) Antilog 3.0 = Itraffic/ 1 x 10-12 Itraffic = 1 x 10-9
60 = 10 log (Itraffic/ Io) Antilog 6.0 = Itraffic/ 1 x 10-12 Itraffic = 1 x 10-6
Total Intensities, ITotal
Combined SPL,
= 1 x 10-5 + 1 x 10-9 + 1 x 10-6
= 10 log (ITotal/ Io)
= 1.1 x 10-5
= 10 log (1.1 x 10 -5 / 1 x 10-12) = 70 dB
During non peak hours, with lesser traffic, The external noises which have a combined SPL of 70dB generated from traffic noise along Jalan Haji salleh, street activity noises along the 6 foot walkway and noises from the back lane travels into the library compound without passing through walls that will cause transmission loss. Therefore, the combined SPL of the external noise is approximately the total sound pressure level in the library. Conclusion: The required sound pressure level for a library for a sufficient reading environment is 35dB but the sound pressure level calculated still has extremely exceeded at 70dB.
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3.2 REVERBERATION TIME 3.2.1 - Multipurpose Creative studio (first floor) Reverberation Time Calculation The reverberation time of a room characterizes how long acoustic energy remains in a room. It is usually defined as the time for the acoustic intensity (or energy density) to decrease by a factor of one million (60 dB). Reverberation time is deliberated to define the space quality in relation to human comfort. Hence, the space chosen is the multipurpose studio room because all sorts of activities can be done here so an optimum acoustic surrounding is vital. The table below shows criteria for typical reverberation of spaces use Speech Multi-purpose music
Small rooms ( 750m3) 0.75 1.00 1.50
Medium room(7500m3) 0.75 – 1.00 1.00-1.25 1.50-2.00
Large rooms (>7500m3) 1.00 1.00-2.00 >2.00
First floor plan
Multi purpose creative studio Room Height: 3.5 m Standard Reveberation Time for multipurpose discussion room : less than 1 second Peak Hour Capacity : 30 people Volume of Multipurpose, (V): (7.8m x 8.9m) = 69.42M2 = 243 m3
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Components
Materials
Area (m2)
Wall Floor Ceiling Window and Door Chair Table Occupants
Concrete concrete Plaster Glass
31 70 70 54.6
Fabric timber
0.5(30 pax) 9.0( 5 tables ) 30 pax
Absorption Coefficient (2000Hz) 0.05 0.02 0.02 0.07
Area of Absorption Coefficient, (A) 1.55 1.4 1.4 3.82
0.28 (per seat) 0.3 0.46 Total
4.2 2.7 13.8 28.87
Area of wall = ( 8.9m x 3.5m ) = 31 m2 Area of carpet = ( 7.8m x 8.9m ) = 70 m2 Window Area = ( 7.8m x 3.5m ) = ( 27.3 x 2) = 54.6m2 RT = 0.16 V/A = 0.16 x 243/ 28.87 = 1.35s conclusion : The reverberation time for the Multipurpose room during peak hours is 1.35s in 2000Hz. According to the standards of reverberation time, the standard comfort reverberation time for a multipurpose room is 1.0, however given the moderate size of the space which is less than 250m2, 0.75s is adequate for a comfortable reading and interaction atmosphere. Hence the reverberation time of the area is slightly above the standard comfort reverberation time. In order to provide solution to this, there is a few changes that can be applied. A new baffle system is proposed on the ceiling as an acoustical blanket, with floating fiberglass sound absorbing panels that are faced in perforated metal, which increases the sound absorbing surface on the ceiling, decreasing the reverberation time. Another simple solution is to substitute or put a layer of acoustic carpet over the concrete flooring. Given the absorption coefficient of carpet for a frequency 2000Hz, which is 0.60, the reverberation time of the space can be recalculated as: Components
Materials
Area (m2)
Floor
Carpet
70
Absorption Coefficient (2000Hz) 0.60
Area of Absorption Coefficient, (A) 42
0.16 x 243/70 new reverberation time= 0.55s A simple solution such as decreasing impact sound on the flooring can provide various acoustic benefits as proven by the calculation, Accompanied by other materials and creative solution.
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REVERBERATION TIME CALCULATION
3.2.2 - ICT ROOM (second floor) The table below shows criteria for typical reverberation of spaces use Speech Multi-purpose music
Small rooms ( 750m3) 0.75 1.00 1.50
Medium room(7500m3) 0.75 – 1.00 1.00-1.25 1.50-2.00
Large rooms (>7500m3) 1.00 1.00-2.00 >2.00
ICT AND E-LEARNING ROOM
Room Height : 3.5 m Standard Reveberation Time for discussion rooms: less than 1 second Peak Hour Capacity: 30 people Volume of ICT room, (V): 13.4m x 9.5m = 127.3m2 volume = 445m3
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Components
Materials
Area (m2)
Wall Floor Ceiling Window and Door Chair Table Occupants
Concrete carpet Plaster Glass
78 108 108 82.3
Absorption Coefficient (2000Hz) 0.05 0.60 0.02 0.07
Fabric timber
3.0(30 pax) 17.76( 8 tables ) 30 pax
0.28 0.3 0.46
Area of Absorption Coefficient, (A) 3.9 64.8 2.16 5.76
0.84 5.3 13.8 Total 96.56
Area of wall = ( 3.6 x 3.5m ) + (5.7m x 3.5m) + ( 9.2m x 3.5m ) + ( 3.8m x 3.5m ) = 78m2 Area of glass = ( 14m x 3.5m ) + (7.8m x 3.5m ) + (2m x 3m ) = 82.3 m2 Area of tables = ( 3.7m x 0.6m ) x 8 = 17.76 m2
RT = 0.16 V/A = 0.16 x 445/ 96.56 = 0.737 conclusion : The reverberation time for the ICT hall during peak hours is 0.737s in 2000Hz. According to the standards of reverberation time, the standard comfort reverberation time for a silent ICT room is between 0.5 – 1.4s. Hence the reverberation time of the area is within the standard comfort reverberation time. The reverberation time is achieved via the application of acoustic materials which have high sound absorption properties such as carpet flooring, acoustic glass windows with air spacing, fabric furnitures etc.. If the reverberation time for ‘supposedly silent’ spaces is too large, such as computer rooms and reading rooms, the atmosphere would be too ‘lively’ and hence it will produce echo which would cause undesirable sound effects. In order to further adjust solve this issue, a baffle system can be installed on the ceiling to counter a lesser reverberation time, and a quieter acoustic environment.
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AESTHETIC AND EFFECTIVE PROPOSAL TO REDUCE REVERBERATION TIME In situations where materials with lesser absorption coefficient are used for flooring instead of carpet ( 0.60 ), the reverberation time would be much higher than that proposed above. In such situations, the following application can be adopted to reduce reverberation time, while using other materials such as concrete ( 0.05 ) and timber flooring. A baffle system is both functionable and an aesthetic approach to creating a subtle and comfortable acoustic environment. BAFFLE SYSTEM:
ADVANTAGES
• • • • • •
excellent acoustic properties in a wide spectrum, which can be altered, added or removed to meet required reverberation standards Open cell structure, which guarantees a high acoustic performance Safe to install because of low weight. Does not substantially increase the load on the structure, a significant advantage where a high quantity is required. Cost saving because of its efficient installation technique. Resistant against high humidity Does not age, and corrosion resistant materials are available which does not need Regular maintenance.
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3.3 TRANSMISSION LOSS CALCULATION 3.3.1 - CHILD CARE/CHILDREN READING ROOM The children reading room is located on the first floor at the front of the building to give a subtle view of the main street also looking inwards into the large interior void, with many floating reading pods aligned along the perimeter of the void/courtyard. Hence, it is exposed to the noises coming from the back road, as well as the sound from activities from the courtyard. Therefore, a good partition is needed to filter and absorb the sound waves before it enters the space.
TL = 10 Log Tav =
1 Tav
T1 × A1 + T2 ×A2 + T3 ×A3 +…(Tn×An) Total Surface Area
Tcn = the transmission coefficient of material Sn = the surface area of the material n
Assuming the external noise from Jalan Haji Salleh( main road) is 80dB, the minimum interior noise required for a discussion room is 40dB. Therefore, the transmission loss should be 27dB.
Components
Materials
Area (m2)
Curtain Wall Wall
Glass Concrete
57.5 36.4
Sound Reduction Index (SRI) 35 42
Transmission Coefficient of Materials Curtain Wall SRI (glass)
= 10 log (1/ Tglass)
35
= 10 log (1/ Tglass)
Antilog 3.5
= 1/ Tglass
Tglass
= 3.16 × 10-4
Wall
21
SRI (concrete) = 10 log (1/ Tconcrete) 42
= 10 log (1/ Tconcrete)
Antilog 42
= 1/ Tconcrete
Tconcrete
= 6.31 Ă— 10-5
Average Transmission Coefficient of Materials
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đ?‘†1đ?‘‡đ?‘?1 + đ?‘†2đ?‘‡đ?‘?2 ‌ ‌ đ?‘†đ?‘›đ?‘‡đ?‘?đ?‘› đ?‘‡đ?‘œđ?‘Ąđ?‘Žđ?‘™  đ?‘†đ?‘˘đ?‘&#x;đ?‘“đ?‘Žđ?‘?đ?‘’  đ??´đ?‘&#x;đ?‘’đ?‘Ž
3.16  ×  10!! +  6.31  ×  10!! ��� =  57.5 + 36.4
         = 4.0�10!!
Total Sound Reduction index, SRI SRI = 10 log
1 Tav
= 10 log (1/ 4.0 x 10-6) = 53.9 dB
Noise level in Child care room = 80 dB – 53.9 dB = 26.1 dB
Proven from the calculation, the external noise from the front lane and interior courtyard, 80dB is reduced by 53dB during transmission, resulting in a sound level of 26.1dB when it reaches the interior of the children reading room . 26.1 dB is within the range of recommended level for a childcare room. Hence the acoustical comfort can be achieved by having double glazed curtain walls and concrete walls as external sound barriers.
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SOUND TRANSMISSION LOSS 3.3.2 SILENT READING ROOM The silent reading room is located on the third floor at the back of the building to give a subtle view of the back street park and greenery,. Hence, it is exposed to the noises coming from the back road, as well as the sound from the Av room next door. Therefore, a good partition is needed to filter and absorb the sound waves before it enters the this space, which required a very quiet reading environment.
TL = 10 Log Tav =
1 Tav
T1 × A1 + T2 ×A2 + T3 ×A3 +…(Tn×An) Total Surface Area
Tcn = the transmission coefficient of material Sn = the surface area of the material n
Assuming the external noise from the back street is 75 dB, the minimum interior noise required for a silent reading room is 30dB. Therefore, the transmission loss should be 45dB.
Components
Materials
Double glazed Curtain Glass Wall Wall Concrete
Area (m2) 56.7
Sound Reduction Index (SRI) 30
32.55
42
Transmission Coefficient of Materials Curtain Wall SRI (glass)
= 10 log (1/ Tglass)
30
= 10 log (1/ Tglass)
Antilog 3.0
= 1/ Tglass
Tglass
= 1x10-3
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Concrete Wall SRI (concrete) = 10 log (1/ Tconcrete) 42
= 10 log (1/ Tconcrete)
Antilog 42
= 1/ Tconcrete
Tconcrete
= 6.31 Ă— 10-5
Average Transmission Coefficient of Materials
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đ?‘†1đ?‘‡đ?‘?1 + đ?‘†2đ?‘‡đ?‘?2 ‌ ‌ đ?‘†đ?‘›đ?‘‡đ?‘?đ?‘› đ?‘‡đ?‘œđ?‘Ąđ?‘Žđ?‘™  đ?‘†đ?‘˘đ?‘&#x;đ?‘“đ?‘Žđ?‘?đ?‘’  đ??´đ?‘&#x;đ?‘’đ?‘Ž
1×10!! +  6.31  ×  10!! ��� =  56.7 + 32.5
= 1.19Ă—10!!
Total Sound Reduction index, SRI SRI = 10 log
1 Tav
= 10 log (1/ 1.19Ă—10!! ) = 49.24
Noise level in Child care room = 80 dB – 49.24 dB = 25.76 dB
Proven from the calculation, the external noise from the back lane and adjacent AV room, 75dB is reduced by 49dB during transmission, resulting in a sound level of 25.76dB when it reaches the interior of the Silent reading room . 25.76 dB is within the range of recommended level for a quit library space. Hence the acoustical comfort can be achieved by having double glazed curtain walls and concrete walls as external sound barriers.
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