ARC3413 BUILDING SCIENCE 2
PROJECT 1: LIGHTING & ACOUSTIC PERFORMANCE EVALUATION AND DESIGN Wanaka the bungalow
No.22, Lorong Dungun, Damansara Heights, Kuala Lumpur.
GROUP MEMBERS: GARNETTE DAYANG ROBERT
0315491
JOLENE HOR WEI FERN
0313751
TE LI THENG (JUSTINE)
0314198
OOI ZHI-QIAN (JANE)
0313999
CRYSTALLINA ALECIA KAYA
0318742
MAHI ABDUL MUHUSIN
0314421
DANAR JOVIAN ADITYA PUTRA
0314575
TUTOR:
MR. EDWIN CHAN YEAN LIONG
SUBMISSION DATE: 9TH MAY 2016
TABLE OF CONTENT abstract 1.0 introduction
1.1 Aim and Objectives 1.2 Site Study 1.2.1 Introduction 1.2.2 Reason for Selection 1.2.3 Measured Drawings
2.0 lighting 2.1 Literature Review 2.1.1 INTRODUCTION TO LIGHT 2.1.2 IMPORTANCE OF LIGHT IN ARCHITECTURE 2.1.3 LUMEN 2.1.4 ILLUMINANCE 2.1.5 NATURAL DAYLIGHTING 2.1.6 ARTIFICIAL DAYLIGHTING 2.1.7 DAYLIGHTING FACTORS AND DISTRIBUTIONS 2.1.8 LUMEN METHOD 2.2 METHODOLOGY 2.2.1 PRECEDENT STUDIES 2.2.2 PREPARATION 2.2.3 MEASURING DEVICE 2.2.4 DATA COLLECTION 2.3 PRECEDENT STUDY 2.3.1 introduction to the building 2.3.2 floor plans 2.3.3 building design intenetion 2.3.4 lighting and daylight evaluation 2.3.5 methodolgy 2.3.6 recommendation 2.3.7 illuminance measurements 2.3.8 daylighting measurements 2.3.9 design interiors to maximize day lighting contribution 2.3.10 considerations from the analysis of cambria office building
1
2.4 NATURAL LIGHTING 2.4.1 DATA COLLECTION 2.4.2 DAYLIGHT FACTOR ANALYSIS 2.4.3 2.5 ARTIFICIAL LIGHTING 2.5.1 LIGHTING SPECIFICATIONS 2.5.2 LUMEN METHOD CALCULATION 2.6 analysis and lighting conditions of the zones 2.5.1 Improvements of Lighting 2.5.2 Limitations of Lighting 2.6 Conclusion
3.0 acoustic performance 3.1 Literature Review 3.1.1 introduction to acoustic 3.1.2 architecture acoustic 3.1.3 sound pressure level 3.1.4 reverberation time 3.1.5 sound reduction index 3.2 methodology 3.2.1 precedent studies 3.2.2 preparation 3.2.3 measuring device 3.2.4 data collection 3.3 precedent study 3.3.1 introduction to the building 3.3.2 floor plan indicating cafe 3.3.3 reverberation analysis 3.3.4 analysis of sound transmission class (stc) 3.3.5 new proposed baffled system 3.3.6 conclusion
3.4 Case Study 3.4.1 OUTDOOR NOISE SOURCE 3.4.2 TABULATION OF DATA 3.4.3 INDOOR NOISE SOURCE 3.4.4 ACOUSTICS FIXTURE & SPECIFICATION 3.4.5 CALCULATION OF SIL 3.4.6 ZONING OF SPACE 3.4.7 CACULATION 3.4.8 TABULATION 3.4.9 ANALYSIS AND CONCLUSION 3.4.10 REVERBERATION TIME 3.4.11 SOUND REDUCTION INDEX 3.4.12 ANALYSIS CONCLUSION 3.5 Site Evaluation 3.5.1 Improvements of Acoustic Performance 3.5.2 Limitations of Acoustic Performance 3.6 Conclusion
References Appendix
1.0
Introduction
Lighting at work is an important issue as it affects the health and safety of the building’s occupants. Hazards are more easily avoided with good lighting. Poor lighting within the building could cause health issues such as migraine, eyestrain, and headaches. Suitable lighting is necessary to create the optimum environmental conditions for maximum productivity of the workers. Acoustics design is another important factor in order to control the levels of noise within different spaces. Requirements for every space differ based on its function. A good acoustic design preserves the desired noise and eliminates the unwanted sound to provide a comfortable environment for the users. In a group of seven, we have chosen the Wanaka Bungalow as our site of study. We visited the place several times in order to collect all the necessary data, which include measured drawings of the plan, measurement of lighting and acoustics.
1.1
aims and objectives
The aim and objectives are as followings: • To understand the day-lighting, artificial lighting and acoustic characteristic. • To determine the characteristics and function of day-lighting & artificial lighting and sound & acoustic within the intended space. •
To critically report and analyse the space and suggest ways to improve the lighting and acoustic qualities within the space.
•
To also be able to produce a complete documentation on analysis of space in relation to lighting requirement.
To able to evaluate and explore the improvisation by using current material and
•
technology in relevance to present construction industry.
This projects also aims to help us to get basic understanding and analysis of lighting and acoustics design layout and arrangements by using certain methods or calculations. We will be choosing three spaces and by understanding the volume and area of each functional space will also help in determining the lighting requirements based on acoustical or lighting inadequacy that is reflected in the data collection.
1.3
REASON OF CHOICE Located in Damansara Heights, Kuala Lumpur, the Wanaka was once a bungalow
residence, which was then converted into an office. On some occasions, the house is used to hold small events and functions such as wedding receptions. This makes the building more interesting to study as we get to understand the lighting and acoustic in a space used for different functions. Besides that, we chose this building as a place to conduct our studies because of location that is strategic, and has a lot of potential in terms of our studies. It’s located right beside the road, which is interesting because then the acoustics would play an important role in this house as well as the light penetration within the building. We wanted to study how much the noise from the road affected the acoustic and noise in the building. There are many opening as well in the building which allow light to light the place. There is even an oculus at one part of the building which allow a lot of natural daylighting to the space. Materials installed interiorly create an ambiance, which differs each room’s ambiance and creates different kinds of usage for each room. However, since it was originally designed as a residential space rather than an office space which is what it is used as today, the lighting and acoustic standards might not be met or might be too high compared to the standards. Therefore, we have decided that this building was very suitable to conduct our lighting and acoustic
studies.
3.1
ACOUSTIC Literature Review
3.1.1
Introduction to ACOUSTIC
Acoustics is the branch of physics or the science concerned with the production, control, transmission, reception, and effects of sound. Its origins began with the study of mechanical vibrations and the radiation of these vibrations through mechanical waves in gases, liquid and solid, and still continues today. Research was done to look into the many aspects of the fundamental physical processes involved in waves and sound and into possible applications of these processes in modern life. Many people mistakenly think that acoustics is strictly musical or architectural in nature. While acoustics does include the study of musical instruments and architectural spaces.
3.1.2
architecture ACOUSTIC
Architectural acoustics is concerned with improving the sound in rooms: we might want to reduce the background noise in a recording studio; improve the design of a public address system to make speech more intelligible in railway stations, or put acoustic treatments on walls to make music in a concert hall sound better. We carry out research into new methods for measuring and predicting how sound moves within rooms and buildings such as schools and auditoria. Another key element is measuring peoples’ responses to sound so we can understand what people want from a room design. This enables us to develop innovative ways to design rooms and building elements.
3.1.3
Sound intensity level
Sound intensity is measured as a relative ratio to some standard intensity, lo. The response of the human ear to sound waves follows closely to a logarithmic function of the form R = k log I, where R is the response to a sound that has an intensity of I, and k is a constant of proportionality. So, the formula of the sound intensity level is
The formula: đ?‘şđ?‘°đ?‘ł = đ?&#x;?đ?&#x;Ž đ?’?đ?’?đ?’ˆđ?&#x;?đ?&#x;Ž Â
3.1.4
đ?‘° đ?‘°đ?’?
Reverberation time
Reverberation time (RT) is defined as the length of time required for sound to decay from its initial level. This study is the most important factor for acoustical engineers and architects when assessing a space with noise problems. A reverberation is created when a sound or signal is reflected causing a large number of reflections to build up and then decay as the sound is absorbed by the surface of objects in the space including the furniture, the people and the air. This happens when the reflection of the sound continues even when the source of the sound has already stopped, also causing a decrease in its amplitude until it reaches zero.
The formula: đ?‘šđ?‘ť =
đ?&#x;Ž.đ?&#x;?đ?&#x;”đ?‘˝ đ?‘¨
where RT is reverberation time, s V is volume of the room, đ?‘š! A is absorption coefficient
Every architectural space needs to have its own analysis of specific reverberation time in order to achieve its optimum performance based on the function of the space. For example, spaces with a higher RT would encounter problems with noise as sound travels room with a high RT generally has a problem with noise as sound travels for long distances without being absorbed. Rooms with a high RT almost always have an issue with echo as sound is reflected from hard surface to hard surface.
3.1.5
Sound reduction index
Sound Reduction Index is used to measure the level of sound insulation provided by a structure such as a wall, window, door, or ventilator. The understanding of a sound reduction index is important to incorporate acoustic system design into a given space to decrease the possibility of sound from permeating from a loud space to a quiet space.
đ?&#x;?
The formula: đ?‘şđ?‘šđ?‘° = đ?&#x;?đ?&#x;Ž đ??Ľđ??¨đ??  (đ?‘ť)
where SRI is sound reduction index, dB T is transmission of sound frequency
3.2 Methodlogy 3.2.1
PRECEDENT STUDIES
Precedent study chosen helps to have a better understanding how surrounding sound, materials, appliances affects the acoustics of a certain space.
 3.2.2 preparations 1.
Preliminary study and identification of the type of spaces were studied to choose the suitable case study.
2.
Precedent studies were done to have a better understanding of how acoustics functions and affecting my the surrounding in a certain space.
3.
In obtaining approval to use site as case study, visitations, calls and emails were made to the different chosen places.
4.
The plan drawings were obtained from the management office.
5.
The spaces were determined.
6.
Grid lines with distance of 1.5m was plotted on the plan for recording purposes.
7.
Sound level meter meter was supplied by tutors.
8.
The equipment was tested before attending the site visit.
9.
A basic standard and regulations such as CIBSE, ASHRAE and MS1525 were also studied before hand to analyze and compare the readings later on.
Â
3.1.3
Measuring device
Figure 3.2a - Sound level meter
Figure 3.2b - Digital Single Lens Reflex 3.1.4
data collection
Data were collected at non peak hours between 10am-12pm and 5pm-6pm, and peak hours between 2pm-4pm. The acoustics’ readings were taken according to the intersection of the grid lines at 1m above ground. It was ensured that the sound level meter stabilizes with the surrounding noise before the readings were taken. The noise source, furnitures and materials used in the spaces were analyzed and recorded as these may affect the sound level recorded.
3.3 precedent studies 3.3.1 introduction to the building
MUSIC CAFÉ, AUGUST WILSON CENTRE FOR AFRICAN AMERICAN CULTURE Prominently located on Liberty Avenue, The August Wilson Center for African American Culture is designed to be a signature element of downtown Pittsburgh. Rich materials and bold geometric forms set the stage for a magnificent cultural experience in which any visitor is sure to participate. It is timeless, flexible and powerful in its simplicity The facility is a center for the visual and performing arts for international music and education. Designed by Perkins+Will, the two-story, 64,500 gsf facility includes a 486-seat proscenium theater, 11,000 gsf of exhibit galleries, a flexible studio, a music café, and an education center. The building exploits the solar orientation of this tight triangular urban infill. The north facing façade takes full advantage of this limited solar exposure with a predominately glass wall that is transparent yet able to incorporate graphics and projected images, visually permeable by day and a stage for dramatic lighting at night. The acoustic properties of the Music Café has been analyzed and a new design has been proposed with dimensions, to compare and make a conclusion about the features that can enhance the existing acoustic design. As a signature building filled with performance spaces, the acoustics of the August Wilson Center are a key element to the building’s success and function.
Figure 3.3a - View from Liberty Avenue of the existing design for the August Wilson Cente
DESIGN INTENTION MULT-IPURPOSE MUSIC CAFÉ, AUGUST WILSON CENTRE
Figure 3.3b- Interior perspectives of music cafe
The café is located transparent to the sidewalk, accessible directly from the street and also from within the center. The music café’ is designed to function as a multi purpose space as both a traditional museum café and sidewalk café during the day. A seating terrace is located outside and adjacent to the café. Wired for Internet access and designed to accommodate a wide range of emerging technologies, the Café provides an electronic link to visitors worldwide. The Café’ also function as an alternative performance space for intimate performances for special occasions such as indoor jazz concerts , spoken word, poetry and other new performance in a club setting at night.
Figure 3.3c - Interior of music cafe
3.3.2 FLOOR plan indicating cafe
SPACE DESCRIPTION
Diagram 3.3a - First floor plan of august wilson centre indicating the location of the music café
The music café’ is a large rectangular box covered by glass walls, a hard floor, and sound absorbing treatment on the ceiling behind baffles and ductwork. The space is designed to acknowledge the café’s mechanical and natural sound produced, need for acoustical design elements, with hanging metal baffles and acoustical blanket over 80% of the underside of the floor structure above. Based on the user description provided by the architect of August Wilson center, a reverberation time of approximately 1.0 second is ideal for such multi-purpose spaces. This would place the space somewhere between speech and speech/music use. According to the Architectural Acoustics: Principles and Design a significally high STC value of over 60+ is desirable across the music café and the user lobby. This is important to both spaces, as two different functions might simultaneously be carried out in either space. A spoken word performance or a public speech performance in the café could be disturbed if a large crowd was gathering in the lobby for a performance in the main theater causing noise diffusion into the café. Similarly, the lobby must remain quiet during a performance in the main theater if patrons are entering or exiting the auditorium since a main set of doors is directly across from the café. This function is very important as it relates back to our chosen site, where spaces are multi functionary and divided by shared walls, which do not separate the spaces completely.
3.3.3 reverberation analysis Reverberation is the persistence of sound after a sound is produced. A reverberation, or reverb, is created when a sound or signal is reflected causing a large number of reflections to build up and then decay as the sound is absorbed by the surfaces of objects in the space – which could include furniture, people, and air. The reverberation times for the music cafe’ were calculated in order to understand how the space achieves its acoustic function
Diagram 3.3b - Music Café Reflected Ceiling Plan – Existing Design
Table 3.3a - Music Café Reverberation Time – Existing Design.
Figure x illustrates that the existing reverberation times do not support the ideal time recommended for such spaces. One important consideration, however, is that the acoustical data of the metal baffle ceiling system (Chicago Metallic) is not regarded in the measurements as it is not provided by the manufacturer. Including the baffles in the calculation would reduce the very high reverberation times at the lower frequencies, but it would also reduce the reverberation times at the higher frequencies, which are already lower than ideal number for the space, in relation to its usage.
3.3.4 analysis of sound transmission class (stc) Sound Transmission Class (or STC) is an index rating of how well a building partition attenuates airborne sound. Analysis of the sound transmission class (STC) on the wall between the café and the main lobby reveals a potential for unwanted noise transfer between the two spaces. At 46, the calculated STC falls far below the ideal value of 60+. This problem is generated due to the use of glass doors and partitions between the spaces instead of proper separating walls. Changing the glass type from 1⁄2” tempered glass to 1⁄2” laminated glass improves the STC to 49, but this is only a marginal increase. To really improve this potentially negative situation, architectural changes can be applied to counter the passage of unwanted noises. Figure 3.3d – Proposed baffle system
These changes may include changing the glass to another material such as wood or creating a small vestibule at the entrances.. Adding absorptive insulation (e.g., fiberglass batts, blow-in cellulose, recycled cotton denim batts) in the wall cavity increases the STC for fiberglass to more than 50 with cotton denim, depending on stud and screw spacing. Doubling up the drywall in addition to fiberglass insulation can yield an even higher STC provided the wall gaps and penetrations are sealed properly In contrast to that, improving the reverberation time is a much more realistic change. In order to do this, a new baffle system is proposed by eliminating the metal baffles and acoustical blanket, replacing them with floating fiberglass sound absorbing panels that are faced in perforated metal.
Figure 3.3e - Existing hanging metal baffle system from Chicago Metallic.
3.3.5 new proposed baffled system
Diagram 3.3c - Music Café Reflected Ceiling Plan – New Design
Table 3.3b - Music Café Reverberation Time – New Design
Table 3.3c - Music Café New Baffle Schedule of Materials
3.3.6 conclusion The proposed solution for improving reverberation times is both economical and aesthetically pleasing for the analyzed space, the multi-purpose music cafe. The noise reduction qualities of the barriers separating these spaces from the lobbies that surround them have also been identified as problematic, but solutions to these problems are far more complex and are not feasible within the current architectural design. As a designer working with an architect, it is ultimately the architect’s decision to maintain a visual quality or sacrifice appearance for performance. Although it successfully delivers as a visual treat and a convenient resting spot for cafÊ-goers and music lovers, the music cafÊ does not acoustically deliver to its maximum potential. Proposals for a better acoustic system would be also be in terms of materiality. Improving the reverberation time by eliminating the metal baffles and acoustic blanket and replacing them with floating fiberglass sound absorbing panels that are faced in perforated metal seems like the ideal option to counter this problem. The new reverberation times are very close to the ideal values that are optimum as acoustic reverberation. According to Architectural Acoustics: Principles and Design optimum reverberation times at 125 hertz should be 1.3 times the ideal reverberation time at 500 hertz and a multiplier of 1.15 should be used at 250 hertz. These multipliers are used to correct for the fact that the human ear is less sensitive at lower frequencies. With these factors included, the new design is very near the target. The new ceiling system will provide superior acoustical performance at a reduced cost. Overall, the biggest challenge in analyzing and working with the systems of the August Wilson Center has been the unique character of the architecture. The spaces created are far from standard and certainly strive to embody signature qualities. However, as is often the case, this unyielding visual character makes the engineering of the building systems a complex task.
3.4 site study 3.4.1
outdoor noise source
Precedent study chosen helps to have
3.4.2 tabulation of data
Diagram 3.4a – Ground Floor Plan – Office 1
DATE: 27th April 2016
DATE: 27th April 2016
TIME: 10am-12pm
TIME: 2pm- 4pm
HEIGHT: 1.5m
HEIGHT: 1.5m
GRID
A
B
C
D
E
F
GRID
A
B
C
D
E
F
1
43
43
43
45
50
48
1
45
45
44
50
53
55
2
43
43
43
45
51
51
2
45
48
47
55
55
57
3
45
45
45
48
50
3
47
50
49
57
57
4
48
48
48
48
50
4
52
52
52
62
68
5
48
48
48
5
57
58
58
6
45
45
45
6
56
58
58
7
45
45
45
7
55
56
56
Table 3.4a – Data tabulated for Office 1
Diagram 3.4b – Ground Floor Plan – Office 2
DATE: 27th April 2016
DATE: 27th April 2016
TIME: 10am -12pm
TIME: 2pm -4pm
HEIGHT: 1.5m
HEIGHT: 1.5m
GRID
A
B
C
D
E
F
GRID
A
B
C
D
E
F
8
45
45
48
45
45
45
8
47
51
51
59
57
55
9
45
45
48
45
45
45
9
50
53
53
55
56
57
10
48
50
48
50
50
10
55
55
55
60
66
11
48
50
50
50
11
55
55
60
66
48
50
57
60
12
12
Table 3.4b – Data tabulated for Office 2
Diagram 3.4c – Ground Floor Plan – Kitchen
DATE: 27th April 2016
DATE: 27th April 2016
TIME: 10am – 12pm
TIME: 2pm – 4pm
HEIGHT: 1.5m
HEIGHT: 1.5m
GRID
D
E
F
GRID
D
E
F
5
45
48
45
5
63
66
63
6
45
48
45
6
68
73
70
7
45
48
45
7
65
70
71
Table 3.4c – Data tabulated for Kitchen
Diagram 3.4d – Ground Floor Plan – Foyer
DATE: 27th April 2016
DATE: 27th April 2016
TIME: 10am – 12pm
TIME: 2pm – 4pm
HEIGHT: 1.5m
HEIGHT: 1.5m
GRID
C
D
E
F
GRID
C
D
E
F
3
50
50
55
54
3
55
60
74
58
4
50
50
60
56
4
55
60
68
60
5
43
43
45
5
70
60
60
6
43
43
48
6
60
70
75
Table 3.4d – Data tabulated for Foyer
3.4.3 indoor noise source
AIR CIRCULATORS
Figure x – Placement of fans in First Floor
Fans are essential in buildings in order to circulate the air in the rooms as well as cool down the air. These are highly efficient air moving devices. Fans are placed in both the stair way and foyer In order to provide a cool entrance and a comfortable and conductive foyer space for visitors. The fans produce a certain amount of noise in these rooms compared to the air conditioners. Air conditioners produce less noise pollution compared to fans. Fan noise levels however can be reduced by replacing or maintaining them on a regular schedule. Additional energy losses and noise is produced when fan motors are operated in higher loads. A small, perfectly balanced, clean, modern ceiling fan in pristine condition should be whisper quiet. But the reality is that with almost any ceiling fan, over time the weight shifts, the blades move slightly, and screws can loosen, meaning that without skilled care, they’re probably going to go from a quiet whirr to a slightly more pronounced motor sound that could keep light sleepers awake or be slightly distracting in a quiet room.
Figure x – Placement of fans in ground floor
The ground floor has a combination of both fans and air conditioners. Running a ceiling fan and an air conditioner at the same time can increase room comfort as well as save energy. The windows of the air conditioned rooms and offices are usually closed, due to this less outside sound enters the rooms. Even the noise from the air-conditioners are fairly low. Due to this there is quietness inside the rooms. The noise inside the air conditioned room can be further reduced by soundproofing the room.
HUMAN ACTIVITY
figure x – Nodes of Human Activity in First floor
The human noise in the first floor is caused in the stairway which is a circulation node and also in the entrance of the foyer contributed by exterior noise by human activity outside.
figure x - Nodes of Human Activity in the Ground Floor
The nodes of human activity on the Ground floor is contributed mainly by the Office spaces and the kitchen, which is also used a multi-purpose meeting room. Since the offices are used for telecommunication operation, outsourcing information, the noise production is fairly moderate throughout the day, slightly rising during peak hours.
3.4.4 acoustics fixture and specification acoustic equipment specifications
Name of Unit Model Total Cooling Capacity (Btu / h) Input Power (W) Running Current (A) Power Source ( V/Ph/Hz ) Refrigerant Type / Control Indoor Air Flow ( Cfm ) Sound Pressure Level ( Dba ) Unit Dimension ( Panel ) – H x W x D ( mm ) Indoor Unit Outdoor Unit Unit Weight ( kg ) Indoor Unit Outdoor Unit
Ceiling Cassette Unit Yck 10C 10000 942 4.16 220 – 240 / 1 / 50 R-22 / Outdoor Cap. Tube 410 41 250 x 570 x 570 ( 20 x 640 x 640 ) 540 x 700 x 250 16 + 2 29
Name of Unit Model Total Cooling Capacity (Btu / h) Input Power (W) Running Current (A) Power Source ( V/Ph/Hz ) Refrigerant Type Indoor Air Flow ( Cfm ) Sound Pressure Level ( Dba ) Unit Dimension ( Panel ) – H x W x D ( mm ) Indoor Unit Outdoor Unit Unit Weight ( kg ) Indoor Unit Outdoor Unit
Ceiling Suspended Unit ACM 10 C/ALC 10C 10000 942 4.16 220 – 240 / 1 / 50 R-22 300 41 235 x 824 x 666 ( 305 x 910 x 730 ) 540 x 700 x 250 30 28
Name of Unit Model Total Cooling Capacity (Btu / h) Input Power (W) Running Current (A) Power Source ( V/Ph/Hz ) Refrigerant Type Indoor Air Flow ( Cfm ) Sound Pressure Level ( Dba ) Unit Dimension ( Panel ) – H x W x D ( mm ) Indoor Unit Outdoor Unit Unit Weight ( kg ) Indoor Unit Outdoor Unit
Wall Mounted Unit AWM 10NP – ALC 10CN 10000 980 4.16 220 – 240 / 1 / 50 R-22 342 38 288 x 800 x 203 ( 340 x 874 x 274 ) 494 x 600 x 245 9 25
Name of Unit Model Colour Blade Size Dimension Fan Size ( cm ) Low High Air Delivery ( m3 / min ) Low High Motor HP Motor Type Noise Level ( dB ) Nett Weight ( kg ) Length from pully to PCB cover ( mm ) Length from pully to blade ( mm )
Regulator 3 Blades Ceiling Fan F-M 15A0 (60”) White 150 cm ( 60” ) 1500 mm ( W ) x 439 mm ( H ) 81 – 118 216 – 264 15 – 20 67 – 82 0.11 14 Pole Condenser Motor <54 7.3 439 348
3.4.5 calculation of sound intensity level Office 1 Non-peak hour Highest reading: 51dB SIL
=
51
= 5.1
10
=
I , Iref 1ref =1x10 I 10 log Iref
10 log
−12
I -12
1x10
I
=
−7
1.259x10
Lowest reading : 43dB SIL
=
43
= 4.3
10
=
I
I , Iref 1ref =1x10 I 10 log Iref
10 log
−12
I -12
1x10 =
−8
1.995x10
Total intensity = 1.259x10−7 + 1.995x10−8 = 1.459x10−7 Total SIL
= 10 log = 52dB
1.459x10- 7 1x10- 12
Peak hour Highest reading : 68dB SIL
=
68
= 6.8
10
=
I , Iref 1ref =1x10 I 10 log Iref
10 log
−12
I -12
1x10
I
=
−6
6.310x10
Lowest reading : 62dB SIL
=
62
=
10
=
I
=
6.2
I , Iref 1ref =1x10 I 10 log Iref
10 log
−12
I -12
1x10
−6
1.585x10
Total intensity = 6.310x10−6 + 1.585x10−6 = 7.895x10−6
Total SIL
= 10 log
7.895x10- 6 1x10- 12
= 69dB
The average noise level during peak hours is higher compared to the average noise data collected during non-peak hours. The drastic change of sound level occurs in office 1 is due to the amount of people occupying the space.
Office 2 Non-peak hour Highest reading : 50dB SIL
=
50
=
10
=
I
=
5
I , Iref 1ref =1x10 I 10 log Iref
10 log
−12
I -12
1x10
−7
1x10
Lowest reading : 45dB SIL
=
45
= 4.5
10
=
I Total intensity
Total SIL
I , Iref 1ref =1x10 I 10 log Iref
10 log
−12
I -12
1x10 =
−8
3.162x10
= 1.259x10−7 + 1.995x10−8 = 1.459x10−7
1.459x10- 7 = 10 log 1x10- 12 = 52dB
Peak hour Highest reading : 66dB SIL
=
66
= 6.6
10
=
I
=
I , Iref 1ref =1x10 I 10 log Iref
10 log
−12
I -12
1x10
−6
3.981x10
Lowest reading : 57dB SIL
=
10 log
I , Iref 1ref =1x10
57
=
10 log
I Iref
5.7
10
=
I
=
Total intensity
Total SIL
−12
I -12
1x10
−7
5.012x10
= 3.981x10−6 + 5.012x10−7 = 4.482x10−6
4.482x10- 6 = 10 log 1x10- 12 = 67dB
The average noise level during peak hours is higher compared to the average noise data collected during non-peak hours. The drastic change of sound level occurs in the office 2 due to the amount of people occupying the space.
Kitchen Non-peak hour Highest reading : 48dB SIL
=
48
=
I , Iref 1ref =1x10 I 10 log Iref
10 log
10
=
I
= 6.310x10
4.8
−12
I -12
1x10 −8
Lowest reading : 45dB SIL
=
10 log
I , Iref 1ref =1x10
45
=
10 log
I Iref
10
=
I
=
4.5
−12
I -12
1x10
−8
3.162x10
Total Intensity = 6.310x10− 8 + 3.162x10− 8 = 9.472X10− 8 Total SIL
-8 = 10 log 9.472x10 1x10- 12 = 51dB
Peak hour Highest reading : 73dB SIL 73
= =
7.3
10
10 log
10 log
=
I , Iref 1ref =1x10
−12
I Iref
I -12
1x10
I
= 1.995x10−5
Lowest reading : 65dB SIL
=
10 log
I , Iref 1ref =1x10
65
=
10 log
I Iref
6.5
10
=
I
−12
I -12
1x10 =
−6
3.162x10
Total intensity = 1.995x10−5 + 3.162x10−6 = 2.311x10−5
Total SIL = 75dB
2.311x10- 5 = 10 log 1x10- 12
The average noise level during peak hours is higher compared to the average noise data collected during non-peak hours. The drastic change of sound level occurs in the kitchen due to the amount of people occupying the space.
Foyer Non-peak hour Highest reading :60dB SIL
=
10 log
I , Iref 1ref =1x10
60
=
10 log
I Iref
6
10
=
−12
I -12
1x10
I
=
−6
1x10
Lowest reading :56dB SIL
=
10 log
I , Iref 1ref =1x10
56
=
10 log
I Iref
5.6
10
=
I
Total intensity
−12
I -12
1x10 =
−7
3.981x10
= 1x10−6 + 3.981x10−7 = 1.398x10−6
Total SIL
1.398x10- 6 = 10 log 1x10- 12 = 62dB
Peak hour
Highest reading : 70dB SIL
=
10 log
I , Iref 1ref =1x10
70
=
10 log
I Iref
7
10
=
I
−12
I -12
1x10 =
−5
1x10
Lowest reading : 68dB SIL
=
10 log
I , Iref 1ref =1x10
68
=
10 log
I Iref
6.8
10
=
I
=
Total intensity
−12
I -12
1x10
−6
6.310x10
= 1x10−5 + 6.310x10−6 = 1.631x10−5
Total SIL
= 10 log
1.631x10- 5 1x10- 12
= 72dB
The average noise level during peak hours is higher compared to the average noise data collected during non-peak hours. The drastic change of sound level occurs in the foyer due to the amount of people occupying the space.
3.4.6 calculation of sound reduction index ZONE 1 & ZONE 3
Building element
Material
44
3.981x10
Door
Polished wood
28
1.585x10
= 10 log ( 1 )
44
= 10 log ( 1 )
T T
4.4
=(1)
T
= 3.981x10−5
Area, S ( m2 )
Coefficient, T
Concrete plaster with finishes
TL
T
Transmission
Wall
Concrete Wall
10
Sound Reduction Index, SRI (dB)
−5
23.238
−3
1.932
Door TL
= 10 log ( 1 )
28
= 10 log ( 1 )
T T
2.8
10
=(1)
T
T
= 1.585x10−3
T
av
= ( 3.981x10− 5 x 23.238) + ( 1.585x10− 3 x 1.932) / 25.17 = 3.987x10− 3 / 25.17 = 1.584x10− 4
Overall SRI
= 10 log ( 1 )
T
= 10 log (
1 1.584X10- 4
)
= 38dB
The sound intensity level data calculated during peak hour in zone 1 is 69dB whereas zone 3 is 75dB. Based on the overall SRI, this shows that the sound level in these zones are able to reduce to 38dB. This may be due to the air gap that exist between the walls and also the door that is usually closed. The sealed door of Zone 3 (dry kitchen) occupying some of the area of a concrete wall reduces the average SRI of that wall from 44 dB to 38 dB. The final sound insulation is influenced by relative areas but is always closer to the insulation of the poorer component than to the better component.
ZONE 2 & ZONE 3
Building element
Material
Concrete plaster with finishes
Wall
Concrete Wall TL
= 10 log ( 1 )
44
= 10 log ( 1 )
T T
4.4
10 T
=(1)
T
= 3.981x10−5
Sound Reduction Index, SRI (dB)
Transmission
44
3.981x10
Area, S ( m2 )
Coefficient, T −5
13.530
T
av
= ( 3.981x10− 5 x 13.530) / 130 = 3.981x10− 5 / 130 = 3.981x10− 5
Overall SRI
= 10 log ( 1 )
T
= 10 log (
1 3.981X10- 5
)
= 44dB
The sound intensity level data calculated during peak hour in zone 1 is 69dB whereas zone 3 is 75dB. Based on the overall SRI, this shows that the sound level in these zones are able to reduce to 44dB. This may be due to the air gap that exist between the walls .
ZONE 1 & ZONE 2
Building element
Material
Sound Reduction Index, SRI (dB)
Transmission Coefficient, T
Wall
Concrete plaster with finishes
44
3.981x10
Door
Glass
30
1x10
Concrete Wall TL
= 10 log ( 1 )
44
= 10 log ( 1 )
T T
4.4
10 T
=(1)
T
= 3.981x10−5
Door TL
= 10 log ( 1 )
T
Area, S ( m2 )
−5
−3
6.126 5.124
= 10 log ( 1 )
30
T
3
10
=(1)
T
T
= 1x10−3
T
av
= ( 3.981x10− 5 x 6.126) + ( 1x10− 3 x 5.124) / 11.25 = 5.368x10− 3 / 11.25 = 4.771x10− 4
Overall SRI
= 10 log ( 1 )
T
= 10 log (
1 4.771X10- 4
)
= 33dB
The sound intensity level data calculated during peak hour in zone 1 is 67dB whereas zone 3 is 69dB. Based on the overall SRI, this shows that the sound level in these zones are able to reduce to 33dB. This may be due to the air gap that exist between the walls that consists of a glass sliding door which too increases the transmission loss.
3.4.10 reverberation time Reverberation time is calculated to determine the amount of sound energy that is absorbed into different types of construction materials in the structure as well as the interior elements such as building occupants and furniture that are housed within the closed space. Calculated Space
Ground Floor Office 1 Reverberation times are calculated based on different material absroption coefficient at 500Hz for peak hours and non- peak hours. -
Material Absorption Coefficient at 500 Hz for peak hours. Material Absorption Coefficient at 500 Hz for non-pek hours.
Surface area, S (đ?&#x2019;&#x17D;đ?&#x;? )
Absorption coefficient, s
Sound Absorption, SA
Wall â&#x20AC;&#x201C; Concrete
65.238
0.06
3.914
Door â&#x20AC;&#x201C; Glass
28.950
0.18
5.211
Door â&#x20AC;&#x201C; Wood
1.932
0.10
0.193
Ceiling â&#x20AC;&#x201C; Wood
48.70
0.10
4.870
Floor â&#x20AC;&#x201C; Terrazzo
48.70
0.015
0.731
19
0.46
8.740
Surface type
Occupants
Total absorption
Table 3.4d â&#x20AC;&#x201C; Data tabulated for Office 1
A
= 23.659
V
= (1a+1b+1c) = 68.88 + 24.84 + 43.2 + 7.92 = 144.84
đ?&#x2018;&#x2026;đ?&#x2018;&#x2021; =
đ?&#x2018;&#x2026;đ?&#x2018;&#x2021; =
0.16đ?&#x2018;&#x2030; đ??´
0.16(144.84) 23.659
đ?&#x2018;&#x2026;đ?&#x2018;&#x2021; =
23.174 23.659
đ?&#x2018;šđ?&#x2018;ť = đ?&#x;&#x17D;. đ?&#x;&#x2014;đ?&#x;&#x2013; Â đ?&#x2019;&#x201D;
23.659
Ground Floor Office 2
Table 3.4d â&#x20AC;&#x201C; Data tabulated for Office 2 Surface area, S (đ?&#x2019;&#x17D;đ?&#x;? )
Absorption coefficient, a
Wall â&#x20AC;&#x201C; Concrete
78.946
0.06
4.737
Door â&#x20AC;&#x201C; Glass
5.124
0.18
0.922
Door â&#x20AC;&#x201C; Wood
1.890
0.10
0.189
Window â&#x20AC;&#x201C; Glass
8.810
0.18
1.586
Ceiling â&#x20AC;&#x201C; Plaster
54.70
0.02
1.094
Floor â&#x20AC;&#x201C; Terrazzo
54.70
0.015
0.821
16
0.46
7.360
Surface type
Occupants
Total absorption
SA
16.709
A
= 16.709
V
= 164.10
𝑅𝑇 =
𝑅𝑇 =
0.16𝑉 𝐴
0.16(164.10) 16.709
𝑅𝑇 =
26.256 16.709
𝑹𝑻 = 𝟏. 𝟓𝟕 𝒔
Ground Floor Kitchen
Surface area, S (đ?&#x2019;&#x17D;đ?&#x;? )
Absorption coefficient, a
Wall â&#x20AC;&#x201C; Concrete
48.408
0.06
2.904
Door â&#x20AC;&#x201C; Wood
1.932
0.10
0.193
Ceiling â&#x20AC;&#x201C; Plaster
17.40
0.02
0.348
Floor â&#x20AC;&#x201C; Terrazzo
17.40
0.015
0.261
6
0.46
2.760
Surface type
Occupants
Total absorption
SA
6.466
A
= 6.466
V
= 57.60
𝑅𝑇 =
𝑅𝑇 =
0.16𝑉 𝐴
0.16(57.60) 6.466
𝑅𝑇 =
9.216 6.466
𝑹𝑻 = 𝟏. 𝟒𝟑 𝒔
Surface area, S (đ?&#x2019;&#x17D;đ?&#x;? )
Absorption coefficient, a
Wall â&#x20AC;&#x201C; Concrete
79.948
0.06
4.797
Door â&#x20AC;&#x201C; Wood
9.114
0.10
0.911
Window - Glass
3.320
0.18
0.598
Window â&#x20AC;&#x201C; Wood
1.60
0.10
0.160
Ceiling â&#x20AC;&#x201C; Plaster
35.66
0.02
0.713
Floor â&#x20AC;&#x201C; Concrete
35.66
0.06
2.140
9
0.46
4.140
Surface type
Occupants
Total absorption
SA
13.459
A
= 13.459
V
= 132.02
𝑅𝑇 =
𝑅𝑇 =
0.16𝑉 𝐴
0.16(132.02) 13.459
𝑅𝑇 =
21.123 13.459
𝑹𝑻 = 𝟏. 𝟓𝟕 𝒔
Reverberation Time Analysis and Conclusion