This document discusses strategies for improving acoustic comfort in air conditioning and mechanical ventilation (ACMV) systems. It begins by outlining some of the key acoustic issues that can arise from ACMV systems, such as equipment noise and vibration, duct noise, and terminal device noise. It then presents three case studies of successful noise reduction projects involving ACMV systems. Measurement techniques and criteria for assessing noise and vibration are also described. The overall aim is to provide guidance on designing and retrofitting ACMV systems to minimize noise and maximize acoustic comfort in buildings.
This seminar report summarizes techniques for noise control in buildings. It discusses sources of noise like vibration, fluid flow, and transportation. It also covers strategies like soundproofing floors and walls, improving room acoustics, selecting quiet equipment, and planning spaces to separate noisy and quiet areas. The report concludes that the architectural design should be reviewed to meet acoustical requirements.
Review journal Acoustic –essential requirement for public building”Sayed Umam
This document discusses the importance of acoustics in public buildings. It begins by introducing acoustics as the science dealing with sound and how buildings are designed and constructed for proper acoustical conditions. Good acoustics in buildings promotes comfort, efficiency, and proper functioning of spaces like theaters, auditoriums, and hospitals. Requirements for good acoustics include adequate sound levels distributed evenly without dead spots or focusing, intelligible speech, and minimal external noise or reverberation. Design aspects like site selection, size, shape, absorbent materials, and reverberation times must meet guidelines. The conclusion emphasizes the importance of architects considering acoustical guidelines and treatments to control noise and insulate spaces for effective results.
Master of Facilities management Thesis, June, 2015Joel Nyoni
This document provides an introduction to a thesis that investigates the effects of noise and excessive sound pressure levels on office occupants, and strategies to improve acoustic comfort in office buildings. The thesis aims to identify methods and strategies to mitigate or eliminate traffic noise transmission into office buildings, and to identify other elements within buildings that could create a noise-free environment to increase acoustic comfort and productivity. The document outlines the objectives, limitations, problem analysis, research methodology, and structure of the thesis. It discusses the problem of noise in buildings, consequences of excessive noise, and relevant regulations regarding acceptable noise levels.
Noise Control Stratagies in Reinforced Concrete BuildingsIJRES Journal
This study is aimed at bringing out the salient aspects of building noise control. An analysis has been carried out with respect to the noise transmission as well as the characteristics of noise inside buildings. The key issues on building noise control have been included and discussed. A comprehensive study on building noise and on acoustically divisible spaces has been made. It has been observed that a sound insulation of the order of 30 to 35 dB is possible in a given building. Further, the noise propagation parameters in an exhibition hall have been theoretically estimated. The data so obtained has been compared with actual SPL measurements and recorded. Variations in noise levels observed have been explained. Before the partition is made, the SPL drop is faster inside the building but after the partition the drop falls at the rate of 3dB for doubling the distance. The cost of the acoustically divisible partition wall is found to be very high, but the advantage of this partition seems to be creating acoustically divisible spaces where in one can conduct two programs simultaneously, without any disturbance to each other. Prior to the selection and design of control measures, noise sources must be identified and the noise produced must be carefully evaluated.
Chapter 8 noise mitigation and measurementNoor Farahin
This document discusses noise pollution mitigation and measurement. It begins by explaining the goals of understanding noise pollution mitigation strategies to reduce noise at its source or protect receivers, as well as measuring noise pollution levels. It then provides details on various noise mitigation techniques including barriers, traffic control methods, and architectural acoustic designs. Noise measurement procedures and equipment like sound level meters and dosimeters are also outlined. Key steps include calibrating devices, taking measurements at specific distances and heights, and accounting for environmental conditions.
Chapter 8 noise mitigation and measurementNoor Farahin
This document discusses noise pollution mitigation and measurement. It explains that noise pollution mitigation aims to reduce noise pollution at its source, control noise pollution sources, and protect receivers from noise pollution. Methods include installing double-paned windows, using noise barriers like walls, and controlling traffic. Noise is measured using sound level meters and dosimeters which measure sound pressure levels and intensities. Proper use and calibration of this equipment allows for effective noise pollution measurement.
This document discusses noise control in buildings. It introduces noise and noise control, then covers topics like sound and noise, room acoustics, floor construction, space planning, and noise control for main building equipment. The goal of noise control is to reduce unwanted sound pollution through strategies like addressing noise at its source, using appropriate floor assemblies, and planning spaces to separate noisy and quiet areas. Proper equipment selection and placement can also help control noise from mechanical systems.
This document discusses noise control techniques for landscape design. It begins with basic definitions of sound, noise, frequency, and decibels. It then discusses approaches to sound control, including acoustical planning during the design stage to minimize noise and retrofitting existing developments. Key aspects of acoustical planning include setbacks, buffer zones, and noise barrier mounds. Retrofitting is more difficult and costly but can incorporate barriers, fences, and soundproofing. The document also covers noise measurement tools, calculations, outdoor noise control methods like barriers and screening, and factors that influence barrier effectiveness.
This seminar report summarizes techniques for noise control in buildings. It discusses sources of noise like vibration, fluid flow, and transportation. It also covers strategies like soundproofing floors and walls, improving room acoustics, selecting quiet equipment, and planning spaces to separate noisy and quiet areas. The report concludes that the architectural design should be reviewed to meet acoustical requirements.
Review journal Acoustic –essential requirement for public building”Sayed Umam
This document discusses the importance of acoustics in public buildings. It begins by introducing acoustics as the science dealing with sound and how buildings are designed and constructed for proper acoustical conditions. Good acoustics in buildings promotes comfort, efficiency, and proper functioning of spaces like theaters, auditoriums, and hospitals. Requirements for good acoustics include adequate sound levels distributed evenly without dead spots or focusing, intelligible speech, and minimal external noise or reverberation. Design aspects like site selection, size, shape, absorbent materials, and reverberation times must meet guidelines. The conclusion emphasizes the importance of architects considering acoustical guidelines and treatments to control noise and insulate spaces for effective results.
Master of Facilities management Thesis, June, 2015Joel Nyoni
This document provides an introduction to a thesis that investigates the effects of noise and excessive sound pressure levels on office occupants, and strategies to improve acoustic comfort in office buildings. The thesis aims to identify methods and strategies to mitigate or eliminate traffic noise transmission into office buildings, and to identify other elements within buildings that could create a noise-free environment to increase acoustic comfort and productivity. The document outlines the objectives, limitations, problem analysis, research methodology, and structure of the thesis. It discusses the problem of noise in buildings, consequences of excessive noise, and relevant regulations regarding acceptable noise levels.
Noise Control Stratagies in Reinforced Concrete BuildingsIJRES Journal
This study is aimed at bringing out the salient aspects of building noise control. An analysis has been carried out with respect to the noise transmission as well as the characteristics of noise inside buildings. The key issues on building noise control have been included and discussed. A comprehensive study on building noise and on acoustically divisible spaces has been made. It has been observed that a sound insulation of the order of 30 to 35 dB is possible in a given building. Further, the noise propagation parameters in an exhibition hall have been theoretically estimated. The data so obtained has been compared with actual SPL measurements and recorded. Variations in noise levels observed have been explained. Before the partition is made, the SPL drop is faster inside the building but after the partition the drop falls at the rate of 3dB for doubling the distance. The cost of the acoustically divisible partition wall is found to be very high, but the advantage of this partition seems to be creating acoustically divisible spaces where in one can conduct two programs simultaneously, without any disturbance to each other. Prior to the selection and design of control measures, noise sources must be identified and the noise produced must be carefully evaluated.
Chapter 8 noise mitigation and measurementNoor Farahin
This document discusses noise pollution mitigation and measurement. It begins by explaining the goals of understanding noise pollution mitigation strategies to reduce noise at its source or protect receivers, as well as measuring noise pollution levels. It then provides details on various noise mitigation techniques including barriers, traffic control methods, and architectural acoustic designs. Noise measurement procedures and equipment like sound level meters and dosimeters are also outlined. Key steps include calibrating devices, taking measurements at specific distances and heights, and accounting for environmental conditions.
Chapter 8 noise mitigation and measurementNoor Farahin
This document discusses noise pollution mitigation and measurement. It explains that noise pollution mitigation aims to reduce noise pollution at its source, control noise pollution sources, and protect receivers from noise pollution. Methods include installing double-paned windows, using noise barriers like walls, and controlling traffic. Noise is measured using sound level meters and dosimeters which measure sound pressure levels and intensities. Proper use and calibration of this equipment allows for effective noise pollution measurement.
This document discusses noise control in buildings. It introduces noise and noise control, then covers topics like sound and noise, room acoustics, floor construction, space planning, and noise control for main building equipment. The goal of noise control is to reduce unwanted sound pollution through strategies like addressing noise at its source, using appropriate floor assemblies, and planning spaces to separate noisy and quiet areas. Proper equipment selection and placement can also help control noise from mechanical systems.
This document discusses noise control techniques for landscape design. It begins with basic definitions of sound, noise, frequency, and decibels. It then discusses approaches to sound control, including acoustical planning during the design stage to minimize noise and retrofitting existing developments. Key aspects of acoustical planning include setbacks, buffer zones, and noise barrier mounds. Retrofitting is more difficult and costly but can incorporate barriers, fences, and soundproofing. The document also covers noise measurement tools, calculations, outdoor noise control methods like barriers and screening, and factors that influence barrier effectiveness.
With over 17 years experience in business management and extensive experience in the building industry, specifically with building improvements, restoration and design in the greater Seattle market. Lorin Emtage is an entrepreneurial minded thinker with skillful coordination skills, creativity and an excellent ability to build long-term client trust and relationships.
This document provides an overview of stretched membrane acoustic systems and their architectural applications. It begins with learning objectives and introduces major aspects of acoustics like reverberation time, frequency response, and sound containment. It discusses health effects of poor acoustics and how stretched membrane systems can improve acoustics in various spaces like workplaces, classrooms, homes, and more. The document reviews lab test results that show how stretched membrane systems effectively absorb sound. It concludes with numerous case studies of real-world projects where stretched membrane acoustic systems were implemented in spaces like offices, restaurants, performance halls, houses of worship, and more.
This document discusses the acoustical design criteria and analysis for a new teaching hospital in Austin, Texas. The project team was required to meet criteria from the Facility Guidelines Institute (FGI) and LEED acoustical requirements. The acoustical consultant analyzed the architectural designs using theoretical calculations and measurements to document compliance with criteria for sound isolation between rooms, speech privacy, interior noise levels, and exterior noise intrusion. Meeting the criteria involved selecting appropriate interior finishes, demising partition designs, and considering noise control measures and sound masking systems.
Sound masking is the addition of an unobtrusive background sound, similar to airflow, to reduce the intelligibility of human speech and reduce distractions. The resulting environment leads to greater productivity and increased privacy and comfort.
The document discusses noise control in architecture. It defines noise as unwanted sound and explains how sound intensity level is measured scientifically using a logarithmic scale. There are two main sources of noise: airborne noise transmitted through air, and structure-borne noise transmitted through building materials. Noise control techniques in architecture aim to reduce transmitted sound levels by selecting appropriate sound insulating materials and redirecting sound paths away from receivers using barriers. Case studies demonstrate how architectural design integrates these approaches.
IRJET- Controlling Techniques of Noise Pollution in the Forging IndustryIRJET Journal
This document discusses noise pollution control techniques for a forging industry. It begins by measuring noise levels from various machines like mechanical presses and drop hammers, finding levels from 92-104 dB, above safety limits. It then describes several noise control methods like equipment modifications, administrative controls, shields/barriers, enclosures, curtains, and louvers. The goal is to reduce worker exposure to hazardous noise levels through engineering and process changes.
Duct quiet zones utilization for an enhancement the acoustical air-condition...IJECEIAES
This paper investigates the duct’s noise distribution pattern due to the heating, ventilation, and air conditioning systems. This study is considering the longitudinal sound wave distribution that can permit a higher reduction of these heating, ventilation, and air conditioning systems duct noise. The proposed technique is depending on the lowest sound pressure level points in the duct or duct quiet zones. Moreover, each heating, ventilation, and air conditioning systems duct has several quiet zones, depending on the sound pressure level of the fan noise source and the duct length as well as the duct diameter. Furthermore, the noise standing wave has a wavelength (λ) which is the distance between two successive quiet zones. This work utilizes orthogonal acoustical noise with the standing wave via feed-forward control speakers. This system confirmed that the distance (λ) is linearly proportional to the duct source noise level. This system noise reduction enhancement has been fulfilled by installing further noise feed-forward control speakers at different duct quiet zones. The system simulation results were displaying satisfactory agreement with the field experimental results.
Cambridge Sound Masking White Noise ReviewPaul Richards
Sound Masking review from Cambridge Sound Management. Reviewing the Sound Masking White Noise products presented by Cambridge Sound Management. These Sound Masking products are offered to increase privacy and productivity. Each sound masking emitters, module and system is available for sale on http://soundmasking-whitenoise.com and on our GSA Contract.
Unwelcomed workplace noise disrupts concentration, decreases productivity and increases stress amongst your associates according to a recent University of California study. And these are challenges that are being over-looked in even the most modern of working environments.
This guide illustrates the key acoustic challenges and the measures needed to minimise their effect on your smarter working environment.
This document provides an overview of indoor environmental quality (IEQ) in healthcare and office buildings. It discusses factors that affect IEQ like thermal comfort, indoor air quality, lighting, and acoustics. Sources of poor IEQ are identified as inadequate ventilation, indoor and outdoor air pollutants, thermal discomfort, biological contaminants, and acoustic discomfort. The document also outlines the roles of various professionals in maintaining good IEQ through an integrative design process.
Quam Sound Masking Application Guide 2016Rick Thompson
This document provides guidance on installing a sound masking system. It discusses choosing equipment like amplifiers, noise generators, and speakers. Key steps include measuring ambient noise levels, setting the sound masking curve 20-25 dB above ambient, and installing speakers in the ceiling or plenum space. Transition zones may require individual volume controls on speakers. Proper installation aims to provide conversational privacy without noticeable masking noise.
The document discusses acoustics in buildings and outlines conditions for good acoustics such as producing sound that can be heard evenly throughout a space without distortions. It also covers types of noise from indoor and outdoor sources and how noise can be classified based on transmission path. The document proposes measures for noise control including suppressing noise at its source, layout planning, insulation design, and absorption design.
This document provides guidance on noise control methods for building exterior HVAC equipment. It notes that HVAC equipment can generate noise that propagates to nearby buildings, so early consultation with an acoustical consultant is recommended. Source controls like equipment selection and placement are most effective at reducing noise. Example control methods include noise barriers, acoustic louvers, duct silencers, and absorption materials. The document lists regulations for HVAC noise limits and example product vendors.
“a science that deals with the production, control, transmission, reception, and effects of sound.”
it is the science of controlling sound within buildings.
This document summarizes an analysis of the acoustics at the Haas School of Business at UC Berkeley. Measurements found that background noise levels generally met standards, except for a few instances where construction noise was too high. A survey found occupants with high partitions were least satisfied with noise levels and sound privacy. It was hypothesized that noise issues were due more to overcrowding than building materials. Implementing sound masking systems was recommended to increase focus by adding background noise without using partitions.
IRJET- Study of Acoustic Problem in SDPS Women’s College Classrooms and i...IRJET Journal
The document discusses studying the acoustic problems in classrooms at SDPS Women's College and proposing viable solutions. It begins with introducing key concepts in acoustics and factors affecting classroom acoustics. Measurements were taken of an existing classroom and calculations showed reverberation times were too high (8 seconds with no students down to 1.38 seconds with full occupancy). To achieve the recommended reverberation time of 1.2 seconds, additional sound absorption was required. Viable solutions proposed to improve acoustics without major redesign included adding windows or ventilators at the top of rooms and installing acoustic panels on walls. Calculations verified these solutions could successfully reduce reverberation times to provide better classroom acoustics.
This document provides an overview of Dr. Kenneth P. Roy's background and expertise in architectural acoustics and green building indoor environmental quality. It outlines his participation and leadership roles in numerous acoustical standards organizations. The document then discusses current challenges with acoustic comfort in buildings and evolving workplace designs that integrate different functional spaces. It reviews approaches to acoustic comfort in the LEED green building rating system, with a focus on offices, healthcare, and schools. Overall, the document emphasizes the importance of acoustic comfort as an aspect of indoor environmental quality in building design.
Noise pollution can come from various sources like transportation, construction, and industrial activities. It is measured in decibels and exposure to loud noise over 85dB can cause hearing damage over time. Noise affects humans physically and psychologically, reducing sleep quality and increasing stress. It also harms animal communication and habitats. Methods to reduce noise include better urban planning, equipment modifications, noise barriers, and controlling vehicle speed. Regulations establish limits and standards provide guidelines but enforcement can be improved.
This document discusses guidelines for human comfort design in buildings. It addresses how buildings should keep occupants comfortable, efficient, healthy and safe as they go about their tasks. Comfort is influenced by temperature, humidity, noise, light, smell and other factors. Passive design strategies like daylighting and natural ventilation can help keep people comfortable without purchased energy. Active strategies like HVAC systems are also discussed. The document provides recommendations and considerations for maintaining thermal, visual, acoustic and olfactory comfort.
VARIABLE FREQUENCY DRIVE. VFDs are widely used in industrial applications for...PIMR BHOPAL
Variable frequency drive .A Variable Frequency Drive (VFD) is an electronic device used to control the speed and torque of an electric motor by varying the frequency and voltage of its power supply. VFDs are widely used in industrial applications for motor control, providing significant energy savings and precise motor operation.
Gas agency management system project report.pdfKamal Acharya
The project entitled "Gas Agency" is done to make the manual process easier by making it a computerized system for billing and maintaining stock. The Gas Agencies get the order request through phone calls or by personal from their customers and deliver the gas cylinders to their address based on their demand and previous delivery date. This process is made computerized and the customer's name, address and stock details are stored in a database. Based on this the billing for a customer is made simple and easier, since a customer order for gas can be accepted only after completing a certain period from the previous delivery. This can be calculated and billed easily through this. There are two types of delivery like domestic purpose use delivery and commercial purpose use delivery. The bill rate and capacity differs for both. This can be easily maintained and charged accordingly.
With over 17 years experience in business management and extensive experience in the building industry, specifically with building improvements, restoration and design in the greater Seattle market. Lorin Emtage is an entrepreneurial minded thinker with skillful coordination skills, creativity and an excellent ability to build long-term client trust and relationships.
This document provides an overview of stretched membrane acoustic systems and their architectural applications. It begins with learning objectives and introduces major aspects of acoustics like reverberation time, frequency response, and sound containment. It discusses health effects of poor acoustics and how stretched membrane systems can improve acoustics in various spaces like workplaces, classrooms, homes, and more. The document reviews lab test results that show how stretched membrane systems effectively absorb sound. It concludes with numerous case studies of real-world projects where stretched membrane acoustic systems were implemented in spaces like offices, restaurants, performance halls, houses of worship, and more.
This document discusses the acoustical design criteria and analysis for a new teaching hospital in Austin, Texas. The project team was required to meet criteria from the Facility Guidelines Institute (FGI) and LEED acoustical requirements. The acoustical consultant analyzed the architectural designs using theoretical calculations and measurements to document compliance with criteria for sound isolation between rooms, speech privacy, interior noise levels, and exterior noise intrusion. Meeting the criteria involved selecting appropriate interior finishes, demising partition designs, and considering noise control measures and sound masking systems.
Sound masking is the addition of an unobtrusive background sound, similar to airflow, to reduce the intelligibility of human speech and reduce distractions. The resulting environment leads to greater productivity and increased privacy and comfort.
The document discusses noise control in architecture. It defines noise as unwanted sound and explains how sound intensity level is measured scientifically using a logarithmic scale. There are two main sources of noise: airborne noise transmitted through air, and structure-borne noise transmitted through building materials. Noise control techniques in architecture aim to reduce transmitted sound levels by selecting appropriate sound insulating materials and redirecting sound paths away from receivers using barriers. Case studies demonstrate how architectural design integrates these approaches.
IRJET- Controlling Techniques of Noise Pollution in the Forging IndustryIRJET Journal
This document discusses noise pollution control techniques for a forging industry. It begins by measuring noise levels from various machines like mechanical presses and drop hammers, finding levels from 92-104 dB, above safety limits. It then describes several noise control methods like equipment modifications, administrative controls, shields/barriers, enclosures, curtains, and louvers. The goal is to reduce worker exposure to hazardous noise levels through engineering and process changes.
Duct quiet zones utilization for an enhancement the acoustical air-condition...IJECEIAES
This paper investigates the duct’s noise distribution pattern due to the heating, ventilation, and air conditioning systems. This study is considering the longitudinal sound wave distribution that can permit a higher reduction of these heating, ventilation, and air conditioning systems duct noise. The proposed technique is depending on the lowest sound pressure level points in the duct or duct quiet zones. Moreover, each heating, ventilation, and air conditioning systems duct has several quiet zones, depending on the sound pressure level of the fan noise source and the duct length as well as the duct diameter. Furthermore, the noise standing wave has a wavelength (λ) which is the distance between two successive quiet zones. This work utilizes orthogonal acoustical noise with the standing wave via feed-forward control speakers. This system confirmed that the distance (λ) is linearly proportional to the duct source noise level. This system noise reduction enhancement has been fulfilled by installing further noise feed-forward control speakers at different duct quiet zones. The system simulation results were displaying satisfactory agreement with the field experimental results.
Cambridge Sound Masking White Noise ReviewPaul Richards
Sound Masking review from Cambridge Sound Management. Reviewing the Sound Masking White Noise products presented by Cambridge Sound Management. These Sound Masking products are offered to increase privacy and productivity. Each sound masking emitters, module and system is available for sale on http://soundmasking-whitenoise.com and on our GSA Contract.
Unwelcomed workplace noise disrupts concentration, decreases productivity and increases stress amongst your associates according to a recent University of California study. And these are challenges that are being over-looked in even the most modern of working environments.
This guide illustrates the key acoustic challenges and the measures needed to minimise their effect on your smarter working environment.
This document provides an overview of indoor environmental quality (IEQ) in healthcare and office buildings. It discusses factors that affect IEQ like thermal comfort, indoor air quality, lighting, and acoustics. Sources of poor IEQ are identified as inadequate ventilation, indoor and outdoor air pollutants, thermal discomfort, biological contaminants, and acoustic discomfort. The document also outlines the roles of various professionals in maintaining good IEQ through an integrative design process.
Quam Sound Masking Application Guide 2016Rick Thompson
This document provides guidance on installing a sound masking system. It discusses choosing equipment like amplifiers, noise generators, and speakers. Key steps include measuring ambient noise levels, setting the sound masking curve 20-25 dB above ambient, and installing speakers in the ceiling or plenum space. Transition zones may require individual volume controls on speakers. Proper installation aims to provide conversational privacy without noticeable masking noise.
The document discusses acoustics in buildings and outlines conditions for good acoustics such as producing sound that can be heard evenly throughout a space without distortions. It also covers types of noise from indoor and outdoor sources and how noise can be classified based on transmission path. The document proposes measures for noise control including suppressing noise at its source, layout planning, insulation design, and absorption design.
This document provides guidance on noise control methods for building exterior HVAC equipment. It notes that HVAC equipment can generate noise that propagates to nearby buildings, so early consultation with an acoustical consultant is recommended. Source controls like equipment selection and placement are most effective at reducing noise. Example control methods include noise barriers, acoustic louvers, duct silencers, and absorption materials. The document lists regulations for HVAC noise limits and example product vendors.
“a science that deals with the production, control, transmission, reception, and effects of sound.”
it is the science of controlling sound within buildings.
This document summarizes an analysis of the acoustics at the Haas School of Business at UC Berkeley. Measurements found that background noise levels generally met standards, except for a few instances where construction noise was too high. A survey found occupants with high partitions were least satisfied with noise levels and sound privacy. It was hypothesized that noise issues were due more to overcrowding than building materials. Implementing sound masking systems was recommended to increase focus by adding background noise without using partitions.
IRJET- Study of Acoustic Problem in SDPS Women’s College Classrooms and i...IRJET Journal
The document discusses studying the acoustic problems in classrooms at SDPS Women's College and proposing viable solutions. It begins with introducing key concepts in acoustics and factors affecting classroom acoustics. Measurements were taken of an existing classroom and calculations showed reverberation times were too high (8 seconds with no students down to 1.38 seconds with full occupancy). To achieve the recommended reverberation time of 1.2 seconds, additional sound absorption was required. Viable solutions proposed to improve acoustics without major redesign included adding windows or ventilators at the top of rooms and installing acoustic panels on walls. Calculations verified these solutions could successfully reduce reverberation times to provide better classroom acoustics.
This document provides an overview of Dr. Kenneth P. Roy's background and expertise in architectural acoustics and green building indoor environmental quality. It outlines his participation and leadership roles in numerous acoustical standards organizations. The document then discusses current challenges with acoustic comfort in buildings and evolving workplace designs that integrate different functional spaces. It reviews approaches to acoustic comfort in the LEED green building rating system, with a focus on offices, healthcare, and schools. Overall, the document emphasizes the importance of acoustic comfort as an aspect of indoor environmental quality in building design.
Noise pollution can come from various sources like transportation, construction, and industrial activities. It is measured in decibels and exposure to loud noise over 85dB can cause hearing damage over time. Noise affects humans physically and psychologically, reducing sleep quality and increasing stress. It also harms animal communication and habitats. Methods to reduce noise include better urban planning, equipment modifications, noise barriers, and controlling vehicle speed. Regulations establish limits and standards provide guidelines but enforcement can be improved.
This document discusses guidelines for human comfort design in buildings. It addresses how buildings should keep occupants comfortable, efficient, healthy and safe as they go about their tasks. Comfort is influenced by temperature, humidity, noise, light, smell and other factors. Passive design strategies like daylighting and natural ventilation can help keep people comfortable without purchased energy. Active strategies like HVAC systems are also discussed. The document provides recommendations and considerations for maintaining thermal, visual, acoustic and olfactory comfort.
VARIABLE FREQUENCY DRIVE. VFDs are widely used in industrial applications for...PIMR BHOPAL
Variable frequency drive .A Variable Frequency Drive (VFD) is an electronic device used to control the speed and torque of an electric motor by varying the frequency and voltage of its power supply. VFDs are widely used in industrial applications for motor control, providing significant energy savings and precise motor operation.
Gas agency management system project report.pdfKamal Acharya
The project entitled "Gas Agency" is done to make the manual process easier by making it a computerized system for billing and maintaining stock. The Gas Agencies get the order request through phone calls or by personal from their customers and deliver the gas cylinders to their address based on their demand and previous delivery date. This process is made computerized and the customer's name, address and stock details are stored in a database. Based on this the billing for a customer is made simple and easier, since a customer order for gas can be accepted only after completing a certain period from the previous delivery. This can be calculated and billed easily through this. There are two types of delivery like domestic purpose use delivery and commercial purpose use delivery. The bill rate and capacity differs for both. This can be easily maintained and charged accordingly.
Discover the latest insights on Data Driven Maintenance with our comprehensive webinar presentation. Learn about traditional maintenance challenges, the right approach to utilizing data, and the benefits of adopting a Data Driven Maintenance strategy. Explore real-world examples, industry best practices, and innovative solutions like FMECA and the D3M model. This presentation, led by expert Jules Oudmans, is essential for asset owners looking to optimize their maintenance processes and leverage digital technologies for improved efficiency and performance. Download now to stay ahead in the evolving maintenance landscape.
Null Bangalore | Pentesters Approach to AWS IAMDivyanshu
#Abstract:
- Learn more about the real-world methods for auditing AWS IAM (Identity and Access Management) as a pentester. So let us proceed with a brief discussion of IAM as well as some typical misconfigurations and their potential exploits in order to reinforce the understanding of IAM security best practices.
- Gain actionable insights into AWS IAM policies and roles, using hands on approach.
#Prerequisites:
- Basic understanding of AWS services and architecture
- Familiarity with cloud security concepts
- Experience using the AWS Management Console or AWS CLI.
- For hands on lab create account on [killercoda.com](https://killercoda.com/cloudsecurity-scenario/)
# Scenario Covered:
- Basics of IAM in AWS
- Implementing IAM Policies with Least Privilege to Manage S3 Bucket
- Objective: Create an S3 bucket with least privilege IAM policy and validate access.
- Steps:
- Create S3 bucket.
- Attach least privilege policy to IAM user.
- Validate access.
- Exploiting IAM PassRole Misconfiguration
-Allows a user to pass a specific IAM role to an AWS service (ec2), typically used for service access delegation. Then exploit PassRole Misconfiguration granting unauthorized access to sensitive resources.
- Objective: Demonstrate how a PassRole misconfiguration can grant unauthorized access.
- Steps:
- Allow user to pass IAM role to EC2.
- Exploit misconfiguration for unauthorized access.
- Access sensitive resources.
- Exploiting IAM AssumeRole Misconfiguration with Overly Permissive Role
- An overly permissive IAM role configuration can lead to privilege escalation by creating a role with administrative privileges and allow a user to assume this role.
- Objective: Show how overly permissive IAM roles can lead to privilege escalation.
- Steps:
- Create role with administrative privileges.
- Allow user to assume the role.
- Perform administrative actions.
- Differentiation between PassRole vs AssumeRole
Try at [killercoda.com](https://killercoda.com/cloudsecurity-scenario/)
Digital Twins Computer Networking Paper Presentation.pptxaryanpankaj78
A Digital Twin in computer networking is a virtual representation of a physical network, used to simulate, analyze, and optimize network performance and reliability. It leverages real-time data to enhance network management, predict issues, and improve decision-making processes.
Prediction of Electrical Energy Efficiency Using Information on Consumer's Ac...PriyankaKilaniya
Energy efficiency has been important since the latter part of the last century. The main object of this survey is to determine the energy efficiency knowledge among consumers. Two separate districts in Bangladesh are selected to conduct the survey on households and showrooms about the energy and seller also. The survey uses the data to find some regression equations from which it is easy to predict energy efficiency knowledge. The data is analyzed and calculated based on five important criteria. The initial target was to find some factors that help predict a person's energy efficiency knowledge. From the survey, it is found that the energy efficiency awareness among the people of our country is very low. Relationships between household energy use behaviors are estimated using a unique dataset of about 40 households and 20 showrooms in Bangladesh's Chapainawabganj and Bagerhat districts. Knowledge of energy consumption and energy efficiency technology options is found to be associated with household use of energy conservation practices. Household characteristics also influence household energy use behavior. Younger household cohorts are more likely to adopt energy-efficient technologies and energy conservation practices and place primary importance on energy saving for environmental reasons. Education also influences attitudes toward energy conservation in Bangladesh. Low-education households indicate they primarily save electricity for the environment while high-education households indicate they are motivated by environmental concerns.
Software Engineering and Project Management - Software Testing + Agile Method...Prakhyath Rai
Software Testing: A Strategic Approach to Software Testing, Strategic Issues, Test Strategies for Conventional Software, Test Strategies for Object -Oriented Software, Validation Testing, System Testing, The Art of Debugging.
Agile Methodology: Before Agile – Waterfall, Agile Development.
Applications of artificial Intelligence in Mechanical Engineering.pdfAtif Razi
Historically, mechanical engineering has relied heavily on human expertise and empirical methods to solve complex problems. With the introduction of computer-aided design (CAD) and finite element analysis (FEA), the field took its first steps towards digitization. These tools allowed engineers to simulate and analyze mechanical systems with greater accuracy and efficiency. However, the sheer volume of data generated by modern engineering systems and the increasing complexity of these systems have necessitated more advanced analytical tools, paving the way for AI.
AI offers the capability to process vast amounts of data, identify patterns, and make predictions with a level of speed and accuracy unattainable by traditional methods. This has profound implications for mechanical engineering, enabling more efficient design processes, predictive maintenance strategies, and optimized manufacturing operations. AI-driven tools can learn from historical data, adapt to new information, and continuously improve their performance, making them invaluable in tackling the multifaceted challenges of modern mechanical engineering.
DEEP LEARNING FOR SMART GRID INTRUSION DETECTION: A HYBRID CNN-LSTM-BASED MODELijaia
As digital technology becomes more deeply embedded in power systems, protecting the communication
networks of Smart Grids (SG) has emerged as a critical concern. Distributed Network Protocol 3 (DNP3)
represents a multi-tiered application layer protocol extensively utilized in Supervisory Control and Data
Acquisition (SCADA)-based smart grids to facilitate real-time data gathering and control functionalities.
Robust Intrusion Detection Systems (IDS) are necessary for early threat detection and mitigation because
of the interconnection of these networks, which makes them vulnerable to a variety of cyberattacks. To
solve this issue, this paper develops a hybrid Deep Learning (DL) model specifically designed for intrusion
detection in smart grids. The proposed approach is a combination of the Convolutional Neural Network
(CNN) and the Long-Short-Term Memory algorithms (LSTM). We employed a recent intrusion detection
dataset (DNP3), which focuses on unauthorized commands and Denial of Service (DoS) cyberattacks, to
train and test our model. The results of our experiments show that our CNN-LSTM method is much better
at finding smart grid intrusions than other deep learning algorithms used for classification. In addition,
our proposed approach improves accuracy, precision, recall, and F1 score, achieving a high detection
accuracy rate of 99.50%.
Rainfall intensity duration frequency curve statistical analysis and modeling...bijceesjournal
Using data from 41 years in Patna’ India’ the study’s goal is to analyze the trends of how often it rains on a weekly, seasonal, and annual basis (1981−2020). First, utilizing the intensity-duration-frequency (IDF) curve and the relationship by statistically analyzing rainfall’ the historical rainfall data set for Patna’ India’ during a 41 year period (1981−2020), was evaluated for its quality. Changes in the hydrologic cycle as a result of increased greenhouse gas emissions are expected to induce variations in the intensity, length, and frequency of precipitation events. One strategy to lessen vulnerability is to quantify probable changes and adapt to them. Techniques such as log-normal, normal, and Gumbel are used (EV-I). Distributions were created with durations of 1, 2, 3, 6, and 24 h and return times of 2, 5, 10, 25, and 100 years. There were also mathematical correlations discovered between rainfall and recurrence interval.
Findings: Based on findings, the Gumbel approach produced the highest intensity values, whereas the other approaches produced values that were close to each other. The data indicates that 461.9 mm of rain fell during the monsoon season’s 301st week. However, it was found that the 29th week had the greatest average rainfall, 92.6 mm. With 952.6 mm on average, the monsoon season saw the highest rainfall. Calculations revealed that the yearly rainfall averaged 1171.1 mm. Using Weibull’s method, the study was subsequently expanded to examine rainfall distribution at different recurrence intervals of 2, 5, 10, and 25 years. Rainfall and recurrence interval mathematical correlations were also developed. Further regression analysis revealed that short wave irrigation, wind direction, wind speed, pressure, relative humidity, and temperature all had a substantial influence on rainfall.
Originality and value: The results of the rainfall IDF curves can provide useful information to policymakers in making appropriate decisions in managing and minimizing floods in the study area.
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
1. 1
ACOUSTIC COMFORT STRATEGIES IN AIR CONDITIONING AND
MECHANICAL VENTILATION SYSTEM
Tuan Suhaimi Salleh
Mechanical Engineering Branch, PWD Headquarters, 18th
-21st
Floor,
Centrepoint North, The Boulevard, Mid Valley City,
59200 Kuala Lumpur, Malaysia
Phone : +603-9235-4521 ; Fax : +603-2287-3946
Email: tsuhaimi@jkr.gov.my
ABSTRACT
The comfort acoustical environment of a workplace is typically given very little
attention or always overlooked during buildings project planning and design. The
functionality and aesthetics of the workspace are usually the primary focus of the
designer. Providing a comfortable environment for office occupants contributes
significantly to their optimum performance and eliminates symptoms associated to sick
building syndrome. In modern green office concepts, workplace comfort is really a
combination of factors that includes day lighting and electric lighting, indoor
environmental quality, temperature, humidity level and acoustics. The assault on ears in
the workplace can come from traffic noise outside, mechanical equipment in adjacent
spaces, air conditioning system, copiers, phones, and voices within the workplace.
However this article only discusses issues relating to acoustic comfort control strategies
in Air Conditioning and Mechanical Ventilation System (ACMV) that are usually
encountered in buildings. Some success rectification works in ACMV system noise and
vibration problems are presented as a case study.
Keywords: ACMV system; acoustic comfort; workplace; noise; vibration.
INTRODUCTION
Thermal comfort is the main goals for mechanical engineers at Public Work
Department, Malaysia (PWD) in the process of designing and preparing the technical
specification of Air Conditioning and Mechanical Ventilation System (ACMV) in
various buildings project. At the same time it is very important to keep the background
noise of the ACMV system low to a level that ensures comfortable working
environment for office building occupants. The degree of occupants’ satisfaction is
determined by many factors, for example, meeting and conference rooms, auditoriums
or recording studios only tolerate a low level of background noise. On the other hand,
high levels of background noise are acceptable and even desirable in certain situations,
such as open-plan offices where a certain amount of speech and activity masking is
essential. The ideal background noise should be a balance distribution of sound energy
over a broadband frequency range with no dominant band of noise, smooth and steady
with no audible tones such as whine or rumble and few fluctuations in noise pressure
level.
Acoustic comfort means having the right level and quality of sound to use the
space as intended especially for office buildings. People are more productive and
happier when they are not distracted by noises from outside or from surrounding.
2. 2
Humans perceive to sounds and loudness is a subjective measure. We can create a
comfortable environment by controlling objective measures like sound pressure level (in
decibel), reverberation time, the sound reflection and damping properties of materials
such as acoustic panels on ceilings and walls. Acoustic environment can manipulate a
person’s ability to work. A person’s productivity will decrease when they are in a noisy
and uncomfortable workplace and vice versa, it can enhance productivity when it
supplies an environment which supports easy verbal communication (Hodgson, M,
2008). Noisy and uncomfortable working space also will create disturbance and break
concentration and eventually result in stressful occupants (Evans, G. W., & Johnson, D,
2000).
ACOUSTIC IN GREEN BUILDINGS
Most of the literature reviews are the outcome of analysis, studies and surveys done on
offices and educational buildings in the U.S. These buildings are rated as green building
based on LEED (Leadership in Energy and Environmental Design) which was
developed by U.S. Green Building Council (USGBC) in 1998.
The literature studies reviewed mainly focus on occupants’ satisfaction in green
buildings and comparing them to satisfaction from occupants in conventional buildings.
The types of acoustical complaints were also being surveyed to determine the major
acoustical problems occur. Rao, S.P. et al (2011) discovered only Hodgson (2008)
reported the result of the acoustical measurement done. Table 1 shows the measurement
parameters and acceptability criteria used in Hodgson’s study compared to ASHRAE
Design Guideline for HVAC-Related Background Sound in Room. ACMV system
noise always determined by NC curves which is correlate well with occupant
satisfaction in office buildings without excessive levels of low frequency noise or
disturbing tonal noises. NC values are defined by a series of curves that give noise level
limits in octave bands across the frequency range of human hearing.
Table 1. Measurement parameters and acceptability criteria (Hodgson’s study)
Measurement
Parameter
Acceptability Criteria
(Hodgson)
ASHRAE
Background
Noise-level, NC
NC 30-35 in meeting and
conference rooms
NC 35-40 in workspaces
NC 25-35 in meeting and
conference rooms
NC 30-40 in workspaces
The surveys by many researchers found huge occupant dissatisfaction on acoustic
quality in green buildings compared to conventional buildings, especially in working
spaces which utilizes the open plan office layout. The main acoustic problems
established are the lack of speech privacy and the problem with intermittent noise.
Major acoustic complaints made were people talking on the phone; people talking in
neighbouring area, people overhearing their private conversation, getting caught up in
others’ conversation and telephone ringing. Other complaints were also received on
noises projected by office equipment, mechanical system, office lighting, outdoor traffic
and people in corridors.
3. 3
It was found that there are four major green building design strategies which
might contributes to the poor acoustical performance. They are natural ventilation,
daylighting, reduced use of finishes and open plan office layout.
Acoustic in Green Building Rating System
The acoustic performance in Green building rating system generally consider the
background noise in the space (Noise Criteria - NC, Preferred Noise Criterion - PNC,
Room Criteria - RC), the noise isolation from adjacent spaces (Sound Transmission
Class - STC, Noise Isolation Class - NIC) and from the exterior (Outdoor-Indoor
Transmission Class - OITC), and the room acoustics (reverberation time, speech
intelligibility). These acoustic parameters can be controlled by providing sufficient
attenuation to the ACMV systems, by designing appropriate room boundaries, and by
selecting suitable room finishes.
The acoustic comfort should be tackled in many ways in green building rating
system as mentioned above but only contributes a low point in overall weightage. Table
2 shows the acoustic percentage rating system available in sustainable design.
Table 2. Acoustic credits of the overall credits available for sustainable design
Rating System Total point Acoustic Point Acoustic Value
GBI (Malaysia) 100 1 1.0%
PH (Malaysia) 117 1 0.85%
BCA Green Mark
(Singapore)
190 1 0.5%
LEED (USA) 100 1 1.0%
A low credit doesn’t mean acoustic comfort shall be put aside but need to be tackled
wisely or otherwise could create major annoying problems which had proved through
our ACMV noise and vibration forensic cases.
ACOUSTIC ISSUES IN ACMV SYSTEM
Nowadays building structures are designed to be light so that careful coordination in
structural design and mechanical layout is essential. Otherwise proper isolation for
ACMV equipment located inside the mechanical room is a must to avoid structure-
borne noise phenomena. In another word, the ACMV system excessive noise appears to
arise more from lack of proper design process than from inadequate technology that
contributes to the noise.
Typical ducted ACMV system acoustics problems arise from its main components,
they are;
1. Equipment noise and vibration
a. Location (radiated noise)
b. Isolation
2. Duct system
a. Duct borne noise
b. Duct break-in and break-out noise
4. 4
c. Airflow-self generated noise (terminal noise)
The design of ducted ACMV system must address the two distinct points above to
control the noise and vibration otherwise the design will fail.
Mechanical Equipment Noise and Vibration
The rotating or motor-driven machinery that incorporate in ACMV systems will
generate vibration energy that can travel through a building's structure and spread from
the walls, floors and ceilings in the form of structure-borne noise and radiate noise into
the receiver spaces. It is essential to control vibration at its source, because once it is
allowed to transmit into the building structure, vibration from building services
equipment are widespread and extremely difficult to contain.
Duct System (airflow)
Duct borne noise propagates along the ductwork, follows all branches and bends and
ultimately exits at the supply diffuser impacting the occupied space. The sound
generated by the fan will travel along the ductwork both upstream and downstream of
the Air Handling Unit (AHU) easily because the velocity of sound is much higher than
the velocity of the air in the ducts. The noise is generated aerodynamically by the flow
of air through the duct system. This regenerated noise is very much dependent on the
velocity of the air and smoothness of the flow. It increases very rapidly as the flow
velocity is increased by changes in cross-sectional area of the duct. Airflow generated
noise is proportional to the sixth power of velocity. In practice for room not highly
sensitive to noise, airflow generated noise can be ignored when velocities are below 8
m/s in the main duct and 3 m/s in branch duct.
Duct break-in noise is radiated ACMV equipment noise that enters ductwork
and propagates into rooms. A flexible duct is light in weight, flexible and ease for
installation is commonly used in air conditioning systems. Noise can more easily
penetrate flexible ducts because of their lightweight nature.
Duct break-out also propagates along ductwork and transmits through the wall
of the duct impacting the adjacent space. At frequencies above the transition between
axial and multi-mode transmission of sound (f > c/(2*duct width/height)) in a duct, the
sound field inside the duct may be considered as diffuse and the breakout of the noise
from inside to the outside of the duct is protected by the sound reduction index or
transmission loss of the duct wall. However since the duct runs over a significant length
inside the receiving room, the total amount of the noise breakout increases as the length
increases. The final points in the ACMV air distribution system are the terminal air
devices. There are “grilles”, “diffusers”, “register” and “vent cover” that go over duct
opening in the room. Air noise from diffusers and from transitions can cause additional
noise in the receiving room.
ACMV NOISE AND VIBRATION STATISTIC
Noise and Vibration Control Specialist Unit of Mechanical Engineering Branch, Public
Work Department was established in the year 2008. Since that year there have been 24
cases of noise and vibration problems entertained which include 5 cases on noise level
measurement during testing and commissioning of shooting range belonged to the
5. 5
Royal Malaysia Police Department and The Maritime Institute of Malaysia, which were
to make sure noise from guns shooting activities do not affect the neighbourhood. Out
of the 24 cases, 19 were related to noise and vibration control on ACMV systems.
Although there were least cases, graph on Figure 1 shows the details breakdown of
dominant noise and vibration sources which were emanated from equipment and airflow
based on 19 forensics studies. There were 12 cases or 63% of noise problems attributed
from the equipment (chillers, cooling tower, pump, AHU and condensing unit), and the
remaining 7 cases or 37% were excessive noise from airflow.
Figure 1. Noise and Vibration Sources Based on CKM Forensics Data
In addition to noise problem, the equipment of ACMV systems also
triggered building structural vibration due to plant location and improper installation of
isolator attached to the equipments. From sites investigation there were 3 cases or 25%
of studied equipment vibration problems transmitted to equipment ancillaries such as
pipe support/hanger and also to the building structure.
ACMV BASIC ACOUSTIC DESIGN TECNIQUES
Good space planning and location of mechanical room at the early stage of design
process is the best way to avoid noise and vibration problem in the office building. It is
a good practice to position particularly noisy equipment in mechanical room or place
where they are located away from critical area such as meeting or office room.
Mechanical room shall large enough to allow adequate turning before duct exit and defy
any alleged floor space constraints if possible, avoid placing AMCV equipments
enclosures close to walls or ceilings to avoid ‘close coupling effect’ where a small air
space will conduct equipment vibratory motion to wall or ceiling. Air tight mechanical
room construction is advantage since sound can leak through as small as 1 mm
openings. Alternatively creating a buffer zone of less critical space such as store room
between a mechanical room and noise-sensitive space allows simpler and less costly
6. 6
constructions to provide the desired isolation, and this minimizes the risk of noise leaks
at penetrations.
Floating concrete floors which are supported above the structure floor on
resilient mounts are required to separate mechanical rooms from noise-sensitive spaces
that are above or below the mechanical room. Floating floor is not generally designed as
part of a vibration isolation scheme for mechanical equipment but their primary use is
for airborne sound isolation. Addition to that, it is sometimes necessary to have special
noise-isolation ceilings above or below mechanical rooms and ducts routes.
Right sizing of ACMV equipments, distribution system and choosing the
correct size (cooling capacity) is critical not only in getting the cooling comfort but also
lowest maintenance and life cost cycle (LCC) of the system and the best acoustic
efficiency. The basic duct design concepts to minimizing ACMV system noise should
not be ignored. Some type of solution shows in Table 3 to minimize air flow noise
Table 3. Ductwork for the limitation of air flow noise
Strategy Action Sample of solution
Minimize
rumble
noise
Keep airflow
velocity in the
duct as low as
possible (max.
7.5m/s) near
critical noise
areas.
Optimum
NOTE 1: Slope 1 in 7 preferred
for 10m/s above
Bad
Locate elbows
or duct branch
takeoffs (A) at
least 1.5 duct
diameters apart
(B). Good
NOTE 3: Rugged turning vanes
should extend full radius elbow
Bad
Minimize
flow
resistance
and
turbulence
Use turning
vanes in large
90° rectangular
elbows and
branch takeoffs
Quietest
Noisier solution
NOTE 2:
Minimum
15mm
radius
required
7. 7
Duct
expansion
angle not more
than 15°
Quietest Noisier solution
Proper duct tee
design
Quietest
Noisier solution
CASE STUDIES
Usually we will perform in-field forensic investigation regarding to noise and vibration
problems when there is a request from other government bodies through our counterpart
in JKR nationwide. Most cases appear during pre-occupancy of the building or during
defect and liability period. For each case we need to investigate the causes of the
problem, analyse and finally bind a technical report which consists of a few alternative
solutions to be followed voluntarily by the requester. We will also perform a follow up
inspection to verify the effectiveness of our suggestion followed by the client or
building owner. In this paper three successful rectifications are presented as case study.
Most of the suggested retrofit works to suppress equipment’s noise and vibration such
as water and air cooled chillers are still under client consideration before proceeding to
the retrofit work because of the cost and complexity. Thus these kinds of cases were not
highlighted in this paper.
Equipment
Hand held Sound Level Meter Type 2; SoundPro DL Data logging SLM 1/3 Octave
with QuestSuite Professional II Software are used for noise level assessment and Photon
Pro Analyzer; Single Axis Accelerometer (3056B2- 50g range, 100 mV/g, 10-32 top)
with RT ProPhoton Software are used to measure vibration level for our forensic
studies.
Noise Descriptors
Noise descriptors such as Leq, L10, L90, Lmax and NC were recorded. Usually in steady
state noise condition the noise level measurement was carried out for 1-5 minutes using
SLM data logger. Definition for the noise descriptors are presented as followed:
Leq : The equivalent continuous dBA level which has the same energy as original
fluctuating noise for the same given period time.
L10 : A specified dBA levels which is exceeded ten percent of the time during the
whole period of measurement.
8. 8
L90 : A specified dBA levels which is exceeded ninety percent of the time during
the whole period of measurement.
Lmax : The root means squared maximum level of a noise source or environment
where peak is the maximum level of the raw noise source.
NC : Noise Criteria curves define the limits that the octave band spectrum of a
noise source must not exceed in order to achieve a level of occupant acceptance.
Vibration Criteria
Vibration criteria can be specified relatively to three areas: (1) human response to
vibration, (2) vibration levels associated with potential damage to sensitive equipment
in a building, and (3) vibration severity of a vibration machine. Equipment and
structural vibration severity ratings are based on measured RMS velocity (mm/s).
Case Study 1: Noise From Duct Airborne
In this case we investigated causes of the annoying noise from air conditioning system
which exceeded standard NC30 for Operation Theatre (OT) room during pre-occupancy
stage. The main contributors to this noise were high velocity airflow and air turbulence
in duct system serving to OT room. This ductborne noise occurred because of existing
supply duct size did not follow the design parameter causing airflow velocity inside
supply duct slightly higher and created annoying noise.
a) Before Rectification Work
Rating: NC37/ NC20 (ambient)
Leq: 46.4dBA/27.1dBA (ambient)
Airflow velocity: 6.3 m/s
b) After Rectification Work
Rating: NC30/ NC21 (ambient)
Leq: 38dBA/30.1dBA (ambient)
Airflow velocity: 5.4 m/s
Figure 2. Operation Theatre Room NC Curve
9. 9
The smoothness of air flow in duct also could not be achieved because of air turbulence
at the Air Handling Unit (AHU) outlet since the original design did not attach a turning
vane at the first bend of the AHU outlet duct. With this finding we suggested to project
superintending officer to advice the responsible consultant to replace existing duct with
a new one according to the design parameter. We also recommended them to install
turning vanes inside the AHU outlet duct to reduce air turbulence.
The retrofit works was done accordingly and as a result OT room noise rating
NC30 was achieved. Figure 2 show the comparison result before and after retrofit
works. Although this is just a simple fault in ACMV system and could be find anywhere
but the annoying noises will give critical impact to the end user if not tackled wisely
during early stage of construction especially for room that required low level
background noise.
Case Study 2: Vibration Cause Condenser Water Pipe Leak
In this case we were requested to investigate the cause of condenser water pipe leak
while in operation. These piping’s system are connected to a cooling tower and the
pumps to circulate condenser water in the air conditioning system. Although this client
has their own internal maintenance team, they still need our technical advice to solve
this problem since we are among the technical advisors to the Malaysia government.
Figure 3. Vibration Measured on Pump Set
10. 10
Figure 4. Vibration Measured on Building Floor
Figure 3 and 4 shows the vibration level measured based on RMS velocity level
for condenser water pump set and floor near to the condenser water pump set located on
the rooftop. The peak RMS velocity for one of condenser water pump set was 6.4227
mm/s and RMS velocity of resonance interaction between pump sets and floor was
0.6047 mm/s respectively. Both values exceeded the maximum allowable RMS
Velocity Levels as recommended in 2003 ASHRAE Application Handbook. These
situations occurred due to lack of maintenance causing excessive bearings wear which
contributed to the condenser water pump sets being operated unbalanced. Assuming that
impurity inclusion or defects existed inside pipe material and/or inside arc welded
portion, the severity pump vibration had initiates fatigue crack, propagates and finally
condenser water pipe leaked, spoiling the ACMV operation.
From this finding, we suggested to the building owner to perform major
overhaul and re-alignment the entire condenser water pump sets. As a result, after
rectification works done, both situations show very low vibration effects and almost
negligible; the peak RMS velocity for the same condenser water pump set is 0.0759
mm/s and RMS velocity for floor is 0.0652 mm/s.
Case Study 3: Excessive Exhaust Fan Noise
Investigation of this case began because of an official complaint received by building
management from adjacent resident due to annoying noise released by the kitchen
exhaust system. Neighbourhood apartments are located 10 meters away from the
building perimeter fence or 40 meters from the exhaust fan outlet. The complainant
would bring this matter to court and sue the building owner if this problem is not
resolved. To avoid this matter prolong, building management has requested the State
PWD Mechanical to solve this problem since their internal maintenance team does not
11. 11
have the expertise. Finally, our state counterpart has sought technical advice on these
matters from us.
From our observation, although this premise location can be designated as mixed
area development with high traffic movement, the noise from exhaust fan is obviously
annoying residents nearby. Noise pressure level measured at affected apartment showed
that it exceeding maximum permissible sound level (60 dBA) as specified in
Department of Environment Malaysia (DOE) guideline. As shows in Figure 6 (a) the
noise pressure level measured at balcony of affected apartment, Leq = 66.3 dBA. The
background noise at that time should be same as measured ambient noise, Leq = 53.9
dBA. We decided to re-design back the kitchen exhaust duct and changed the fan to a
new one based on a backward design process since they have no as-built drawing or
specification document of the existing system as a reference. All needed measurements
and raw data were taken based on actual site condition for calculation and analysis
before preparing a complete specification and technical drawing of the kitchen exhaust
system, enabling our PWD state counterpart to complete their procurement tendering
process. Table 4 shows important data or parameters of existing and re-designed
condition that most influences noise level of the kitchen exhaust system. Re-calculation
has been made based on onsite measurement shows that the existing fan size is
oversized, as a result the actual contaminated air volume to be exhaust out is slightly
less, hence the new design needs a fan with much lower speed to lower the airflow
speed and contributes in reducing airflow noise and more economical.
Table 4. Design Data and Parameter
Factor Existing Condition Re-design Condition
Contaminated air volume 127,425 m3
/hr 95,144 m3
/hr
Fan Speed/Diameter 1,450 rpm/1,000 mm 960 rpm/1,400 mm
Motor Rating 40 kW 30 kW
Other improvements that have been made to assist the exhaust system reducing the
background noise are introduced hereof:
i) Acoustic wall barrier facing to affected apartment.
ii) Acoustic louvers facing exhaust fan outlet, so that exhaust air disperse
and at the same time acts as a noise filter to the adjacent office room.
iii) Oversized duct to reduce contaminated airflow velocity complete with
internal insulation and turning vanes inside duct bend.
iv) Introduced the plenum chamber concept to reduce air turbulent.
Figure 6(b) shows the result after rectification works done. Noise pressure level
tremendously fell to ambient level 55.5 dBA and noise criteria rating also show a lot of
improvement from NC63 reduced to NC50, hence noise emission level diffused by
kitchen exhaust fan system is lower than DOE maximum permissible sound level.
Although the new installed exhaust fan outlet facing only 15 meters away from
the adjacent office room, noise pressure level and noise criteria inside that office room
remain at a comfort level, where Leq = 43.5 dBA and NC33 respectively.
12. 12
a) Before Rectification Works
Rating: NC63/NC51 (ambient)
Leq: 66.3dBA/53.9dBA (ambient)
b) After Rectification Works
Rating: NC50/NC48 (ambient)
Leq: 55.5dBA/55.7dBA (ambient)
Figure 6. Noise Data Measured at Affected Apartment’s Balcony
CONCLUSION
It can be concluded that without careful implementation in overall ACMV system
design strategies, acoustic quality is easily compromised. The designers should not
overlook on these influence as it could jeopardize the acoustical environment. It is
hoped that this article demonstrated a simple guide in predicting the potential acoustical
problems that might occur in office building. The selected three case studies of noise
and vibration problems in office building claims the immediate countermeasure action
i.e. minimizing error is a must or no compromise to occurrence of mistakes during the
initial stage of design processes such as ACMV equipments sizing, suitable location or
positioning to avoid any noise and vibration effects from ACMV system especially to
sensitive rooms. Full attention on supervisory work during ACMV system installation
promises high quality products in the sense of human comfort. Perform without fail the
scheduled predictive maintenance on ACMV equipments is very important to eliminate
system failure creating side effect problem such as tendency of crack initiation on floor
structure due to excessive equipment vibration while in operation. On top of that, for
long term corrective measure, new specifications and technical drawing for noise and
vibration control details have been drafted and incorporated into documents known as i)
Standard Technical Specification for Air Conditioning and Mechanical Ventilation
System and ii) Standard Mechanical Design Detail Drawing For Designers/Contractors.
With these documents, noise and vibration control designs can be implemented in new
projects and retrofits installation to meet the JKR standard of requirements.
13. 13
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