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Acoustics and the
Building Envelope
Alberta Building Envelope Council South
October 25, 2017
Justin Caskey, P.Eng., [email protected]
• Managing Partner
• 15 years experience in acoustical engineering
• Completed over 1,000 projects
• Investigated hundreds of noise complaints
Lessons Learned
• Complaints are painful for owners and typically result in: costly retrofit, costly litigation, or costly delays
• As populations grow, noise is becoming increasingly important in building design and quality of life
• Noise is subjective
Patching Associates Acoustical Engineering
www.patchingassociates.com
• Extensive experience in the field of architectural acoustics and design for both noise mitigation and sound enhancement
• 27 years in business
• 5,000 projects
• Largest team in Calgary focusing on acoustics
• Innovative focus: leverage new technologies
Purpose
Share our experience related to acoustical considerations in building envelope design and
how these affect the value of your projects
Agenda
• Basics of Acoustics
• Regulations
• Building Envelope Case Studies
• Questions
Basicsof Acoustics
Alberta Building Envelope Council South
October 25, 2017
Basics of Acoustics
• Sound: Vibrations or pressure fluctuations that travel through air that are heard when they reach a persons ear
• Noise: Sound the is unwanted
• Acoustics: The “art” and science of sound
1 Sound Source 60 dB at the receiver
2 Equal Sound Sources 3 dB higher than one source
63 dB at the receiver
2 Unequal Sound Sources 60 dB at the receiver
60 dB 10 dB
Sound and Decibel Math
The Importance of Frequency
• Perception: Humans hear mid-frequencies better than high and low frequencies
• Propagation: Low frequency sound travels further than high frequency sound
• Transmission: Low frequency sound travels through everything, high frequency is stopped readily
Frequency Perception Propagation Transmission
Low Good Excellent Excellent
Mid Excellent Good Good
High Good Poor Poor
~ ~ ~ ~ ~ ~
Noise Intrusion Paths
Components matter: wall, windows,
roof, air leaks
Partition Performance
Airborne vs. Structure-Borne
Structural vibrations
amplify sound
~ ~ ~ ~ ~ ~
Sound Reflection-Inside
STC, OITC and TLAlberta Building Envelope Council South
October 25, 2017
Partition Classifications
STC (Sound Transmission Class)• Commonly used to describe of how well building
partitions attenuate sound
• Emphasis on mid frequencies and common household noise
OITC (Outdoor-Inside Transmission Class• Measure of sound transfer between outdoor and indoor
spaces
• Emphasis on lower frequencies and exterior noises
TL (Transmission Loss)• Quantifies the ability for any partition to stop sound
• Assesses all frequencies in octave bands
STC: A Single Number May Not Tell The Whole Story!
OITC: Single Number Better for Low Frequency
TL: The Complete Picture
Walls and WindowsRules of Thumb
• 1% leak limits the performance to 20 dB
• ~6 dB improvement with doubling mass per unit area
• ~3 dB improvement with doubling airspace
• Insulation does not always increase STC/OITC/TL
• Unbalanced construction can dramatically increase performance
RegulationsAlberta Building Envelope Council South
October 25, 2017
What Can We Control?
Real value is created when the source, receiver, and envelope are
considered in harmony. No regulation exists that considers all three.
Macro Trends
• Urban densification• More people• More noise• More complaints
• Land is becoming scarce • Encroachment on rail, traffic and airports• Property values increasing, higher expectations by the
end user
• Transportation is changing• More trains, planes & automobiles• Electric vehicles, quieter planes, drones
• Spin cycle studios…
Technology Trends
Information availability
• Jurisdictions mimic each other
• Faster adoption of regulations
• People use google
• Social media gives power to complaints
Technological advancements in design
• Exponential growth in computer modeling
• Acoustic imaging is becoming more efficient
• Detailed analysis is more cost effective
< 50.0 dBA
50.0 - 53.0 dBA
53.0 - 56.0 dBA
56.0 - 59.0 dBA
59.0 - 62.0 dBA
62.0 - 65.0 dBA
65.0 - 68.0 dBA
68.0 - 71.0 dBA
71.0 - 74.0 dBA
74.0 - 77.0 dBA
77.0 < dBA
Facility Unit Measurement Distance Measurement Date (YYYY-MM-DD) Document ID
PAAE Office Front Building Facade 0.25 m 2017-10-23 IPP-16-007-NAW-007
Detailed data makes decisions easier!
Technology Trends
Global Influences
Germany• All building partitions require sound insulation
values
• “Sound Insulation Passport” to rate a building and to advertise its value
• Limits for interior noise from structure-borne transmission
Australia (Queensland)• Building envelope acoustic assessment required
Global Influences – North America
California• Building code mandates a maximum allowable interior
noise exposure from external sources for all new residential
New York• Every construction site requires a Construction Noise
Mitigation Plan including temporary barriers and enclosures
Ontario• Guideline with maximum indoor sound level limits for
road, rail and aircraft noise are specific for all types of architecture, including residential, institutional and commercial
Regulations vs. Best Practices
Regulations Best Practices
Reactive Proactive
Lower up front cost More investment in pre-design
Lower cost to build Less risk of costly litigation/retrofit
Forced Choice
Same as the other building Opportunity to stand out
Status quo Causes innovation
Adopting best practices benefits everyone
Regulatory Evolution
• Development of Regulations for Oil & Gas Industry
• Noise regulation evolution1. Regulations arise in response to complaints
2. Design adapts to regulations
3. Regulations adopt stringent design requirements
4. Complaints prevented
• Pattern repeats itself across industries
Real LifeExamples #1
The Chiller on the Roof
Alberta Building Envelope Council South
October 25, 2017
The Chiller on the Roof
The Challenge
• Multi-story residential tower
• Air-cooled chiller system located on the roof
• Chiller located immediately above the penthouse master bedroom
• Tenant complained about excessive noise and tones from chiller
• Tenant moved out and apartment became unrentable
The Chiller on the Roof
Key Findings
• Levels within the suite over 40 dBA with discrete tone
• Levels were 15 dB above background
• Recommended levels for sleeping are 35 dBA
• Retrofit requiredTonal Noise is More Annoying
Solution vs. Preventative Measures
Solution
• Retrofit the ceiling (drop), chiller (VFDs or new fans) or roof
• Isolate piping connections
Preventative Measures
• Design for chiller to be over a mechanical or utility room
• Procure quieter chiller without tones
• Consider all flanking paths from the chiller (i.e. piping)
• Improve building envelope through a drop ceiling or heavier roof construction
Real LifeExamples #2
Design vs. Reality
Alberta Building Envelope Council South
October 25, 2017
Design vs. Reality
The Challenge
• Multi-family residential development with the Airport Vicinity Protection Area (AVPA)
• Required acoustic analysis for building envelope design
• Added requirement from the City:Acoustic field reviews
Design vs. Reality
Key Findings
• AVPA analysis sensitive to number of components and surface area
• Developed schedule for permissible windows and walls
• Field review found construction didn’t match design
• Resilient channels installed incorrectly
• Timing of acoustic field review is difficult to coordinate, boarding was done in some areas making field review impossible
Solution vs. Preventative Measures
Solution
• Remove and replace windows and doors
• Adjust installation practices for resilient channel
• Provide clear direction for acoustic construction
Preventative Measures
• Integrate acoustic design in construction drawings
• Select one specific construction for a given building envelope
• Conduct regular field reviews prior to boarding
• Educate contractors on installation requirements of acoustic treatments
Summary
Acoustics matter!
They can be designed intentionally and when they are considered they create spaces people
value.
Thank You
Questions?
