Post on 06-Mar-2018
Acoustics: The Sounds of Sustainable Design
JUNE 9, 2014
LEARNING OBJECTIVES
• Discuss how acoustics impact productivity, learning and occupant comfort
• Examine the differences between STC, NRC, RT, and IIC.
• Illustrate best practices for managing acoustic concerns
• Analyze how acoustics contribute to sustainable design certifications like LEED
COURSE OUTLINE
Acoustic Impacts
The Acoustical ABCs
Design Best Practices
Sustainable Certifications
ACOUSTIC IMPACTS
OFFICE ENVIRONMENTS
CLASSROOM ENVIRONMENTS
RESIDENTIAL ENVIRONMENTS
OFFICE ENVIRONMENTS
“Acoustical conditions profoundly impact human performance in office settings…”
‐ David M. Sykes, PhD“Productivity: How Acoustics Affect Worker’s Performance In Offices and Open Areas”
OFFICE ENVIRONMENTS
Improving acoustical conditions to improve speech privacy resulted in the following gains:
Source: David M. Sykes, PhD: “Productivity: How Acoustics Affect Worker’s Performance In Offices and Open Areas”
• Focus improved by 48%
• Error‐rates decreased by 10%
• Physical symptoms of stress were decreased by 27%
CLASSROOM ENVIRONMENTS
“With a classroom having good acoustical characteristics, learning is easier, deeper, more sustained, and less fatiguing.”
‐ ANSI/ASA S12.60‐2010
CLASSROOM ENVIRONMENTS
Classroom acoustics are especially important because:
• Young children do not effectively listen and understand speech in reverberant conditions
• Many children have trouble focusing their attention in noisy environments
• Many students have low proficiency in English or are non‐native language speakers
Source: Acoustical Society of America: “Acoustical Barriers to Learning”
CLASSROOM ENVIRONMENTS
The Acoustical Society of America and the American National Standards Institute, Inc. have developed acoustical performance criteria, design requirements and guidelines for schools.
RESIDENTIAL ENVIRONMENTS
Noise is the No. 2 litigation issue brought before the courts by owners and residents of condominiums, apartments and co‐ops.
‐ McGraw Hill Construction MagazineDecember 2005
RESIDENTIAL ENVIRONMENTS
• Many building codes contain acoustical requirements for separating dwelling units
• Special attention to acoustics can be an important marketing feature for multifamily residences
• Exterior noises such as traffic and airport noise can decrease property values.
PRIMARY ACOUSTICAL CONCERNS
Interior Noise
Transmission
Exterior Noise
Transmission
Background Noise
Reverberationor Echo Impact Noise
K‐12 Schools ● ● ● ●Higher Ed ● ● ●Open Offices ● ●Private Offices ● ●Multifamily ● ● ●Single Family ● ●
THE ACOUSTICAL ABCs
ABSORPTION
BLOCKING
COVERING
A
B
C
ABSORPTION• Used to control reverberation and echo• Measured through a material’s Noise Reduction
Coefficient (NRC) or Sound Absorption Average (SAA) and the resulting Reverberation Time (RT)
ABSORPTION
REVERBERATION TIME (RT): the period of time it takes for a sound to decay by 60 dB after it has stopped.
Reverberation time is directly related to the amount of absorptive material in a space and the spatial volume of the space.
ABSORPTION
Designing for appropriate reverberation times is a primary means of enhancing speech intelligibility.
ABSORPTION
Reverberation Time
.8 – 1.3 1.4 – 2.0 2.1 – 3.0 OptimumSpeech Good Fair – Poor Unacceptable 0.8 – 1.1
Contemporary Music Fair – Good Fair Poor 1.2 – 1.4
Choral Music Poor‐ Fair Fair – Good Good – Fair 1.8 – 2.0+
ABSORPTION
No Reverberation 0.6 sec RT 0.8 sec RT
1.3 sec RT 2.0 sec RT 5.0 sec RT
Audio File Source: www.mcsquared.com
NOISE REDUCTION COEFFICIENT (NRC): a representation of the amount of sound energy that is absorbed upon striking a specific surface. An NRC of 0 indicates perfect reflection and an NRC of 1 indicates perfect absorption.
NRC is a single number value that averages absorption at four 1/3 octave frequencies: 250, 500, 1000 and 2000 Hz.
ABSORPTION
ABSORPTION
Image Source: www.egger.com
SOUND ABSORPTION AVERAGE (SAA): a representation of the amount of sound energy that is absorbed upon striking a specific surface. An SAA of 0 indicates perfect reflection and an SAA of 1 indicates perfect absorption.
SAA is a single number value that averages absorption at twelve one‐third octave bands from 200 to 2500 Hz
ABSORPTION
ABSORPTION
Perfect Reflection‐ NRC or SAA = 0
Image Source: www.egger.com
ABSORPTION
Perfect Absorption‐ NRC or SAA = 1
Image Source: www.egger.com
ABSORPTION
Partial Absorption‐ NRC or SAA around .8
Image Source: www.egger.com
ABSORPTION
Source: Architectural Acoustics, M. David Egan
Material NRC
Brick .00 ‐ .05
Carpet .15 ‐ .55
Concrete .00 ‐ .20
Cork (floor – ¾”) .10 ‐ .15
Cork (wall – 1”) .30 ‐ .70
Drapery .05 ‐ .60
Gypsum Board /Plaster .05
Glass .05 ‐ .10
Linoleum .05
Marble/Terrazzo .00
Wood .05 ‐ .15
Material NRC
Seating (occupied) .80 ‐ .85
Seating (unoccupied), metal .30
Seating (unoccupied), wood .30
Seating (unoccupied), fabric .60
Seating (unoccupied), leather .50
Acoustical Ceiling Tile .40 ‐ .80
BLOCKING
BLOCKING• Used to combat noise transfer between spaces• Measured through Sound Transmission Class
(STC) and Impact Insulation Class (IIC)
BLOCKING
Sound Transmission Class (STC):a rating of how well a building assembly attenuates (blocks) the transfer of airborne sound. A larger number means greater attenuation.
Like NRC, STC also assesses multiple frequencies of sound (125 – 4000 Hz).
Calculated as an assembly.
BLOCKING
STC can be increased by:
• Adding mass
• Adding air space
• Adding absorptive material inside an assembly
BLOCKING
STC 38 ‐ 40
STC 43 ‐ 44
STC 32 ‐ 35
STC 34 ‐ 39
BLOCKING
STC 43 ‐ 45
STC 45 ‐ 52
STC 34 ‐ 39
STC 39 ‐ 40
BLOCKING
STC 45 ‐ 59STC 46 ‐ 47
Wall Thickness Hollow Units Sand Filled Grout Filled
4” STC 44 STC 46 STC 47
6” STC 46 STC 49 STC 51
8” STC 48 STC 52 STC 55
10” STC 53 STC 55 STC 60
BLOCKING
Masonry Wall STC Values
BLOCKING
Flanking Paths: a path for sound to travel over, under, around or through an assembly.
Noise Leaks: areas of poor sealing that can allow sound to pass through an assembly.
Image Source: www.STCratings.com
F1‐ Open plenums aboveF2‐ Common ductworkF3‐ Adjacent exterior windowsF4‐ Common floor heatersF5‐ Open ventsF6‐ Louvered doorsF7‐ Under doors
L1‐ Poor seal at wall/ceiling connectionL2‐ Poor seal at wall/wall connectionL3‐ Poor seal at wall/mullion connectionL4‐ Poor seal around outlet penetrationL5‐ Poor seal at wall penetrationL6‐ Poor seal at floor penetrationL7‐ Poor seal at wall/floor connectionL8‐ Poor seal around door
Noise Leaks Flanking Paths
BLOCKING
Impact Insulation Class (IIC): a rating of how well a building assembly attenuates impact sounds. A larger number means greater attenuation.
Like NRC, IIC also assesses multiple frequencies of sound (100 – 3150 Hz).
Calculated as an assembly.
BLOCKING
IIC can be increased by:
• Adding layers of resilient materials
• Adding layers of fibrous materials
BLOCKING
Topping (on concrete slab) IIC
None, Ceramic Tile or Marble Tile 28
Vinyl Flooring 35 ‐ 40
Hardwood Flooring 30 ‐ 35
Hardwood flooring on 6mm resilient underlayment 45 ‐ 50
Concrete topping over 25mm mineral fiber board 60 ‐ 65
Carpet and Underlay (pad) 75 ‐ 85
BLOCKING
Topping (on wood floor joists) IIC
Ceramic Tile or Marble Tile 40
No Topping 45
Vinyl Flooring 47
Hardwood Flooring 47
Hardwood flooring on 6mm resilient underlayment 47
Resilient Flooring on 35 mm concrete topping 52
Carpet and Underlay (pad) 75 ‐ 85
COVERING
COVERING• Use of sound masking to “cover” other noises• Measured through the decibel level of masking
sound
COVERING
White Noise: a random signal with constant power spectral density that contains sounds across the frequency range. White noise is often used to block sound distractions and increase focus.
COVERING
HVAC Background Noise: the sound an HVAC system uses can be used as a covering mechanism, but at higher or inconsistent levels, it can also be a distraction.
COVERING
Space Type Decibel LevelApartment 35 ‐ 45Private Home 30 ‐ 38Private Office 40 ‐ 45Open‐plan Office 45 ‐ 50Conference Room 35 ‐ 40Classrooms 35 ‐ 40
Recommended Background Noise Levels
DESIGN BEST PRACTICES
WALL COVERINGS
SOUND INSULATION/ SEALING
MASS
WHITE NOISE
CEILING MATERIALS
FLOORING
HVAC NOISE
FURNITURE
AIR SPACE
WHICH STRATEGIES CAN DECREASE
REVERBERATION TIME?
WALL COVERINGS
SOUND INSULATION/ SEALING
MASS
WHITE NOISE
CEILING MATERIALS
FLOORING
HVAC NOISE
FURNITURE
AIR SPACE
WALL COVERINGS
CEILING MATERIALS
FLOORING
FURNITURE
WHICH STRATEGIES CAN INCREASE WALL STC?
WALL COVERINGS
SOUND INSULATION/ SEALING
MASS
WHITE NOISE
CEILING MATERIALS
FLOORING
HVAC NOISE
FURNITURE
AIR SPACE
WALL COVERINGS
SOUND INSULATION/ SEALING
MASS
AIR SPACE
WHICH STRATEGIES WILL INCREASE FLOOR IIC?
WALL COVERINGS
SOUND INSULATION/ SEALING
MASS
WHITE NOISE
CEILING MATERIALS
FLOORING
HVAC NOISE
FURNITURE
AIR SPACE
SOUND INSULATION/ SEALING
CEILING MATERIALS
FLOORING
WHICH ARE COVERING STRATEGIES?
WALL COVERINGS
SOUND INSULATION/ SEALING
MASS
WHITE NOISE
CEILING MATERIALS
FLOORING
HVAC NOISE
FURNITURE
AIR SPACE
WHITE NOISE
HVAC NOISE
FURNITURE
OFFICE ENVIRONMENTS
CLASSROOM ENVIRONMENTS
RESIDENTIAL ENVIRONMENTS
DESIGN STRATEGIES
PRIMARY ACOUSTICAL CONCERNS
Interior Noise
Transmission
Exterior Noise
Transmission
Background Noise
Reverberationor Echo Impact Noise
K‐12 Schools ● ● ● ●Higher Ed ● ● ●Open Offices ● ●Private Offices ● ●Multifamily ● ● ●Single Family ● ●
PRIVATE OFFICE
Primary Concerns:• Interior Noise Transmission (STC)• Background Noise• Reverberation Time
PRIVATE OFFICE
Primary Concerns:• Interior Noise Transmission (STC)• Background Noise• Reverberation Time
PRIVATE OFFICE
Primary Concerns:• Interior Noise Transmission (STC)• Background Noise• Reverberation Time
Full height STC 50 Wall‐metal stud with resilient
channels
Acoustical Sealant
PRIVATE OFFICE
Primary Concerns:• Interior Noise Transmission (STC)• Background Noise• Reverberation Time
PRIVATE OFFICE
Primary Concerns:• Interior Noise Transmission (STC)• Background Noise• Reverberation Time
Low Velocity HVAC System
PRIVATE OFFICE
Primary Concerns:• Interior Noise Transmission (STC)• Background Noise• Reverberation Time
PRIVATE OFFICE
Primary Concerns:• Interior Noise Transmission (STC)• Background Noise• Reverberation Time
Absorptive Carpet
Cork Board
OPEN OFFICES
Primary Concerns:• Background Noise• Reverberation Time
OPEN OFFICES
Primary Concerns:• Background Noise• Reverberation Time
OPEN OFFICES
Primary Concerns:• Background Noise• Reverberation Time
High velocity HVAC system used as sound masking
OPEN OFFICES
Primary Concerns:• Background Noise• Reverberation Time
OPEN OFFICES
Primary Concerns:• Background Noise• Reverberation Time
Absorptive Carpet
High NRC Ceiling Tile
ELEMENTARY SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
ELEMENTARY SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
ELEMENTARY SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
Full height STC 50 masonry wall between classrooms
ELEMENTARY SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
ELEMENTARY SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
High STC Window Assembly
STC 65 Masonry Cavity Wall
ELEMENTARY SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
ELEMENTARY SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
Constant volume, low velocity HVAC
system
ELEMENTARY SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
ELEMENTARY SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
High NRC Ceiling Tile
Absorptive Carpet
MIDDLE/HIGH SCHOOL SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
MIDDLE/HIGH SCHOOL SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
MIDDLE/HIGH SCHOOL SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
Full height STC 45 metal stud wall with 4 layers of gypsum board between classrooms
MIDDLE/HIGH SCHOOL SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
MIDDLE/HIGH SCHOOL SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
High STC Window Assembly
STC 65 Masonry Cavity Wall
MIDDLE/HIGH SCHOOL SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
MIDDLE/HIGH SCHOOL SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
Sound Reinforcement System
Low Velocity HVAC System
MIDDLE/HIGH SCHOOL SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
MIDDLE/HIGH SCHOOL SCHOOL CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Exterior Noise Transmission (STC)• Background Noise• Reverberation Time
High NRC Ceiling Tile
Fabric Baffles
Gypsum Board Walls
UNIVERSITY CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Background Noise• Reverberation Time
UNIVERSITY CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Background Noise• Reverberation Time
UNIVERSITY CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Background Noise• Reverberation Time
Full height STC 50 Wall‐metal stud with resilient
channels between classrooms
UNIVERSITY CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Background Noise• Reverberation Time
UNIVERSITY CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Background Noise• Reverberation Time
Medium velocity, constant volume HVAC system
UNIVERSITY CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Background Noise• Reverberation Time
UNIVERSITY CLASSROOM
Primary Concerns:• Interior Noise Transmission (STC)• Background Noise• Reverberation Time
Absorptive Wall Pads
High NRC Ceiling Tiles
MULTIFAMILY HOUSING
Primary Concerns:• Interior Noise Transmission (STC) • Background Noise• Impact Noise (IIC)
MULTIFAMILY HOUSING
Primary Concerns:• Interior Noise Transmission (STC) • Background Noise• Impact Noise (IIC)
MULTIFAMILY HOUSING
Primary Concerns:• Interior Noise Transmission (STC) • Background Noise• Impact Noise (IIC)
Full height STC 50 Wall‐metal stud with resilient channels between rooms
Use of storage between rooms (increases mass and
air space)
Single room HVAC system to limit flanking paths
MULTIFAMILY HOUSING
Primary Concerns:• Interior Noise Transmission (STC) • Background Noise• Impact Noise (IIC)
MULTIFAMILY HOUSING
Primary Concerns:• Interior Noise Transmission (STC) • Background Noise• Impact Noise (IIC)
Medium velocity, constant volume HVAC system
MULTIFAMILY HOUSING
Primary Concerns:• Interior Noise Transmission (STC) • Background Noise• Impact Noise (IIC)
MULTIFAMILY HOUSING
Primary Concerns:• Interior Noise Transmission (STC) • Background Noise• Impact Noise (IIC)High IIC ceiling/floor
assembly of carpet on wood joists.
Image Source: www.blenture.com
SINGLE FAMILY HOUSING
Primary Concerns:• Exterior Noise Transmission (STC) • Background Noise
Image Source: www.blenture.com
SINGLE FAMILY HOUSING
Primary Concerns:• Exterior Noise Transmission (STC) • Background Noise
Image Source: www.blenture.com
SINGLE FAMILY HOUSING
Primary Concerns:• Exterior Noise Transmission (STC) • Background Noise
Exterior wall and vegetation to block environmental noise
Well sealed, high STC windows
Image Source: www.blenture.com
SINGLE FAMILY HOUSING
Primary Concerns:• Exterior Noise Transmission (STC) • Background Noise
Image Source: www.blenture.com
SINGLE FAMILY HOUSING
Primary Concerns:• Exterior Noise Transmission (STC) • Background Noise
Radiant Floor Heating
SUSTAINABLE CERTIFICATIONS
Many sustainable certification programs have requirements or points that relate
to acoustics.
LEED 2009
LEED for New Construction and Commercial Interiors
The base rating system does not have any acoustics related prerequisites or credits. However, there is a “pilot credit” that has background noise requirements, reverberation time requirements, STC requirements, and requirements for sound reinforcement and sound masking in certain situations.
LEED 2009
LEED for New Construction and Commercial Interiors
The base rating system does not have any acoustics related prerequisites or credits. However, there is a “pilot credit” that has background noise requirements, reverberation time requirements, STC requirements, and requirements for sound reinforcement and sound masking in certain situations.
Background Noise Requirements: As prescribed by ASHRAE
RT Requirements: As prescribed for each space type
STC Requirements: 45 – 60 depending on adjacent space types
Sound Reinforcement: Required in spaces for 50 or more people
Sound Masking: Must not exceed 48 dB
LEED
LEED for New Construction and Commercial Interiors
There is a new credit for acoustic performance that limits HVAC background noise, sets STC requirements and reverberation time requirements and requires sound reinforcement and sound masking systems in certain situations.
LEED
LEED for New Construction and Commercial Interiors
There is a new credit for acoustic performance that limits HVAC background noise, sets STC requirements and reverberation time requirements and requires sound reinforcement and sound masking systems in certain situations.
Background Noise Requirements: As prescribed by ASHRAE
RT Requirements: As prescribed for each space type
STC Requirements: 45 – 60 depending on adjacent space types
Sound Reinforcement: Required in spaces for 50 or more people
Sound Masking: Must not exceed 48 dB
LEED 2009
LEED for Schools
This version of the LEED Rating System has an acoustics prerequisite that has limits for HVAC background noise and reverberation time. There is also a credit that lowers the acceptable HVAC background noise levels and adds STC requirements for interior and exterior walls.
Background Noise Requirements: 45 dB max for HVAC
RT Requirements: High NRC (0.70) ceilings in small spacesReverberation time of 1.5 seconds or less
PREREQUISITE REQUIREMENTS:
LEED 2009
LEED for Schools
This version of the LEED Rating System has an acoustics prerequisite that has limits for HVAC background noise and reverberation time. There is also a credit that lowers the acceptable HVAC background noise levels and adds STC requirements for interior and exterior walls.
Background Noise Requirements: 40 dB max for HVAC
STC Requirements: Meet ASHRAE requirements in core learning spaces
CREDIT REQUIREMENTS:
LEED
LEED for Schools
The acoustics prerequisite in this version of the rating system is very similar to that contained in LEED 2009 for Schools, but it adds an exterior noise control requirement and lowers the allowable HVAC background noise decibel level. Similarly, the related credit also lowers the allowable HVAC background noise level.
Background Noise Requirements: 40 dB max for HVAC
RT Requirements: High NRC (0.70) ceilings in small spacesReverberation times meet Design Guideline
Exterior Noise Control: High noise sites must control exterior noise
PREREQUISITE REQUIREMENTS:
LEED
LEED for Schools
The acoustics prerequisite in this version of the rating system is very similar to that contained in LEED 2009 for Schools, but it adds an exterior noise control requirement and lowers the allowable HVAC background noise decibel level. Similarly, the related credit also lowers the allowable HVAC background noise level.
Background Noise Requirements: 35 dB max for HVAC
STC Requirements: Meet ASHRAE requirements in core learning spaces
CREDIT REQUIREMENTS:
LEED 2009 and
LEED for Homes
The base rating system does not have any acoustics related prerequisites or credits. However, there is a “pilot credit” for acoustics.
Background Noise Requirements: HVAC guidelines or 40 dB
Exterior Noise Control Requirements: Sealing and STC
STC Requirements: 55 between dwelling units
IIC Requirement: 55 for floors between dwelling units
• Requires separation of noisy occupancies and other common sense strategies
• Open offices have sound masking
• STC requirements for wall, doors and windows
• IIC of 50 for all floor/ceiling assemblies
• Reverberation time maximums by space volume
• Requires separation of noisy occupancies and other common sense strategies
• Open offices have sound masking
• STC requirements for wall, doors and windows
• IIC of 50 for all floor/ceiling assemblies
• Reverberation time maximums by space volume
• May vary by state
• Prerequisite has background noise and RT requirements
• Credit has lower background noise requirements
CONCLUSIONSUnderstand each space’s acoustic design priorities
Keep the alphabet soup straight
Identify strategies that can multi‐task
Collect some credits!
SHP LEADING DESIGN4805 Montgomery Road, Suite 400Cincinnati, OH 45212www.shp.com
QUESTIONS?
Allison McKenzieamckenzie@shp.comwww.buildingmygreenlife.com