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Transcript of Acoustics of Green Buildings
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Acoustics of Green Buildings
Ralph T Muehleisen Ph.D., P.E., LEED AP BD+C, INCE Board Certified, FASA Principal Building Scientist Argonne National Lab
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Outline
Part I: What is a Green Building?
Environmental Impacts of Buildings
How Green Buildings Help
The LEED Green Building Rating system
Part II: Acoustics of Green Buildings
Conflicts between Green Building Design and Office Acoustics
Synergies and Opportunities for Better Acoustics in Green Buildings
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Part I: What is a Green Building
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Why Do We Need Green Buildings?
To understand the Acoustics of Green Buildings, we also have to understand what Green buildings are and understand how they are different than conventional buildings.
But, before we discuss what they are, lets take a minute to discuss why people want to make buildings more green to begin with
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Rise in CO2 Emissions and Global Warming
The scientific community agrees that the earth is warming from man made CO2 emissions. Much of that is from buildings
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How Is This Related to Buildings?
Global CO2 Emissions by Sector:
#1: Buildings #2: Industry
#3: Transportation
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CO2 Sources and Emitters in
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2444
Of
6576
Source: EIA Emissions of Greenhouse Gases in the US 2009
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Energy Flow in the US
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Source: EIA Annual Energy Review 2009
US Energy use in Quads (Quadrillions of BTU)
1 Quad =1010therms= 1015BTU = 3.141015Wh= 3.14109MWh
39.36
Of
94.58
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Why Do We Need Green Buildings?
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13% of Potable
Water Use
37% of Greenhouse Gas
41% of Primary
Energy Use
72% of Electricity
Consumption
Buildings account for a LOT of resource use and greenhouse gas emission. In the US buildings account for:
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What Can We Reduce With Green Buildings?
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What Other Benefits Do Green Buildings Provide?
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What is a Green Building?
Green buildings are buildings that are better for the environment (i.e more sustainable) than a conventional building in one or more ways. These ways include:
Lower energy use in construction and operation
Less water use in construction and/or operation
Destroy less of the environment during construction and/or operation
Provide a better indoor environmental quality (leading to better worker satisfaction and performance)
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How Are Green Buildings Different?
Green building design aspects focus on reduced energy use, water use, and more use of sustainable materials through:
More use of natural ventilation
More use of daylight and passive solar heating
More use of radiant heating/cooling
More use of wood and stone and less use of fiberglass or mineral fibers
More use of glass for daylight integration and views of outside world
Less interior walls and partitions
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How Do We Know If A Building Is Green?
One way in which buildings are determined to be Green or not is through Green building rating systems
Energy Star (from US EPA and DOE)
LEED (from US Green Building Council)
Green Globes (from Green Building Initiative)
ASHRAE 189 (standard from ASHRAE)
BREEAM (from UK)
Green Star (from Green Building Council Australia)
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Introduction to LEED
LEED is the predominate Green Building Rating system in the US so lets explain it in a bit more detail.
Most of the other rating systems are fairly similar, it tends to be details that are different.
Those of you who were familiar with LEED and maybe even are a LEED Accredited Professional (LEED AP) but have not kept up to date might find something new in here
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What is LEED?
Leadership in Energy and Environmental Design (LEED) is a system for rating Green Buildings
Buildings are Certified as LEED when they have a high enough rating.
There are multiple levels of certification
Getting a building LEED certified is voluntary except when it isnt
Many state and local governments require LEED certification of any building built with public funds
Some municipalities (e.g. San Francisco) are requiring LEED certification for any new construction or major renovation
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What LEED is NOT
LEED is NOT a city in the UK
That would be Leeds
Is NOT building code
That is municipal law that regulates building design and construction E.G. The International Building Code
Is NOT a construction standard
They usually define performance levels of specific building components and describe methods of how to measure performance E.G. ASHRAE 90.1 Energy Standard, ANSI
S12.60
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LEED Rating Systems
There are different LEED Rating systems for different types of buildings
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Who Creates LEED Rating Systems?
LEED is a consensus based rating system that is organized by the US Green Building Council, a non-profit organization with members from all of the building industry including members from the design, construction, and owner/developer industries.
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Four Levels of LEED Certification
LEED Certified: 40-49 points
LEED Silver: 50-59 points
LEED Gold: 60-79 points
LEED Platinum: > 80 points
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LEED Prerequisites and Points
To get any certification, a building must meet all the prerequisites of the rating system and achieve at least 40 points
Prerequisites are minimum building standards and they basically ensure that the building is not bad
The prerequisites are often found as part of the local building code so meeting them is already a requirement to build
Points are awarded for enhanced performance in many areas including construction, material use, energy use, and indoor environmental quality.
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What Things Go Into a LEED Rating?
LEED prereqs and points are broken down into 5 main areas with differing levels of importance
Additional areas for points are design innovation and regional priority
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Overview of the LEED 2009 NC Rating System
The following slides show the categories, list the prerequisites and available design points for one rating system, LEED 2009 for New Construction and Major Renovation (LEED NC 2009)
With Innovation and Design and Regional Priority credits there are up to 110 points available.
There are only 100 points available in the main rating system
This is going to stay fixed in future updates, although the prereqs and details of the available points may change
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Sustainable Sites (SS)
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Possible Points: 26
Prereq 1
Credit 1 1
Credit 2 5
Credit 3 Brownfield Redevelopment 1
Credit 4.1 6
Credit 4.2 1
Credit 4.3 Alternative TransportationLow-Emitting and Fuel-Efficient Vehicles 3
Credit 4.4 2
Credit 5.1 Site DevelopmentProtect or Restore Habitat 1
Credit 5.2 Site DevelopmentMaximize Open Space 1
Credit 6.1 Stormwater DesignQuantity Control 1
Credit 6.2 Stormwater DesignQuality Control 1
Credit 7.1 Heat Island EffectNon-roof 1
Credit 7.2 1
Credit 8 Light Pollution Reduction 1
Sustainable Sites
Alternative TransportationParking Capacity
Heat Island EffectRoof
Construction Activity Pollution Prevention
Site Selection
Development Density and Community Connectivity
Alternative TransportationPublic Transportation Access
Alternative TransportationBicycle Storage and Changing Rooms
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Water Efficiency (WE)
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Possible Points: 10
Prereq 1
Credit 1 Water Efficient Landscaping 2 to 4
Reduce by 50% 2
No Potable Water Use or Irrigation 4
Credit 2 Innovative Wastewater Technologies 2
Credit 3 2 to 4
Reduce by 30% 2
Reduce by 35% 3
Reduce by 40% 4
Water Efficiency
Water Use Reduction20% Reduction
Water Use Reduction
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Energy and Atmosphere (EA)
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Materials and Resources (MR)
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Possible Points: 14
Prereq 1
Credit 1.1 1 to 3
Reuse 55% 1
Reuse 95% 3
Credit 1.2 Building ReuseMaintain 50% of Interior Non-Structural Elements 1
Credit 2 1 to 2
50% Recycled or Salvaged 1
75% Recycled or Salvaged 2
Credit 3 1 to 2
Reuse 5% 1
Reuse 10% 2
Credit 4 1 to 2
20% of Content 2
Credit 5 1 to 2
20% of Materials 2
Credit 6 Rapidly Renewable Materials 1
Credit 7 1
Materials and Resources
Storage and Collection of Recyclables
Building ReuseMaintain Existing Walls, Floors, and Roof
Construction Waste Management
Materials Reuse
Recycled Content
Regional Materials
Certified Wood
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Indoor Environmental Quality (IEQ)
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Possible Points: 15
Prereq 1
Prereq 2
Credit 1 1
Credit 2 1
Credit 3.1 1
Credit 3.2 1
Credit 4.1 1
Credit 4.2 1
Credit 4.3 1
Credit 4.4 1
Credit 5 1
Credit 6.1 Controllability of SystemsLighting 1
Credit 6.2 1
Credit 7.1 1
Credit 7.2 Thermal ComfortVerification 1
Credit 8.1 1
Credit 8.2 1
Indoor Environmental Quality
Minimum Indoor Air Quality Performance
Environmental Tobacco Smoke (ETS) Control
Outdoor Air Delivery Monitoring
Increased Ventilation
Construction IAQ Management PlanDuring Construction
Construction IAQ Management PlanBefore Occupancy
Low-Emitting MaterialsAdhesives and Sealants
Low-Emitting MaterialsPaints and Coatings
Low-Emitting MaterialsFlooring Systems
Low-Emitting MaterialsComposite Wood and Agrifiber Products
Indoor Chemical and Pollutant Source Control
Controllability of SystemsThermal Comfort
Thermal ComfortDesign
Daylight and ViewsDaylight
Daylight and ViewsViews
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Innovation and Design (ID) and Regional Priority
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Possible Points: 6
Credit 1.1 1
Credit 1.2 1
Credit 1.3 1
Credit 1.4 1
Credit 1.5 1
Credit 2 1
Possible Points: 4
Credit 1.1 1
Credit 1.2 1
Credit 1.3 1
Credit 1.4 1
Innovation in Design: Specific Title
Innovation in Design: Specific Title
Innovation in Design: Specific Title
LEED Accredited Professional
Regional Priority: Specific Credit
Regional Priority: Specific Credit
Regional Priority: Specific Credit
Regional Priority: Specific Credit
Innovation and Design Process
Regional Priority Credits
Innovation in Design: Specific Title
Innovation in Design: Specific Title
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LEED Prerequisite and Points in More Detail
Lets look at a prerequisite and a point so you can see a little more about what must be done. Each prereq and point has several sections:
Intent: This explains why it is in LEED
Requirements: This explains what has to be done
Potential Technologies and Strategies: This gives some brief ideas of how to achieve the prereq or point
Required Documentation (In the Full Reference Guide Only): This explains what you have to submit
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From the LEED 2009 NC Rating System PDF
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From the LEED 2009 NC Rating System PDF
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Important LEED Documents
LEED Rating Systems
PDF Documents that give an overview of all the prereq and points. Does not explain required documentation or required submittals. Free download from USGBC
LEED Checklist
Excel spreadsheet that lists the prereq and points useful for double checking your design, Free download from USGBC
LEED Reference Guide
PDF or print book that explains the rating system in details, includes references and explains required documentation and submittals. Must be bought from USGBC
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References and Resources
US Energy Information Administration. 2010. Annual Energy Review 2009. http://www.eia.gov/totalenergy/data/annual/.
US Energy Information Administration. 2011. Emissions of Greenhouse Gases in the United States 2009. http://www.eia.gov/environment/emissions/ghg_report/.
USGBC. 2011. Building Impacts - Why Build Green? https://www.usgbc.org/ShowFile.aspx?DocumentID=4317.
USGBC. 2011. LEED 2009 For New Construction and Major Renovations. http://www.usgbc.org/ShowFile.aspx?DocumentID=8868.
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Part II: Acoustics of Green Buildings Conflicts and Synergies
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What is Architectural Acoustics
Architectural acoustics is the study of sound in buildings and the design of buildings for proper acoustics including Control of sound transmission throughout building
Maintaining conditions for good speech intelligibility
Maintaining sound isolation for speech privacy
Enhancing the acoustic signal in performance spaces
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Reverberation
Reverberation is the bouncing sound in a room from the room surfaces We characterize by the Reverberation Time, RT, the amount of time
it takes the sound energy to decay from absorption by 60 dB
The shorter the reverberation time, the less reverberation and the easier it is to understand speech. Most rooms should have reverberation times well under 1 second
to be good for speech
High reverberation tends to mask sound reducing speech intelligibility
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Sound Isolation
Sound isolation is the ability to block sound transmission from one area to another
Sound isolation capability depends upon the mass and construction details of a partition or fenestration
We often characterize sound isolation by a single number called the sound transmission class or STC The higher STC, the better the isolator
Measured with ASTM Standards
STC > 50 is desired for high sound isolation
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Speech Intelligibility
Speech Intelligibility is the ability to hear and understand a conversation The higher the speech intelligibility, the more a conversation is understood
Speech intelligibility is related to the sound power and directivity of the speaker, the background noise level at the listener, the attenuation between speaker Sentence understanding of 90-95% is usually desired Speech Intelligibility is objectively measured with the Speech Intelligibility
Index ( ANSI S3.5) or the Speech Transmission Index (IEC 60268-16)
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Speech Privacy
Speech Privacy is the inability to understand someone else's speech Its basically the opposite of speech intelligibility This is important for legal and security issues as well as annoyance
Like Speech Intelligibility, Speech Privacy is related to sound power, background noise level, attenuation, and listener language skills Speech privacy is measured by the Privacy Index (ASTM 1130) in open offices
and the Speech Privacy Class (ASTM 2638) in closed offices Good Speech Privacy has a PI > 95% or SPC > 80
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Office Acoustics
The acoustics of a room in an office are largely defined by
the overall background noise level
the speech intelligibility between co-workers who are working together
speech privacy between workers who are not working together
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What affects Office Acoustics?
The noise generated by building systems and people
The sound absorption of the rooms surfaces Low sound absorption means high reverberation
Workstation-to-workstation reflections mean reduced speech privacy
The sound isolation capabilities of walls/roofs/windows and partitions Poor sound isolation means increased background noise and reduced
speech privacy
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How Do Buildings Affect Occupants?
Poor building designs can cause or exacerbate:
hidden sick days higher absenteeism
high stress levels
high blood pressure
respiratory ailments
allergies, asthma
These all result in reduced productivity and increased health insurance costs Note: A 1% decrease in productivity (about 5
minutes per day) equals $600-700 per employee per year!
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Acoustics is an important part of employee comfort and well-being it is a significant portion of Indoor Environmental Quality (IEQ)
Poor acoustics will
Inhibit Communication
Create Vocal Strain
Limit Attention Span
These problems lead to
Increased Stress Levels
Higher Absenteeism
Decreased Productivity
Where Does Acoustics Fit In?
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Acoustics in Green Building Standards
The new ASHRAE 189.1 has some acoustics AIA Guidelines for Healthcare Facility Design (which
is quite Green) has some acoustics LEED for Schools
LEED for Schools requirements are a reduced version of the ANSI S12.60 Classroom Acoustics Standard
LEED for Healthcare will have a little acoustics LEED for Healthcare requirements are a reduced version of
the acoustics in AIA Guidelines
The most popular LEED rating systems (NC and EB/OM) have no acoustics whatsoever (yet) As a result, design teams have no incentive (from the rating
system) to design for good acoustics or even consider them within the design phase
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Are Green Buildings Really Better Buildings?
To evaluate if green buildings really are better we can:
Look at resource use to see if it is reduced
Most green buildings really do have reduced energy and water use. A few do not perform as well as expected.
Look at surveys of occupants to see if they find that the indoor environmental quality is improved
We call these surveys of the occupants after they have used the building, Post Occupancy Evaluation (POE) surveys
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Results of the UC Berkeley POE Surveys
-0.5 0 0.5 1 1.5 2
Overall Building
Overall Workspace
Office Layout
Cleaning/Maintenance
Lighting
Air Quality
Thermal Comfort
Acoustics
Berkeley Post Occupancy Survey Results
LEED/Green New Non-Green All Buildings
Over 400 total buildings and thousands of respondents in the survey
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Acoustics Survey Results are Poor
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Acoustics is the only category where the performance is worse in new green buildings compared to non-green buildings and it is the category with the lowest ratings in all buildings.
In short green buildings have worse acoustics
-0.4 -0.2 0 0.2 0.4
Thermal Comfort
Acoustics
Berkeley Post Occupancy Survey Results
LEED/Green New Non-Green All Buildings
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Acoustics Complaints
Obvious problem:
Poor speech privacy and sound isolation
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Office Noise Sound Examples
Acoustically Good Open Office
Absorptive ceiling and floors
cubicles with 5 6 ft absorptive walls
Typical Green Office
Hard walls, floors and ceilings
Short or no cubicles
Simple Private Office
Thin walls
Thin, unsealed, but closed door
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Causes of Poor Green Building Acoustics
Let us examine some of the causes of poor acoustics:
Natural Ventilation
Daylighting
Radiant Heating and Cooling
Exposed Thermal Mass
Lightweight Steel Frames
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Natural Ventilation
Natural ventilation uses indoor/outdoor pressure differences to drive air flow through holes in walls and open windows
Reduces the energy use to move air in ducts
Can provide higher quality air to occupants
This type of system results in: Reduced HVAC noise
This can be good but sometimes it is too quiet
Poor sound isolation Outside to Inside Room to Room Cubicle to Cubicle
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Daylighting and Passive Solar
Green buildings use a lot more sunlight for illumination (daylighting) and passive solar heating. More sunlight means more windows and skylights
Some even use glass for internal walls to allow more interior sunlight penetration
The result of all this is:
Reduced indoor/outdoor sound isolation
Reduced interior sound isolation
More acoustically reflective surfaces on room walls and ceilings
Less surface area available for sound absorptive treatments
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Radiant Heating/Cooling
Radiant Heating and Cooling is being used more for improved energy efficiency and improved thermal comfort. This results in:
More exposed metal and concrete which are sound reflective surfaces
This results in higher reverberant sound levels and high reflection of direct sound Increased background noise in general
from high reverberation
Decreased speech privacy from direct reflections
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Thermal Mass
More Thermal Mass is being used in design
Thermal mass is a high heat capacity material like CMU block or concrete
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Use of thermal mass results in Reduced inside thermal variation
Time delay in peak loads
Reduce overall energy costs
Using thermal mass requires direct heat exchange with room This means we cannot cover surfaces with
typical sound absorbing materials
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Use of Sustainable Materials
Green buildings tend to use more sustainably farmed wood, metal (recycled and recyclable), stone, and concrete than conventional buildings. This means
Reduced use of acoustic ceiling tile
Reduced use of acoustic absorptive panels
Reduced use of carpeting
Note: acoustic tiles, panels, and carpeting all are being made in more sustainable ways by some firms so the trend away from them might be changing.
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Lightweight Steel Frame Design
If thermal mass systems are not used, buildings are often being designed with lighter weight, welded steel frames and much thinner walls and floors. This results in Reduced Airborne Sound Isolation
Reduced damping of structure borne sound
Increased coupling of vibration between structural members
Decreased isolation to impact and vibration excitation.
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Conflicts with Natural Ventilation and Daylight
There is no simple way to provide sound isolation if partitions need to be reduced or eliminated for natural ventilation and daylighting
Sound masking, the generation of background noise to cover up other noise, can help provide cubicle-to-cubicle sound isolation but only with an increase in the overall noise level
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Conflicts with Natural Ventilation and Daylight
There are no magic bullets to provide good sound isolation with large amounts of glass.
High sound isolation windows are available, but are expensive and their sound isolation is still worse than most opaque wall constructions
Clear and translucent sound absorbing materials are available but are still extremely expensive
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Synergies
Careful construction to avoid thermal bridging and air infiltration usually results in improved outdoor-indoor sound isolation
Use of high mass construction (concrete, filled CMU) in walls and floors can provide better sound isolation opportunities Must be careful to install high acoustic
absorbing materials where they are acceptable to ensure reverberation is controlled
Reduced use of forced air HVAC mean less HVAC generated noise and vibration May need to install noise masking systems to
provide speech privacy
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Synergies
Green Roofs can provide improved sound isolation
Green roofs are being used to reduce urban heat islands, reduce heating and cooling load, increase roof membrane lifetimes, improve local air quality, reduce roof water runoff, and roof clean water runoff
Studies show that the increased mass and absorbing properties of green roofs can increase sound isolation of roofs by 3-15 dB The transmission loss difference
between the green/pink and blue curves is from the green roof
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Opportunities
The use of coordinated and integrated design teams can take advantage of synergies and try to minimize conflicts early in design.
Owners, architects, and building systems designers frequently meet together in design charrettes early in the design phase
The old school methods with discipline separated design must be abandoned in green buildings to ensure energy use is minimized
For this to be able to provide improved acoustics someone on the design team needs to have training in acoustics!
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Opportunities
Post-occupancy evaluations can be used to find and document acoustic complaints of workers even if upper management is not aware of problems
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Market for sustainable acoustic products Make traditional acoustic treatments more
sustainable Transparent Acoustic Absorbers
Available but very high cost now
Absorbing Radiative Heat Exchangers None commercially available but the idea is sound (pun
intended)
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Designer Needs
Need to get some acoustics into the criteria for green building rating systems This is slowly starting to happen, in part because
of advocacy of ASA members like Dan Bruck, Alexis Kurtz, Charles Salter, Dave Lubman, David Sykes, Brandon Tinianov, and others
Need to educate architects and engineers on the need to consider acoustics in the design, even if the rating system does not Make them aware of the implications of poor
acoustics (unhappy and unproductive applicants)
Make them understand that some things cannot always be fixed afterward
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Research Needs
More human performance studies
We need to be able to determine which environmental components have the greatest effect on environmental acceptability, productivity, and human performance so we can prioritize design
New Materials and Treatments
Affordable transparent sound absorbers
Sound absorbing radiative heat exchangers
Noise control for natural ventilation
Better acoustic models for green roofs
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Summary
Green Buildings usually have worse acoustical performance than conventional because:
Rating systems do not incentivize good acoustics. We need to change that
Green building designs tend to remove sound absorbing materials for daylighting, radiative heating and cooling, and exposed thermal mass
Green building designs tend to reduce isolating construction for daylighting and natural ventilation.
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Summary
Green buildings can provide some good opportunities for improved acoustic performance through:
Coordinated, integrated design teams
High mass construction provides opportunity for improved sound isolation
Green Roofs provide better sound isolation
New markets for sustainable acoustical materials
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Common Standards Used in Office Acoustics
ANSI S3.5-1997: Methods for the Calculation of the Speech Intelligibility Index
ASTM E90-04, Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements.
ASTM E336-05, Standard Test Method for Measurement of Airborne Sound Attenuation between Rooms in Buildings.
ASTM E413-04: Classification for Rating Sound Insulation.
ASTM E1130-08: Objective Measurement of Speech Privacy in Open Plan Spaces Using Articulation Index.
ASTM E2368-10: Standard Test Method for Objective Measurement of the Speech Privacy Provided by a Closed Room
IEC 60268-16: Sound system equipment Part 16: Objective rating of speech intelligibility by speech transmission index.
ISO 3382:1997 Acoustics -- Measurement of the reverberation time of rooms with reference to other acoustical parameters.
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Green Building Acoustics Resources and
References
Center for the Built Environment: Occupant Indoor Environmental Quality (IEQ) Survey. http://www.cbe.berkeley.edu/research/survey.htm
Muehleisen, R. T. (2010). "Acoustics of Green Buildings," in InformeDesign Implications (InformeDesign), pp. 1-7 http://www.informedesign.umn.edu/_news/jan_v08.pdf.
Field, C. (2008). "Acoustical design in green buildings," ASHRAE Journal 50, 60-70.
Muehleisen, R. T. (2009). "Review of the Implementation and Recent Changes of Several Acoustic Criteria Used in United States Schools," in Inter-Noise 2009 (Institute of Noise Control Engineers, Ottawa, CA).
Hodgson, M. (2009). "Occupant Satisfaction with the Acoustical Environment," in PLEA2009 - 26th Conference on Passive and Low Energy Architecture (Quebec City, CA).
Hodgson, M., Khaleghi, A., Richter, M., and Razavi, Z. (2009). "Design and evaluation of noise-isolation measures for the natural-ventilation openings in a `green' building," Noise Control Engineering Journal 57, 493-506.
Abbaszadeh, S., Zagreus, L., Lehrer, D., and Huizenga, C. (2006). "Occupant satisfaction with indoor environmental quality in green buildings," in Proceedings of Healthy Buildings 2006, Lisbon, Vol III (International Society of Indoor Air Quality and Climate), pp. 365-370.
31-Oct-2011 Ralph T. Muehleisen - Acoustics of Green Buildings
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