acoustics of green buildings

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

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


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


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


How Is This Related to Buildings?

Global CO2 Emissions by Sector:

#1: Buildings #2: Industry

#3: Transportation


CO2 Sources and Emitters in

31-Oct-2011 Ralph T. Muehleisen - Acoustics of Green Buildings

2444

Of

6576

Source: EIA Emissions of Greenhouse Gases in the US 2009

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Energy Flow in the US


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?


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?


What Other Benefits Do Green Buildings Provide?


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


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)


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


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


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


LEED Rating Systems

There are different LEED Rating systems for different types of buildings


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.


Four Levels of LEED Certification

LEED Certified: 40-49 points

LEED Silver: 50-59 points

LEED Gold: 60-79 points

LEED Platinum: > 80 points


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.


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


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


Sustainable Sites (SS)


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)


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)


Materials and Resources (MR)


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)


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


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



LEED Accredited Professional

Regional Priority: Specific Credit




Innovation and Design Process

Regional Priority Credits



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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


From the LEED 2009 NC Rating System PDF


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


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.


Part II: Acoustics of Green Buildings Conflicts and Synergies


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


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)


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


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


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


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!


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?


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


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


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


Acoustics Survey Results are Poor


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


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


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


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


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


Thermal Mass

More Thermal Mass is being used in design

Thermal mass is a high heat capacity material like CMU block or concrete


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.


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


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


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


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


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.


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


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.


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.


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