Schools-2009 IEQc9: Enhanced Acoustical Performance

  • Schools IEQc9 Enhanced Acoustical Perf Diagram

  • Not business as usual

    You won’t meet the requirements for this credit with conventional building design. You’re likely to need additional insulation, increased wall mass, adjust wall assemblies and layout, and make changes to the mechanical system design.

    Making it cost-effective

    The credit does not have to be difficult, though, and it can be cost-effective in any project as long as you consider acoustics in the early stages of design. Waiting to consider acoustics until the design is set can lead to additional costs and needless frustration as mechanical systems and the building envelope will likely need some redesign. 

    Having the entire design team focused on acoustics—including stakeholders such school board members, the principal, and teachers—helps to ensure a consistent focus throughout the project and to overcome obstacles that may arise. 

    The payoff for earning this credit is likely to be more effective and less-fatigued teachers, and better student performance, as both teachers and students can focus better, not talk over distractions, and communicate effectively.

    Understanding the credit requirements

    To earn this credit, you have to meet two requirements, one of which is a step up from IEQp3, and one of which is not considered in the prerequisite. (ReverberationReverberation is an acoustical phenomenon that occurs when sound persists in an enclosed space because of its repeated reflection or scattering on the enclosing surfaces or objects within the space. (ANSI S12.60–2002) time, a measure of how long it takes for sound to be absorbed by a room’s interior materials, is not covered by this credit.)

    Background Noise Level of HVAC

    Background noise may come from a variety of sources: traffic on nearby streets, mechanical equipment, sounds from adjacent classrooms or multi-purpose spaces, and more. LEED only addresses background noise from HVAC equipment. The noise level is determined through calculations that the mechanical engineer or acoustics consultant can run.

    This credit requires a background noise level of 40 dBAA decibel (dBA) is a sound pressure level measured with a conventional frequency weighting that roughly approximates how the human ear hears different frequency components of sounds at typical listening levels for speech. (ANSI S12.60–2002) or less—a step up from IEQp3, which requires 45dBA or less. Meet this requirement by focusing on mechanical system design, with measures such as avoiding the placement of fans and mechanical systems directly above classrooms, insulating ducts, and using low-velocity air delivery or displacement ventilationA system in which air slightly cooler than the desired room temperature is introduced at floor level and is lifted up by warmer air to exhaust outlets at the ceiling, increasing air circulation and removal of pollutants..

    Sound Transmission Class

    Sound Transmission Class (STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002)) is a measure of the capacity of a partition (a wall, window, door, ceiling, or floor) to isolate noise from adjacent spaces. The required STC rating for a given partition varies and is determined by the adjacent spaces and the requirements of ANSI standard S12.60-2002. For example, a classroom wall located next to the gym will have to meet a different STC rating (STC rating of 60) than a different wall in the same classroom that is near the library (STC rating of 50).

    Higher STC ratings for partitions can be met with thicker, more massive walls, and higher-STC rated products like specially insulated windows and doors. All of these typically translate to higher costs. To meet the STC requirements cost-effectively, start by locating classrooms away from noisy exterior and interior spaces, so that the STC ratings for the partitions don’t need to be as high.  

    Compliance Options

    Both of the credit requirements (HVAC background noise level reduction and STC ratings) have two compliance paths, one requiring calculations during design and the other requiring onsite measurements after construction.

    The calculation option is recommended because it is far safer. If you wait till after construction to take these measurements, and you find areas that are non-compliant, making changes will be expensive and inconvenient. 

    You will likely need an acoustics consultant

    Meeting IEQp3 can be relatively easy without the help of an acoustics consultant. However, many projects find the requirements of even the prerequisite beyond their capability and opt for professional acoustical help. Analyzing the STC of the wall assemblies for the credit will likely require the expertise of a consultant. STC ratings for assemblies come from laboratory tests and it may be difficult to find the required STC testing information on your own and verify that it is accurate and appropriate for your project.

Legend

  • Best Practices
  • Gotcha
  • Action Steps
  • Cost Tip

Pre-Design

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  • All Cases

  • You’ll probably need an acoustics consultant to analyze the Sound Transmission Class (STC) requirements. Hire one early in the design stage to avoid the need for later redesign. If the mechanical engineer is comfortable running the necessary calculations for HVAC system background noise level, the acoustics consultant may only be required for assistance and final verification. If the mechanical engineer is willing to run the HVAC background noise calculations, you will want to include this in their scope of work.

  • Consider the certifications of prospective acoustics consultants. Many are INCE Board Certified or members of the National Council of Acoustical Consultants (NCAC). These certifications are not necessary but can help distinguish true experts. See Resources for more information. 

  • Hiring an acoustics consultant will incur additional cost, but may be necessary or helpful to keep the process going smoothly. By helping to avoid costly mistakes, it can ultimately save money.

  • Sound Transmission Class

  • Meeting the STC rating requirements for background noise isolation requires partition design that attenuates adjacent exterior and interior noise transmission. 

  • Especially in urban areas, measure exterior background noise levels before design and construction begins. This will help the team choose design strategies to reduce background noise from exterior sources. 

  • Conventional building assemblies are not likely to meet the credit requirements. Added costs are likely from adding insulation to wall assemblies, using thicker wall assemblies, and windows and doors with higher STC ratings.

  • HVAC Background Noise Level

  • Meeting the required HVAC background noise levels requires HVAC system design and layout that minimizes noise from mechanical equipment.  See the Introduction to Mechanical Sound Data in the Documentation Toolkit for more information. 

Schematic Design

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  • The owner and design team set preliminary acoustical performance goals and add them to the Owner Project Requirements (OPR) for the building commissioning credits EAp1 and EAc3. 

  • Sample classroom design for improved acousticsA good acoustic design takes into consideration classroom and building orientation, size and shape of the classroom, adjacent spaces, wall construction, materials selection (doors, windows, wall covers, ceiling, and floor), placement of the mechanical system, and duct design.

  • Avoid costly changes to existing plans by addressing the credit requirements early in design. Typical changes often include adding supply silencers or return silencers; duct layout reworking; adding lined ducts or flexible ducts, diffusers, lined sound boots, double gypsum layers; or making classroom location changes. The need to make changes like these late in the game could be minimized or eliminated with early incorporation of acoustical goals. 

  • Meet with the owner, teachers, or principal to review programmatic uses and layout of individual classrooms and core learning spaces. Doing so will help to inform both the school administrators and the design team of each other’s goals and intentions. 

  • Sound Transmission Class

  • Determine a layout and envelope design that will reduce exterior and interior adjacent noise levels, in order to minimize the need for wall, ceiling, and floor assemblies to have high STC ratings. Review ANSI standard S12.60-2002 for help.

  • The STC rating requirement is guided by ANSI standard S12.60-2002, which requires partition assemblies (including doors, walls, ceilings and floors) to have a specified STC rating based on the noise level coming from the adjacent space. In many cases, each wall in a classroom will have a different STC rating requirement due to different adjacent spaces. 

  • Careful attention to building layout can help keep costs low. For example, mechanical rooms adjacent to classrooms require STC 60—an expensive wall to build, and better avoided through changing the layout. Locate classrooms and core learning spaces away from noisy exterior spaces such as athletic fields, roadways, and parking lots, as well as noisy interior spaces such as mechanical rooms, bathrooms, kitchens, music rooms, cafeterias, and gymnasiums. 

  • When designing a partition to meet the required STC rating you will also want to consider wall massing (massive walls generally block sound), breaking the path of vibration and sound (staggering studs and decoupling), providing absorptive materials (added insulation), and sealing penetrations (from plumbing and HVAC systems). See the STC Introduction in the Documentation Toolkit for more detail on determining the STC rating of various partition types. 

  • HVAC Background Noise Level

  • Determine HVAC systems and layouts that will meet the requirements for background noise level. 

  • Isolating mechanical equipment and installing low-noise and low-velocity equipment, including fans and boxes, will help project teams meet the HVAC background noise level requirements. 

  • Selecting mechanical equipment with noise levels in the 60 Hz and 125 Hz octave-bands will help to mitigate noise from HVAC systems and the associated costs needed to reach the acceptable background noise levels. 

  • HVAC system layout also plays a large role in mitigating background noise from mechanical equipment. It is important to avoid placing fans and mechanical systems directly above classrooms and core learning spaces and insulating ducts. Projects may also want to consider displacement ventilation, which uses lower-velocity air and is quieter. 

  • When it comes to documenting the credit through LEED Online, you will have two choices: performing calculations during design, or taking measurements after construction. Choose your path now.

  • It is usually better to run calculations during design, to allow for changes to meet the requirements, if necessary. If measurements of the completed building show that you do not meet the credit requirements you will be required to make costly changes.

  • If performing calculations or software simulation, you’ll base them on the 2007 HVAC Applications ASHRAE Handbook, Chapter 47.

  • The calculation for background noise level can be performed by a mechanical engineer if they are familiar with the calculations or have common software, such as the Trane Acoustics Program (TAP). (See Resources). 

  • ASHRAE has guidelines on running the calculations without software, but these are fairly detailed measurements and a consultant will most likely be needed. See the Sample Background Noise Calculations in the Documentation Toolkit for more information. 

  • If you decide to take measurements after construction, you will need to comply with ANSI standard S12.60-2002 and meet the after construction measurements requirements.

  • Compliance with the ANSI standard requires projects to limit maximum allowable background noise levels from HVAC equipment based on section 4.3 of the ANSI standard and provide after construction measurements to verify compliance. Projects will have a better chance of meeting the measurement requirements by following these practices. (See the ANSI standard—and in particular Annex B—for full details.) 

    • Do not use unducted systems.
    • Provide grilles and diffusers with a catalog Noise Criteria (NC) rating of 18 or less.
    • Trunk ducts airflow velocity must not exceed 4.1 m/s.
    • Install duct silencers inside the air-handling unit or in supply and return ducts.
    • Design and install all duct work to have a low static pressure loss in accordance with SMACNA for HVAC System Duct Design.
    • Locate all rotating equipment and equipment with static pressure control dampers at least 10 feet from classrooms.
    • Use airfoil-shaped blades with centrifugal fans, in most cases.
    • Ductwork serving more than one core learning space may need sound attenuators or sound-absorbing duct lining.
    • Do not locate VAV boxes or fan-powered boxes over core learning spaces.

  • Projects complying with the credit requirements through the ANSI standard should also consider researching the design recommendations for HVAC in the 2007 HVAC Applications ASHRAE Handbook, Chapter 47. This handbook will provide you with useful information when designing HVAC systems for noise reduction. 

  • Simply following the ANSI recommendations for HVAC design and waiting to take measurement until after construction is not recommended as you can follow all of the recommendations but still have a noisy system, and not achieve credit compliance. Following the calculation path, as outlined above, is recommended. 

Design Development

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  • Meeting the STC and HVAC background noise level requirements can be documentation-intensive. If an acoustics consultant is doing the documentation, then they will be experienced enough to make this relatively easy. If it is a mechanical engineer who is not used to working with noise measurements, the terminology and procedures may take some time to get used to.  

  • Including a microphone and speakers or other electronic amplifiers in a classroom design will not contribute to credit compliance. Amplification allows the teacher to be heard more easily but does not reduce background noise. 

  • Sound Transmission Class

  • Determine the required STC rating for all wall, floor, ceiling, and composite assemblies (a wall with doors and windows) in classrooms and core learning spaces. The required STC rating will be dependent upon the adjacent spaces to each partition in the space (wall, ceiling, etc.). Use ANSI S12.60-2002 to determine these ratings.  

  • The LEED reference guide gives a quick summary of STC requirements (shown here), but it’s worth referring to the ANSI standard, which gives you more information on determining the required STC ratings and provides design guidance on how to meet these requirements for each space type, most notably composite assemblies (such as wall with windows and doors). Note that the STC rating for adjacency to exterior spaces provided in the table is the typical minimum requirement and the appropriate STC rating will need further research on a case-by-case basis.

  • The STC rating for each partition in a given classroom will vary depending on the adjacent space. For example, a classroom wall that is adjacent to an exterior space will need to have an STC rating of 50, a wall that is adjacent to a public restroom will need an STC rating of 53, a wall that is adjacent to the hallway will need an STC rating of 45, and a wall adjacent to a music classroom will need an STC rating of 60. 

  • Research windows with an STC rating of 35 or greater. See the STC Introduction in the Documentation Toolkit for more detail on determining the STC rating of windows. 

  • Windows must have an STC rating of at least 35. Double-pane windows with a half-inch or greater air gap and laminated glass are usually best. The STC rating of windows is usually available from larger manufacturers. 

  • Design all wall, floor, ceiling and composite assemblies to meet the required STC rating. See the STC Introduction in the Documentation Toolkit for more detail on determining the STC rating of various partition types.

  • Determine if the calculation or measurement method is best suited for your project. 

  • Calculations and lab STC ratings for credit compliance must be made based on ANSI standard S12.60-2002 section D2.4. 

  • Measurements of STC values taken after construction must be based on ANSI standard S12.60-2002 section E5.1.

  • Running calculations for credit compliance is the safest strategy to take. Relying on measurements taken after construction can be risky, in case you fall short and need to make costly changes.

  • Obtaining STC ratings that are accurate typically require the assistance of an acoustics consultant. The ratings should be taken directly from laboratory tests and verified by a professional or modeling tool. Designers should be wary of information obtained from marketing materials (except for window STC from an acoustics window manufacturer, which are generally reliable). An acoustics consultant is the best person to determine the actual STC rating for a partition, especially an atypical one.

  • The STC requirements apply to exterior walls as well as interior partitions (walls, ceiling and floor). Meeting the requirements usually requires insulation between interior common walls, double layers of gypsum or acoustical drywall on at least one side of the wall, air gaps between common walls, sound-rated doors, and sealants around penetrations and door openings. 

  • It is important to control sound transmission through joints and penetrations from duct work, plumbing, electrical wiring, and other openings made in the walls, ceiling or floors. It is best to seal these penetrations with a non-hardening acoustic sealant. These sealants may also double as fire caulk—check that you meet local fire codes.   

  • When designing noisy spaces such as a music room, you may need to control sound transmission with breaks, so that the noise cannot travel through floors and walls. Breaks typically include double-stud walls, staggering the studs, or installing resilient channels or neoprene isolators to provide an air gap between the stud and drywall. 

  • Multi-story schools will require close attention to sound transmission through floor-ceiling assemblies. Incorporate similar acoustical design strategies as with walls, increase mass and insulation, allow for air gaps to break vibration travel, and seal any penetrations.

  • STC ratings for floor-ceiling assemblies are also available from laboratory test results, can be harder to find, as they are harder and more expensive to test. An experienced acoustic consultant will be invaluable for finding accurate STC ratings for floor-ceiling assemblies. 

  • HVAC Background Noise Level

  • The mechanical engineer, in collaboration with the acoustics consultant, design compliant mechanical systems and a delivery system that will meet the LEED credit requirements of 40 dBA or less, at maximum operating conditions. 

  • Depending on the compliance path selected:

    • Run preliminary calculations calculated by the acoustics consultant or mechanical engineer, as defined by the 2007 HVAC Applications ASHRAE Handbook, Chapter 47, Sounds and Vibration Control and determine any design changes needed for compliance. 
    • Follow the design recommendation in ANSI S12.60-2002 and determine any design changes needed for compliance. 

  • Follow recommendations based on these preliminary calculations or assessment, including acoustical changes integrated by the mechanical engineer into mechanical plans and project specifications.

  • Ductless mechanical systems or open-plan classrooms will most likely not conform to the background noise level requirements of this credit. 

  • Calculations for “duct breakout noise” should also be made if there is large, high-velocity ductwork in the core learning space or above lay-in tile ceilings. Acoustic duct lagging may be needed in these situations.

  • It may be difficult to appropriately calculate the effectiveness of duct silencers. It is important to select an appropriate silencer and to place them properly within the ductwork layout. 

  • The mechanical engineer should work with an acoustics consultant, or closely with the manufacturer, if they are not familiar with these installation and calculation issues.

  • Meeting the background noise level requirements typically will bring a minimal cost increase due to upgrades in mechanical equipment and calculations. There could be a substantial cost increase if a redesign with upgrades is necessary. 

Construction Documents

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  • Specify windows with an STC rating of 35 or greater. 

  • Run final acoustical mechanical background noise calculations and determine the final STC ratings for the appropriate building assemblies (if applicable). Verify that the project goals are met. 

  • Ensure that all acoustical considerations are included on project drawings and specifications. 

  • Include detailed drawings of the wall, ceiling, and floor assemblies. This ensures that the constructed assembly performs as intended. 

  • Document HVAC background-noise compliance on LEED Online, with specifics depending on your compliance method: 

    • Projects performing calculations based on 2007 HVAC Applications ASHRAE Handbook – Chapter 47 will need to provide a summary report from the calculations or simulation confirming 40 dBA or less.
    • Projects following the ANSI standard methodology will need to write a narrative of the design strategies used to ensure compliance with the standard and meeting the 40dBA requirement.

  • If demonstrating compliance through measurement, defer your credit submittal until after construction. 

  • Document compliance with the required STC rating for adjacent spaces, with specifics depending on your compliance method:

    • If doing STC rating calculations based on ANSI standard S12.60-2002 section D2.4, projects will need to fill out the LEED Online credit form including adjacent space type and STC of assembly for walls, floors and ceilings of all classrooms and core learning spaces. 
    • If doing STC rating measurements based on ANSI standard S12.60-2002 section E5.1, projects will need to fill out the table on the LEED Online credit form including adjacent space type and STC of assembly for walls, floors and ceilings of all classrooms and core learning spaces. Projects must also provide a narrative describing the methodologies used to conduct the STC measurements and verify that they are in compliance with section E5.1 of the ANSI standard.

Construction

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  • Involve contractors in an acoustics discussion before construction begins to help them understand the importance of specific designs and drawing details. 

  • The contractor coordinates with subcontractors to ensure that construction practices adequately address the acoustics design. 

  • Install acoustic materials according to manufacturers’ recommendations in order to ensure optimum performance. 

  • Keep all calculations and STC ratings on file for easy accessibility if detailed calculations are required during project review. 

Operations & Maintenance

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  • If demonstrating compliance via measurements, take measurements of STC ratings and HVAC background noise levels according the relevant ANSI standard section. 

  • Facilities personnel can monitor and respond to any complaints about acoustics. This could include periodically metering decibel levels during the school day.

  • USGBC

    Excerpted from LEED 2009 for Schools New Construction and Major Renovations

    COPYRIGHT © 2009 BY THE U.S. GREEN BUILDING COUNCIL, INC. ALL RIGHTS RESERVED

    IEQ Credit 9: Enhanced acoustical performance

    1 Point

    Intent

    To provide classrooms that facilitate better teacher-to-student and student-to-student communications through effective acoustical design.

    Requirements

    Sound transmission

    Design classrooms and other core learning spacesCore learning spaces are spaces for educational activities where the primary functions are teaching and learning and where good speech communication is critical to a student's academic achievement. These spaces include, but are not limited to, classrooms, enclosed or open plan), instructional pods or activity areas, group instruction rooms, conference rooms, libraries, offices, speech clinics, offices used for educational purposes and music rooms for instruction, practice and performance. to meet the Sound Transmission Class (STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002)) requirements of ANSI Standard S12.60-2002, Acoustical Performance Criteria, Design Requirements and Guidelines for Schools, except windows, which must meet an STC rating of at least 35. Projects outside the U.S. may use a local equivalent to ANSI Standard S12.60-2002.

    AND

    Background noise

    Reduce background noise level1 to 40 dBAA decibel (dBA) is a sound pressure level measured with a conventional frequency weighting that roughly approximates how the human ear hears different frequency components of sounds at typical listening levels for speech. (ANSI S12.60–2002) or less from heating, ventilating and air conditioning (HVAC) systems in classrooms and other core learning spaces.

    Potential Technologies & Strategies

    Design considerations include reducing noise from exterior to interior spaces, between spaces within the building, and within the classroom space. External to internal noise transmission can be reduced by orienting classrooms away from external noise sources and using thick and/or massive materials in walls and roofs. Also, windows should be well-sealed and have adequate air gaps between sheets of glass. See IEQ Prerequisite 3:Minimum Acoustical Performance for more potential technologies and strategies.

Technical Guides

ANSI S12.60-2002: American National Standard Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools

ANSI S12.60-2002 is the standard for LEED acoustics credits and should be referenced when designing spaces for acoustics. Free download from the Acoustical Society of America.

2007 HVAC Applications ASHRAE Handbook, Chapter 47, "Sound and Vibration Control"

This ASHRAE standard is the standard for LEED acoustics credits and should be referenced when designing mechanical equipment for acoustics.

Maryland Classroom Acoustics Guidelines

A publication from the Maryland State Department of Education that provides design guidance based on the ANSI standard.

Whole Building Design Guide, Acoustic Comfort

This section of the Whole Building Design Guide focuses on acoustic comfort in offices, classrooms, and conference rooms and discusses the following issues: site selection, glazing, HVAC noise issues, natural ventilation, sound masking, emerging issues, relevant codes and standards, and additional resources. 

Software Tools

Trane Acoustics Program (TAP)

TAP is used to help mechanical engineers determine a room's background noise level. It costs $500.

Publications

Education Stakeholders and the ANSI Standard for School Acoustics

This article addresses some questions asked by stakeholders in the education and school building process.

Classroom Acoustics resource page from U.S. Access Board

This website from the United States Access Board, the federal agency devoted to accessibility, provides an overview of acoustics in classrooms including many links.

Organizations

National Council of Acoustical Consultants (NCAC)

The NCAC website provides information on selecting an acoustics consultant and provides a list of registered consultants.

Institute of Noise Control Engineering (INCE)

The INCE was developed to provide engineering solutions to noise problems from mechanical equipment.

Quiet Classrooms

This organization provides information for architects, teachers, parents and students on the importance of good acoustics in classrooms.

Acoustical Society of America

The Acoustical Society of America (ASA) is an international scientific society dedicated to increasing and diffusing the knowledge of acoustics and its practical applications. ASA’s website contains a variety of resources, including publications, standards information, and links. Of special note are the 2 ASA booklets on classroom acoustics at http://asa.aip.org/classroom/booklet.html and http:// asa.aip.org/classroom/bookletII.pdf. 

Project Narrative

Projects must complete a narrative describing compliance.

Acoustic Consultant

An acoustics consultant can be a great help for this credit.

Mechanical Sound Data

Before attempting background noise measurements, especially if not hiring an acoustics consultant, develop a basic understanding of acoustics terminology. An acoustics expert provides this document as an introduction.

Construction Details

Successful acoustical design often comes down to the details—like these sample wall details completed for Casey Middle School.

Acoustics Calculators

Use this calculator to assess and document compliance.

Introduction to Sound Transmission Class (STC)

This document gives an overview of STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) rating, testing, estimation and modeling—all of which are helpful to understand for earning this credit.

Building for Acoustics

Good acoustical performance requires attention to specific construction details.

LEED Online Forms: Schools-2009 IEQ

The following links take you to the public, informational versions of the dynamic LEED Online forms for each Schools-2009 IEQ credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.

Version 4 forms (newest):

Version 3 forms:

These links are posted by LEEDuser with USGBC's permission. USGBC has certain usage restrictions for these forms; for more information, visit LEED Online and click "Sample Forms Download."

Design Submittal

PencilDocumentation for this credit can be part of a Design Phase submittal.

31 Comments

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Premnath Sundharam Architect, Senior Associate DLR Group
May 03 2013
LEEDuser Member
122 Thumbs Up

STC for Ceiling Assembly

I'm filling out the Table IEQc9-1 and it asks me for a STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) rating for the ceiling assembly. I set the space "adjacent to assembly" to "outdoors " because it is only a 1-story building. How do I find out how to calculate the STC of my roof/ceiling assembly?

Thanks.

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates May 06 2013 LEEDuser Expert 1352 Thumbs Up

I think an acoustical consultant is probably your best bet for a roof/ceiling assembly STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) rating. You might be able to find something similar in the UL design guide, but I usually don't recommend UL guides for STC ratings because they're often not very accurate.

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Nicole Ferrini via Greengrade LEED Management Software
Mar 13 2013
Guest
151 Thumbs Up

DBA for HVAC Background Noise

Is the 40 dbaA decibel (dBA) is a sound pressure level measured with a conventional frequency weighting that roughly approximates how the human ear hears different frequency components of sounds at typical listening levels for speech. (ANSI S12.60–2002) a direct value for the equipment itself, or is it a net value based on a sound path analysis to the space?

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates Mar 13 2013 LEEDuser Expert 1352 Thumbs Up

40 dB(A) is the net effect from sound path analysis to the space.

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Sally Zahner
Jun 14 2012
LEEDuser Member
26 Thumbs Up

Acoustics in 'Schools of 21st Century' Design

How are the acoustical requirements for this credit treated in 'open plan' designs where several classroom 'studios' are grouped together, as in the Schools of the 21st Century design approach? I assume one would call each 'group' a classroom for the purposes of calculating STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) separations. Otherwise, would a system of moveable partitions, etc be necessary to meet the intent of the credit?

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates Jun 18 2012 LEEDuser Expert 1352 Thumbs Up

The STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) requirements between learning spacesCore learning spaces are spaces for educational activities where the primary functions are teaching and learning and where good speech communication is critical to a student's academic achievement. These spaces include, but are not limited to, classrooms, enclosed or open plan), instructional pods or activity areas, group instruction rooms, conference rooms, libraries, offices, speech clinics, offices used for educational purposes and music rooms for instruction, practice and performance. used to be a prerequisite in the older 2007 version of LEED and was moved to the enhanced acoustics credit for 2009 to accommodate open plan classrooms.

You would need operable partitions that meet the STC requirements for the enhanced acoustics credit.

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renee jimenez principal mnk architects
Mar 27 2012
LEEDuser Member
46 Thumbs Up

4" Slab on Grade STC rating

The first floor of my classrooms are slab on grade which per the LEED template should have an STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) of 50 because its ajacent to the outdoors (grade being the outdoors). My slab is 4" thick and a 4" thick concrete panel has an STC of 49. Should I change my space adjacent to Assembly column to other (as I am adjacent to the earth) and put the required STC at 0?

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates Mar 28 2012 LEEDuser Expert 1352 Thumbs Up

STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) is only valid for occupied spacesOccupied Spaces are defined as enclosed spaces that can accommodate human activities. Occupied spaces are further classified as regularly occupied or non-regularly occupied spaces based on the duration of the occupancy, individual or multi-occupant based on the quantity of occupants, and densely or non-densely occupied spaces based upon the concentration of occupants in the space.. There is no adjacent space beneath a slab on grade. You do not need to input "outdoors" for beneath the building and can leave it blank.

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Rebecca Griffith
Oct 10 2011
LEEDuser Member
244 Thumbs Up

STC Rating - ANSI S12.60-2010 exceptions

This is a followup and additional question to my June 7, 2011 post.

On 8/1/2011 a LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. was posted for IEQc9: Enhanced Acoustical Performance (ID Number: 10095). It basically says that the use of the 2010 version of ANSI S12.60 is acceptable for LEED for Schools 2007 and 2009.

In ANSI S12.60-2010 Table 4 there is a footnote (b) that says “A 20cm (8”) concrete masonry unit wall having a surface weight density of at least 180 kg/m2 painted and sealed on both sides, acoustically sealed at the entire perimeter and extending from the floor slab to the structural deck above, is an acceptable alternate assembly that conforms to the intent of 5.4.2.1.” This could impact us greatly, because we had to issue an addenda to add Perlite or foam-in-insulation to our 8” CMU walls between classrooms to mee the STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) 50 rating between core learning spacesCore learning spaces are spaces for educational activities where the primary functions are teaching and learning and where good speech communication is critical to a student's academic achievement. These spaces include, but are not limited to, classrooms, enclosed or open plan), instructional pods or activity areas, group instruction rooms, conference rooms, libraries, offices, speech clinics, offices used for educational purposes and music rooms for instruction, practice and performance.. It seems that according to this footnote, this would not be required, which would could have a big dollar cost savings. I believe we are meeting all the requirements of the footnote, but I am not sure about the “surface weight density of at least 180kg/m2” part. I’ve researched and asked masonry and paint technical reps, but no one seems to understand what this means.

Has anyone heard of this or had any experience with it? I want to ensure we are meeting all the requirements of the exception before we tell the client we no longer need Perlite/foam-in-insulation.

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates Oct 10 2011 LEEDuser Expert 1352 Thumbs Up

The mass of the block you are using will determine the amount of sound isolation that the block will provide. Light blocks will perform worse than normal weight concrete, if that makes sense.

The surface weight density is a way to specify the mass of the block without knowing one of the dimensions. 180 kg/m2 is approximately 36.8 lb/ft2.

With the block you are using, take it's weight (lb) and divide by the face area of the block (ft2). If it is 36.8 or higher, you're in luck. If not, you'll have to use the insulation, or increase the thickness of the block to obtain a higher overall mass (if that's an option).

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Rebecca Griffith Oct 10 2011 LEEDuser Member 244 Thumbs Up

Thank you, Daniel! That is a very clear explanation and just the clarification we needed to figure this out! Much appreciated!

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Dana Murdoch
Oct 06 2011
Guest
542 Thumbs Up

Window STC vs. OITC

If our windows have an STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) of 35 but an OITC of 25 would they qualify? I don't think so, but I don't know how to interpret or relate the OITC to STC.

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates Oct 06 2011 LEEDuser Expert 1352 Thumbs Up

Yes, they qualify. The requirement is for STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) 35 or better. There are no OITC requirements.

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Gary Madaras Soundscaper Building Momentum Group
Aug 29 2011
LEEDuser Member
29 Thumbs Up

IIC in IEQc9

Just want to double check . . . As far as I can see, there are no IIC requirements in IEQc9. Can someone confirm please? Thanks.

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates Sep 30 2011 LEEDuser Expert 1352 Thumbs Up

You are correct.

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Dana Murdoch
Jul 18 2011
Guest
542 Thumbs Up

S12.2-2010

I went to the asastore.aip.org site and they did not have the 2002 version available. Can I use the 2009/2010 version? Will it be more stringent??

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates Jul 19 2011 LEEDuser Expert 1352 Thumbs Up

You can use the new 2010 revision.

The only changes in the revision that would be relevant to the LEED credits is the ANSI standard is now using Outdoor Indoor Transmission Class (OITC) for the exterior walls and roof assemblies instead of STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) ratings. This is more technically correct but complicates things.

The 2002 ANSI standard required an STC 50 wall assembly between core learning spacesCore learning spaces are spaces for educational activities where the primary functions are teaching and learning and where good speech communication is critical to a student's academic achievement. These spaces include, but are not limited to, classrooms, enclosed or open plan), instructional pods or activity areas, group instruction rooms, conference rooms, libraries, offices, speech clinics, offices used for educational purposes and music rooms for instruction, practice and performance. and the outdoors. I would use this until the LEED language says "use ANSI S12.60-2010".

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Dana Murdoch Jul 19 2011 Guest 542 Thumbs Up

Does anyone know how I can get a copy of the 2002 version, though?

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates Jul 20 2011 LEEDuser Expert 1352 Thumbs Up

I searched online and found this site

http://www.techstreet.com/standards/ansi_asa/s12_60_2002?product_id=1031761

There may be other places that have the old version too.

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Rebecca Griffith
Jun 07 2011
LEEDuser Member
244 Thumbs Up

STC Rating - Classroom to In-Classroom Toilet for Kindergarten

Currently our walls from Kindergarten classrooms to in-classroom toilets are scheduled for an STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) rating of 50, but will probably meet 52 with our specified foamed-in-place insulation in 8" CMU. The doors to the in-classroom toilet rooms will be gasketed. The standard says classroom to toilet rooms must be 53, but I'm not sure how else to accomplish this without changing the design and wall construction. I understand the noise if were a gang toilet, but these are single user toilets for kindergarten students, so I wouldn't think the sound transimission would be that large of an issue. Any thoughts?

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Rebecca Griffith Jun 07 2011 LEEDuser Member 244 Thumbs Up

I forgot to mention, this project is under LEED for Schools 2007. I posted it here, because there was no place to post about STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) ratings under the previous versions. I found the exact exception to my question in ANSI/ASA S12.60-2010. However, since this project is under LEED for Schools 2007, ANSI/ASAS12.60-2002 is referenced in the Reference Guide. Can we apply newer versions of the standard to old rating systems? This may be a question for another forum.

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates Jun 07 2011 LEEDuser Expert 1352 Thumbs Up

There are two ways you might go about this.

The first is with the rating of the assembly. I would almost expect your assembly to rate an STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) 53 as you are describing it as long as the block is 35lbs/block or higher. With the cores filled with loose mineral insulation, I would rate the assembly approximately STC 52. With it being foamed in place you will most likely get more fill in the cores which means a higher density assembly and higher rating...probably closer to STC 53. If the blocks are 45lbs/block or higher, you definitely have an STC 53 assembly, so that might be a quick way to solve the problem by specifying slightly heavier block in that area.

The other way would be to reference the updated ANSI standard. I don't know if that is exactly "allowed" (check other forums if you can) but it would definitely hold more weight than just trying to make the "STC 52 should be enough because..." argument on your own without backup. A LEED reviewer would most likely hold fast to an "STC 53 means STC 53" point of view if there were no official basis for an exception, like the updated ANSI standard.

Hope this helps.

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aaron smith director of sustainable building solutions, ASSA ABLOY Door Security Solutions Jun 07 2011 LEEDuser Member 210 Thumbs Up

It is possible to get an STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) rated door assembly (door, frame, hardware and gasketing) rated to a 53 or the door assembly can be rated as part of the entire partition. One thing to look at with high STC door solutions, is that you may want to provide an automatic operator in a K12 environment, as the sound gasketing and weight of the door makes it a challenge for children to operate.

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Lauren Fakhoury Research Assistant Sustainable Design Consulting, LLC
Apr 04 2011
LEEDuser Member
560 Thumbs Up

2009 Criteria for a 2007 Project - STC rating

I'm working on a LEED-S 2007 project that is pursuing this credit but I have a question about the requirements. The 2007 rating system requirement says "Also design classrooms and other core learning spacesCore learning spaces are spaces for educational activities where the primary functions are teaching and learning and where good speech communication is critical to a student's academic achievement. These spaces include, but are not limited to, classrooms, enclosed or open plan), instructional pods or activity areas, group instruction rooms, conference rooms, libraries, offices, speech clinics, offices used for educational purposes and music rooms for instruction, practice and performance. to meet the STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) requirements, excepting windows, which must meet an STC rating of at least 35" in addition to the building shellThe exterior walls, roof, and lowest floor of a building, which serve to separate and protect the interior from the elements (precipitation, sunlight, wind, temperature variations). and classroom partitions.

I checked the 2007 rating system errata but didn't see the change there. Does anyone know if the errata for this exists? If not, are we able to use the 2009 requirements instead of the 2007 requirements without upgrading the project to v3?

Thanks for your help!

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates Apr 05 2011 LEEDuser Expert 1352 Thumbs Up

You are correct, in 2007 the STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) requirements were in the Prerequisite. In 2009 they were moved to the Enhanced Credit 9.

I do not know if you would be able to use the 2009 requirements in the 2007 rating system. I have personally been involved in projects that had changed from 2007 to 2009 specifically because of this issue (open plan classrooms were desired), so my initial reaction would be to say it's not an option. Asking USGBC directly would be your best bet.

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Russell Philstrom
Oct 04 2010
Guest
103 Thumbs Up

Window STC scope

Does the STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) of 35 requirement for windows include the mullion system if curtainwall is the glazing system? Most STC values that I've seen are for glass assemblies and ignore the mullion, spacer, etc.

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates Oct 04 2010 LEEDuser Expert 1352 Thumbs Up

Hi Eileen:

It's not specific, but I would assume that the requirement is for the entire widow assembly including the mullions. Some manufacturer's have tested entire assemblies, but you're right, the majority of data is just for the glazing.

An STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) 35 rating shouldn't be too hard to achieve, however, with aluminum or steel mullions. If it is a large area, packing the framing with mineral wool would help improve the STC rating.

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Keith Robertson
Oct 15 2009
LEEDuser Member
195 Thumbs Up

Window STC

The requirement for a window STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) of 35 - does this apply to exterior AND interior windows?

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates Oct 15 2009 LEEDuser Expert 1352 Thumbs Up

The STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) 35 requirement applies to exterior windows. Interior windows would need to be accounted for in a composite STC rating for the interior wall and window assemblies combined.

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aaron smith director of sustainable building solutions, ASSA ABLOY Door Security Solutions Aug 25 2010 LEEDuser Member 210 Thumbs Up

would STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) 35 apply to exterior doors?

Would interior doors be accounted for in the composite STC rating of the assembly? (most doors have a stand-alone STC rating).

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates Aug 30 2010 LEEDuser Expert 1352 Thumbs Up

ANSI S12.60 isn't very clear on this. In 4.5.3.1, the standard says that a composite rating including the doors should be made. Later in 4.5.5 the standard says that classroom entry doors should have a minimum STCSound transmission class (STC) is a single-number rating for the acoustic attenuation of airborne sound passing through a partition or other building element, such as a wall, roof, or door, as measured in an acoustical testing laboratory according to accepted industry practice. A higher STC rating provides more sound attenuation through a partition. (ANSI S12.60–2002) 30 rating and music room doors should have a minimum STC 40 rating.

I would say that if a classroom has a single, standard-sized door opening, that the standalone ratings outlined in 4.5.5 would be sufficient. If the classroom has multiple door openings or if the doors are oversized, that it would make sense to make a composite rating. For doors located between classrooms, a composite rating would be appropriate.

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