Data-Centers-NC-v4 EQc9: Acoustic performance

  • Provide an acoustically superior environment for occupants

    This credit encourages quality acoustical design, which provides many benefits to occupants including increased comfort and productivity. 

    However, the credit requirements can be difficult and expensive to achieve, and can require careful balancing against other project concerns, such as materials selection or open floor planning. Consider enlisting the expertise of an acoustical consultant to ensure your project meets the applicable requirements for all occupied spacesEnclosed space intended for human activities, excluding those spaces that are intended primarily for other purposes, such as storage rooms and equipment rooms, and that are only occupied occasionally and for short periods of time. Occupied spaces are further classified as regularly occupied or nonregularly occupied spaces based on the duration of the occupancy, individual or multioccupant based on the quantity of occupants, and densely or nondensely occupied spaces based on the concentration of occupants in the space.

    For non-U.S. projects, this credit does allow for an alternative compliance path based on local standards. Project teams will have to show that the local standard is equivalent to the ANSI S12.60–2002 standard.

    What’s New in LEED v4

    This is a new credit for New Construction, Data Centers, Warehouses and Distribution Centers, and Hospitality.

    For Schools:

    • USGBC reduced the noise-level limit from 40 to 35 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).
    • The referenced ANSI S12.60 standard was updated from the 2002 to the 2010 version.
    • The background noise AHRI Standard 885–2008 was added as a referenced standard.
    • The credit requires that all equivalent local codes are used in place of national codes.

    For Healthcare:

    • The Acoustic Environment credit name is changed.

    FAQs

    Is it possible to pursue this as an Innovation credit in a Core & Shell project?

    Yes, it’s possible. Your project would be required to clearly identify which components of the credit will be implemented as part of the developer’s scope of work, and which portions will be part of the tenant’s scope of work and enforced through binding tenant lease or sales agreements. Both the developer and the tenant must sign a legally binding document that includes the technical credit requirements. The document must explicitly state performance requirements for the tenant work. 

    Our project has small meeting rooms in an open-office plan. This situation appears to require an STC of 50. However, this level seems to be (unrealistically) high, especially considering the doors in the wall partition. STC 50 with a (closed) wall can be achieved, but even high STC doors won't achieve an STC of more than 45. Would this mean that the credit is not achievable?

    The credit asks for a Composite STC rating. This essentially means the transmission loss of the wall in addition to the transmission loss of the door, averaged based on their respective areas. So you won't need an STC 50 rated door assembly, but it may still be hard to achieve an STC 50 composite rating unless you have a large wall area with a high STC rating and a small, standard STC 35-40, door.

    Sound transmission requirements for adjacency combinations are listed in Reference Guide Table 1, but not all combinations are included. For example, an STC rating requirement is not provided for conference room and standard/executive office adjacency. Is sound transmission compliance achieved by addressing only project applicable adjacency combinations listed in Table 1?

    All occupied spaces listed in Table 1 should be addressed. If the adjacency combination present in the project is not included in the table, select the most appropriate combination or propose an alternative composite STC rating for that combination.

  • EQ Credit 9: Acoustic performance

    Intent

    To provide workspaces and classrooms that promote occupants’ well-being, productivity, and communications through effective acoustic design.

    Requirements

    For all occupied spacesEnclosed space intended for human activities, excluding those spaces that are intended primarily for other purposes, such as storage rooms and equipment rooms, and that are only occupied occasionally and for short periods of time. Occupied spaces are further classified as regularly occupied or nonregularly occupied spaces based on the duration of the occupancy, individual or multioccupant based on the quantity of occupants, and densely or nondensely occupied spaces based on the concentration of occupants in the space., meet the following requirements, as applicable, for HVAC background noise, sound isolation, 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, and sound reinforcement and masking.

    HVAC Background Noise

    Achieve maximum background noise levels from heating, ventilating, and air conditioning (HVAC) systems per 2011 ASHRAE Handbook, HVAC Applications, Chapter 48, Table 1; AHRI Standard 885-2008, Table 15; or a local equivalent. Calculate or measure sound levels.

    For measurements, use a sound level meter that conforms to ANSI S1.4 for type 1 (precision) or type 2 (general purpose) sound measurement instrumentation, or a local equivalent.

    Comply with design criteria for HVAC noise levels resulting from the sound transmission paths listed in ASHRAE 2011 Applications Handbook, Table 6; or a local equivalent.

    Sound Isolation

    Meet the composite sound transmission class (STCC) ratings listed in Table 1, or local building code, whichever is more stringent.

    Table 1. Minimum composite sound transmission class ratings for adjacent spaces

    Adjacency combinations STCC
    Residence (within a multifamily residence), hotel or motel room Residence, hotel or motel room 55
    Residence, hotel or motel room Common hallway, stairway 50
    Residence, hotel or motel room Retail 60
    Retail Retail 50
    Standard office Standard office 45
    Executive office Executive office 50
    Conference room Conference room 50
    Office, conference room Hallway, stairway 50
    Mechanical equipment room Occupied area 60



    Reverberation Time

    Meet the reverberation time requirements in Table 3 (adapted from Table 9.1 in the Performance Measurement Protocols for Commercial Buildings1).

    Table 3. Reverberation time requirements

    Room type Application T60 (sec), at 500 Hz, 1000 Hz, and 2000 Hz
    Apartment and condominium < 0.6
    Hotel/motel Individual room or suite < 0.6
    Meeting or banquet room < 0.8
    Office building Executive or private office < 0.6
    Conference room < 0.6
    Teleconference room < 0.6
    Open-plan office without sound masking < 0.8
    Open-plan office with sound masking 0.8
    Courtroom Unamplified speech < 0.7
    Amplified speech < 1.0
    Performing arts space Drama theaters, concert and recital halls Varies by application
    Laboratories Testing or research with minimal speech communication < 1.0
    Extensive phone use and speech communication < 0.6
    Church, mosque, synagogue General assembly with critical music program Varies by application
    Library   < 1.0
    Indoor stadium, gymnasium Gymnasium and natatorium < 2.0
    Large-capacity space with speech amplification < 1.5
    Classroom < 0.6



    Sound Reinforcement and Masking Systems


    Sound Reinforcement

    For all large conference rooms and auditoriums seating more than 50 persons, evaluate whether sound reinforcement and AV playback capabilities are needed.

    If needed, the sound reinforcement systems must meet the following criteria:

    • Achieve a speech transmission index (STI) of at least 0.60 or common intelligibility scale (CIS) rating of at least 0.77 at representative points within the area of coverage to provide acceptable intelligibility.
    • Have a minimum sound level of 70 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) and must
    • Maintain sound-level coverage within +/–3 dB at the 2000 Hz octave bandA section of a frequency scale in which the upper band-edge frequency (f2) is twice the lower band-edge frequency (f1). Each octave band is identified by its center frequency. throughout the space.

    Masking Systems

    For projects that use masking systems, the design levels must not exceed 48 dBA. Ensure that loudspeaker coverage provides uniformity of +/–2 dBA and that speech spectra are effectively masked.


    1 Adapted from ASHRAE (2007d), ASA (2008), ANSI (2002), and CEN (2007)


Acoustic Performance Calculator

Project teams can complete the USGBC Acoustic Performance Calculator for LEED v4 for Schools EQ Prerequisite Minimum Acoustic Performance, LEED v4 BD+C EQ Credit Acoustic Performance, and LEED v4 ID+C EQ Credit Acoustic Performance.  This calculator contains reference values from ANSI S12.60–2010, ASHRAE 2011 applications Handbook, AHRI 885-2008, and the 2010 FGI Guidelines.

2 Comments

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neeraj arora
Dec 19 2014
Guest
6 Thumbs Up

Acoustic performance

Project Location: India

How to calculate composite 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) for a room?

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Daniel Hicks Daniel Hicks, E.I., INCE, Geiler & Associates Apr 13 2016 LEEDuser Expert 2519 Thumbs Up

Do you have access to standard ANSI S12.60? There is Table D.2 that is helpful for finding composite 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.

Unfortunately, that is the only resource I know of that I can point you to other than an acoustical consultant who can make the calculation for you.

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May 26 2017
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