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LEED BD+C: New Construction | v3 - LEED 2009

Acoustics

EQpc24 | Possible 1 point

Intent

Pilot Credit Closed

This pilot credit is closed to new registrations

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

Requirements

For all occupied spaces, meet the following requirements as applicable to the space:

  • room noise levels
  • sound isolation performance of constructions,
  • limiting reverberation time and reverberant noise buildup
  • paging, masking and sound reinforcement systems

Projects that cannot meet sections of the requirements due to limited scope of work or historic preservation requirements must meet at least 3 of the above sections and submit a detailed description justifying design decisions.

Room noise levels

Room noise levels from building mechanical systems shall fall within the sound level ranges shown in either the 2011 ASHRAE Handbook, HVAC Applications, Chapter 48, Table 1, or the AHRI Standard 885-2008, Table 15, or local equivalent.

Measurements for room sound levels shall be measured using a sound level meter that conforms to ANSI S1.4 for type 1 (precision) or type 2 (general purpose) sound measurement instrumentation, or local equivalent.

Comply with design criteria for HVAC noise levels in regularly occupied spaces resulting from the sound transmission paths listed in Table 6 in the ASHRAE 2011 Applications Handbook or AHRI Standard 885-2008, or local equivalent.

Sound isolation

In lieu of a building code, meet the following composite Sound Transmission Class (STCC)ratings:

As applicable, use the following table to estimate the composite STC rating (STCC) of interior partitions.

Table 1. Maximum 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

Limiting reverberation time and reverberant noise buildup

Meet the reverberation time requirements in the following table, adapted from Table 9.1 in the Performance Measurement Protocols for Commercial Buildings2:

Table 2. 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

Paging, masking and sound reinforcement systems

Sound Reinforcement

  1. All large conference rooms and auditoria seating more than 50 persons shall consider sound reinforcement and AV playback capabilities, depending on their use. If it is determined that these systems are not required, the design team must submit a detailed description justifying their design decisions.
  2. Sound reinforcement system shall achieve a minimum Speech Transmission Index (STI) of 0.60 or a Common Intelligibility Scale (CIS) rating 0.77 at representative points within the area of coverage to provide acceptable intelligibility from the system.
  3. Performance of the system shall achieve:
    • 70 dBA minimum sound level
    • Maintain sound level coverage within +/- 3 dB at the 2000 Hz octave band throughout the space.
  4. Upgraded sound isolation shall be considered for acoustically-sensitive spaces that are adjacent to spaces with sound reinforcement systems.

Masking systems
For projects that use masking systems, meet the following:

  1. Systems shall be designed for levels that do not exceed 48 dBA.
  2. Loudspeaker coverage shall provide uniformity of +/- 2 dBA
  3. Suitable spectra shall be designed to effectively mask speech spectra3.

.

1 The sound isolation ratings are considered the composite sound isolation performance values associated with the demising constructions, whether they are the floor/ceiling or wall partitions. Details such as the ceiling plenum conditions, windows, doors, penetrations through the constructions, etc. shall be addressed to provide this composite sound isolation rating. The values will provide Normal speech privacy (except at corridor walls with doors), assuming a background sound level of at least 30 dBA in the receiving room and “conversational” voice level of 60 dBA at three feet. The values will provide confidential speech privacy if the sum of the composite STC and A-weighted background noise level total is at least 75. For “raised” and “loud” voice levels, add 5 to 10 dBA to the total, respectively.

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

3 “Masking speech in open-plan offices with simulated ventilation Noise: Noise level and spectral composition Effects on Acoustical Satisfaction”, Veitch, J.A. Bradley, J.S.; Legault, L.M. Norcross, S., and Svec, J.M. IRC – IR – 846, National Resource Council Canada, April 2002.

Credit Specific:

Room noise level calculations (NC, RC(N) or dBA).
Sound isolation assessment (STCC).
Speech privacy analysis.
RT calculations, and Discussion of sound absorbing materials used in the project.
Sound reinforcement or masking system description

Additional Questions
  1. The goal of this credit is to provide the optimal acoustical environment for occupants in a space; how did the sound isolation needs analysis change the design of your space?
  2. Are there parts of the analysis that you opted not to address? If so, why?
Background Information

This pilot credit is based upon the LEED for Schools Enhanced Acoustical Design credit, and has been developed in order to meet the market need for guidance around acoustical design in the office and new construction setting.

Changes:
  • 01/02/2014:
    Added Table 1 and Table 2
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