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By Daniel Overbey
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In addition to Schools and Healthcare, LEED Building Design and Construction (BD+C) v4 expands acoustic performance into several other variations of the rating system, such as New Construction, Data Centers, and Hospitality. LEED Interior Design and Construction (ID+C) v4 also includes a new EQ credit for Acoustic Performance.
LEED BD+C v4 EQ Prerequisite: Minimum Acoustic Performance (Schools only). This Schools-only prerequisite ratchets up the v2009 criteria by specifying a maximum HVAC background noise level of 40 dBA. A new requirement requires high-noise sites to implement measures to mitigate sound transmission into core learning spaces (including between spaces).
Core learning spaces at or over 20,000 cubic feet will need to reduce the reverberation time in accordance with the 2002 NRC-CNRC Construction Technology Update No. 51, Acoustical Design of Rooms for Speech (or local equivalent). Spaces under 20,000 cubic feet must either exhibit sound-absorbent finishes (NRC rating of 0.70 or higher) that equal or exceed the ceiling area, or teams must confirm conformance to ANSI Standard S12.60-2010.
LEED BD+C v4 EQ Credit: Acoustic Performance (1 point). Unlike the Schools-only prerequisite, this credit also applies to LEED for New Construction, Data Centers, Warehouses & Distribution Centers, Hospitality, and Commercial Interiors. There is Schools-specific credit language and the two-point Healthcare-2009 EQc2 credit is also parsed.
New Construction, Data Centers, Warehouses & Distribution Centers, Hospitality, and Commercial Interiors Criteria: Teams shall minimize HVAC background noise per the 2011 ASHRAE Handbook, HVAC Applications, Chapter 48, Table 1 or AHRI Standard 885-2008, Table 15 (or a local equivalent). Teams must calculate or measure sound levels to confirm compliance. The credit also references the ASHRAE 2011 Applications Handbook, Table 6 (or a local equivalent) for maximum allowable HVAC noise levels resulting from sound transmission paths.
Next, teams must meet the composite STCc ratings and reverberation time requirements as tabulated in the LEED credit language. Lastly, for large conference rooms and assembly spaces, teams shall address the need for sound reinforcement systems. If needed, teams shall meet the specified Speech Transmission Index (STI) or Common Intelligibility Scale (CIS) rating, keep sound levels at or below 70 dBA, and maintain specified sound-level coverage. For projects that use masking systems, the design levels must not exceed 48 dBA.
Schools Criteria: Building off of the schools-specific prerequisite, HVAC background noise levels may not exceed 35 dBA. The credit also requires projects to meet ANSI Standard S12.60-2010, Part 1, except windows — which must have an STC rating of at least 35 unless noise levels can be verified to justify a lower rating.
Healthcare Criteria: The healthcare-specific criteria is basically the Healthcare-2009 EQc2: Acoustic Environment criteria with some minor revisions to the credit language. The two basic options remain:
Option 1: Address speech privacy, sound isolation, and background noise (1-2 points).
Option 2: Acoustical finishes and site exterior noise (1 point).
LEED O+M v4 EQ Credit: Occupant Comfort Survey. Even the Occupant Comfort Survey credit within LEED Building Operations and Maintenance (O+M) v4 requires an acoustic evaluation. This underscores the green building industry's increasing understanding that our sense of hearing plays a significant factor in comfort, wellness, and the ability to perform in a space.
Daniel Overbey, AIA, LEED AP BD+C, is the director of sustainable design practices for Browning Day Mullins Dierdorf Architects in Indianapolis. He can be reached at email@example.com.
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