To provide workspaces and classrooms that promote occupants’ well-being, productivity, and communications through effective acoustic design.
For all occupied spaces, meet two of the following: HVAC background noise, Sound Transmission, and/or Reverberation time. Meet all three for an exemplary performance point.
Confirm compliance via calculations or measurements in representative rooms, and/or design documentation from a person experienced in the field of acoustics.
HVAC Background Noise
Achieve maximum background noise levels from heating, ventilating, and air conditioning (HVAC) systems per 2015 ASHRAE Handbook-- HVAC Applications, Chapter 48, Table 1 ; AHRI Standard 885-2008, Table 15; or a local equivalent.
If confirming compliance via measurements, use a sound level meter that conforms to ANSI S1.4 for type 1 (precision) or type 2 (general purpose) sound measurement instrumentation, the International Electrotechnical Commission (2013) IEC 61672-1:2013 Electroacoustics – Sound Level Meters – Part 1: Specifications, or a local equivalent.
Comply with design criteria for HVAC noise levels resulting from the sound transmission paths listed in 2015 ASHRAE Handbook—HVAC Applications, Chapter 48, Table 6; or a local equivalent.
Categorize all occupied spaces by use and desired level of acoustic privacy.
Table 1. Minimum composite sound transmission class ratings or noise isolation class for adjacent spaces
|Adjacency combinations||STC C **||NIC**|
|Collaborative / multi-use||Hallway, stairway||25||20|
|Collaborative / multi-use||Collaborative / multi-use||35||30|
|Collaborative / multi-use||Private||45||40|
|Collaborative / multi-use||Confidential||50||45|
|Conference room||Conference room||50||45|
|Mechanical equipment room*||Hallway, stairway||50||45|
|Mechanical equipment room*||Occupied area||60||55|
*Minimum STCc or NIC has to be met unless proven that the equipment noise in conjunction with the sound isolation performance of the partitions and doors will not exceed the maximum background noise requirements of the adjacent space.
**If a sound masking system is implemented at a minimum level of 40 dBA, the STCc ratings or NIC values in Table 1 may be lowered by 5 points. This applies to all space types except mechanical equipment rooms. The sound masking system must be designed by an acoustical professional and meet the following criteria:
- The overall level for sound masking must be set by an acoustical professional and must not exceed 48 dBA in open offices, libraries, cafeterias, corridors/hallways, 45 dBA in enclosed offices, and 42 dBA in conference rooms, and wellness rooms. The combined level of masking and HVAC background noise must not exceed these limits.
- The system design and commissioning must provide overall level uniformity of +/-1 dBA and one-third octave band uniformity of +/-2 dB from at least 100 to 5,000 Hz when tested according to ASTM E1573-18
- The sound masking spectrum must conform to the National Research Council of Canada COPE Optimum Masking Spectrum or an alternate spectrum if specified by an acoustical engineer.
Meet the reverberation time requirements in Table 2 (adapted from Table 9.1 in the Performance Measurement Protocols for Commercial Buildings1).
Table 2. Reverberation time requirements
|Room type||Application||T60 (sec), at 500 Hz, 1000 Hz, and 2000 Hz|
|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|
|Indoor stadium, gymnasium||Gymnasium and natatorium||< 2.0|
|Large-capacity space with speech amplification||< 1.5|