WELL Building Acoustic FAQ

Q: How are masking systems specified under WELL?

WELL v2 Feature S03 specifies that electronic sound masking systems in open plan areas must achieve: overall masking level of 40–48 dBA (adjustable by the facilities team), spatial uniformity of ±2 dBA across the masked zone, one-third octave band spectrum following a defined contour (typically peaking around 400–800 Hz and rolling off at higher frequencies), and temporal stability of ±1 dBA over 60 seconds. System components: small loudspeakers (typically 100 mm diameter) installed above the suspended ceiling at 1.2–1.8 m centres, aimed upward toward the ceiling which reflects diffuse sound downward. A central controller generates the masking signal and allows zone-by-zone level adjustment. Specification requirements: provide a system from an established manufacturer (Cambridge Sound Management, Soft dB, Lencore) with documented performance data. Commission the system with a calibrated sound level metre, adjusting zone levels to achieve the required uniformity. The WELL Performance Testing Agent measures the masking level during the verification visit.

Q: What does WELL require for exterior noise control?

WELL v2 Feature S02 (Maximum Noise Levels) implicitly addresses exterior noise because the background noise criteria must be met with all sources considered — including external noise ingress through the building envelope. If a building is located on a busy road (external noise 70+ dBA), the facade must provide sufficient sound insulation to achieve the internal criteria (40 dBA open plan, 35 dBA enclosed offices). WELL does not specify a separate facade insulation requirement, but the performance testing verifies the achieved internal level regardless of how it is achieved. For projects in noisy locations: conduct an external noise survey early in design, calculate required facade Rw (typically 30–45 dB depending on external noise), specify acoustic glazing (Rw 35–42 dB), sealed ventilation (MVHR or acoustic louvres), and ensure wall and roof constructions provide adequate insulation. WELL Feature S07 (Exterior Noise) is a future feature currently in development that may add explicit facade criteria. AcousPlan models facade insulation requirements based on external noise data.

Q: What reverberation time does WELL require?

WELL v2 Feature S06 (Reverberation Time) specifies maximum RT60 values: enclosed offices and conference rooms ≤ 0.60 s, open plan offices ≤ 0.80 s. RT60 is measured as the mid-frequency average (500 Hz and 1000 Hz octave bands) per ISO 3382-2:2008. Rooms must be furnished but unoccupied during measurement. For enclosed offices (typically 20–60 m³): achieving 0.60 s requires an acoustic ceiling (NRC ≥ 0.70) and modest wall absorption (2–4 panels). For open plan areas (typically 500–5000 m³): achieving 0.80 s requires a high-performance ceiling (NRC ≥ 0.90) across the full area plus carpet flooring. These criteria are moderate by international standards — BS 8233:2014 recommends 0.5–1.0 s for offices, and ANSI S12.60 requires 0.6 s for classrooms. The WELL RT60 requirement is relatively easy to achieve and should be the first Sound Feature targeted because it provides the foundation for all other acoustic improvements.

Q: How is WELL acoustic performance verified?

WELL acoustic verification is conducted through on-site performance testing by a WELL Performance Testing Agent (PTA), typically during the first 6 months of occupation. The PTA visits the completed, occupied (or furnished) building and conducts: (1) Background noise measurement — LAeq per IEC 61672-1 at representative positions in each space type, with HVAC operating at design condition and rooms unoccupied. (2) Masking level measurement — LAeq and one-third octave spectrum at multiple positions across masked zones. (3) RT60 measurement — per ISO 3382-2 using an omnidirectional source and measuring at 3+ positions per room type. (4) Documentation review — product data sheets for ceiling NRC, wall treatment NRC, partition STC, and ceiling CAC. (5) Sound map review — verification that the S01 sound map is complete and current. Results are compiled into a performance verification report submitted to IWBI. Projects must meet all preconditions and achieve minimum scores in optimisations to maintain certification. AcousPlan's design-stage predictions help ensure first-time pass.

Q: How does WELL compare to BREEAM for acoustic requirements?

WELL and BREEAM both address acoustics but with different approaches and stringency. WELL v2 Sound Feature: detailed prescriptive criteria across 6 sub-features (S01–S06), verified through on-site performance testing by an independent agent. Maximum 7 points from acoustics. Applies globally. BREEAM Hea 05 (Acoustic Performance): up to 4 credits, assessed through design-stage compliance with BS 8233:2014 (or equivalent national standard). Verification is primarily through design-stage acoustic report with optional post-completion testing for additional credits. Applies mainly in UK/Europe. Key differences: WELL specifies explicit NRC, CAC, and masking level values; BREEAM references national standards. WELL requires performance testing; BREEAM accepts design-stage evidence. WELL is stricter on masking and ceiling performance; BREEAM is broader in scope (also considers noise disturbance between units, external noise). For dual-certified projects: design to the more stringent requirement for each parameter. AcousPlan generates documentation suitable for both WELL and BREEAM submissions.

Complete guide to the WELL Building Standard acoustic requirements — Sound Feature preconditions, optimisations, background noise criteria, masking, reverberation, and the verification process.

Quick Navigation

1. What is the WELL Building Standard Sound Feature?
2. What are the WELL Sound preconditions?
3. What are the WELL Sound optimisation levels?
4. What background noise levels does WELL require?
5. What speech privacy requirements does WELL include?
6. How are masking systems specified under WELL?
7. What does WELL require for exterior noise control?
8. What reverberation time does WELL require?
9. How is WELL acoustic performance verified?
10. How does WELL compare to BREEAM for acoustic requirements?

What is the WELL Building Standard Sound Feature?

The WELL Building Standard v2 Sound Feature (Feature S) addresses acoustic comfort as a component of occupant health and wellbeing. It includes preconditions (mandatory for WELL certification) and optimisations (earning points toward the total score). The Sound Feature recognises that noise is a major source of occupant dissatisfaction and health impact in buildings, contributing to stress, reduced productivity, sleep disruption, and cardiovascular effects. It covers six acoustic domains: sound mapping (understanding the acoustic environment), maximum noise levels (from building services and external sources), sound masking (for speech privacy), sound reducing surfaces (absorption), sound barriers (partitions and ceilings), and reverberation time. WELL v2 is applicable to all commercial interior projects, new construction, and core and shell projects globally. Verification is through on-site performance testing by a WELL Performance Testing Agent. AcousPlan models WELL Sound Feature criteria for design-stage compliance assessment.

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What are the WELL Sound preconditions?

WELL v2 includes one Sound precondition that all certified projects must meet: S01 Sound Mapping. This requires the project team to develop a sound map identifying: all acoustic zones within the project (open plan, enclosed offices, meeting rooms, focus areas, circulation), noise sources (HVAC equipment, elevator shafts, loading docks, external traffic), noise-sensitive uses (conference rooms, focus zones, wellness rooms), and the planned acoustic strategy for each zone. The sound map must be documented and maintained. This precondition ensures that acoustic design is considered from the outset rather than as an afterthought. It does not set numerical performance criteria — those are in the optimisations. The sound map is submitted as part of the WELL documentation and reviewed during the performance verification visit. AcousPlan's project documentation feature can generate the acoustic zone mapping required for S01 compliance, showing predicted noise levels and treatment strategies per zone.

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What are the WELL Sound optimisation levels?

WELL v2 Sound optimisations (S02–S06) earn points toward the overall WELL score. Each can be achieved independently. S02 Maximum Noise Levels (up to 2 points): background noise ≤ 40 dBA in open offices, ≤ 35 dBA in enclosed offices and conference rooms. S03 Sound Masking (up to 1 point): electronic masking at 40–48 dBA with ±2 dBA spatial uniformity in open plan areas. S04 Sound Reducing Surfaces (up to 2 points): NRC ≥ 0.90 ceiling in open plan, NRC ≥ 0.80 wall treatment covering ≥ 25% of wall area, and speech-range absorption coefficient ≥ 0.70 for open plan workstation partitions. S05 Sound Barriers (up to 1 point): CAC ≥ 35 for ceiling tiles, STC ≥ 45 for enclosed office walls, and STC ≥ 40 for conference room walls. S06 Reverberation Time (up to 1 point): RT60 ≤ 0.60 s in enclosed offices, ≤ 0.80 s in open plan areas. Total potential: 7 Sound Feature points. AcousPlan checks all optimisation criteria.

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What background noise levels does WELL require?

WELL v2 Feature S02 (Maximum Noise Levels) sets background noise limits measured as A-weighted equivalent continuous level (LAeq,T): open offices ≤ 40 dBA, enclosed offices ≤ 35 dBA, conference rooms ≤ 35 dBA (or NC 30), teleconference rooms ≤ 30 dBA (or NC 25), wellness rooms ≤ 30 dBA. These levels are measured with all building systems operating at design condition, the room unoccupied, and windows and doors closed. The measurement is conducted by a WELL Performance Testing Agent using calibrated equipment per IEC 61672-1. Measurements are taken at representative positions (minimum 3 per room type) for at least 5 minutes per position. These criteria are broadly aligned with BS 8233:2014 Table 4 recommendations but with the added enforcement mechanism of independent verification. Achieving 30 dBA in teleconference rooms is particularly challenging and requires ultra-quiet HVAC design. AcousPlan's noise criteria tool predicts background noise against WELL thresholds.

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What speech privacy requirements does WELL include?

WELL v2 addresses speech privacy through three complementary features. S03 (Sound Masking): electronic masking at 40–48 dBA in open plan zones, shaped to the speech spectrum, with ±2 dBA spatial uniformity — this raises the noise floor to reduce intelligibility of overheard conversations. S04 (Sound Reducing Surfaces): high-NRC ceilings and workstation partitions reduce the propagation of speech between workstations. S05 (Sound Barriers): CAC ≥ 35 ceiling tiles prevent sound flanking over partitions, STC ≥ 45 walls for enclosed offices ensure confidential conversations remain private. Together, these features implement the ABC strategy (Absorb, Block, Cover) that acoustic engineers recommend for open plan privacy. WELL does not specify a numerical STI or Privacy Index target, but achieving all three features typically results in STI < 0.30 at the distraction distance and PI ≥ 0.80 between enclosed offices and open plan. Verification includes masking level measurement, NRC confirmation from product data, and STC verification through construction review.

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How are masking systems specified under WELL?

WELL v2 Feature S03 specifies that electronic sound masking systems in open plan areas must achieve: overall masking level of 40–48 dBA (adjustable by the facilities team), spatial uniformity of ±2 dBA across the masked zone, one-third octave band spectrum following a defined contour (typically peaking around 400–800 Hz and rolling off at higher frequencies), and temporal stability of ±1 dBA over 60 seconds. System components: small loudspeakers (typically 100 mm diameter) installed above the suspended ceiling at 1.2–1.8 m centres, aimed upward toward the ceiling which reflects diffuse sound downward. A central controller generates the masking signal and allows zone-by-zone level adjustment. Specification requirements: provide a system from an established manufacturer (Cambridge Sound Management, Soft dB, Lencore) with documented performance data. Commission the system with a calibrated sound level metre, adjusting zone levels to achieve the required uniformity. The WELL Performance Testing Agent measures the masking level during the verification visit.

Try Calculator WELL v2 Open Plan Office

What does WELL require for exterior noise control?

WELL v2 Feature S02 (Maximum Noise Levels) implicitly addresses exterior noise because the background noise criteria must be met with all sources considered — including external noise ingress through the building envelope. If a building is located on a busy road (external noise 70+ dBA), the facade must provide sufficient sound insulation to achieve the internal criteria (40 dBA open plan, 35 dBA enclosed offices). WELL does not specify a separate facade insulation requirement, but the performance testing verifies the achieved internal level regardless of how it is achieved. For projects in noisy locations: conduct an external noise survey early in design, calculate required facade Rw (typically 30–45 dB depending on external noise), specify acoustic glazing (Rw 35–42 dB), sealed ventilation (MVHR or acoustic louvres), and ensure wall and roof constructions provide adequate insulation. WELL Feature S07 (Exterior Noise) is a future feature currently in development that may add explicit facade criteria. AcousPlan models facade insulation requirements based on external noise data.

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What reverberation time does WELL require?

WELL v2 Feature S06 (Reverberation Time) specifies maximum RT60 values: enclosed offices and conference rooms ≤ 0.60 s, open plan offices ≤ 0.80 s. RT60 is measured as the mid-frequency average (500 Hz and 1000 Hz octave bands) per ISO 3382-2:2008. Rooms must be furnished but unoccupied during measurement. For enclosed offices (typically 20–60 m³): achieving 0.60 s requires an acoustic ceiling (NRC ≥ 0.70) and modest wall absorption (2–4 panels). For open plan areas (typically 500–5000 m³): achieving 0.80 s requires a high-performance ceiling (NRC ≥ 0.90) across the full area plus carpet flooring. These criteria are moderate by international standards — BS 8233:2014 recommends 0.5–1.0 s for offices, and ANSI S12.60 requires 0.6 s for classrooms. The WELL RT60 requirement is relatively easy to achieve and should be the first Sound Feature targeted because it provides the foundation for all other acoustic improvements.

Try Calculator WELL v2 Open Plan Office Glossary

How is WELL acoustic performance verified?

WELL acoustic verification is conducted through on-site performance testing by a WELL Performance Testing Agent (PTA), typically during the first 6 months of occupation. The PTA visits the completed, occupied (or furnished) building and conducts: (1) Background noise measurement — LAeq per IEC 61672-1 at representative positions in each space type, with HVAC operating at design condition and rooms unoccupied. (2) Masking level measurement — LAeq and one-third octave spectrum at multiple positions across masked zones. (3) RT60 measurement — per ISO 3382-2 using an omnidirectional source and measuring at 3+ positions per room type. (4) Documentation review — product data sheets for ceiling NRC, wall treatment NRC, partition STC, and ceiling CAC. (5) Sound map review — verification that the S01 sound map is complete and current. Results are compiled into a performance verification report submitted to IWBI. Projects must meet all preconditions and achieve minimum scores in optimisations to maintain certification. AcousPlan's design-stage predictions help ensure first-time pass.

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How does WELL compare to BREEAM for acoustic requirements?

WELL and BREEAM both address acoustics but with different approaches and stringency. WELL v2 Sound Feature: detailed prescriptive criteria across 6 sub-features (S01–S06), verified through on-site performance testing by an independent agent. Maximum 7 points from acoustics. Applies globally. BREEAM Hea 05 (Acoustic Performance): up to 4 credits, assessed through design-stage compliance with BS 8233:2014 (or equivalent national standard). Verification is primarily through design-stage acoustic report with optional post-completion testing for additional credits. Applies mainly in UK/Europe. Key differences: WELL specifies explicit NRC, CAC, and masking level values; BREEAM references national standards. WELL requires performance testing; BREEAM accepts design-stage evidence. WELL is stricter on masking and ceiling performance; BREEAM is broader in scope (also considers noise disturbance between units, external noise). For dual-certified projects: design to the more stringent requirement for each parameter. AcousPlan generates documentation suitable for both WELL and BREEAM submissions.

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