Open Plan Office Acoustic Requirements Under WELL v2 Feature 74
Open plan workspaces, trading floors, collaborative offices. Typical volume: 500-5,000 m².
What WELL v2 Feature 74 Requires for a Open Plan Office
Clause reference: WELL v2 Feature 74 Parts 1, 2, 3
RT60 target: ≤ 0.5s (meeting rooms within) | open plan: distraction distance rD < 5m
STI target: STI < 0.50 between workstations (speech privacy)
Background noise limit: ≤ 45 dBA (open plan) | ≤ 35 dBA (HVAC mechanical)
Measurement condition: Furnished, unoccupied
Note: Three-part requirement. Part 3 speech privacy is most commonly failed.
How to Calculate WELL v2 Feature 74 Compliance for a Open Plan Office
- 1
Identify the applicable standard and target
Look up WELL v2 Feature 74 (WELL v2 Feature 74 Parts 1, 2, 3). For a open plan office, the RT60 target is ≤ 0.5s (meeting rooms within) | open plan: distraction distance rD < 5m. Measurement condition: furnished, unoccupied.
- 2
Measure or model the room geometry
Record the length, width, and height of the room to calculate the volume. A typical open plan office has a volume of 500-5,000 m².
- 3
List all surfaces and their absorption coefficients
For each surface (floor, ceiling, walls, windows, doors), find the absorption coefficient at each octave band frequency (125Hz to 4kHz) from ISO 354 test data or a materials database.
- 4
Calculate total absorption and apply the Sabine or Eyring equation
Sum all surface absorption values: A = sum of (alpha x area). Then apply T60 = 0.161 x V / A (Sabine) or T60 = -0.161 x V / (S x ln(1 - alpha_avg)) (Eyring). Use Eyring when average alpha exceeds 0.20.
- 5
Compare result against the standard and specify treatment if needed
If the calculated RT60 exceeds the target of ≤ 0.5s (meeting rooms within) | open plan: distraction distance rD < 5m, specify additional absorption. 65-80% of ceiling area + masking system is typical for a open plan office to achieve compliance.
Typical Acoustic Treatment for a Open Plan Office
Treatment Area
65-80% of ceiling area + masking system
Estimated Cost
AUD 130-220/m² of floor area installed
Open Plan Office: WELL v2 Feature 74 vs Other Standards
| Requirement | WELL v2 Feature 74 | BS 8233:2014 |
|---|---|---|
| RT60 Target | ≤ 0.5s (meeting rooms within) | open plan: distraction distance rD < 5m | ≤ 0.8s (large open offices) |
| STI Target | STI < 0.50 between workstations (speech privacy) | Not specified |
| Background Noise | ≤ 45 dBA (open plan) | ≤ 35 dBA (HVAC mechanical) | 35-40 dBA (ambient) |
| Measurement | Furnished, unoccupied | Furnished |
Frequently Asked Questions
What RT60 does WELL v2 Feature 74 require for a open plan office?
WELL v2 Feature 74 (WELL v2 Feature 74 Parts 1, 2, 3) requires a reverberation time of ≤ 0.5s (meeting rooms within) | open plan: distraction distance rD < 5m for open plan office spaces, measured in the furnished, unoccupied condition per ISO 3382-2.
What background noise level is acceptable in a open plan office under WELL v2 Feature 74?
WELL v2 Feature 74 sets a background noise limit of ≤ 45 dBA (open plan) | ≤ 35 dBA (HVAC mechanical) for open plan office spaces. This typically refers to HVAC and building services noise measured with the room unoccupied.
How much acoustic treatment does a open plan office need to comply with WELL v2 Feature 74?
A typical open plan office requires 65-80% of ceiling area + masking system of acoustic treatment to meet WELL v2 Feature 74 compliance. Estimated installed cost is AUD 130-220/m² of floor area installed.
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