Open Plan Office Acoustic Requirements Under BS 8233:2014
Open plan workspaces, trading floors, collaborative offices. Typical volume: 500-5,000 m².
What BS 8233:2014 Requires for a Open Plan Office
Clause reference: BS 8233:2014 Table 4
RT60 target: ≤ 0.8s (large open offices)
Background noise limit: 35-40 dBA (ambient)
Measurement condition: Furnished
Note: Less prescriptive than WELL F74. Does not mandate STI.
How to Calculate BS 8233:2014 Compliance for a Open Plan Office
- 1
Identify the applicable standard and target
Look up BS 8233:2014 (BS 8233:2014 Table 4). For a open plan office, the RT60 target is ≤ 0.8s (large open offices). Measurement condition: furnished.
- 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 ≤ 0.8s (large open offices), specify additional absorption. 50-70% of ceiling area is typical for a open plan office to achieve compliance.
Typical Acoustic Treatment for a Open Plan Office
Treatment Area
50-70% of ceiling area
Estimated Cost
£85-£140/m² of floor area installed
Open Plan Office: BS 8233:2014 vs Other Standards
| Requirement | BS 8233:2014 | WELL v2 Feature 74 |
|---|---|---|
| RT60 Target | ≤ 0.8s (large open offices) | ≤ 0.5s (meeting rooms within) | open plan: distraction distance rD < 5m |
| STI Target | Not specified | STI < 0.50 between workstations (speech privacy) |
| Background Noise | 35-40 dBA (ambient) | ≤ 45 dBA (open plan) | ≤ 35 dBA (HVAC mechanical) |
| Measurement | Furnished | Furnished, unoccupied |
Frequently Asked Questions
What RT60 does BS 8233:2014 require for a open plan office?
BS 8233:2014 (BS 8233:2014 Table 4) requires a reverberation time of ≤ 0.8s (large open offices) for open plan office spaces, measured in the furnished condition per ISO 3382-2.
What background noise level is acceptable in a open plan office under BS 8233:2014?
BS 8233:2014 sets a background noise limit of 35-40 dBA (ambient) 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 BS 8233:2014?
A typical open plan office requires 50-70% of ceiling area of acoustic treatment to meet BS 8233:2014 compliance. Estimated installed cost is £85-£140/m² of floor area installed.
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