Worked Example: Neighbourhood Cafe — BS 8233 Acoustic Comfort
150 m³ cafe with acoustic plaster, exposed brick, and timber floor
A 150 m³ restaurant designed to BS-8233 requires RT60 ≤ 0.8s. With Acoustic plaster 15mm on the ceiling, the calculated RT60 is 0.58s — PASS.
Room Setup
Total surface area: 197.0 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| Ceiling — acoustic plaster | Acoustic plaster 15mm | 35.0 | 0.66 |
| Ceiling — painted plaster | Painted plaster | 25.0 | 0.04 |
| Floor | Timber floor (sealed) | 60.0 | 0.09 |
| Walls — brick | Brick (unglazed) | 40.0 | 0.04 |
| Walls — plasterboard | Plasterboard on studs | 12.0 | 0.07 |
| Seating (30 covers) | Upholstered seating | 8.0 | 0.55 |
| Window (shopfront) | Single glazing | 15.0 | 0.16 |
| Door | Solid timber door | 2.0 | 0.09 |
Absorption coefficients sourced from manufacturer datasheets and ISO 354 test reports. Browse the full acoustic materials database.
Step-by-Step Calculation
- 1
Room Volume
V = L × W × H = 10 × 6 × 2.5 = 150 m³
- 2
Total Surface Area
Stotal = 35.0 + 25.0 + 60.0 + 40.0 + 12.0 + 8.0 + 15.0 + 2.0 = 197.0 m²
- 3
Absorption per Surface at 500 Hz
Ceiling — acoustic plaster: 35.0 m² × 0.65 = 22.75 Sabins
Ceiling — painted plaster: 25.0 m² × 0.04 = 1.00 Sabins
Floor: 60.0 m² × 0.10 = 6.00 Sabins
Walls — brick: 40.0 m² × 0.03 = 1.20 Sabins
Walls — plasterboard: 12.0 m² × 0.05 = 0.60 Sabins
Seating (30 covers): 8.0 m² × 0.56 = 4.48 Sabins
Window (shopfront): 15.0 m² × 0.18 = 2.70 Sabins
Door: 2.0 m² × 0.08 = 0.16 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 22.75 + 1.00 + 6.00 + 1.20 + 0.60 + 4.48 + 2.70 + 0.16 = 38.89 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 150 / 38.89 = 0.62s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.58s. Target: 0.5--0.8s per BS-8233. Verdict: PASS
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 24.5 | 28.7 | 38.9 | 42.9 | 43.5 | 41.1 |
| RT60 (s) | 0.99 | 0.84 | 0.62 | 0.56 | 0.55 | 0.59 |
| Target (s) | — | — | 0.80 | 0.80 | 0.80 | — |
| Verdict | — | — | PASS | PASS | PASS | — |
Compliance Verdict
Reference:
Open the AcousPlan calculator pre-loaded with the exact room dimensions (10m × 6m × 2.5m) and RT60 target (0.8s).
Open CalculatorField Story
A specialty coffee roaster is opening its first cafe in a converted shop unit in Edinburgh. The exposed Victorian brick walls and restored timber floor create the artisanal character the brand requires, but these hard parallel surfaces create flutter echo when more than half the 30 seats are occupied. Acoustic plaster applied to 58% of the ceiling provides invisible treatment — guests see what appears to be a painted ceiling. The large single-glazed shopfront window acts as a useful low-frequency absorber through panel vibration. Upholstered bench seating provides absorption at ear height. Plasterboard partitions to the kitchen provide panel absorption. BS 8233 recommends RT60 below 0.8 s for cafes; the calculation confirms this is achievable while preserving the interior design intent that makes the space commercially attractive.
Frequently Asked Questions
What RT60 does a Neighbourhood Cafe — BS 8233 Acoustic Comfort achieve?
With the specified materials and dimensions (10m x 6m x 2.5m, volume 150m3), the calculated mid-frequency RT60 is 0.58s using the Sabine equation. The target under BS-8233 is 0.5--0.8s. The result is a PASS.
What materials are used in this hospitality acoustic example?
This example uses Acoustic plaster 15mm on the Ceiling — acoustic plaster (NRC 0.66), Painted plaster on the Ceiling — painted plaster (NRC 0.04), Timber floor (sealed) on the Floor (NRC 0.09), Brick (unglazed) on the Walls — brick (NRC 0.04), Plasterboard on studs on the Walls — plasterboard (NRC 0.07), Upholstered seating on the Seating (30 covers) (NRC 0.55), Single glazing on the Window (shopfront) (NRC 0.16), Solid timber door on the Door (NRC 0.09). The total absorption at 500 Hz is 38.9 Sabins.
How much does acoustic treatment cost for this room?
Cost data is not available for this example. Use the AcousPlan calculator to estimate treatment costs for your specific room configuration.
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All calculations are advisory and based on the Sabine equation (ISO 3382-2:2008 Annex A). Results require professional verification for compliance submissions. Absorption coefficients are sourced from manufacturer datasheets and ISO 354 test reports.