Worked Example: Operating Theatre — Cleanroom Acoustic Design
RT60 calculation for a hospital operating theatre requiring cleanroom-compatible materials. Perforated metal ceiling and acoustic plaster walls meet both hygienic and acoustic requirements in this critical clinical environment.
A 126 m³ hospital ward designed to ISO-3382 requires RT60 ≤ 0.6s. With Perforated metal ceiling on the ceiling and Acoustic plaster 15mm on walls, the calculated RT60 is 0.36s — PASS.
Room Setup
Total surface area: 165.6 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| ceiling | Perforated metal ceiling | 42.0 | 0.75 |
| walls-main | Painted plaster | 54.0 | 0.04 |
| walls-treatment | Acoustic plaster 15mm | 24.0 | 0.70 |
| floor | Vinyl/linoleum floor | 42.0 | 0.03 |
| windows | Double glazing 6mm | 0.0 | 0.04 |
| door | Solid timber door | 3.6 | 0.08 |
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 = 7 × 6 × 3 = 126 m³
- 2
Total Surface Area
Stotal = 42.0 + 54.0 + 24.0 + 42.0 + 0.0 + 3.6 = 165.6 m²
- 3
Absorption per Surface at 500 Hz
ceiling: 42.0 m² × 0.80 = 33.60 Sabins
walls-main: 54.0 m² × 0.04 = 2.16 Sabins
walls-treatment: 24.0 m² × 0.65 = 15.60 Sabins
floor: 42.0 m² × 0.03 = 1.26 Sabins
windows: 0.0 m² × 0.04 = 0.00 Sabins
door: 3.6 m² × 0.08 = 0.29 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 33.60 + 2.16 + 15.60 + 1.26 + 0.00 + 0.29 = 52.91 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 126 / 52.91 = 0.38s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.36s. Target: ≤ 0.6s per ISO-3382. Verdict: PASS
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 21.1 | 40.5 | 52.9 | 59.6 | 56.6 | 50.4 |
| RT60 (s) | 0.96 | 0.50 | 0.38 | 0.34 | 0.36 | 0.40 |
| Target (s) | — | — | 0.60 | 0.60 | 0.60 | — |
| Verdict | — | — | PASS | PASS | PASS | — |
Compliance Verdict
Reference: ISO 3382-2:2008; HTM 08-01 §4.3
Operating theatres require cleanroom-compatible acoustic materials that can be washed and disinfected. Perforated metal ceiling panels with sealed mineral wool backing and smooth acoustic plaster meet both infection control and acoustic requirements.
STI result: 0.74 (per IEC 60268-16:2020)
Cost Estimate
Costs are indicative and vary by region, supplier, and installation complexity. For a detailed cost breakdown, use the AcousPlan calculator.
Open the AcousPlan calculator pre-loaded with the exact room dimensions (7m × 6m × 3m) and RT60 target (0.6s).
Open CalculatorField Story
A surgical team reports that communication errors during operations are contributing to near-miss incidents. The WHO Surgical Safety Checklist requires clear verbal confirmation between team members, but the operating theatre's hard surfaces create an RT60 of 1.1 seconds, masking speech especially when equipment alarms are sounding. The infection control team initially blocks all acoustic treatment proposals, citing contamination risk. After extensive product research, the acoustic consultant identifies a perforated stainless steel ceiling system with encapsulated mineral wool that can withstand high-pressure steam cleaning, and a smooth-finish acoustic plaster that meets ISO Class 5 cleanroom standards.
Frequently Asked Questions
What RT60 does a Operating Theatre — Cleanroom Acoustic Design achieve?
With the specified materials and dimensions (7m x 6m x 3m, volume 126m3), the calculated mid-frequency RT60 is 0.36s using the Sabine equation. The target under ISO-3382 is 0.6s or less. The result is a PASS.
What materials are used in this healthcare acoustic example?
This example uses Perforated metal ceiling on the ceiling (NRC 0.75), Painted plaster on the walls-main (NRC 0.04), Acoustic plaster 15mm on the walls-treatment (NRC 0.7), Vinyl/linoleum floor on the floor (NRC 0.03), Double glazing 6mm on the windows (NRC 0.04), Solid timber door on the door (NRC 0.08). The total absorption at 500 Hz is 52.9 Sabins.
How much does acoustic treatment cost for this room?
The estimated treatment cost is £6,270 for 66 m2 of absorptive material at approximately £95/m2. Actual costs vary by region, supplier, and installation complexity.
Related Examples
Hospital Ward — BS 8233 Patient Recovery
GP Consulting Room — Speech Privacy Design
Dental Surgery — Acoustic Treatment for Anxiety
MRI Suite — Patient Acoustic Comfort Design
Explore More
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.