Worked Example: Pathology Laboratory — ASHRAE NC 35-45 Compliance
200 m³ clinical laboratory with Rockfon ceiling and controlled ventilation noise
A 200 m³ hospital ward designed to ASHRAE requires RT60 ≤ 0.7s. With Rockfon Sonar 25mm ceiling tile on the ceiling, the calculated RT60 is 0.61s — PASS.
Room Setup
Total surface area: 248.5 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| Ceiling — Rockfon Sonar | Rockfon Sonar 25mm ceiling tile | 50.0 | 0.82 |
| Ceiling — plaster | Painted plaster | 30.0 | 0.04 |
| Floor | Vinyl/linoleum floor | 80.0 | 0.04 |
| Walls — painted plaster | Painted plaster | 58.0 | 0.04 |
| Walls — plasterboard | Plasterboard on studs | 15.0 | 0.07 |
| Fume hood glazing | Single glazing | 6.0 | 0.16 |
| Door | Solid timber door | 3.5 | 0.09 |
| Window | Double glazing 6mm | 6.0 | 0.03 |
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 × 8 × 2.5 = 200 m³
- 2
Total Surface Area
Stotal = 50.0 + 30.0 + 80.0 + 58.0 + 15.0 + 6.0 + 3.5 + 6.0 = 248.5 m²
- 3
Absorption per Surface at 500 Hz
Ceiling — Rockfon Sonar: 50.0 m² × 0.82 = 41.00 Sabins
Ceiling — plaster: 30.0 m² × 0.04 = 1.20 Sabins
Floor: 80.0 m² × 0.03 = 2.40 Sabins
Walls — painted plaster: 58.0 m² × 0.04 = 2.32 Sabins
Walls — plasterboard: 15.0 m² × 0.05 = 0.75 Sabins
Fume hood glazing: 6.0 m² × 0.18 = 1.08 Sabins
Door: 3.5 m² × 0.08 = 0.28 Sabins
Window: 6.0 m² × 0.04 = 0.24 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 41.00 + 1.20 + 2.40 + 2.32 + 0.75 + 1.08 + 0.28 + 0.24 = 49.27 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 200 / 49.27 = 0.65s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.61s. Target: 0.4--0.7s per ASHRAE. Verdict: PASS
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 25.3 | 40.3 | 49.3 | 55.4 | 53.5 | 52.9 |
| RT60 (s) | 1.27 | 0.80 | 0.65 | 0.58 | 0.60 | 0.61 |
| Target (s) | — | — | 0.70 | 0.70 | 0.70 | — |
| Verdict | — | — | PASS | PASS | PASS | — |
Compliance Verdict
Reference:
Open the AcousPlan calculator pre-loaded with the exact room dimensions (10m × 8m × 2.5m) and RT60 target (0.7s).
Open CalculatorField Story
A university teaching hospital in Melbourne is fitting out a new histopathology laboratory where pathologists examine tissue samples while dictating findings. The 10 m by 8 m space must balance hard, cleanable surfaces with acoustic comfort for concentrated work. Rockfon Sonar ceiling tiles — rated for cleanroom environments — cover 60% of the ceiling, with painted plaster above service corridors where access hatches are needed. The vinyl floor resists chemical spills while painted plaster walls can be decontaminated after incidents. Six fume hoods along one wall generate broadband mechanical noise; the ASHRAE NC 35-45 target ensures this remains below the threshold impairing speech dictation accuracy. Plasterboard partition walls separating adjacent labs provide low-frequency absorption through panel resonance, complementing the ceiling treatment.
Frequently Asked Questions
What RT60 does a Pathology Laboratory — ASHRAE NC 35-45 Compliance achieve?
With the specified materials and dimensions (10m x 8m x 2.5m, volume 200m3), the calculated mid-frequency RT60 is 0.61s using the Sabine equation. The target under ASHRAE is 0.4--0.7s. The result is a PASS.
What materials are used in this healthcare acoustic example?
This example uses Rockfon Sonar 25mm ceiling tile on the Ceiling — Rockfon Sonar (NRC 0.82), Painted plaster on the Ceiling — plaster (NRC 0.04), Vinyl/linoleum floor on the Floor (NRC 0.04), Painted plaster on the Walls — painted plaster (NRC 0.04), Plasterboard on studs on the Walls — plasterboard (NRC 0.07), Single glazing on the Fume hood glazing (NRC 0.16), Solid timber door on the Door (NRC 0.09), Double glazing 6mm on the Window (NRC 0.03). The total absorption at 500 Hz is 49.3 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.