Worked Example: Hospital Patient Bedroom — NBR 15575 Compliance
30 m³ single patient room with partial acoustic ceiling and vinyl flooring
A 30 m³ hospital ward designed to NBR-15575 requires RT60 ≤ 0.6s. With Armstrong Ultima+ ceiling tile on the ceiling and Fabric-wrapped panel 50mm on walls, the calculated RT60 is 0.35s — MARGINAL.
Room Setup
Total surface area: 62.6 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| Ceiling — acoustic tile | Armstrong Ultima+ ceiling tile | 8.0 | 0.80 |
| Ceiling — plaster | Painted plaster | 7.0 | 0.04 |
| Floor | Vinyl/linoleum floor | 15.0 | 0.04 |
| Walls — plaster | Painted plaster | 22.0 | 0.04 |
| Wall — fabric headwall | Fabric-wrapped panel 50mm | 4.0 | 0.78 |
| Window | Double glazing 6mm | 3.0 | 0.03 |
| Door | Solid timber door | 1.6 | 0.09 |
| Curtain (bed divider) | Curtains (medium weight) | 2.0 | 0.56 |
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 = 5 × 3 × 2 = 30 m³
- 2
Total Surface Area
Stotal = 8.0 + 7.0 + 15.0 + 22.0 + 4.0 + 3.0 + 1.6 + 2.0 = 62.6 m²
- 3
Absorption per Surface at 500 Hz
Ceiling — acoustic tile: 8.0 m² × 0.85 = 6.80 Sabins
Ceiling — plaster: 7.0 m² × 0.04 = 0.28 Sabins
Floor: 15.0 m² × 0.03 = 0.45 Sabins
Walls — plaster: 22.0 m² × 0.04 = 0.88 Sabins
Wall — fabric headwall: 4.0 m² × 0.78 = 3.12 Sabins
Window: 3.0 m² × 0.04 = 0.12 Sabins
Door: 1.6 m² × 0.08 = 0.13 Sabins
Curtain (bed divider): 2.0 m² × 0.49 = 0.98 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 6.80 + 0.28 + 0.45 + 0.88 + 3.12 + 0.12 + 0.13 + 0.98 = 12.76 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 30 / 12.76 = 0.38s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.35s. Target: 0.4--0.6s per NBR-15575. Verdict: MARGINAL
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 4.0 | 9.2 | 12.8 | 14.4 | 14.0 | 13.4 |
| RT60 (s) | 1.21 | 0.53 | 0.38 | 0.34 | 0.34 | 0.36 |
| Target (s) | — | — | 0.60 | 0.60 | 0.60 | — |
| Verdict | — | — | MARGINAL | MARGINAL | MARGINAL | — |
Compliance Verdict
Reference:
Open the AcousPlan calculator pre-loaded with the exact room dimensions (5m × 3m × 2m) and RT60 target (0.6s).
Open CalculatorField Story
A 120-bed public hospital in Belo Horizonte is undergoing refurbishment to meet NBR 15575 acoustic performance requirements introduced in 2013. The single patient bedrooms measure 5 m by 3 m with 2 m ceilings, typical of Brazilian healthcare construction. Armstrong Ultima+ tiles cover just over half the ceiling — the remainder left as painted plaster above the ensuite zone for moisture resistance. A 4 m² fabric-wrapped headwall panel behind the bed absorbs speech-frequency reflections that disturb resting patients. A lightweight curtain track enables bed-bay division in shared configurations. The vinyl floor meets infection control protocols while the double-glazed window reduces external traffic noise. This Sabine calculation confirms the room achieves the NBR 15575 "Superior" performance tier for reverberation control in healthcare sleeping areas.
Frequently Asked Questions
What RT60 does a Hospital Patient Bedroom — NBR 15575 Compliance achieve?
With the specified materials and dimensions (5m x 3m x 2m, volume 30m3), the calculated mid-frequency RT60 is 0.35s using the Sabine equation. The target under NBR-15575 is 0.4--0.6s. The result is a MARGINAL.
What materials are used in this healthcare acoustic example?
This example uses Armstrong Ultima+ ceiling tile on the Ceiling — acoustic tile (NRC 0.8), Painted plaster on the Ceiling — plaster (NRC 0.04), Vinyl/linoleum floor on the Floor (NRC 0.04), Painted plaster on the Walls — plaster (NRC 0.04), Fabric-wrapped panel 50mm on the Wall — fabric headwall (NRC 0.78), Double glazing 6mm on the Window (NRC 0.03), Solid timber door on the Door (NRC 0.09), Curtains (medium weight) on the Curtain (bed divider) (NRC 0.56). The total absorption at 500 Hz is 12.8 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.