Worked Example: Australian Classroom — NCC/AS 2107 Compliance
Sabine RT60 calculation for an Australian primary classroom meeting NCC 2022 and AS 2107 requirements. Demonstrates how carpet flooring and Armstrong ceiling tiles achieve the 0.5s target in a warm climate school.
A 189 m³ classroom designed to NCC-AS2107 requires RT60 ≤ 0.5s. With Armstrong Ultima+ on the ceiling and Fabric-wrapped panel 50mm on walls, the calculated RT60 is 0.29s — PASS.
Room Setup
Total surface area: 245.2 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| ceiling | Armstrong Ultima+ | 70.0 | 0.80 |
| walls-main | Painted plaster | 69.6 | 0.04 |
| walls-treatment | Fabric-wrapped panel 50mm | 20.0 | 0.80 |
| floor | Carpet (heavy) | 70.0 | 0.30 |
| windows | Single glazing | 12.0 | 0.15 |
| 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 = 10 × 7 × 2.7 = 189 m³
- 2
Total Surface Area
Stotal = 70.0 + 69.6 + 20.0 + 70.0 + 12.0 + 3.6 = 245.2 m²
- 3
Absorption per Surface at 500 Hz
ceiling: 70.0 m² × 0.85 = 59.50 Sabins
walls-main: 69.6 m² × 0.04 = 2.78 Sabins
walls-treatment: 20.0 m² × 0.78 = 15.60 Sabins
floor: 70.0 m² × 0.14 = 9.80 Sabins
windows: 12.0 m² × 0.18 = 2.16 Sabins
door: 3.6 m² × 0.08 = 0.29 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 59.50 + 2.78 + 15.60 + 9.80 + 2.16 + 0.29 = 90.13 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 189 / 90.13 = 0.34s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.29s. Target: ≤ 0.5s per NCC-AS2107. Verdict: PASS
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 27.3 | 63.0 | 90.1 | 111.1 | 124.1 | 122.8 |
| RT60 (s) | 1.11 | 0.48 | 0.34 | 0.27 | 0.25 | 0.25 |
| Target (s) | — | — | 0.50 | 0.50 | 0.50 | — |
| Verdict | — | — | PASS | PASS | PASS | — |
Compliance Verdict
Reference: AS 2107:2016 Table 1
AS 2107 recommends RT60 ≤ 0.5s for primary school classrooms. The NCC 2022 references this standard for acoustic performance requirements in educational buildings.
STI result: 0.73 (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 (10m × 7m × 2.7m) and RT60 target (0.5s).
Open CalculatorField Story
A new primary school in suburban Sydney features large windows to maximise natural light — a sustainability goal that creates an acoustic challenge. The architect's original design with polished concrete floors and a flat plaster ceiling produces predicted RT60 values of 1.9 seconds. Parents at an existing school in the district have complained about poor acoustics affecting their children's learning. The education department mandates AS 2107 compliance for the new build, requiring the design team to integrate acoustic ceiling tiles and heavy carpet without compromising the light-filled aesthetic.
Frequently Asked Questions
What RT60 does a Australian Classroom — NCC/AS 2107 Compliance achieve?
With the specified materials and dimensions (10m x 7m x 2.7m, volume 189m3), the calculated mid-frequency RT60 is 0.29s using the Sabine equation. The target under NCC-AS2107 is 0.5s or less. The result is a PASS.
What materials are used in this education acoustic example?
This example uses Armstrong Ultima+ on the ceiling (NRC 0.8), Painted plaster on the walls-main (NRC 0.04), Fabric-wrapped panel 50mm on the walls-treatment (NRC 0.8), Carpet (heavy) on the floor (NRC 0.3), Single glazing on the windows (NRC 0.15), Solid timber door on the door (NRC 0.08). The total absorption at 500 Hz is 90.1 Sabins.
How much does acoustic treatment cost for this room?
The estimated treatment cost is A$9,600 for 160 m2 of absorptive material at approximately A$60/m2. Actual costs vary by region, supplier, and installation complexity.
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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.