Worked Example: Private Office — ASHRAE Acoustic Guidelines
RT60 calculation for a single-occupant private office under ASHRAE guidelines. The small volume achieves excellent results with standard Armstrong ceiling tiles and carpet, demonstrating that private offices are straightforward to treat.
A 37.8 m³ meeting room designed to ASHRAE requires RT60 ≤ 0.6s. With Armstrong Ultima+ on the ceiling and Fabric-wrapped panel 50mm on walls, the calculated RT60 is 0.24s — PASS.
Room Setup
Total surface area: 69.3 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| ceiling | Armstrong Ultima+ | 14.0 | 0.80 |
| walls-main | Plasterboard on studs | 28.5 | 0.07 |
| walls-treatment | Fabric-wrapped panel 50mm | 8.0 | 0.80 |
| floor | Carpet (heavy) | 14.0 | 0.30 |
| windows | Double glazing 6mm | 3.0 | 0.04 |
| door | Solid timber door | 1.8 | 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 = 4 × 3.5 × 2.7 = 37.8 m³
- 2
Total Surface Area
Stotal = 14.0 + 28.5 + 8.0 + 14.0 + 3.0 + 1.8 = 69.3 m²
- 3
Absorption per Surface at 500 Hz
ceiling: 14.0 m² × 0.85 = 11.90 Sabins
walls-main: 28.5 m² × 0.05 = 1.43 Sabins
walls-treatment: 8.0 m² × 0.78 = 6.24 Sabins
floor: 14.0 m² × 0.14 = 1.96 Sabins
windows: 3.0 m² × 0.04 = 0.12 Sabins
door: 1.8 m² × 0.08 = 0.14 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 11.90 + 1.43 + 6.24 + 1.96 + 0.12 + 0.14 = 21.79 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 37.8 / 21.79 = 0.28s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.24s. Target: ≤ 0.6s per ASHRAE. Verdict: PASS
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 13.9 | 17.2 | 21.8 | 25.9 | 29.7 | 29.9 |
| RT60 (s) | 0.44 | 0.35 | 0.28 | 0.23 | 0.20 | 0.20 |
| Target (s) | — | — | 0.60 | 0.60 | 0.60 | — |
| Verdict | — | — | PASS | PASS | PASS | — |
Compliance Verdict
Reference: ASHRAE Handbook HVAC Applications, Ch. 48
ASHRAE guidelines recommend RT60 ≤ 0.6s for private offices. Small volumes make compliance straightforward with standard ceiling tiles and carpet. Focus shifts to sound insulation of partitions for speech privacy.
STI result: 0.82 (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 (4m × 3.5m × 2.7m) and RT60 target (0.6s).
Open CalculatorField Story
A corporate real estate team is fitting out a new floor of private offices for senior managers. The standard specification calls for hard ceiling tiles and luxury vinyl plank flooring for a modern aesthetic. During the first week of occupancy, managers complain that phone conversations echo and video calls sound unprofessional. The facilities team replaces the standard ceiling tiles with Armstrong Ultima+ acoustic tiles and installs carpet tiles — a simple retrofit that reduces the RT60 from 0.9 seconds to well below the ASHRAE guideline. The lesson: acoustic specification should be part of the initial fit-out, not a reactive fix.
Frequently Asked Questions
What RT60 does a Private Office — ASHRAE Acoustic Guidelines achieve?
With the specified materials and dimensions (4m x 3.5m x 2.7m, volume 37.8m3), the calculated mid-frequency RT60 is 0.24s using the Sabine equation. The target under ASHRAE is 0.6s or less. The result is a PASS.
What materials are used in this office acoustic example?
This example uses Armstrong Ultima+ on the ceiling (NRC 0.8), Plasterboard on studs on the walls-main (NRC 0.07), Fabric-wrapped panel 50mm on the walls-treatment (NRC 0.8), Carpet (heavy) on the floor (NRC 0.3), 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 21.8 Sabins.
How much does acoustic treatment cost for this room?
The estimated treatment cost is $1,512 for 36 m2 of absorptive material at approximately $42/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.