Worked Example: Hot-Desking Floor — WELL F74 Open Plan Design
RT60 calculation for a large flexible hot-desking workspace pursuing WELL Building Standard certification. Maximum ceiling and floor absorption plus wall treatment create an environment where diverse work styles can coexist.
A 950.4 m³ open plan office designed to WELL-F74 requires RT60 ≤ 0.5s. With Ecophon Focus E on the ceiling and Fabric-wrapped panel 50mm on walls, the calculated RT60 is 0.3s — PASS.
Room Setup
Total surface area: 964.4 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| ceiling | Ecophon Focus E | 352.0 | 0.90 |
| walls-main | Plasterboard on studs | 147.6 | 0.07 |
| walls-treatment | Fabric-wrapped panel 50mm | 57.6 | 0.80 |
| floor | Carpet (heavy) | 352.0 | 0.30 |
| windows | Double glazing 6mm | 48.0 | 0.04 |
| door | Solid timber door | 7.2 | 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 = 22 × 16 × 2.7 = 950.4 m³
- 2
Total Surface Area
Stotal = 352.0 + 147.6 + 57.6 + 352.0 + 48.0 + 7.2 = 964.4 m²
- 3
Absorption per Surface at 500 Hz
ceiling: 352.0 m² × 0.90 = 316.80 Sabins
walls-main: 147.6 m² × 0.05 = 7.38 Sabins
walls-treatment: 57.6 m² × 0.78 = 44.93 Sabins
floor: 352.0 m² × 0.14 = 49.28 Sabins
windows: 48.0 m² × 0.04 = 1.92 Sabins
door: 7.2 m² × 0.08 = 0.58 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 316.80 + 7.38 + 44.93 + 49.28 + 1.92 + 0.58 = 420.88 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 950.4 / 420.88 = 0.36s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.3s. Target: ≤ 0.5s per WELL-F74. Verdict: PASS
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 189.9 | 320.0 | 420.9 | 521.5 | 591.7 | 591.8 |
| RT60 (s) | 0.81 | 0.48 | 0.36 | 0.29 | 0.26 | 0.26 |
| Target (s) | — | — | 0.50 | 0.50 | 0.50 | — |
| Verdict | — | — | PASS | PASS | PASS | — |
Compliance Verdict
Reference: WELL v2 Feature 74, L07
WELL v2 Feature 74 requires open plan offices to demonstrate sound mapping with RT60 ≤ 0.5s and appropriate background sound levels. This large floor plate achieves compliance through consistent high-performance treatment.
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 (22m × 16m × 2.7m) and RT60 target (0.5s).
Open CalculatorField Story
A global consulting firm is fitting out four floors of a new London tower for agile working — no assigned desks, with staff choosing between quiet focus zones, collaboration areas, and phone booths. The WELL Building Standard certification is a corporate requirement for all new offices. Feature 74 demands stringent acoustic performance across the entire open plan floor. The acoustic consultant's challenge is ensuring consistent RT60 across 352 m² despite varying furniture density zones. The solution: uniform premium ceiling treatment and carpet throughout, with additional wall panels at perimeter zones where window reflections increase reverberation.
Frequently Asked Questions
What RT60 does a Hot-Desking Floor — WELL F74 Open Plan Design achieve?
With the specified materials and dimensions (22m x 16m x 2.7m, volume 950.4m3), the calculated mid-frequency RT60 is 0.3s using the Sabine equation. The target under WELL-F74 is 0.5s or less. The result is a PASS.
What materials are used in this office acoustic example?
This example uses Ecophon Focus E on the ceiling (NRC 0.9), 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 420.9 Sabins.
How much does acoustic treatment cost for this room?
The estimated treatment cost is $45,696 for 762 m2 of absorptive material at approximately $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.