Worked Example: Spa Treatment Room — WELL Feature 74 Compliance
30 m³ treatment room with Ecophon ceiling, fabric walls, and divider curtain
A 30 m³ hospital ward designed to WELL-F74 requires RT60 ≤ 0.5s. With Ecophon Focus E ceiling tile on the ceiling and Fabric-wrapped panel 50mm on walls, the calculated RT60 is 0.26s — MARGINAL.
Room Setup
Total surface area: 60.0 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| Ceiling — Ecophon | Ecophon Focus E ceiling tile | 8.0 | 0.86 |
| Ceiling — plaster | Painted plaster | 7.0 | 0.04 |
| Floor | Vinyl/linoleum floor | 15.0 | 0.04 |
| Walls — plaster | Painted plaster | 14.0 | 0.04 |
| Walls — fabric panels | Fabric-wrapped panel 50mm | 8.0 | 0.78 |
| Curtain (divider) | Curtains (medium weight) | 4.0 | 0.56 |
| Window | Double glazing 6mm | 2.4 | 0.03 |
| Door | Solid timber door | 1.6 | 0.09 |
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 + 14.0 + 8.0 + 4.0 + 2.4 + 1.6 = 60.0 m²
- 3
Absorption per Surface at 500 Hz
Ceiling — Ecophon: 8.0 m² × 0.90 = 7.20 Sabins
Ceiling — plaster: 7.0 m² × 0.04 = 0.28 Sabins
Floor: 15.0 m² × 0.03 = 0.45 Sabins
Walls — plaster: 14.0 m² × 0.04 = 0.56 Sabins
Walls — fabric panels: 8.0 m² × 0.78 = 6.24 Sabins
Curtain (divider): 4.0 m² × 0.49 = 1.96 Sabins
Window: 2.4 m² × 0.04 = 0.10 Sabins
Door: 1.6 m² × 0.08 = 0.13 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 7.20 + 0.28 + 0.45 + 0.56 + 6.24 + 1.96 + 0.10 + 0.13 = 16.92 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 30 / 16.92 = 0.29s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.26s. Target: 0.3--0.5s per WELL-F74. Verdict: MARGINAL
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 5.4 | 12.8 | 16.9 | 19.3 | 19.0 | 18.0 |
| RT60 (s) | 0.90 | 0.38 | 0.29 | 0.25 | 0.25 | 0.27 |
| Target (s) | — | — | 0.50 | 0.50 | 0.50 | — |
| Verdict | — | — | MARGINAL | FAIL | FAIL | — |
Compliance Verdict
Reference:
Open the AcousPlan calculator pre-loaded with the exact room dimensions (5m × 3m × 2m) and RT60 target (0.5s).
Open CalculatorField Story
A wellness resort on the Algarve coast is pursuing WELL Building Standard certification for its new spa wing. Each 5 m by 3 m treatment room must achieve Feature 74 Sound requirements: background noise below 30 dBA and reverberation time under 0.5 seconds. The Ecophon Focus E ceiling covers just over half the ceiling area providing Class A absorption, while maintaining the clean aesthetic essential in spa environments. Fabric-wrapped panels cover 8 m² of wall surface behind the treatment bed, absorbing reflections at the client ear position. A heavyweight curtain provides room division for dual treatments, adding variable mid-frequency absorption. The quiet vinyl floor avoids footstep sounds that would break the meditative atmosphere. Soft ambient music through ceiling speakers remains intimate rather than reverberant.
Frequently Asked Questions
What RT60 does a Spa Treatment Room — WELL Feature 74 Compliance achieve?
With the specified materials and dimensions (5m x 3m x 2m, volume 30m3), the calculated mid-frequency RT60 is 0.26s using the Sabine equation. The target under WELL-F74 is 0.3--0.5s. The result is a MARGINAL.
What materials are used in this hospitality acoustic example?
This example uses Ecophon Focus E ceiling tile on the Ceiling — Ecophon (NRC 0.86), 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 Walls — fabric panels (NRC 0.78), Curtains (medium weight) on the Curtain (divider) (NRC 0.56), Double glazing 6mm on the Window (NRC 0.03), Solid timber door on the Door (NRC 0.09). The total absorption at 500 Hz is 16.9 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.