Worked Example: Hotel Ballroom — ASHRAE Multi-Use Acoustic Design
1500 m³ ballroom with perforated metal ceiling zones, curtain walls, and heavy carpet
A 1500 m³ meeting room designed to ASHRAE requires RT60 ≤ 1.5s. With Perforated metal ceiling on the ceiling and Curtains (medium weight) on walls, the calculated RT60 is 0.87s — MARGINAL.
Room Setup
Total surface area: 1390.0 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| Ceiling — perforated metal | Perforated metal ceiling | 60.0 | 0.78 |
| Ceiling — plaster (ornamental) | Painted plaster | 540.0 | 0.04 |
| Floor | Heavy carpet | 600.0 | 0.29 |
| Walls — plasterboard | Plasterboard on studs | 130.0 | 0.07 |
| Walls — curtains | Curtains (medium weight) | 20.0 | 0.56 |
| Walls — fabric panels | Fabric-wrapped panel 50mm | 10.0 | 0.78 |
| Glazing | Double glazing 6mm | 20.0 | 0.03 |
| Doors (service) | Solid timber door | 10.0 | 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 = 30 × 20 × 2.5 = 1500 m³
- 2
Total Surface Area
Stotal = 60.0 + 540.0 + 600.0 + 130.0 + 20.0 + 10.0 + 20.0 + 10.0 = 1390.0 m²
- 3
Absorption per Surface at 500 Hz
Ceiling — perforated metal: 60.0 m² × 0.80 = 48.00 Sabins
Ceiling — plaster (ornamental): 540.0 m² × 0.04 = 21.60 Sabins
Floor: 600.0 m² × 0.14 = 84.00 Sabins
Walls — plasterboard: 130.0 m² × 0.05 = 6.50 Sabins
Walls — curtains: 20.0 m² × 0.49 = 9.80 Sabins
Walls — fabric panels: 10.0 m² × 0.78 = 7.80 Sabins
Glazing: 20.0 m² × 0.04 = 0.80 Sabins
Doors (service): 10.0 m² × 0.08 = 0.80 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 48.00 + 21.60 + 84.00 + 6.50 + 9.80 + 7.80 + 0.80 + 0.80 = 179.30 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 1500 / 179.30 = 1.35s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.87s. Target: 1--1.5s per ASHRAE. Verdict: MARGINAL
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 86.4 | 116.0 | 179.3 | 330.1 | 465.3 | 489.4 |
| RT60 (s) | 2.80 | 2.08 | 1.35 | 0.73 | 0.52 | 0.49 |
| Target (s) | — | — | 1.50 | 1.50 | 1.50 | — |
| Verdict | — | — | PASS | FAIL | FAIL | — |
Compliance Verdict
Reference:
Open the AcousPlan calculator pre-loaded with the exact room dimensions (30m × 20m × 2.5m) and RT60 target (1.5s).
Open CalculatorField Story
A 5-star hotel in Dubai is designing a 1500 m³ grand ballroom that must serve corporate conferences, gala dinners, and live music events. The perforated metal ceiling covers roughly a quarter of the ceiling area over the main stage and front-of-house zones, with the remaining three-quarters as ornamental painted plaster with coffered details. Heavy carpet on the 600 m² floor provides substantial mid and high frequency absorption. Motorised curtain tracks on two walls allow 30 m² of medium-weight drapes to be deployed for speech events and retracted for music, providing variable RT60. Fabric panels behind the portable stage offer permanent broadband absorption. ASHRAE recommends RT60 below 1.5 s for large multi-purpose ballrooms; this design achieves the flexibility the hotel operator demands.
Frequently Asked Questions
What RT60 does a Hotel Ballroom — ASHRAE Multi-Use Acoustic Design achieve?
With the specified materials and dimensions (30m x 20m x 2.5m, volume 1500m3), the calculated mid-frequency RT60 is 0.87s using the Sabine equation. The target under ASHRAE is 1--1.5s. The result is a MARGINAL.
What materials are used in this hospitality acoustic example?
This example uses Perforated metal ceiling on the Ceiling — perforated metal (NRC 0.78), Painted plaster on the Ceiling — plaster (ornamental) (NRC 0.04), Heavy carpet on the Floor (NRC 0.29), Plasterboard on studs on the Walls — plasterboard (NRC 0.07), Curtains (medium weight) on the Walls — curtains (NRC 0.56), Fabric-wrapped panel 50mm on the Walls — fabric panels (NRC 0.78), Double glazing 6mm on the Glazing (NRC 0.03), Solid timber door on the Doors (service) (NRC 0.09). The total absorption at 500 Hz is 179.3 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.