Worked Example: Penthouse Living Space — BS 8233 Luxury Residential
200 m³ penthouse with marble floor, floor-to-ceiling glazing, and motorised curtains
A 200 m³ residential living designed to BS-8233 requires RT60 ≤ 0.6s. With Painted plaster on the ceiling, the calculated RT60 is 0.61s — MARGINAL.
Room Setup
Total surface area: 281.2 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| Ceiling | Painted plaster | 100.0 | 0.04 |
| Floor — marble | Terrazzo/marble floor | 30.0 | 0.01 |
| Floor — carpet (living zone) | Heavy carpet | 70.0 | 0.29 |
| Walls — plasterboard | Plasterboard on studs | 14.0 | 0.07 |
| Walls — glazing | Double glazing 6mm | 18.0 | 0.03 |
| Curtains (motorised) | Curtains (medium weight) | 28.0 | 0.56 |
| Sofa + armchairs | Upholstered seating | 12.0 | 0.55 |
| Walls — painted plaster | Painted plaster | 6.0 | 0.04 |
| Doors | Solid timber door | 3.2 | 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 = 10 × 10 × 2 = 200 m³
- 2
Total Surface Area
Stotal = 100.0 + 30.0 + 70.0 + 14.0 + 18.0 + 28.0 + 12.0 + 6.0 + 3.2 = 281.2 m²
- 3
Absorption per Surface at 500 Hz
Ceiling: 100.0 m² × 0.04 = 4.00 Sabins
Floor — marble: 30.0 m² × 0.01 = 0.30 Sabins
Floor — carpet (living zone): 70.0 m² × 0.14 = 9.80 Sabins
Walls — plasterboard: 14.0 m² × 0.05 = 0.70 Sabins
Walls — glazing: 18.0 m² × 0.04 = 0.72 Sabins
Curtains (motorised): 28.0 m² × 0.49 = 13.72 Sabins
Sofa + armchairs: 12.0 m² × 0.56 = 6.72 Sabins
Walls — painted plaster: 6.0 m² × 0.04 = 0.24 Sabins
Doors: 3.2 m² × 0.08 = 0.26 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 4.00 + 0.30 + 9.80 + 0.70 + 0.72 + 13.72 + 6.72 + 0.24 + 0.26 = 36.46 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 200 / 36.46 = 0.88s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.61s. Target: 0.4--0.6s per BS-8233. Verdict: MARGINAL
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 14.2 | 22.4 | 36.5 | 61.9 | 76.4 | 77.2 |
| RT60 (s) | 2.27 | 1.44 | 0.88 | 0.52 | 0.42 | 0.42 |
| Target (s) | — | — | 0.60 | 0.60 | 0.60 | — |
| Verdict | — | — | FAIL | PASS | PASS | — |
Compliance Verdict
Reference:
Open the AcousPlan calculator pre-loaded with the exact room dimensions (10m × 10m × 2m) and RT60 target (0.6s).
Open CalculatorField Story
A penthouse on the 40th floor of a Canary Wharf tower features floor-to-ceiling glazing and polished marble floors defining luxury city living — and creating an acoustic nightmare. The 10 m by 10 m open living space produces flutter echo between the glass wall and opposite plasterboard wall making television dialogue unintelligible. The interior designer specified motorised silk curtains across the full glazing width; when deployed, these transform the acoustic character. Deep wool carpet in the conversation zone — covering 60% of the floor — and oversized upholstered furniture provide the remaining absorption. The marble dining area contributes almost zero absorption but is non-negotiable. BS 8233 targets 0.6 s or below; the calculation reveals the critical acoustic impact of curtain deployment.
Frequently Asked Questions
What RT60 does a Penthouse Living Space — BS 8233 Luxury Residential achieve?
With the specified materials and dimensions (10m x 10m x 2m, volume 200m3), the calculated mid-frequency RT60 is 0.61s using the Sabine equation. The target under BS-8233 is 0.4--0.6s. The result is a MARGINAL.
What materials are used in this residential acoustic example?
This example uses Painted plaster on the Ceiling (NRC 0.04), Terrazzo/marble floor on the Floor — marble (NRC 0.01), Heavy carpet on the Floor — carpet (living zone) (NRC 0.29), Plasterboard on studs on the Walls — plasterboard (NRC 0.07), Double glazing 6mm on the Walls — glazing (NRC 0.03), Curtains (medium weight) on the Curtains (motorised) (NRC 0.56), Upholstered seating on the Sofa + armchairs (NRC 0.55), Painted plaster on the Walls — painted plaster (NRC 0.04), Solid timber door on the Doors (NRC 0.09). The total absorption at 500 Hz is 36.5 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.