Worked Example: Architect Studio — Baffles in Exposed Concrete
RT60 calculation for an architecture practice's own studio with exposed concrete walls and hanging baffles. A case study in practising what you preach — or nearly so — with the design community's favourite materials put to the acoustic test.
A 600 m³ open plan office designed to BS-8233 requires RT60 ≤ 0.6s. With Acoustic baffle (hanging) on the ceiling and Curtains (medium weight) on walls, the calculated RT60 is 0.68s — FAIL.
Room Setup
Total surface area: 447.2 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| ceiling | Acoustic baffle (hanging) | 60.0 | 0.90 |
| walls-main | Exposed concrete | 140.0 | 0.02 |
| walls-treatment | Curtains (medium weight) | 50.0 | 0.55 |
| floor | Carpet (heavy) | 150.0 | 0.30 |
| windows | Double glazing 6mm | 40.0 | 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 = 15 × 10 × 4 = 600 m³
- 2
Total Surface Area
Stotal = 60.0 + 140.0 + 50.0 + 150.0 + 40.0 + 7.2 = 447.2 m²
- 3
Absorption per Surface at 500 Hz
ceiling: 60.0 m² × 0.95 = 57.00 Sabins
walls-main: 140.0 m² × 0.02 = 2.80 Sabins
walls-treatment: 50.0 m² × 0.49 = 24.50 Sabins
floor: 150.0 m² × 0.14 = 21.00 Sabins
windows: 40.0 m² × 0.04 = 1.60 Sabins
door: 7.2 m² × 0.08 = 0.58 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 57.00 + 2.80 + 24.50 + 21.00 + 1.60 + 0.58 = 107.48 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 600 / 107.48 = 0.90s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.68s. Target: ≤ 0.6s per BS-8233. Verdict: FAIL
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 32.9 | 76.6 | 107.5 | 157.6 | 186.2 | 189.9 |
| RT60 (s) | 2.94 | 1.26 | 0.90 | 0.61 | 0.52 | 0.51 |
| Target (s) | — | — | 0.60 | 0.60 | 0.60 | — |
| Verdict | — | — | FAIL | MARGINAL | PASS | — |
Compliance Verdict
Reference: BS 8233:2014 Table 4
Exposed concrete studios are challenging to treat. Hanging baffles at 40% ceiling coverage with floor carpet and heavy curtains can approach compliance, but the concrete walls remain problematic at low frequencies.
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 (15m × 10m × 4m) and RT60 target (0.6s).
Open CalculatorField Story
An award-winning architecture practice moves into a raw concrete shell space, designing their own studio as a showcase project. The partners insist on exposed fair-faced concrete on all walls and ceiling — their signature aesthetic. The office manager reports that after six months, staff are wearing noise-cancelling headphones all day. The practice's acoustic consultant explains that the concrete must be addressed. The compromise: felt baffles in the firm's brand colours suspended from the ceiling, full-height curtains that can be drawn across the concrete walls for presentations, and heavy carpet throughout. The result is visually striking but acoustically marginal.
Frequently Asked Questions
What RT60 does a Architect Studio — Baffles in Exposed Concrete achieve?
With the specified materials and dimensions (15m x 10m x 4m, volume 600m3), the calculated mid-frequency RT60 is 0.68s using the Sabine equation. The target under BS-8233 is 0.6s or less. The result is a FAIL.
What materials are used in this office acoustic example?
This example uses Acoustic baffle (hanging) on the ceiling (NRC 0.9), Exposed concrete on the walls-main (NRC 0.02), Curtains (medium weight) on the walls-treatment (NRC 0.55), 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 107.5 Sabins.
How much does acoustic treatment cost for this room?
The estimated treatment cost is £22,880 for 260 m2 of absorptive material at approximately £88/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.