Worked Example: Startup Office — Exposed Concrete Acoustic Failure
RT60 calculation for a startup office in a converted loft with exposed concrete ceiling, brick walls, and timber floors. This trendy industrial aesthetic produces disastrous acoustics, with RT60 far exceeding the 0.6s target.
A 532 m³ open plan office designed to BS-8233 requires RT60 ≤ 0.6s. With Exposed concrete on the ceiling and Fabric-wrapped panel 50mm on walls, the calculated RT60 is 2.73s — FAIL.
Room Setup
Total surface area: 451.2 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| ceiling | Exposed concrete | 140.0 | 0.02 |
| walls-main | Brick (unglazed) | 121.6 | 0.04 |
| walls-treatment | Fabric-wrapped panel 50mm | 10.0 | 0.80 |
| floor | Timber floor (sealed) | 140.0 | 0.08 |
| windows | Single glazing | 36.0 | 0.15 |
| door | Solid timber door | 3.6 | 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 = 14 × 10 × 3.8 = 532 m³
- 2
Total Surface Area
Stotal = 140.0 + 121.6 + 10.0 + 140.0 + 36.0 + 3.6 = 451.2 m²
- 3
Absorption per Surface at 500 Hz
ceiling: 140.0 m² × 0.02 = 2.80 Sabins
walls-main: 121.6 m² × 0.03 = 3.65 Sabins
walls-treatment: 10.0 m² × 0.78 = 7.80 Sabins
floor: 140.0 m² × 0.10 = 14.00 Sabins
windows: 36.0 m² × 0.18 = 6.48 Sabins
door: 3.6 m² × 0.08 = 0.29 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 2.80 + 3.65 + 7.80 + 14.00 + 6.48 + 0.29 = 35.02 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 532 / 35.02 = 2.45s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 2.73s. Target: ≤ 0.6s per BS-8233. Verdict: FAIL
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 40.6 | 35.8 | 35.0 | 30.6 | 29.1 | 35.5 |
| RT60 (s) | 2.11 | 2.39 | 2.45 | 2.80 | 2.94 | 2.41 |
| Target (s) | — | — | 0.60 | 0.60 | 0.60 | — |
| Verdict | — | — | FAIL | FAIL | FAIL | — |
Compliance Verdict
Reference: BS 8233:2014 Table 4
The industrial aesthetic of exposed concrete, brick, and timber creates an extremely reverberant space. Without substantial acoustic intervention, this office is unsuitable for knowledge work or phone calls.
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 (14m × 10m × 3.8m) and RT60 target (0.6s).
Open CalculatorField Story
A venture-backed startup signs a lease for a trendy converted warehouse space in Shoreditch, drawn by the exposed concrete ceiling, original brick walls, and reclaimed timber floors featured in the estate agent's photos. Within the first week, the CTO declares the space unusable — every conversation carries across the entire floor plate, conference calls echo, and developers cannot concentrate. A handheld RT60 measurement reveals over 2.5 seconds at mid-frequencies. The startup's limited budget allows only token absorption: a few fabric panels on one wall. This example demonstrates the massive acoustic cost of the industrial aesthetic trend.
Frequently Asked Questions
What RT60 does a Startup Office — Exposed Concrete Acoustic Failure achieve?
With the specified materials and dimensions (14m x 10m x 3.8m, volume 532m3), the calculated mid-frequency RT60 is 2.73s 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 Exposed concrete on the ceiling (NRC 0.02), Brick (unglazed) on the walls-main (NRC 0.04), Fabric-wrapped panel 50mm on the walls-treatment (NRC 0.8), Timber floor (sealed) on the floor (NRC 0.08), Single glazing on the windows (NRC 0.15), Solid timber door on the door (NRC 0.08). The total absorption at 500 Hz is 35.0 Sabins.
How much does acoustic treatment cost for this room?
The estimated treatment cost is £400 for 10 m2 of absorptive material at approximately £40/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.