🏢NRA 2000 · France

Open Plan Office Acoustic Design to NRA 2000

Open plan offices present a unique acoustic paradox: speech must be intelligible within conversation groups but unintelligible beyond the distraction distance to preserve privacy and concentration. ISO 3382-3:2012 defines the key metrics — spatial decay rate D2,S, distraction distance rD, and A-weighted SPL of speech at 4 m (Lp,A,S,4m).

TL;DR

Under NRA 2000, a open plan office of 400-600 m³ (typical dimensions 20m × 10m × 2.8m) requires an RT60 of ≤ 0.8s at 500-2000 Hz. Background noise must not exceed 40 dBA. The French NRA and Code du travail set acoustic requirements for workplaces.

RT60 Target

≤ 0.8s

Noise Limit

40 dBA

STI Minimum

N/A

Frequency Range

500-2000 Hz

Specific Requirements

Parameter	Target	Clause Reference	Notes
Reverberation Time (RT60)	≤ 0.6s	Arrêté du 25 avril 2003	500-2000 Hz, Per NF S31-080:2006
Background Noise Limit	≤ 42 dBA (NF S31-080)	—	HVAC + building services, unoccupied
Frequency Range	500-2000 Hz	—	Octave bands for compliance assessment

Step-by-Step Compliance Calculation

1
Identify NRA requirements
Confirm workplace acoustic obligations under Code du travail and NRA for the office space type.
2
Design treatment strategy
Specify ceiling treatment and desk screening to achieve RT60 and background noise targets.
3
Assess external noise
Model facade sound insulation to verify internal noise criteria are met with windows closed.
4
Document compliance
Prepare acoustic assessment as part of the workplace environmental quality documentation.

Recommended Materials

Surface	Material Category	Min NRC	Coverage %
Ceiling	Acoustic plaster or ceiling tile	0.85	85%
Partitions	Absorptive screen	0.80	100%

Browse the full acoustic materials database for absorption coefficients and product specifications.

Common Failure Modes

⚠️Parisian heritage building acoustics

Haussmann-era buildings converted to offices have high ceilings and plaster surfaces that resist acoustic treatment.

⚠️Street noise ingress

Paris offices on busy boulevards struggle with external noise even with double-glazed windows.

Frequently Asked Questions

What RT60 does NRA 2000 require for a open plan office?

NRA 2000 requires a reverberation time of ≤0.8s at 500-2000 Hz for open plan office spaces. The French NRA and Code du travail set acoustic requirements for workplaces. Open-plan offices must achieve background noise levels of 35-40 dBA with RT60 guidance of 0.8s or less. The French labour code specifically addresses workplace noise exposure limits and acoustic comfort requirements.

What is the maximum background noise level for a open plan office under NRA 2000?

NRA 2000 sets a maximum background noise level of 40 dBA for open plan office spaces. This includes noise from HVAC systems, building services, and external intrusion, measured with the room unoccupied. Exceeding this limit degrades speech intelligibility and occupant comfort.

How much acoustic treatment does a open plan office need to comply with NRA 2000?

A typical open plan office (400-600 m³) requires Acoustic plaster or ceiling tile (NRC ≥0.85) covering 85% of the ceiling as the primary treatment. Additional wall absorption on 1 surface(s) is typically needed. Use the AcousPlan calculator with the pre-loaded dimensions (18m × 14m × 2.8m) to calculate the exact absorption deficit for your room.

Calculate NRA 2000 Compliance for Your Open Plan Office

Pre-loaded with typical open plan office dimensions (18m × 14m × 2.8m) and an RT60 target of 0.8s per NRA 2000. Enter your actual dimensions, select materials, and verify compliance instantly.

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