🏫NRA 2000 · France

Classroom Acoustic Design to NRA 2000

Classrooms are the most acoustically critical room type in education buildings, where speech intelligibility directly determines learning outcomes. A well-designed classroom achieves an unoccupied RT60 of 0.

TL;DR

Under NRA 2000, a classroom of 150-300 m³ (typical dimensions 10m × 7m × 3m) requires an RT60 of ≤ 0.6s at 500-2000 Hz. Background noise must not exceed 35 dBA. The French NRA (Nouvelle Reglementation Acoustique) under Arrete du 25 avril 2003 sets RT60 targets for educational buildings classified as ERP (Etablissements Recevant du Public).

RT60 Target

≤ 0.6s

Noise Limit

35 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, Furnished, unoccupied, per Arrêté du 25 avril 2003
Background Noise Limit	≤ 38 dBA	—	HVAC + building services, unoccupied
Frequency Range	500-2000 Hz	—	Octave bands for compliance assessment

Step-by-Step Compliance Calculation

1
Classify building per NRA
Confirm the school is classified as ERP and identify the applicable acoustic requirements under Arrete du 25 avril 2003.
2
Set RT60 and noise targets
Classrooms: RT60 <= 0.6s, background noise <= 35 dBA per NRA Table 2.
3
Design acoustic treatment
Calculate required absorption area and specify ceiling and wall treatments to meet the RT60 target.
4
Verify with acoustic study
Prepare an etude acoustique as required by French building regulations for ERP buildings.

Recommended Materials

Surface	Material Category	Min NRC	Coverage %
Ceiling	Mineral wool ceiling tile	0.85	80%
Rear wall	Acoustic absorber	0.80	45%
Floor	Vinyl flooring with underlay	0.10	100%

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

Common Failure Modes

⚠️Heritage building constraints

Listed French school buildings restrict ceiling treatment options, making it difficult to achieve absorption targets without visible modifications.

⚠️Ventilation noise in summer

Many French schools lack air conditioning and rely on open windows, admitting external noise well above 35 dBA.

Frequently Asked Questions

What RT60 does NRA 2000 require for a classroom?

NRA 2000 requires a reverberation time of ≤0.6s at 500-2000 Hz for classroom spaces. The French NRA (Nouvelle Reglementation Acoustique) under Arrete du 25 avril 2003 sets RT60 targets for educational buildings classified as ERP (Etablissements Recevant du Public). Classrooms require RT60 <= 0.6s with background noise not exceeding 35 dBA. These are mandatory for all new-build and major refurbishment projects in France.

What is the maximum background noise level for a classroom under NRA 2000?

NRA 2000 sets a maximum background noise level of 35 dBA for classroom 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 classroom need to comply with NRA 2000?

A typical classroom (150-300 m³) requires Mineral wool ceiling tile (NRC ≥0.85) covering 80% of the ceiling as the primary treatment. Additional wall absorption on 2 surface(s) is typically needed. Use the AcousPlan calculator with the pre-loaded dimensions (8.5m × 7m × 3m) to calculate the exact absorption deficit for your room.

Calculate NRA 2000 Compliance for Your Classroom

Pre-loaded with typical classroom dimensions (8.5m × 7m × 3m) and an RT60 target of 0.6s per NRA 2000. Enter your actual dimensions, select materials, and verify compliance instantly.

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