📊ASHRAE 189.1-2020 · United States

Meeting Room Acoustic Design to ASHRAE 189.1-2020

Meeting rooms require controlled reverberation for clear face-to-face and video-conference communication. The small volume and hard glass partitions common in modern offices make them prone to excessive reverberation and poor speech clarity.

TL;DR

Under ASHRAE 189.1-2020, a meeting room of 60-100 m³ (typical dimensions 6m × 4m × 2.8m) requires an RT60 of ≤ 0.6s at broadband. Background noise must not exceed 30 NC. ASHRAE Handbook Chapter 49 recommends NC 25-30 for conference rooms, which is stricter than open-plan offices.

RT60 Target

≤ 0.6s

Noise Limit

30 NC

STI Minimum

N/A

Frequency Range

broadband

Specific Requirements

Parameter	Target	Clause Reference	Notes
Reverberation Time (RT60)	≤ 0.6s	—	500-2000 Hz, Per referenced ANSI S12.60 criteria
Background Noise Limit	≤ 35 NC	§8.3.4	HVAC + building services, unoccupied
Frequency Range	broadband	—	Octave bands for compliance assessment

Step-by-Step Compliance Calculation

1
Set NC 25-30 target
Conference rooms per ASHRAE: NC 25 for executive boardrooms, NC 30 for standard meeting rooms.
2
Relocate noisy terminal units
Position VAV boxes, fan coil units, and other noise sources outside the meeting room ceiling plenum.
3
Specify quiet diffusers
Select diffusers with published NC <= 20 at design airflow. Prefer round or perforated face types.
4
Verify with measurement
Measure octave-band background noise levels with HVAC at design conditions and plot against NC curve.

Recommended Materials

Surface	Material Category	Min NRC	Coverage %
Ceiling	Mineral wool ceiling tile	0.85	80%
Duct silencer	Rectangular duct silencer	0.70	100%

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

Common Failure Modes

⚠️VAV box above meeting room

VAV terminal units located in the ceiling plenum above meeting rooms radiate noise directly through ceiling tiles at 35-45 dBA.

⚠️Diffuser whoosh at high flow

Slot diffusers sized for cooling peak produce audible air noise during maximum demand that exceeds NC 30.

Frequently Asked Questions

What RT60 does ASHRAE 189.1-2020 require for a meeting room?

ASHRAE 189.1-2020 requires a reverberation time of ≤0.6s at broadband for meeting room spaces. ASHRAE Handbook Chapter 49 recommends NC 25-30 for conference rooms, which is stricter than open-plan offices. The focus is on HVAC system noise control, particularly from overhead diffusers, fan coil units, and VAV boxes that are common noise sources in meeting room environments.

What is the maximum background noise level for a meeting room under ASHRAE 189.1-2020?

ASHRAE 189.1-2020 sets a maximum background noise level of 30 NC for meeting room 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 meeting room need to comply with ASHRAE 189.1-2020?

A typical meeting room (60-100 m³) requires Mineral wool ceiling tile (NRC ≥0.85) covering 80% 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 (6m × 4.5m × 2.8m) to calculate the exact absorption deficit for your room.

Calculate ASHRAE 189.1-2020 Compliance for Your Meeting Room

Pre-loaded with typical meeting room dimensions (6m × 4.5m × 2.8m) and an RT60 target of 0.6s per ASHRAE 189.1-2020. Enter your actual dimensions, select materials, and verify compliance instantly.

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