This is a legacy version of the WELL Building Standard. Please check the latest version here.

Internally generated noise

Internally generated noise


To reduce acoustic disruptions from internal noise sources and increase speech privacy.


Electronics, HVAC systems, mechanical equipment and other noise-emitting office devices, as well as occupants themselves, can be sources of indoor noise. As offices and workspaces are increasingly designed to promote employee interaction, occupants can experience decreased levels of privacy and acoustic comfort, especially when users with different job types share a space. Office noise can lead to decreased productivity, especially in open-plan offices where aural distractions and interruptions from other employees are frequent. Additionally, studies show that exposure to noise generated within the building can lead to reduced concentration and mental arithmetic performance, and increased distraction due to reduced speech privacy.

Part 1
Acoustic Planning

An acoustic plan is developed that identifies the following spaces and potential sources of disruption:
Loud and quiet zones.
Noisy equipment in the space.

Part 2
Mechanical Equipment Sound Levels

The mechanical equipment system meets the following requirements once interior build-out is complete in the following spaces:
Open office spaces and lobbies that are regularly occupied and/or contain workstations: maximum noise criteria (NC) of 40.
Enclosed offices: maximum noise criteria (NC) of 35.
Conference rooms and breakout rooms: maximum noise criteria (NC) of 30 (25 recommended).

Part 3
Mechanical Equipment Sound Levels in Sensitive Rooms

The following requirement is met in the bedrooms, dining rooms, living rooms, and studies:
The maximum background noise level in the home or unit due to interior noise sources (HVAC systems, lighting, and other building services operating simultaneously) is less than or equal to 40 dBA.

Part 4
Best-Practice HVAC Installation

The following requirements are met:
Ducts are securely attached with no loose connections between sections.
Fan housing is securely anchored.
Damper flaps fully close, without any visible airspaces around the perimeter of the flap.

Part 5
HVAC Sound Ratings

The following requirements are met in all bedrooms, dining rooms, living rooms, and studies for all fans except HVAC air handlers and remote-mounted fans that are located outside habitable spaces with at least 1.2 m [4 ft] of ductwork between the fan and the intake grill:
Intermittent ventilation fans with a maximum rated airflow at or below 11 m³/min [400 cfm] have a maximum sound rating of 1.5 sones.
Continuous ventilation fans have a maximum sound rating of 0.7 sones.

Part 6
Noise Criteria in Schools

Each regularly occupied space must meet the following noise criteria while unoccupied, as measured in the geometric center of the room:
Classrooms: maximum noise criteria (NC) of 35.

Part 7
Disruptive Music Limitation

If music is played in the space, sound levels may not exceed the following:
7 decibels (dBA) above the ambient sound pressure level when measured at a minimum distance of 4.5 m [15 ft] outside of the entrance to the space.