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28 Mar 2022

Whisper Quiet Ventilation

Unovent is whisper quiet. You'll barely even know it's there.

A common concern for homeowners when looking at installing home ventilation is the noise, and rightly so. . With ventilation outlets in every bedroom, it’s important you can sleep comfortably with the system running. Fortunately, the Unovent system is designed to address that concern.

Is it really whisper quiet?

Unovent is manufactured using a fan rated at just 19.8dB. Once assembled this helps to ensure the system is as quiet as possible. We had the assembled Unovent system tested in a lab environment to measure the operating noise level, including the sound of air flowing through the system. Results showed that Unovent is rated at 15NC. This is quieter than a whisper, which is rated at 30dB. The chart below shows the relationship between dB and NC. As you can see 10-20 NC equates to ~25-30 dB. Unovent really is whisper* quiet!

How is Unovent so quiet?

Unovent has been designed ground up to minimise operating noise. It uses a smaller fan designed to move only the air it needs to. Because of this gentle air flow there is substantially less air movement noise. The fan itself uses a self-stabilising oil-pressure bearing (SSO bearing). These surpass current types of ball, sleeve, or liquid bearings in terms of long-term stability and quietness.

Another one of Unovent’s key features is its consistent airflow. Unovent is designed to work throughout most of the day and night, even in colder climates, rather than switching on and off within a limited temperature range. This consistency has a range of benefits, including minimising the need to force large volumes of air into the home at once. It also minimises the frequency of noise fluctuation between turning on and off, which can interrupt sleep.

Are there factors that might seem to increase the noise?

Outside the control of the lab environment, there are external factors that may make Unovent seem louder than the lab results. Lab testing is extremely valuable because a controlled environment allows us to ensure that no other variables are impacting our results. Using a controlled environment also means that different systems can be compared accurately. Unovent was tested under standard lab conditions late at night for minimal ambient noise. Factors that may affect perceived noise in a home setting include:

  • Smaller roof cavity: If your Unovent is installed in a smaller roof cavity, the sound will seem louder because reflected noise has less distance to travel and there is less surface area to absorb sound.
  • Roof material and linings: Different materials absorb/reflect more noise than others.
  • Room furnishings: More soft surfaces in your room will result in less noise.
  • Floor Material: Harder floors will result in more perceived noise.

As you can see, noise is incredibly situation dependant, and you’ll likely get different test results depending on where you have installed your system. However, you probably still won’t be bothered by it.


Engineering ToolBox, (2004). Noise Criterion vs. Noise Rating and dB(A). [online] Available at: [Accessed 24/03/2022].

* For purposes of this article a whisper is taken to be 30dB