NRC and CAC – What are they, and what’s the difference?

If you’re at all familiar with this industry, you will hear the terms NRC and CAC time and time again. They are prominent driving factors that influence decision-making around which ceiling tiles should be installed.

So, let’s take a dive into the terms, and what they mean.

NRC: Noise Reduction Coefficient

According to audimute.com, the Noise Reduction Coefficient is an average rating of how much sound an acoustic product can absorb.

The scale begins at 0 [the product cannot absorb any sound] and increases to 1 [the product absorbs all sound]. So, for example, if a product has an NRC of 0.5, it is absorbing 50% of sound, and the other 50% is reflected.

The NRC of a ceiling tile is improved when it is composed of a soft material. This allows the tile to absorb more sound, and reflect less back into the space.

CAC: Ceiling Attenuation Class

While NRC is applicable across a range of industries and product types, CAC is a measurement developed specifically for ceiling tiles. It is defined as the ability of a product to act as a barrier for sound, between two or more adjacent, closed spaces.

The CAC rating ranges from 25 to 50, with a value 30 and above considered a good rating.

The CAC of a ceiling tile is increased when the tile is constructed with a heavier, denser material. This allows the tile to reduce the transfer of noise and sound between spaces.

So, how do we balance NRC and CAC?

As you will notice, NRC and CAC ratings pull in opposite directions. To improve NRC, the tile must be softer, but to improve CAC, the tile must be harder and denser.

This is the challenge that is faced by ceiling manufacturers across the world. To strike the optimal balance of NRC and CAC is a difficult task. Thus, it is uncommon for a ceiling tile to have an NRC of 0.7, and a CAC higher than 35. The NCS Pinnacle is an example of the optimal balance.

At this time, the only known way to improve both ratings is to increase the thickness of the tile. However, this leads to increased costs and heavier product, which is a drawback for installers and contractors.

In conclusion

In conclusion, NRC and CAC are important measures to consider when choosing a ceiling tile to specify. Be sure to consider the application of the tile, and the types of activity that will be conducted in the spaces.

It’s important to observe the balance of the two ratings in the tile you choose.