Sound Control and Airflow for Louvered Doors
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Considerations relating to sound transmission and air flow through louvers on the doors of an equipment room. April 4, 2011
Question
A client wants me to figure out the air flow on a louvered door for a pool equipment room. The client has a spec that's required but being that it is by the tennis court they don't want to hear anything. Is there any formula I can use?
Forum Responses
(Architectural Woodworking Forum)
From contributor O:
Net free area on louvers is a valid characteristic of louvers and therefore a valid, though obscure, request. Determine the space between the parallel slats - say 3/8", then the length of the that space - say 24", then the number of spaces - say 60.
.375 x 24" = 9 s/inches x 60 = 540 s/inches or 3.75 s/feet net free area.
This is used for calculating airflow for equipment or attic ventilation. Once upon a time, stock attic louvers were labeled with net free area to ease selection. I do not know how louvers can be used to moderate sound levels. I do not think they will decrease any sound. Sound is a function of moving air, and the air is moving through the louver spaces.
From contributor Y:
Air flow is one thing, sound control is quite another. A louvered door will not have any effect on sound deadening, nor is it designed to do so. A quick glance at the steel louver catalogs - Anemostat, AirLouver, and etc reveals a 50% free air flow for most louvers. However, if your door needs to be fire-rated for a mechanical room, you will need to provide a fusible link louver, which has a 40% free air flow. There are size limitations with the fire-rated louvers you should be aware of. Keep in mind that any sort of field modification of a fire-rated door will void the label. (If it applies in your case).
From contributor U:
We used louvered shutters to create an enclosure for two stationary air compressors that were running close to an area where employees were stationed. After considering the matter and finding information that showed that sound waves are directional, we decided to put up the enclosure which was basically a closet built against the existing shop wall, with louvered shutter panels creating the other three walls. The existing shop wall was concrete block and the floor was cement. With only the louvered panels in place we found only a slight decrease in the noise level - maybe 15%.
We then added filter element material to the louvered areas, to help absorb the noise and not block the air flow needed for the compressors - maybe another 15% reduction. We even covered the block wall with a sound absorbing textured material. I forget what we used, but we did get the noise down a little more. I was surprised that the noise level did not reach my expectations, but it did become acceptable for the employees to work in the area. I seriously doubt that just the louvered door will block the sound to your customer’s expectations if they want something approaching peace and quiet.
From contributor G:
How much noise does the pool equipment room generate? It's a pump in there - not a compressor. How about putting anechoic baffles on the walls like the egg cartons we used to put on the garage walls to muffle the sound of the band practicing?
From contributor D:
Products like panels manufactured by Soundown are very effective for insulating noise. They are used for insulating engine rooms on boats, recording studios, and many other uses. Expensive stuff but it works.
From contributor O:
Once the source of sound has been attenuated as much as possible, and the enclosure has been damped, then you may wish to go to chevron louvers to dampen the sound that is still present. Chevron louvers do not allow a straight path for light/sound, and can dampen sound further than conventional louvers. Same net free area calculations apply.
