Use of Space -Anechoic Chamber

[KRS5]

We are installing an anechoic chamber in a business occupancy and trying to determine the use of the chamber according to NFPA 101 Table 7.3.1.2 Occupant Load factor. I was thinking storage with an Occupant Load Factor or 300, since only a few people are in the chamber at one, time to set up tests, and none are in the chamber while tests are running. Anyone else have any input?

Thanks.

 

[KRS5]

We are installing an anechoic chamber in a business occupancy and trying to determine the use of the chamber according to NFPA 101 Table 7.3.1.2 Occupant Load factor. I was thinking storage with an Occupant Load Factor or 300, since only a few people are in the chamber at one, time to set up tests, and none are in the chamber while tests are running. Anyone else have any input?

Thanks.

Sorry I meant OLF of 500 not 300.

 

[classicT]

Had to look that up.... For those in the same boat, an anechoic chamber (an-echoic meaning "non-reflective") is a room designed to stop reflections of either sound or electromagnetic waves.

 

[RLGA]

This is strictly my opinion, but the building official will have the final say on the matter.

Depending on the size of the chamber and the overall size of the rest of the business use, I do not think including it (or excluding it) within the gross area of the business occupant load factor will have a significant impact.

However, if the chamber size is relevant, and those that enter the space are only those that work in the adjacent business areas, it could be logically justified to exclude the chamber areas from the building's total occupant load entirely. Regardless, the space must still comply with the means of egress requirements per Chapter 10 (e.g., travel distance, egress width, common path of egress travel, etc.). To determine egress width, unless you plan on having more than 160 occupants in the room (capacity of a minimum 32-inch clear doorway), the occupant load of the space is irrelevant; thus, finding a load factor to use would be meaningless.

On the other hand, when you have a B.O. requiring every nook and cranny to be accounted for, either the accessory storage (300 sq. ft.) or warehouse (500 sq. ft.) occupant load factors would be acceptable depending on the size of the chamber. Small chambers would use the 300 sq ft. factor, whereas large chambers would use the 500 sq. ft. factor. Typically, the number of technicians accessing the chamber would not vary much if it was small or large antennae being tested. Thus, to keep the occupant load somewhat consistent regardless of size would demand a flexible occupant load factor. However, where the division would be between a small and large chamber is anyone's guess. I would use the owner's guidance to determine the average number of technicians accessing the chamber and find a load factor that best supports that number.

 

[classicT]

To answer your question, I'd point to the following:

1004.5 Areas Without Fixed Seating​

The number of occupants shall be computed at the rate of one occupant per unit of area as prescribed in Table 1004.5. For areas without fixed seating, the occupant load shall be not less than that number determined by dividing the floor area under consideration by the occupant load factor assigned to the function of the space as set forth in Table 1004.5. Where an intended function is not listed in Table 1004.5, the building official shall establish a function based on a listed function that most nearly resembles the intended function.​

Exception: Where approved by the building official, the actual number of occupants for whom each occupied space, floor or building is designed, although less than those determined by calculation, shall be permitted to be used in the determination of the design occupant load.​

So, IMHO, it depends on what is being tested in the space and how large it is. Most likely, if testing equipment/components/etc. and the room will typically be empty, I'd include it within the gross floor area of business area (150 gross).