Total Shaft Area

The total open area of all the mechanical and electrical shafts in a tall office building is normally equal to about 4% of the area served on each floor, and can be estimated at about half this amount for a low-rise building. This should be divided into at least two separate shafts to relieve the congestion that would otherwise occur where the vertical and horizontal distribution networks connect. It is especially effective to provide separate shafts for supply and return ducts because it is often possible to use a separate return shaft as a plenum, a shaft that is itself the duct. Separate supply and return shafts also minimize conflict in the bulky ductwork connections and crossovers. For maximum utility, the horizontal proportions of each shaft should lie in the range of 1:2 to 1:4. To allow sufficient space for connections to horizontal distribution networks at each floor, no shaft should adjoin stair towers or elevator shafts on more than one long side and one short side. All shafts must be enclosed with 1- to 2-hour noncom-bustible walls, except in buildings of Wood Light Frame construction, where shaft enclosures do not need to be fire rated.


Electrical and telecommunications closets must be accessible from public areas of the floor, must each be stacked above one another, must include wiring shafts, and must be kept free of plumbing, steam, and other types of wiring. Typical sizes and configurations for electrical closets are illustrated in the accompanying diagrams. In an office building, major electrical closets should be located in such a way that no point on a floor lies more than 125 ft (40 m) away. If this is difficult to arrange, satellite closets served by cables from the major closets may be used to feed electricity to the more distant areas. In smaller buildings or buildings other than offices, satellite-size closets may serve in place of major closets.

At least one telecommunications distribution closet should be provided for every floor and for every 10,000 sq ft (930 m2) of area served. For commercial office space, telecommunications closets should measure 10 X 12 ft (3.0 x 3.7 m) internally. For less data-intensive occupancies, closets as small as 4 x 7 ft (1.2 x 2.1 m) may be acceptable. Separate cooling zones should be provided to permit independent temperature control of these areas.

Elevator Shaft Cooling





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  • esmeralda burrows
    What is shaft area in building?
    1 year ago
  • D Twofoot
    What is utility shaft in proviet in building?
    9 months ago

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