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Design Rationale: Services
b. The use of factory labor for all but final installation cuts costs both
directly and by adding to the certainty of scheduling.
c. Actual fan ratings (horsepower) can be reduced, as the additional
friction to be overcome in the vertical shaft is eliminated.
It is impossible to predict the actual cost difference between a system of
satellite units and a central fan system as it will vary considerably with
building height and configuration. Higher buildings favor the system of
satellite units.
4. Operating and Maintenance Costs
a. Energy expended in heating or cooling air should be the same in
central fan systems and satellite systems, assuming similar
distribution patterns at the local level.
b. As noted above, energy expended for air circulation will be reduced.
In the case of a tall building, this differential is maximized. In that
case, fan horsepower requirements are reduced ten percent by
eliminating the vertical supply air shaft.
c. The satellite units still take advantage of the economics implicit in
centralized energy conversion devices (boilers and chillers).
d. Maintenance costs can be expected to rise, as servicing is
decentralized. The efficiency of maintenance, given a decentralized
system, is maximized by providing highly accessible mechanical
rooms with adequate clearances around equipment, which are
stacked next to a stairway.
e. In the case of major mechanical malfunction, repair of the smaller
units would be easier, and would not affect hospital areas beyond
the service module in which the malfunction occurred.
5. Availability of Packaged Air-Handling Units
The following list of products is not exhaustive, but it demonstrates the
ready availability of the type of component which is being considered.
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