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Design Rationale: Services
1. Individual Fan-Coil Units.
This type of unit has had wide application, particularly in patient rooms.
Since fan-coil units recirculate part of the supply air within the space
itself, they minimize the possibility of the spread of infection from room
to room. Their drawbacks, however, include:
a. low efficiency filters;
b. impracticality of providing humidification;
c. requirement for outside air to each unit, or a supplemental ventilation
system;
d. limited ability to meet changing needs, as units are built in standard
sizes which fix their capabilities;
e. difficulty in adjusting and maintaining system balance under
changing conditions (greater than with all-air systems).
2. Induction systems, although superior to fan-coil systems, possess
serious drawbacks as well:
a. they are designed primarily for the exterior zone;
b. they are provided in a few standard sizes, and thus suffer the same
limited adaptability as the fan-coil units;
c. they are also inferior to all-air systems in their ability to maintain
system balance easily.
3. There are other systems which might be considered. However, they
would require supplementation to meet the criteria. For example,
radiant heating or cooling could be designed to maintain dry bulb
temperatures, but a supplemental ventilation system must be provided.
In this regard, the possibility is not excluded of a supplemental system
even to an all-air system in areas having extremely cold winter
conditions.
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