Civil Engineering Reference
In-Depth Information
Fig. 8.10
Fan coil unit
8.13
Advance Energy-Effi cient Airside HVAC Systems
8.13.1
Under-Floor Air Distribution CV
Under-fl oor air distribution systems (Fig. 8.11 ) were invented and used in the 1950s
for cooling spaces with higher than usual heat loads such as computer rooms. The
basic concepts are (1) to replace the ductwork network with an open space between
the structure slab and raised fl oor, and (2) to deliver the conditioned air immediately
to lower part of the room where people actually stay and work.
This system is similar to a variable-temperature, constant-volume system, except
that (1) instead of using the duct for air delivery, it uses the under-fl oor plenum
space, (2) there is an additional return-air bypass arrangement which is used to
bypass return air to upstream of the fan in order to provide suffi cient dehumidifi cation
when it is needed, without the need for a reheat coil, and (3) an additional baseboard
radiators or convectors is used for space heating.
This system not only results in saving energy by delivering air with a higher
temperature than what is usually used in traditional cooling systems (in this system
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