720
Design Rationale: Services
724
SERVICES
The three service subsystems are organized into discrete networks each
serving a single service module. The point of entry into the service
module is the service bay, where each service is controlled, zoned or
valved, and equipment rooms are placed.
724.1
HEATING-VENTILATING-COOLING
A uniform system of air distribution throughout the entire service module,
by its simplicity and generality, allows the greatest degree of adaptability.
724.1.1
Single All-Air Supply with Supplementary Perimeter Heating
When the many commonly used air-conditioning systems are each tested
against the performance requirements, it is found that only all-air systems
are capable of meeting all of them. All-air systems may be classified as:
1. single-duct terminal reheat
2. dual-duct
3. variable volume
4. multi-zone
The first three are similar in design and the fourth is eliminated from
consideration only because the size, complexity and frequency of change
of the areas served would require too great an extent of expensive
ductwork and more temperature control zones than packaged multi-zone
units could handle.
Variable volume systems are not considered as suitable as dual-duct and
terminal reheat are for this application, as they cannot easily achieve the
control of pressure differentials required in many areas. Variable volume
systems are also less easily adapted to changes in plan and function than
dual-duct or terminal reheat systems.
724.1.2
Supplementary Perimeter Heating
The most common mixed system uses dual-duct or terminal reheat
distribution for interior zones, and fan-coil or induction systems for
perimeter rooms.
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