System Shutdown Capability. To the extent practical and cost
effective, non-critical, non-bedroom area HVAC systems shall be designed to
permit shutdown (night setback/setup, outside air shutdown) of individual
areas or departments not in operation on a 24-hour basis. Ventilation of
toilets, battery vaults, and other normally-exhausted spaces shall be
continued without interruption as warranted.
Outdoor Air Intakes. Outdoor air intakes shall be located as
far as practical, but not less than 9000 mm (30 ft), from exhaust outlets
of ventilation systems, cooling towers, combustion equipment stacks,
medical/surgical vacuum systems exhaust, plumbing vent stacks, emergency
other noxious fumes. Locate the bottom of air intakes serving central
systems as high as practical but not less than 2400 mm (8 ft) above ground
level, or if installed above the roof, at least 900 mm (3 ft) above roof
level. Outdoor air shall not be drawn from equipment rooms. Designers
must utilize judgement in the location of contaminant exhausts, and not
simply apply the "9M rule" without further consideration of wind direction
and velocity, building geometry, and characteristics of the contaminant
stream. Appropriate consideration shall be given to prevailing wind
direction, summer and/or winter as applicable; however designers are
cautioned not to rely on prevailing wind direction(s)as a primary factor in
in locating outside air intakes in proximity to parking areas, ambulance
garages, loading docks, exhaust air outlets, and equipment stacks. Where
appropriate, Design Agents will provide in individual project design
instructions for special computational fluid dynamics (CFD) or wind tunnel
modeling to provide greater assurance of the correct location of outside
Balancing Provisions. Duct branches serving each individual
space shall be provided with a manual balancing damper, accessible above
the ceiling, located as remote from the space supply or return fixture
(diffuser, register, etc.) as practicable.
The balancing damper provided
as part of air diffusers is not to be used for system balancing.
Noise Control. Noise Criteria (NC) for individual rooms and
spaces in the facility are provided at Appendix A of this document.
Additional and detailed information and requirements of building noise
control are addressed at Section 23, Acoustics, of this military handbook.
Room Breakout. The HVAC designer shall coordinate with the
architectural designer to control equipment noise passing from mechanical
rooms into adjacent spaces through the surrounding walls or partitions.
Crosstalk. The compromising of patient privacy by transmission
of audible speech from one room to another via ductwork is of great concern
in medical facilities, and shall be addressed by HVAC designers.
Examination rooms, physician's offices, and toilets require the designer's
particular attention. Ductwork connecting adjacent rooms must have the
necessary attenuating characteristics to eliminate audible speech
transmission. Typically this is addressed by the provision of well-
separated "takeoffs" and/or several duct elbows in the intervening ductwork
or, in more extreme instances, attenuative lining; Due to the indoor air