UFC 3-580-10
14 July 2004
Including changes 12 April 2005
C-3
MECHANICAL.
C-3.1
General Requirements. NMCI equipment must operate
continuously (year-round), as must other telecommunications equipment co-
located within the NMCI and Telecommunications (NMCI/Telecom) spaces.
These equipment installations generate internal sensible heat, with little to no
latent heat (moisture) except for that produced by any personnel located within
the space. The space cooling equipment must be able to operate year-round,
without regard to whether the rest of the facility requires cooling, heating, or only
ventilation. Heating and cooling systems on building time clocks or other
temperature setback means, are not to be used for NMCI/Telecom spaces
Provide NMCI/Telecom spaces with independent heating &
cooling systems.
The ventilation (outside air) must be provided by the systems
serving the remainder of the building, unless the NMCI/Telecom space is
regularly staffed. If the NMCI/Telecom space is regularly staffed, the
independent heating and cooling systems must condition the outside air for these
spaces.
Provide conditioned outside air ventilation in compliance with
ASHRAE Standard 62 Ventilation for Acceptable Indoor Air Quality.
Unless personnel are located in the NMCI/Telecom spaces most of
the time, size the cooling equipment to be able to provide at least 20% latent
heat (moisture removal) capacity, but size to utilize about 90% of the total
capacity to meet the sensible loads. For calculated loads less than one ton
(12,000 BTU/hr), provide a single air conditioner (A/C) unit, with space and
power capacity available to install another identical one for future load growth.
For loads greater than one ton, install two identical units sized for 50% to 60% of
the load each, and provide space and power capacity for an additional identical
size unit for future load growth. For loads greater than about 10 tons, and where
redundant UPS have been installed in the NMCI/Telecom equipment, provide
more than two A/C units to meet the N + 1 redundancy criteria, where N is the
number of A/C units required to meet the load (not less than 2) and 1 is the
identical size redundant spare. In addition to the 1 redundant spare A/C unit,
provide space and power capacity for one additional identical size A/C unit for
future load growth.
Air conditioning equipment should be installed near an exterior wall,
if possible, to allow easy use of outdoor condensing units, with indoor
evaporators. Since the ventilation load is to be taken by the separate building
system, no HVAC ductwork should need to penetrate the exterior wall, unless the
space is to be regularly manned and outside air is to be conditioned by the NMCI
provided independent system. High wall-mounted ductless split system air
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