TM-5-855-4
efficiency and for material preservation and operation of essential
equipment during standby,
normal-operating, and attack and post-attack periods. Rejuvenation of the air will also be considered for
conditions of extreme emergency and disaster. Steady-state environmental requirements during peace
time and war time will exist only in such facilities as unmanned and sealed-up material storage
facilities. All other hardened facilities within the scope of this manual must be designed to function
throughout a wide range of operating conditions influenced by season, manning levels, and mission.
Facilities are classified by operational requirements in accordance with the following:
(1) Continuous operation. The HVAC designer will be required to develop environmental systems
that will function throughout all operating conditions. Ventilation air must be filtered for space
pressurization. Essential parts of the HVAC system must survive the threat, although some non-essential
components may be sacrificed as long as the system as a whole continues to function. Command and
communication centers, surveillance and intercept radar, and missile launch and control centers are
indicative of this type of facility.
(2) Button-up with active survival., Facilities of this type are designed to cease operations when
attacked, to button-up and become isolated during the attack, and to resume operations after necessary
repairs are made. The primary function of this type of installation is to protect personnel and equipment.
Underground industrial plants, administrative agencies, and air raid shelters normally conform to this
facility category.
(3) Button-up with passive survival. Facilities of this type will be designed as a protective
structure with seal-up provisions only to prevent contamination of the protected material. Seal-up
provisions will consist of closing doors and dampers upon notification of a threat and keeping them
sealed until the threat is over. Underground facilities for storage of materials with high strategic or
replacement value, such as archives and art objects, would be representative of this type of facility.
1-4. Operating modes.
a. Overview. The facilities under consideration must operate in peace, war, and under the threat of
war. It is beyond the scope of this manual to set forth specific operational procedures required for each
condition; however, operational and design assumptions must be made prior to design. The installation
of equipment and operation of the structure is based on the following operating modes.
b. Normal conditions. A normal condition exists when" a structure is continually occupied and
prepared for the accomplishments of a mission. Normal conditions will exist prior to button-up.
(1) Facility power will normally be provided by a commercial utility, though many facilities
switch to emergency power when storms occur because of unreliable commercial power.
(2) HVAC systems will be operating with the design outside air passing through CB filters.
Bypassing the CB filters will not be allowed unless facility mission is minor, and continuous protection
against covert attack is not required by the operational scenario. Air from areas such as toilets,
equipment rooms, and power plants will be exhausted to the outside.
(3) Waste heat will be rejected to the outside through normal cooling towers or radiators. Heat
sinks will normally be filled and maintained at design temperature because the time required to lower
the heat sink to its design temperature is greater than most warning periods.
c. Alert conditions. An alert condition exists during a real or practice exercise. In the alert mode,
steps will be taken to improve the defense posture of the facility.
(1) The facility power plant will be put in operation and will either share the load with the public
utilities or carry it all as prescribed in the operational scenario.
(2) NO CB filter bypasses are permitted under any conditions. This must be the case because
detectors will only indicate that gases or chemicals have been introduced into the system or broken
through the filters, leaving no time to take preventive action. Combustion air will continue to be drawn
through primary dust scrubbers. Personnel movement in the unoccupied facility areas unprotected by the
CB filters will be curtailed.
(3) The button-up period normally commences with the alert alarm and continues until the seal-up
period starts. Limited egress and ingress may be permitted. In shallow buried facilities, the prime
movers are supplied from unhardened fuel storage, and the unhardened cooling towers remain in
operation. All other systems are sealed from the outside except for air supply.
(4) Hardened heat rejection equipment will be utilized if attack is imminent and throughout the
seal-up period covered in d(2) below.
1-2
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