MIL-HDBK-1003/3
APPENDIX A (Continued)
NFGS-15972 was prepared to take advantage of the many
desirable features of a DDC system while minimizing anticipated
problems by specifying appropriate hardware and software and by
requiring adequate training for activity personnel. DDC systems
should be specified for new projects and major renovations where
operators and maintenance personnel are DDC qualified or are
willing to accept DDC and receive proper training. Where these
conditions are not met, use NFGS-15971 and provide pneumatic,
analog electronic, or electric control systems.
DDC systems may be selected for repair or renovation of
existing control systems to save energy and take advantage of the
other features of DDC systems. Where existing pneumatic or
electric valves and other actuators are proper and functional,
they may work with the replacement DDC system with the
appropriate interface.
EMCS is an outmoded concept and should be discouraged
and avoided. EMCS added a computer based system to monitor
existing pneumatic and analog electronic control systems and
provided some energy saving strategies. Success of the EMCS
depended on proper operation of the existing control system.
When the existing control system failed, EMCS failed. If energy
monitoring features are desired, a DDC system should be
specified. If an operating EMCS is to be expanded and a DDC
system will not be installed, refer to the Army Corps of
Engineers, Architectural and Engineering Instructions, Design
Criteria, Chapter 11, "Energy Conservation Criteria," and guide
specification CEGS-15950, Heating, Ventilating, and Air
Conditioning (HVAC) Control Systems for selection and
application.
A-1.04.4 Thermostat Setpoints. Selective thermostat setpoints
provide a temperature range in which no mechanical heating or air
conditioning takes place. See Figure A-2. Deadband thermostats
should not be used. Rather thermostats with separate control and
setpoint for heating and cooling or DDC with separate control
loops should be used. Strategies should control heating and
cooling within one degree F of the respective setpoints.
A-2.00
Energy Conservation with Systems
150
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