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
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
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,
Control Systems for selection and application.
Thermostat Setpoints. Selective thermostat setpoints provide a
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.
Energy Conservation with Systems