18 August 1998
Day of week/holiday.
Time of day.
Cooling and heating high low alarm limits.
Cooling and heating start/stop schedules.
Consecutive start time delay.
c. Application notes. The scheduled start/stop program operates in conjunction with optimum
start/stop, demand limiting, and ventilation-recirculation programs.
3. OPTIMUM START/STOP PROGRAM. The scheduled start/stop program is refined by automatically
adjusting the equipment operation schedule in accordance with space temperatures and outside air (OA)
temperature. In the scheduled start/stop program, HVAC systems are started prior to occupancy to cool
down or heat up the space on a fixed schedule independent of space and OA conditions. The optimum
start/stop program automatically starts and stops the system on a sliding schedule. The program will
adjust start/stop times by taking into account the thermal inertia of the structure, the capacity of the HVAC
system to either increase or reduce space temperatures, OA conditions, and current space temperatures,
using prediction techniques. These techniques determine the latest time for starting HVAC equipment to
satisfy the space environmental requirements at the beginning of the occupied cycle, and determine the
earliest time for stopping equipment at the day's end. Design requirements for this applications program
will be indicated by the letter X adjacent to the program listing on the appropriate database table, as
shown in Chapters 8 and 9.
a. Field hardware requirements. The hardware requirements are:
UMCS inputs from utility system.
(a) Equipment status from pressure switch, auxiliary contact, flow switch or current sensing
relay/transducer - one for each piece of equipment
Space dry bulb temperature (minimum of one per zone).
OA dry bulb temperature.
(2) UMCS outputs to utility system. Start/stop control signal from UMCS to interposing relays
(momentary or maintained signal as required by the equipment control circuit configuration and failure
mode) - one for each piece of equipment.
b. Software I/O requirements. The software requirements are: