User Guide

Table Of Contents
Control Option Comparisons—Start/Stop Time Optimization (SSTO)
Siemens Building Technologies, Inc. 2-13
SSTO Formulas
The following formulas, used for calculating the optimal start and stop
times during the heating and cooling seasons, are outlined on the
following pages:
Cooling Season—Optimum Start Time
Cooling Season—Optimum Stop Time
Heating Season—Optimum Start Time
Heating Season—Optimum Stop Time
Cooling Mode at Occupancy Begin
Cooling Mode at Occupancy End
Heating Mode at Occupancy Begin
Heating Mode at Occupancy End
NOTE: The example values for coefficients shown in this manual
should not be used without first calculating what the
number should be.
APOGEE PPCL User’s Manual
2-14 Siemens Building Technologies, Inc.
Cooling Season—Optimum Start Time
If the indoor temperature is less than the desired temperature, then the
optimum start time is LB.
Where:
LB = Latest begin time defined in the SSTO command.
If the indoor temperature is greater than or equal to the desired
temperature, then the optimum start time is:
OB - (d * CC) - (d * f * (CT/10)) + AB
Where:
OB = Occupancy begin time from SSTO command.
d = Indoor temperature minus the desired temperature.
CC = Cooling coefficient (ccoef1) from SSTOCO command.
f = Outdoor temperature minus the desired temperature.
CT = Cooling transfer coefficient (ccoef3) from SSTOCO
command.
AB = Adjust begin time from SSTO command.