Handbook of air conditioning and refrigeration / Shan K

6.46 CHAPTER SIX
● For the calculation of the energy use, only when the outdoor ventilation air system is separated
from the main supply system is it then possible to choose and to create a schedule in
which the airflow of outdoor ventilation air varies according to people’s occupancy.
● During the calculation of energy use for a variable-air-volume (VAV) system, the airflow of
the outdoor ventilation air may be varied based on its control systems into the following
schedule: 100 percent, 24 h/day; varying according to supply volume flow of the air system;
varying according to people’s occupancy.
● For the calculation of energy use due to infiltration, choose and create a schedule in which
the infiltration varies inversely with supply fan schedule, such as for hours fan schedule
is 100 percent, infiltration is zero; then when fan schedule is 0 percent, the infiltration is
100 percent.
3. Operating schedules of fans that affect the design load and energy use calculations are as
follows:
● At design load, TRACE 600 assumes that the main supply fan and auxiliary fan, if any, are
scheduled at 100 percent, 24 h/day as the default value during cooling mode operation, and
fan heat will be included in the cooling coil load. Similarly, at design load, main supply and
auxiliary fans are scheduled at 0 percent, 24 h/day during heating mode operation, and no
fan heat will be taken into account.
● In the energy use calculation, main supply and auxiliary fans in a constant-volume air system
are scheduled at 100 percent, 24 h/day. Or choose or create a schedule at which fans will be
cycling (on and off) depending on the space cooling and heating load.
● In the energy use calculation, main supply and auxiliary fans in a VAV system are scheduled
depending on the space cooling and heating load.
● For a room exhaust fan operated at cooling design load, it is scheduled at 100 percent,
24 h/day as the default value. For the energy use calculation, choose or create an appropriate
operating schedule.
4. The reheat minimum percentage determines the ratio of reheat minimum airflow for that room
to the design supply airflow.
5. Daylighting schedule describes the availability of daylighting each hour. Choose an available
schedule or create an appropriate daylighting schedule.
Trace 600 Input—Internal Loads
Four cards cover the input data of internal loads and airflows.
Card 27, people and lights, describes the room number, people’s density and corresponding unit,
people’s sensible and latent loads, lighting heat gain and corresponding unit, type of lighting
fixture, ballast factor, and daylighting reference points 1 and 2, to show whether there is
daylighting control or one or two control areas. According to the types of lighting fixtures and
the return airflow per unit floor area, the percentage of lighting load to return air should be
determined more precisely. Refer to Sec. 6.6 for details.
Card 28, miscellaneous equipment (optional), covers the room number, miscellaneous equipment
reference number, equipment description, energy consumption value and corresponding
units, schedule and energy metering code, percentage of sensible load, percentage of miscellaneous
equipment load to space and to air path, radiant fraction, and whether the plenum air,
exhaust air, or return air path picks up the miscellaneous load.
Card 29, room airflows, covers the flow rates of outdoor ventilation air during cooling and heating
operation and their corresponding units, the flow rates of infiltration air for cooling and
heating and their corresponding units, and the amount of minimum reheat and its units.
Card 30, fan flow rates, describes the room number, airflow of the main and auxiliary cooling and
heating supply fans and their corresponding units, and airflow of room exhaust fan and its unit.