Schedules play an important role in load simulations and energy analyses. They define when, and for how long, internal loads and system events occur, both of which affect energy demand and consumption.
Figure 2–14 Define economics
Project Tree view Project Tree view
Project Navigator view Project Navigator view
Entries in the Economics Information section apply to all of the alternatives defined within a project and are only editable from Alternative 1.
Entries in the Utility Rates & Life Cycle Costs section can be redefined for each alternative in a project.
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Five types of schedules are predefined in the TRACE 700 Schedules library:
■ Utilization schedules define the timetables for internal loads (occupancy, lights, infiltration, miscellaneous) and the air-distribution side of the HVAC system (fans, coils, controls).
■ Thermostat schedules establish the cooling and heating set points for each hour.
■ Time-of-day schedules distinguish peak, mid-peak, off-peak, and super-off-peak hours, permitting economic analysis of energy costs.
■ Thermal storage schedules define when the operating modes for thermal-storage equipment occur.
■ Equipment operation schedules define the hours of the day that mechanical cooling and heating equipment is available for operation.
The Library/Template Editors program lets you view the attributes of each standard schedule and create new ones of your own.
Because schedules are key to developing accurate system models, the procedure to create a schedule is summarized here for your convenience. Although the example specifically describes a Utilization schedule, other types of schedules are created in similar fashion.
Table 2–1 Example schedule for year-round building occupancy
Day Begin End Design Occupancy
Monday–Friday midnight 7:00 a.m. 0% (unoccupied)
7:00 a.m. 8:00 a.m. 20%
8:00 a.m. noon 100%
noon 1:00 p.m. 50%
1:00 p.m. 5:00 p.m. 100%
5:00 p.m. 6:00 p.m. 20%
6:00 p.m. midnight 0% (unoccupied)
Saturday–Sunday midnight midnight 0% (unoccupied)
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Table 2–1 on page 2–20 describes the year-round schedule for the occupancy of a building. Use this information to create a new Utilization schedule in the TRACE 700 Schedules library.
Also, keep the following points in mind whenever you apply or customize a schedule:
■ When performing a reduced year simulation, each schedule must include individual definitions for each of four day types: Cooling design, Weekday, Saturday, and Sunday. (For more
information, refer to “Simulation methods” on this page.) To make the schedule available for calculations of the design cooling load, select Cooling design as the starting day type. To identify a separate schedule for weekends, select Weekday as the ending day type.
■ Utilization schedules require you to define a schedule for the Heating design month. The program uses it during the heating load–design calculations of airflow and supply-air dry bulb.
Note: For the heating-design-month schedule, only include loads that contribute significantly to the building heating load—
ventilation and infiltration, for example, but not internal loads such as those associated with occupancy and lights. To exclude a load from the schedule, enter 0 as the percentage.
■ When creating a Utilization schedule, always start with January and end with December.
■ For example, to define a Utilization schedule for an event that starts in May and ends in September, include January through April and October through December at zero percent.
■ When adding start and end times to a schedule definition, use Midnight as the first start time and the last end time. (The program will prompt you to correct periods that overlap.) Simulation methods
To arrive at equipment loads and energy consumption, the TRACE 700 program calculations are based on the simulation hours set for the project. You can choose between two methods of calculation: reduced-year versus full-year analysis (refer to Figure 2–15 on page 2–23).
Enter 0 to exclude a scheduled load from energy calculations To define a 24-hour period, use Midnight as the first start and last end times
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1 Click in the toolbar to open the Schedule library. Then click New Sched to add a new member in that library.
2 Pick Utilization as the schedule type. Then give the new schedule a name in the Description box.
Use the Comments box to add a brief explanation (optional).
3 Click New Definition to begin entering the cooling design and weekday definition for the year.
4 Complete the Schedule Definition entries using the information in Table 2–1 on page 2–20.
5 Repeat Step 3 and Step 4 to enter the Saturday and Sunday definition.
6 Similarly, enter the heating design definition as shown. (These entries exclude the effect of occupancy from the calculation of the design heating load.)
7 Click Save to record your entries and make the new Utilization schedule available for any TRACE 700 entry that lists Utilization schedules. For additional details, refer to “Creating schedules” on page 6–
137.
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design day, a typical weekday, a typical Saturday, a typical Sunday, and a typical Monday, using 24 hours of weather that is typical for that month. A calendar code defines the number of occurrences for each day type.
By contrast, a full-year analysis uses standardized weather data for all 8,760 hours in a year to calculate the actual coil loads for each hour. Sometimes described as an 8760 analysis, it can have Figure 2–15 Choose a simulation method
Use this entry to choose between a reduced-year and a full-year analysis
Existing calendars can be displayed by clicking Calendars on the Libraries menu.
To create a different calendar, use the Library/Template Editors program.
This entry defines when and how often each day type occurs.
Standardized 8760 weather data for a full-year analysis can be purchased from various U.S. federal government agencies or downloaded at no charge from various Web sites. For example, ASHRAE IWEC (International) weather can be downloaded at no cost from tranecds.com. page 6–167 for additional information regarding simulations and adding weather libraries.
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separate schedules for nine different day types—the seven days of the week plus a design day and a holiday. Although the calculation process lasts 5 to 7 times longer than a reduced-year analysis, you can use the additional day types in a full-year analysis to more accurately represent the actual day-to-day operating schedule of the building.
Note: Reduced-year schedules can be used for both methods of calculation. Full-year schedules should only be used with full-year simulations. For additional details, refer to “Creating schedules”
on page 6–137.
Note: When you import a standardized 8760 weather file into TRACE 700, the program creates a separate set of monthly design 24-hour profiles based on the weather extremes for use with the load–design simulation. For a more accurate analysis, be sure to check the design summer and winter dry-bulb
temperature and wet-bulb temperature and adjust them as necessary before completing the import process. Reasonable and accurate design conditions can be obtained from the most recent ASHRAE Handbook of Fundamentals. Importing weather files is discussed in “Adding weather locations and activating the 8760 calculation methodology” on page 6–167.
Figure 2–16 TRACE 700 Weather library
You can use the following types of weather files in a TRACE 700 analysis:
typical meteorological year, .TMY, .TM2■ test reference year, .TRY■ California Energy
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