C.D.S. Newsletter April 2010
In this issue...
- TRACE 700 Version 6.2.5.1 Now Available
- Central Geothermal Modeling
- LEED Modeling Updates
- Fan Library and Curve Library Changes
- Frequently Asked Support Questions
- Meet the C.D.S. Support Staff...Matt Chmielewski
TRACE 700 Version 6.2.5.1 Now Available
Download
update
TRACE 700, Load Design, Chiller Plant
Analyzer, and Load Express updates are now available. The newest
version, 6.2.5.1, includes improved geothermal modeling, a faster
calculation speed, ASHRAE 90.1 updates and changes to the Fan and Fan
Curve Libraries. For a complete list of changes to this version, visit
the TRACE 700 Version
Information section.
TRACE 700 can now model central geothermal systems in addition to
distributed geothermal systems. A central geothermal system consists
of one or more chillers coupled with a geothermal loop that exchanges
heat with the earth. The chillers may be located in a single
mechanical equipment room (thus the term central) and provide heated
and cooled fluid to hydronic heating and cooling air handlers
throughout the building.
New fields have been added to
the Create Plants section for the input of this system. These fields
are documented in the online help (press F1 while on a specific screen
in TRACE). This system configuration is also available as an option
within the Plant Wizard (accessed from the Configuration tab of Create
Plants and TRACE 700 Chiller Plant Analyzer).
In
addition, two new reports are available: the Geothermal Summary report
and Geothermal Plant Load Summary report. The Geothermal Summary
report provides cooling- and heating-related sizing information for
the central plant and chiller/heaters. The Geothermal Plant Load
Summary report consists of the Energy Transfer report, which lists the
monthly energy transferred to and from the geothermal loop, and the
Earth Temperature report, which lists monthly average earth
temperatures and ground loop heat exchanger field fluid
temperatures.
For more information about central
geothermal systems and a sample scenario, refer to “Central geothermal
chillers” on page 3-76 of the TRACE User’s Manual. To access the
manual from TRACE, click Help > Documentation > User’s Manual.
The following new features have been added to TRACE 700 to support
modeling for LEED:
Appendix A Assemblies
During the installation of the update, you will be given the
option to install the ASHRAE Standard 90.1-2007 Appendix A assemblies.
These non-residential assemblies are based on the envelope assemblies
defined in ASHRAE Standard 90.1-2007. If the assembly installation was
skipped, the library export file can be downloaded from the Trane
Download Center.
Fan Power Calculations
TRACE can now compute fan power as described in 90.1-2007
Appendix G. The 90.1-2007 Performance Rating Method (PRM) calculations
can be enabled within the Change Energy Parameters screen. Note that
2004 Energy Cost Budget and PRM calculations remain. Primary airflow
pressure credits (designated A in 90.1-2007), described within table
G3.1.2.9, can be entered within the Fans tab of Create Systems. TRACE
will apply these pressure credits to the fan power calculations. Fan
motor efficiency must be defined within the Overrides section of the
Fans tab.
Building Rotations
The ECB/PRM Summary report now displays the unmet hours for
baseline buildings in the 0-degree rotation only, instead of all
rotations. As always, the Building Temperature Profiles report can be
used to help identify spaces with unmet hours. For more information on
combating unmet hours, see our webinar.
Finally, an option has been added to disable baseline building
rotation when you are not making final simulations. This time-saving
feature allows you to calculate other PRM-related features without the
additional rotations.
Fan Library and Curve Library Changes
Several significant changes were made to the Fan and Curve libraries
in TRACE 700 version 6.2.5.1. These changes will affect building
models when selecting fan types as well as energy usage from a
modified fan. The Z-factor calculations have been removed from the fan
power calculation and some unloading curves have been modified to more
closely approximate the respective fan type.
In addition
to the variable volume fan changes, the fans that include critical
zone reset (also known as fan pressure optimization) have been
modified. The existing fan types listed under the Variable Volume non
SP category have been archived and replaced with new critical zone
reset fans listed in the Variable Volume category. These new fans
include unloading curves to approximate their unloading as well.
When a library member is archived, it is still accessible in the
Library/Template Editors program as well as the TRACE interface. In
TRACE 700, select Show Archive in the Library drop-down menu. In the
Library/Template Editors program, select Show Archive from the View
drop-down menu. As always, you have the ability to create a new curve
or fan in the library or copy an existing/standard library member,
rename it, and modify it as needed. Remember that standard library
members cannot be modified until they are copied and renamed.
For a list of specific changes made to the Fan and Fan Curve
Libraries, visit the TRACE 700 Version
Information section.
For additional questions or
comments, contact CDS Support at 608-787-3926 or email cdshelp@trane.com.
Frequently Asked Support Questions
How do I model demand-control ventilation? How do I model CO2 sensors?
CO2-Based Demand-Control Ventilation calculates the hourly CO2 level
in each space and then determines the required outdoor air quantity.
The hourly CO2 value is a function of the space volume, the number of
people, the ventilation airflow into the space, and the CO2 level of
the previous hour. The amount of CO2 generated by breathing varies
with the people activity level, which is a direct function of the
People Sensible+Latent values entered. The CO2 generated per person is
calculated by the program and the program uses the weather location to
determine ambient CO2 levels. The default ambient CO2 level for all
weather locations is set at 400 ppm and can be changed through the
weather overrides button options under the "Select Weather
Information" section of the program. The hourly space CO2 level
calculation ignores any effect due to infiltration.
CO2
sensors can be modeled in TRACE by following these steps:
Step 1: On the Rooms tab of Create Rooms (or on the thermostat
template), select a CO2 Sensor location (either Room or None) for the
rooms that will have demand-control ventilation control.
Step 2: On the Airflows tab of Create Rooms, select Yes in the
Apply ASHRAE Std 62.1-2004/2007 field and enter the
appropriate information to properly describe space level ventilation
requirements.
Step 3: On the Selection tab of Create
Systems, click the Advanced button. Select the option ASHRAE Std
62.1-2004/2007 w/ Vent Reset in the System Ventilation
Flag field.
Note: System-level ventilation reset
is required for the system to be able to handle zone-level
demand-control ventilation.
Step 4: At the bottom of the screen, select the desired
C02-based DCV option (None, Proportional
Control, or Single Setpoint).
When
Proportional Control is selected, the outdoor air controller
will adjust the outdoor air intake flow proportionally between the
minimum ventilation flow and the design ventilation flow.
When Single Setpoint is selected, the intake airflow is
adjusted to maintain the indoor CO2 concentration at the minimum CO2
concentration in the space for any population. If the OA damper
reaches the minimum outdoor air intake flow and the population in the
zone continues to drop, the OA damper remains at the minimum outdoor
air intake flow as specified in the DCV Minimum OA Intake field
on the Create Rooms – Airflows screen.
The CO2 DCV
controls have no effect on the Design calculations. During the System
Simulation, the CO2 DCV controls are disabled during economizer
operation.
For additional information on CO2-based DCV,
see the Trane Engineering Newsletter, volume 34-5, "CO2-Based
Demand-Controlled Ventilation with ASHRAE Standard 62.1-2004."
How do I change the color of the roof?
The color of the roof is entered under the Advanced button of the
Roof construction library as the Outside Shortwave (Solar)
Absorptivity.
To change the color of the roof, complete
the following steps:
Step 1: From the TRACE menu bar,
select Libraries > Construction Type. The Construction Types
Library screen displays.
Step 2: In the Library
Type field, select Roof from the drop-down menu.
Step 3: In the Description field, select the desired
roof type.
Step 4: Click Copy. This will create a
new library entry for the roof.
Step 5: Enter a unique
name for this roof type in the Description field.
Step 6: Click Advanced. The Advanced Envelope Parameters screen
displays.
Step 7: Enter the appropriate value for the
roof color in the Outside Shortwave (Solar) Absorptivity
field.
- Black = 0.90-0.95
- Brown/Bronze = 0.88-0.91
- Grey = 0.69-0.85
- Blue = 0.79-0.86
- Green = 0.77-0.90
- Red = 0.59-0.79
- Tan/Sandstone = 0.54-0.65
- Cream = 0.40-0.45
- White = 0.30-0.40
Step 8: Once you have entered the appropriate value in the
Outside Shortwave (Solar) Absorptivity field, click
Save.
Step 9: On the Construction Types Library
screen, click Save. The Calculations Results window
displays.
Step 10: Click OK.
Meet the C.D.S. Support Staff...Matt Chmielewski
Matt joined Trane in July 2008 as a marketing engineer with C.D.S.
He graduated from the University of Nebraska – Lincoln with a B.S. in
mechanical engineering. Prior to working at Trane, Matt lived in
Spain, Mexico, and Brazil, and is fluent in Portuguese and Spanish. In
his current role at Trane, Matt provides software training and
support, and has had the opportunity to return to Brazil to give
technical seminars at the CONBRAVA expo and conduct TRACE training. He
is also a LEED AP.
Matt likes to garden and mountain
bike, but dedicates most of his spare time to his brand-new baby girl.
What three items would you take if stranded on a desert island?
Fire, a knife, and an 80-foot yacht.
What is the most enlightening book you've read in the past year?
The Uncivil War at Whitestone Hill by Clair Jacobson.
C.D.S. Newsletter July 2010