C.D.S. Newsletter December 2010

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Accurately Determine ASHRAE 90.1 Fan Full-Load Energy Rates in TRACE

TRACE 700 can automatically determine the fan full-load energy rates based upon the type of analysis being performed: ASHRAE 90.1-2004 Energy Cost Budget (ECB), ASHRAE 90.1-2004 Performance Rating Method (PRM) or the ASHRAE 90.1-2007 Performance Rating Method (PRM). Note that the Energy Cost Budget method for ASHRAE 90.1-2007 is not available, and the existing ASHRAE 90.1-2004 ECB calculations do not account for Addenda AC (released March 2007).

These fan power calculations are enabled in two separate sections of TRACE:

  • Change Energy Parameters screen.
    From the Actions menu, select Change Energy Parameters. Select the Apply ECB/PRM rules to fan sizing? check box, and then select the appropriate method. Currently, there are two options: ASHRAE Standard 90.1-2004 and ASHRAE Standard 90.1-2007 (PRM Only).
  • Calculate and View Results screen.
    On the Calculate and View Results screen, under Base Alternative For, identify the baseline alternative for the method being used. Do not use the same alternative for both the Energy Cost Budget and Performance Rating Method calculations.


Special considerations for PRM calculations
When using the 2004 methodology, the appropriate fan type must be defined to ensure accurate calculations. If the system is constant volume, a constant-volume fan must be selected. If a variable-volume fan is selected in this scenario, the variable-volume fan power calculations will be used, and the calculated full-load energy rates will be wrong.

When using the 2007 fan power calculations, TRACE will look at the baseline system that is chosen to determine which set of calculations are required (see p. 25 of the Trane HVAC Resource Guide for Green Building Design). Choosing the correct type of fan is still important to account for proper unloading; however, the fan type will not impact the actual full-load calculation procedure. There is an additional option that is available when using the 2007 calculations that allows for fan pressure credits to be entered. The 90.1 Primary Fan Power Adjustment input on the Fans tab of Create Systems can be used to enter a summation of applicable pressure credits (in units of inches water gauge) for the system. This value is defined, within the Standard, as A.

Output reports
Two output reports show the calculated values from the procedure. The Equipment Energy Consumption report shows each applicable fan and the original user-entered full-load rate (designated as Orig. FL Rate =) along with the value that TRACE computed based upon the selected calculation procedure.

When the 2004 or 2007 PRM rules are used, an additional report is available. The PRM Fan Power Details report shows the values that are used for each calculation on a system-by-system basis. The PRM procedure determines the system fan power not individual fan power. The calculation procedure may be difficult and a multiple-fan procedure is not defined within the standard; therefore, TRACE uses a Fan Ratio Override to distribute the calculated system power among the applicable fans.

Examples
This PDF includes examples to illustrate how the fan power is calculated for several different types of systems using both the 2004 and 2007 rules. Note that some values are intentionally low to help illustrate and differentiate the procedure.

ASHRAE 90.1-2010 Resources Now Available

ANSI/ASHRAE/IESNA Standard 90.1-2010, Energy Standard for Buildings Except Low-Rise Residential Buildings, was published this fall. The standard set an aggressive goal of 30 percent energy cost savings over the 2004 version. Trane resources are now available that provide an overview of the major changes including updates to the modeling section.

Trane has been actively involved in this development cycle of 90.1 and hosted the Engineers Newsletter Live program, “ASHRAE Standard 90.1-2010.” The program now available on-demand, features Trane experts Mick Schwedler, immediate past Chair of the 90.1 committee, and Susanna Hanson, member of the 90.1 mechanical sub-committee, who discuss major changes to the envelope, mechanical, lighting, and addenda that were incorporated. Presenters also include Matthew Bye, product engineer, who discusses control requirements and Mike Patterson, sales training manager, who provides an overview of energy modeling changes. The on-demand course qualifies as 1.5 C.E. LEED-specific credits for LEED professional credential maintenance.

The latest Engineers Newsletter, available as a supplement to the broadcast, covers the mechanical system mandatory and prescriptive requirements. Contact your local Trane office or C.D.S. Support for more information.

New Courses Available for LEED Credential Maintenance

New on-demand courses have recently been added to the Trane.com Continuing Education offering. Each course qualifies for 1.5 LEED-specific continuing education (CE) hours from the U.S. Green Building Council (USGBC). As part of USGBC’s credential maintenance program, LEED APs are required to earn 30 CE hours biennially, 6 of which must be LEED-specific.

  • LEED 2009 Modeling and Energy Savings Details
  • Energy-Saving Strategies for Rooftop VAV Systems Details
  • ASHRAE Standard 90.1-2010 Details

The courses listed are offered at no charge. Visit www.trane.com/continuingeducation to view all online courses.

Meet the C.D.S. Support Staff... Scott Delo

Scott joined Trane in 2010 as a marketing engineer with C.D.S. He is a graduate of the Virginia Military Institute with a bachelor’s degree in Mechanical Engineering. Scott is a native of Pittsburgh, Pennsylvania, and a 2nd Lieutenant in the Wisconsin National Guard.

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