February 23, 2004—New requirements in the American Society of Heating, Refrigerating and Air-Conditioning Engineers’ (ASHRAE) energy conservation standard will ensure that building energy simulation programs remain bug free.
Proposed addendum 90.1p was approved for publication at ASHRAE’s 2004 Winter Meeting in January.
ANSI/ASHRAE/IESNA Standard 90.1-2001, Energy Standard for Buildings Except Low-Rise Residential Buildings, provides the minimum requirements for the design of energy efficient buildings.
The “energy cost budget” section of Standard 90.1 relies on the use of a building energy simulation program to estimate the energy cost difference between a design building model and a budget building model.
Designers can select any program for these estimates as long as it complies with requirements in the standard describing the minimum capabilities of the software.
The standard currently does not contain any requirements that would indicate the minimum quality of the program being used. Addendum 90.1p requires that the programs be tested with ANSI/ASHRAE Standard 140-2001, Standard Method of Test for the Evaluation of Building Energy Analysis Computer Programs.
The tests in Standard 140 focus on the software’s ability to simulate the building envelope and how that envelope responds to the climate. “This is the most fundamental requirement of a building energy simulation program,” Jason Glazer, chair of the 90.1 energy cost budget method subcommittee, said. “Clearly if this requirement is not met, it does not matter how well chillers and cooling towers are simulated.” The Standard 140 method of test requires the testing of the building energy simulation program by software developers and for developers to examine the differences between the performance of its program and the other programs. This allows errors to be diagnosed, according to Glazer.
“Requiring the program to be tested using the procedure in Standard 140 benefits designers using the energy cost budget method by prompting developers to fix bugs found during the test,” he said.
Other addenda to 90.1 approved for publication are:
- 90.1e creates an informative appendix for rating the performance of building designs that exceed the minimum requirements of the standard. 90.1o revises an exception to Section 6.3.1. to indicate that it applies only to heat recovery systems that are required by Section 6.3.6.2.
There was concern that the existing wording would allow a misinterpretation that by just having condenser heat recovery to preheat hot water without regard to how much energy was being recovered, the requirement for economizers in Section 6.3.1. could be avoided, according to Jerry White, chair of the Standard 90.1 committee.
90.1r adds requirements regarding return duct insulation. For more information, contact ASHRAE.
