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On the Path: Rating the Energy Performance of Commercial Buildings

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For more than a generation, EPA fuel economy labels have allowed consumers to compare the potential environmental impact of a large selection of vehicles. CAFÉ standards have provided a complementary, regulatory platform (albeit a leaky one) to improve vehicle performance. While energy codes have been a regulatory effort to effect building energy performance, building owners and occupants have not had a comparable labeling system. Those missing labels are now almost in reach, beginning with the implementation of a few localized building rating systems that strive to use market-based forces, providing opportunities for:

  • Owners and operators to compare buildings
  • Potential buyers or tenants to review rating labels and documentation and gain additional insight into facility value and potential long term operating expense
  • O&M staff to make better informed decisions about maintenance activities

Early in 2010, the City of Seattle mandated building performance ratings and is phasing in program implementation through 2013 . The rating mandate covers public buildings greater than 10,000 square feet, private non-residential buildings over 50,000 square feet, and multi-family buildings of more than five units. Washington State has a very similar program with the same timeline. The City of Portland has proposed launching a program to rate commercial buildings larger than 20 thousand square feet. New York City, Austin, Texas and the State of California are all in the process of implementing programs. The great majority of these programs rely upon EPA’s Portfolio Manager to assess operating performance.

These local programs have generally used utility billing data to assess and compare operating performance. ASHRAE’s Building Energy Quotient system, abbreviated as Building eQ (“BeQ”), a more comprehensive approach that assesses both as designed and in operation performance, is positioned to become a U.S. national standard.

The BeQ approach, similar to European systems, includes two rating categories. An “As Designed” asset rating assesses building components and the design energy model to consider energy performance potential. The second, an “In Operation” rating, uses billing data to measure actual performance. Together, these two components can be used to assess the divergence between estimated/potential and actual performance.

The “As Designed Asset” Rating

  • Measures the energy-efficiency quality of physical, as-built, building and system components; rating the building, not occupancy and operation
  • Documents energy design features
  • Calculates source EUI based on normalized operations, occupancy and usage patterns
  • Is useful for code-compliance and determining whether design criteria are met (AEDG. ES, LEED, Green Globes)
  • Provides quality control by requiring a certified modeler to do the rating
  • Estimates design energy end uses and benchmarks to ASHRAE Standard 90.1 w/Appendix G and provides quality assurance  through ASHRAE modeling protocols
  • Rates envelope and lighting systems design with COMcheck
  • Requires field verification
  • Is relevant for real estate transactions.

The In Operation” rating   

  • Is meant to improve operations and can be used to manage building portfolios over time
  • Is based on measured energy use, adjusted for weather
  • Requires a site visit to verify performance
  • Documents key energy efficiency operational features
  • Indicates ENERGY STAR labels or LEED-EB earned in specific years
  • Lists information about completed energy efficiency retrofits and building commissioning
  • Provides optional information on potential for additional energy efficiency improvements
  • All ratings will be dated and renewal will be encouraged

The best BeQ score indicates a zero net energy building. As a result, a BeQ rating does not correlate with the more commonly known ENERGY STAR rating and scoring, which is based on the statistical energy use of a building, as recorded in the CBECS database. While it is not possible to make a connection between the two ratings, ASHRAE has developed a certificate that will report the ENERGY STAR score of the buildings that have earned an ENERGY STAR rating.


Building EQ Market Timing

According to Lilas Pratt, ASHRAE Manager—Special Projects:

“ASHRAE is exploring a business plan along with the volunteer/staff structure needed to support that plan for the BeQ program.  Because we anticipate this program moving the industry ahead towards net zero energy buildings, we want to explore all possible options before we make a full scale launch. We especially want to make sure that the program is built on a strong technical foundation.”

The BeQ operational rating and asset rating are proceeding on somewhat different timelines. During a January meeting, the ASHRAE committee responsible for the operational rating system approved a Fall 2011 launch, targeting initial review of two projects per working day. A permanent committee has been established and details are being refined, as the necessary supporting materials, including forms, procedures, and on-line platforms, are being developed.

The asset rating system is in pilot mode, testing procedures to provide consistent comparisons with baseline buildings that are equivalent to the CBECS baseline (the most robust baseline currently available). Multiple modelers are assessing the same building, validating the ability of the rating system protocol to generate consistent results. Pilot asset rating results are expected in September, and at that time, decisions will be made about next steps.
 

Complementary Resources

To support the “As Designed” rating program and to help ensure consistency, ASHRAE, in collaboration with the U.S. affiliate of the International Building Performance Simulation Association (IBPSA-USA) and the Illuminating Engineering Society of North America (IESNA),  has developed a new Building Energy Modeling Professional (BEMP) certification program. The program certifies individual ability to evaluate, choose, use, calibrate, and interpret the results of energy modeling software and individual competence to model new and existing buildings and systems. This will go a long way toward a much needed standardization of modeling procedures.

ASHRAE has also developed a Building Energy Assessment Professional (BEAP) certification program in collaboration with representatives from ASHRAE’s Building Energy Quotient (BeQ) program, IESNA, NIBS, SMACNA, and TABB; to certify individual ability to audit and analyze residential, commercial, and industrial buildings, including determining project scope, collecting data, analyzing building performance, interpreting results, evaluating alternatives, submitting recommendations for energy conservation measures, and assisting with the implementation of these recommendations.

Both the BEMP and BEAP certification exams are widely available at testing centers throughout the United States.

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