Portfolio Manager Technical Reference: ENERGY STAR Score

EPA’s 1 - 100 ENERGY STAR score is an external benchmark for assessing the performance of commercial buildings. The ENERGY STAR score, expressed as a number on a simple 1 - 100 scale, rates performance on a percentile basis: buildings with a score of 50 perform better than 50% of their peers; buildings earning a score of 75 or higher are in the top quartile of energy performance. First introduced in 1999, the score has been adopted by leading organizations across the United States because it offers a simple way to evaluate measured energy use, prioritize investments, and communicate relative performance across a portfolio of buildings. In July of 2013, the Environmental Protection Agency (EPA) and Natural Resources Canada (NRCan) together released a 1 - 100 ENERGY STAR score for Canadian buildings, which applies the same methodology to assess measured performance relative to Canadian building stock. Within each section of this document, distinctions between the U.S. and Canadian methodologies are noted.

Recognizing the widespread adoption of the ENERGY STAR score in the commercial marketplace, EPA continually reviews and updates the technical approach to ensure accurate, equitable, and statistically robust scores. The overall objectives of the ENERGY STAR score are to:

  • Evaluate energy performance for the whole building
  • Reflect actual metered energy consumption
  • Equitably account for different energy sources
  • Normalize for building activity
  • Provide a peer group comparison

Once developed, the ENERGY STAR score is programmed into EPA’s online measurement and tracking tool, ENERGY STAR Portfolio Manager®. The following steps are used to compute the score for an individual property:

  • Enter data into Portfolio Manager
  • Compute actual source energy use intensity
  • Compute the predicted source energy use intensity
  • Compute an efficiency ratio comparing the actual use with the predicted use
  • Assign a score based on how the ratio compares with the national distribution
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