By 2020, will we have a common dialogue on energy use? 

As the building industry has increased its attention on measuring and tracking energy-efficiency data, an array of rating tools and assessment programs have popped up to help manage the collection and analysis of this information. These tools help create baselines from which improvements can be made and tracked, but while the systems are beneficial, they are also confusing as the methodologies are not standardized. Can a framework for energy efficiency evaluation tools be created to better consistency in energy-efficiency data collection and analysis across the globe?

This is the hypothesis behind “Comparing Building Energy Performance Measurement,” a new research paper from the Global Buildings Performance Network and the Institute for Market Transformation (IMT). The research team, led by IMT project manager David Leipziger, compared 17 building energy-performance assessment systems from 10 countries, including the National Australian Built Environment Rating System (NABERS); the Ministry of Housing and Urban and Rural Development (MOHURD) rating in China; Energy Performance Certificates and Display Energy Certificates in the United Kingdom; and the Home Energy Rating System (HERS) and Energy Star in the U.S. Comprehensive green ratings that include energy as one of many elements of assessment, such as LEED, were excluded from analysis. The goal of the report is a standard framework of comparison such as a common set of terms and characteristics—not standardization of the systems as a whole.

While the unique characteristics and definitions of each rating system and tool make an apples-to-apples comparison nearly impossible, the methodology of each system is easier to study, according to Leipziger. The report examined the tools in their approach to six basic underlying characteristics: energy consumption, energy type, building floor area, building type, performance scale, and energy uses. The first conclusion? None of the 17 systems uses the same methodology. Other findings:

  • Meanings behind common terms and concepts are poorly defined. For example, in Australia and the U.S., “rating” refers to an energy performance assessment structure, the associated evaluation methodology, how it is used, and the final result of score. But in Europe, standards limit “energy rating” exclusively to an efficiency evaluation process. The assessment structure is the certification, and the final score is the energy class.
  • Performance assessment systems are extremely flexible to local priorities.
  • While there is consistency in how to define energy quantification methods and energy types, there is little consensus on how to define floor area or which energy loads should be included or excluded from an assessment.
  • It is unclear how rating methodology and assessment structure affect the success of building energy performance.

Above all of these conclusions, Leipziger and his team found a need for closer consideration of what energy efficiency connotes and how it is evaluated, as well as a need for increased transparency of what, precisely, is assessed and how it can help real estate investors, multinational corporations, policymakers, and researchers to make more informed decisions based on energy-performance scores.
“Parsing out the individual characteristics of each system increases transparency in energy performance assessment,” Leipziger writes in the study. “For the real estate industry, the value of a greener, more energy-efficiency asset is easier to ascertain with an understanding of how these characteristics are quantified. While this classification does not allow building-to-building comparisons, it enables the real estate community to peek behind the curtain of energy performance and make determinations about what is important to them.”

Speaking the same language across systems and tools, Leipziger notes, is the first step toward more direct policy comparison.

Click here to download the full study.

Building on its successful launch in 2012, ECOHOME’s Vision 2020 program continues in 2013, focusing on eight critical areas in sustainability. Track our progress all year as our panel of visionary focus-area chairs, our editors, and leading researchers, practitioners, and advocates share their perspectives on initiating, tracking, and ensuring progress toward sustainable priorities and goals in residential construction between now and 2020. The program will culminate in an exclusive Vision 2020 Forum in Washington, D.C., in September 2013, and with a special edition of ECOHOME in Winter 2013. Click here to see the 2012 Wrap-Up.