RESNET Board Reaffirms Technical Basis of the Calculation of Energy Rating Index After Robust Investigation of Cost-Based Rating Index Option

May 10th, 2018 - Posted by under RESNET News

The basis for calculating Energy Rating Index and HERS Index is specified by ANSI/RESNET/ICC Standard 301.  This basis is the normalized Modified End Use Loads (nMEUL) method defined by Section 4.1.1. of the standard.

There have been a number of proposals submitted to RESNET to reconsider the technical basis of the calculation of the Energy Rating Index.  One has been to base the index calculations on energy costs.

To investigate this option, the RESNET Standards Management Board created a New Work Item (NWI) that charged Standards Development Committee 300 with establishing a Cost-Based Energy Rating Index Task Group to investigate the feasibility of a cost-based rating index and, if feasible, to develop a concept and work plan for a cost-based calculation method.

The Cost-Based Energy Rating Index Task Group was chaired by Jerry Phelan of Covestro LLC.  Its other members include:

  • Martha Brook, California Energy Commission
  • Craig Drumheller, National Association of Home Builders
  • Philip Fairey, Florida Solar Energy Center
  • Neil Leslie, Gas Technology Institute
  • Vrushali Mendon, Pacific Northwest National Laboratory
  • Steve Rosenstock, Edison Electric Institute

Informed by the Matrix of Potential Metrics for RESNET HERS Index provided to RESNET Standards Development Committee 300 by the Calculation Subcommittee in 2015, the task group developed a detailed list of parameters, along with a comparison of ways to incorporate those parameters in a rating. A significant analytical effort by Martha Brook of the California Energy Commission and Philip Fairey of the Florida Solar Energy Center comparing different energy rating methods also informed the task group during its deliberations.

The Cost-Based Energy Rating Index Task Group identified key elements of a cost-based rating index, issues associated with the current normalized Modified End Use Loads (nMEUL) methodology, advantages and disadvantages of potential cost-based methodologies, analyses in support of the task group’s needs, and provided joint and individual recommendations and viewpoints.

Key elements considered by the task group included:

  • Point of Use Annual Energy Reduction
  • Time of Use Annual Energy Reduction
  • Reference Home Methodology
  • Renewable Energy Considerations
  • Energy Prices

The Cost-Based Energy Rating Index Task Group worked to achieve consensus on issues, but on critical aspects could not reach agreement.

After years of deliberation and twenty eight meetings, the Cost-Based Energy Rating Index Task Group found that “As a result of fundamental disagreements within the group about the reference home characteristics and treatment of renewable energy, it was not possible to provide a consensus work plan for a cost-based rating index calculation methodology”.

The findings of the task group are contained in the RESNET Cost-Based Rating Feasibility Report.

The report can be downloaded at RESNET Cost-Based Rating Feasibility Report.

The RESNET Board of Directors carefully reviewed and discussed the Cost-Based Rating Feasibility Report.  After deliberations at its meeting on April 3, 2018, the RESNET Board voted to adopt the following RESNET Board policy: “RESNET will not change the basis of the HERS Index calculation until otherwise directed by the Board.”

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