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The City of Boulder, Colorado Adopts Energy Rating Index Requirement as part of Residential Energy Code

May 16, 2017

The City of Boulder, Colorado has joined the ranks of states and municipalities that have adopted the Energy Rating Index as part of their energy code.

Boulder’s action has put its residential energy code on a net zero energy trajectory. Under the new code, all new homes larger than 5,000 square feet must be net-zero energy.  Under the provisions of the new code all homes will have to be net zero by 2031.

The city’s new energy code is based on its previously-adopted 2012 International Energy Conservation Code (IECC) but requires new homes to meet updated Energy Rating Index (ERI) targets based on square footage.  All homes over 500 square feet must have an ERI score.

Homes that are 1,500 square feet or less must have an ERI score of 60 or less.  As the house size increases the ERI scores grow more stringent.  Homes between 4,000 and 5,000 square feet must have an ERI score of 40 and homes that are 5,000 square feet or more must have an ERI score of -0- or less.

Below is the ERI target scores by the square footage of the home.

The new Boulder code also requires increased energy performance stringency on major renovations of existing homes.  The code requires ERI scores for additions to grow more stringent as the percentage of the addition and size of the home increases.

For example, the ERI requirement does not apply to additions to homes that are less than 1,250 square feet in size.  The ERI score requirements, however, kick in when additions on homes are over 1,250 square feet in size and the addition is increasing the square footage of the home by over 80%.   In this case the ERI target score would be 70.  The stringency of the ERI scores increases as the size of the home increases.  A home of 5,000 square feet that increases the square footage by 20% would have a ERI target score of 34.

Boulder’s code also requires that new buildings be solar-ready and electric vehicle-ready, and have sustainable landscaping.

The new code is posted at City of Boulder Energy Code

There are now a total of thirteen states that have adopted the Energy Rating Index as a compliance option to their state energy code.  The states that have incorporated the Energy Rating Index into their energy code are:

  • Alabama
  • Florida
  • Hawaii
  • Illinois
  • Maryland
  • Massachusetts
  • Michigan
  • Nevada
  • New Jersey
  • New York
  • Texas
  • Utah
  • Vermont

Municipalities from New York City to Denver have also adopted an Energy Rating Index option to their residential energy codes.

RESNET and the International Code Council (ICC) conducted a webinar on the Energy Rating Index Option to the 2015 IECC and the opportunities for certified RESNET HERS Raters to be ICC certified Energy Code Inspectors.  To download the webinar go to ICC/RESNET Energy Rating Index Webinar for Code Officials

RESNET and the ICC have produced a video production explaining how HERS can be used to demonstrated compliance to an energy code.  To view the video go to HERS Index and Energy Codes