HERS index

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New York Builder Wins RESNET Prize

The annual Cross Border Challenge recognizes energy-efficient designs by U.S. and Canadian builders

Posted on Apr 5 2017 by Scott Gibson

A house built to the Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. standard in upstate New York has been recognized in this year's Cross Border Challenge for having the lowest HERSIndex or scoring system for energy efficiency established by the Residential Energy Services Network (RESNET) that compares a given home to a Home Energy Rating System (HERS) Reference Home based on the 2006 International Energy Conservation Code. A home matching the reference home has a HERS Index of 100. The lower a home’s HERS Index, the more energy efficient it is. A typical existing home has a HERS Index of 130; a net zero energy home has a HERS Index of 0. Older versions of the HERS index were based on a scale that was largely just the opposite in structure--a HERS rating of 100 represented a net zero energy home, while the reference home had a score of 80. There are issues that complicate converting old to new or new to old scores, but the basic formula is: New HERS index = (100 - Old HERS score) * 5. Index score among U.S. custom built homes.


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Image Credits:

  1. All photos: Matt Bowers

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A Move Toward More Helpful Appraisals

Home buyers in some states will see the HERS Index listed on the appraisal form

Posted on Mar 16 2017 by Scott Gibson

Developers of the Home Energy Rating System and the Appraisal Institute are teaming up to give home buyers a better understanding of how much it will cost to live in the houses they're interested in buying.


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Image Credits:

  1. Kathy Kimpel / CC BY 2.0 / Flickr

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States are Amending, then Adopting, the 2015 IECC

As usual, the code adoption process in the U.S. is a mixed-up mess

Posted on Oct 28 2016 by Martin Holladay
prime

In the U.S., the system for writing, adopting, and enforcing building codes is peculiar. Lots of people are confused about building codes.

Anyone interested in understanding building codes in the U.S. needs to start by learning a few basic facts:

  • The U.S. doesn’t have a national building code. Building codes vary from state to state, and in some cases from city to city.

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Image Credits:

  1. Randy Martin

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Off-Grid in Canada: An Energy Model of the House

A last-minute decision to seek LEED certification prompts an evaluation of energy use and a HERS Index report

Posted on Sep 29 2016 by Craig Anderson

This is one of a series of posts by Craig Anderson describing the off-the-grid house he built with his wife France-Pascale Ménard near Low, Québec. Craig writes about the "Seven Hills Project" in a blog called Sunshine Saved. For a list of Craig's previous posts, see the list of "Blogs by Craig Anderson" in the sidebar below.


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Image Credits:

  1. Image #1: Craig Anderson

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New Energy Code Helps Inform Home Buyers

Revisions to the International Energy Conservation Code include an Energy Rating Index to guide purchasers of new homes

Posted on Aug 10 2015 by Kim Tanner

The International Energy Conservation Code (IECC International Energy Conservation Code.) evolves to meet current energy efficiency needs. Over the years, new requirements have been added to the IECC to make it stricter and increase overall energy efficiency of buildings.

Some states are resistant to these changes, and some choose not to adopt an IECC at all. In fact, of the 50 states and the District of Columbia, ten either haven’t adopted an IECC or are operating under a code older than the 2006 IECC, according to the Online Code Environment and Advocacy Network.


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Image Credits:

  1. International Code Council

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A Home Energy Rating Is an Asset Label

It isn't meant to be an accurate predictor of energy bills

Posted on Mar 25 2015 by Allison A. Bailes III, PhD
prime

When I'm explaining home energy ratings and the HERS Index to people, I often get asked, "How accurate is a HERS rating? Will my energy bills really be close to what it says?" In the mind of the questioner, that's one question. To someone who understands what HERS ratings really measure, it's two separate questions. Let me explain.


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Image Credits:

  1. RESNET

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Why Is the HERS Reference Home Based on an Outdated Energy Code?

Should the HERS Index calculation be updated?

Posted on Feb 18 2015 by Allison A. Bailes III, PhD
prime

The HERS Index is a number that gives you a measure of how energy-efficient a home is. We can debate how relevant that number is or how accurate is the energy model it's based on, but the fact is that it's being used.


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Image Credits:

  1. Energy Vanguard

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Study Finds Huge Variation in California HERS Rating Results

Six HERS raters came up with as much as 48% variation in the HERS Index and >100% in heating and cooling consumption

Posted on Sep 17 2014 by Allison A. Bailes III, PhD

A home energy rating is supposed to tell you how energy-efficient your home is. A certified home energy rater goes to the home and collects all the data relevant to energy consumption in the home (well, all the data included in the rating anyway, which is almost everything).


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Image Credits:

  1. John Proctor, Rick Chitwood, and Bruce Wilcox
  2. Wikimedia Commons, public domain

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The 2015 IECC Recognizes Home Energy Ratings

With a specific HERS Index for each climate zone, the new energy code provides home builders with an alternate compliance path

Posted on Nov 20 2013 by Allison A. Bailes III, PhD

Great news, everyone! (If you read that in the voice of Professor Hubert Farnsworth, please don't let your imagination run away with you. This really is great news.) The HERS Index will part of the 2015 International Energy Conservation Code. Why does that matter?

Because it will help home builders build better homes.


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Image Credits:

  1. Energy Vanguard
  2. RESNET

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Is NIST Serious About Net-Zero-Energy Homes?

Their report cites the need for a scoring system, but inexplicably fails to mention the HERS Index

Posted on Jun 19 2013 by Allison A. Bailes III, PhD

The National Institute of Standards and Technology (NIST) still handles a lot of our basic numbers work, keeping lasers, hunks of metal, and atomic clocks that determine our standards of length, mass, and time. But it turns out they also have an interest in net-zero-energy (NZE) homes.

They’ve built and outfitted an amazing NZE research facility, and they also have convened meetings of experts to develop guidelines for NZE homes. But there’s something about their latest report I just don’t understand.


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Image Credits:

  1. National Institute of Standards and Technology
  2. RESNET

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