Builders Circle Blog: Football, Golf and HERS Ratings
Jim Baker 02/25/2012
The HERS energy rating on a house is more like golf than football. Football is loud, rough, and high score wins. Golf is quiet, skillful, and low score wins, with the typical championship golf courses having par values of 72. The official HERS rating for the HBA's Habitat house is in…and the final ENERGY STAR Rating is 70. That is a thirty percent improvement over a normal new home.
Our goal was to build a house with lower utility bills, better comfort, and avoid costly maintenance issues in the future. This was accomplished by developing a total system that works together using each dollar for its best value. Like golf, there were many small and subtle things we could tweak. Experience always helps, but unlike any sport I have seen, our strategy was pre-tested using computer analysis. The result was an outstanding house using simple, proven techniques and normal building products.
The HERS number that Energy Star uses is based on a national standard with RESNET. It starts with the 2004 code. Your house built to this code would be assigned, by definition, 100 points. This “standard model” is said to have a HERS (Home Energy Rating System) rating of 100. The Energy Star goal is to have a house with a HERS rating of less than 85 (the lower the number the better). Houses built in the 1980’s have HERS ratings generally between 120 and 150 plus, older homes much higher. Those in the 1990’s are a little lower. Building codes in 2004 began to include energy standards that required conservation, but it is fair to say that most houses before 2004 are less than efficient.
In golf minor adjustments can significantly help lower a score, and in building houses the adjustments are in shape, size, orientation, location, windows, insulation, HVAC equipment, and hundreds of other details that get the rating score lower. It is not difficult to lower the rating, but at some point cost begins to be the limiter on tight budgets, as in the above-mentioned project. What was done there was all about smart choices and correct energy saving building practices, not big money.
Stop and think about what a rating of “70” means. That is almost a one-third lower utility cost. This means we can build three houses for about the same utility costs of two older homes. This is good news to a growing community. Price-wise, building new power plants is becoming impossible. More houses mean peak loads that eventually can't be met. Homes with low HERS Ratings do best in peak load conditions. The green techniques produce a tighter house that greatly outperforms normal construction, particularly in extreme conditions.
A HERS rating of 70 may not bring thousands of fans to their feet with a thunderous applause, but if you listen closely, you can almost hear the sigh of relief as the homeowner scores another small utility bill. That’s reason for a standing ovation any day of the year!
Jim D. Baker, B and G Drafting – HERS Rater and NAHB Verifier on this project.
In January 2011, the HBA of Greater Springfield announced it would partner with Habitat for Humanity of Springfield to build the first two homes in Habitat’s new Builders Circle development. The homes will be certified to the National Green Building Standard and their construction will serve as a demonstration of flexible and affordable methods by which construction professionals can build green in a residential setting.
Jim Baker (B&G Drafting) is a Certified Green Professional (CGP), a HERS Rater, and a certified NAHB Green Building Verifier. He also helped design these and other green-built homes throughout the area. This Builders Circle Project Blog helps keep HBA industry professionals and curious consumers up to date on the latest green building features being incorporated into the project. The blog also provides updates on the project’s latest progress and upcoming needs. Those who would like to help with the project are encouraged to leave their comments at the end of blog posts, or on the project's facebook page, to offer your assistance.