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A Home Energy Rating Is Not an Award

 

hers home energy rating duct leakage testENERGY STAR. LEED for Homes. Builders Challenge. HERS. It's easy to fall into the wrong line of thinking about this. I did it myself when I was new to the HERS rating industry. It's even easier now that RESNET is out there pushing hard for builders to adopt the HERS Index as a marketing tool. I'm talking about what a home energy rating is all about and how it's different from energy efficiency and green building programs.

Basically, a HERS rating is just an evaluation. A home doesn't have to meet any level of air tightness or insulation R-values or ventilation or overall energy efficiency. Any home can get a home energy rating. The worst home you can imagine can get a home energy rating. Its HERS Index might be 400 (a really bad number, by the way) and it'll even have one star. But it can still have a HERS rating.

The standards for home energy ratings don't list performance requirements for homes. They list performance requirements for home energy raters and their providers, who do quality assurance on raters' work. The requirements in the HERS standards include things like:

  • All the insulation in a home has to have a grade — I, II, or III — that describes the quality of installation.
  • Conditioned volume includes everything inside the conditioned space boundary (i.e., the building envelope).
  • To measure duct leakage for ducts in an encapsulated crawl space, the rater needs to make sure the crawl space is at the same pressure as the house.

I bring this up today because of some of the comments in my latest article at Green Building Advisor, the one on energy codes versus energy efficiency programs. I think the commenters probably do understand the difference, but those who aren't as involved as HERS raters or who are new to the industry may not see the difference between a home energy rating and an ENERGY STAR label on a new home.

So, what's the proper answer to a question like, How much air leakage does a home energy rating allow? It doesn't matter! A house can be as leaky as a sieve and still have a home energy rating and a HERS Index. It's an evaluation tool. Nothing more.

 

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Comments

Couldn't agree more Alison. We have met with many builders that despite our advice that they set a company minimum HERS threshold if they are going to only use the HERS Index, have not elected to do so. In many cases, they are also only rating their house plans and specs and do not plan to test any houses. The MOU they signed allows for this.
Posted @ Thursday, June 07, 2012 7:49 AM by Matthew Cooper
Agreed, Allison, and I think we will quickly move towards a consumer demand for benchmarking and thresholds once everyone knows how to read the yardstick. A measurement is only good if we have a scale to apply. We have that now. Do you not agree that at some level it is just educational; knowing what a good or bad score means?
Posted @ Thursday, June 07, 2012 8:15 AM by T.C. Feick
true. an energy rating is just to see where the house rates at the time of testing. 
 
 
 
in existing homes the rating is the start point prior to improvements. 
 
 
 
once upgrades are complete then the house is re-tested to verify what % improvements were achieved. 
 
 
 
in new homes, the house has to rate below 70 points to meet energy star standards. 
 
(I think that is the number..don't do a lot of new construction these days) 
 
 
 
I've always thought that the thermal bypass checklist inspection should be mandatory.  
 
if you don't catch the problems while the build is ongoing..its hard to fix it on the end.  
 
contractors are gone to next project and fully paid. 
 
 
 
if insulation isn't inspected then the assumption is level one..bad install. 
 
 
 
very few raters in my area have always done this intermediate inspection. and these homes perform on the end. others who do not do this additional inspection do not achieve the savings due to duct leakage, insulation issues 
 
and air sealing mistakes. 
 
 
 
once the insulation is installed the ducts are roughed in, windows are flashed..its just a good time to get an overall feel for how well the house will test. and trades are still on site...that is important! 
 
 
 
as RESNET evolves into other areas, they should incorperate intermediate inspections as a manditory requirement. otherwise the rating is just paper.  
 
 
 
this is based on my decade of doing this type of work. it doesn't make me popular with the other raters in my area to push for this additional site visit.  
 
 
 
good article alison. keep them comming.
Posted @ Thursday, June 07, 2012 9:24 AM by Debbie
Matthew C.: Wow! I guess I haven't read the MOUs closely enough. Marketing a HERS Index from a projected rating sounds almost deceptive. Any home builder doing that could be setting themselves up for legal action. 
 
TC Feick: Yes, there's a whole lot of education that needs to happen in the construction, remodeling, and home improvement industry. And speaking of setting thresholds, there's been a really good discussion of this very topic related to the question of, What would it take to build a Pretty Good House? Have you seen that? 
 
Debbie: The answer to your question about the HERS Index for ENERGY STAR Version 3 is that there isn't a single number anymore. Instead, the folks at ENERGY STAR decided on a 'variable HERS Index target,' which depends on the house you're rating.
Posted @ Thursday, June 07, 2012 10:44 AM by Allison Bailes
@Matthew, have you actually seen an MOU that allows for unconfirmed ratings from plans? The reason I ask is because the HERS Standard specifically requires all ratings to be confirmed. And as far as I know, there's no proposed or in-process amendment that would change this, at least none are posted on the RESNET website. 
 
"102.1.4.1 Ratings from plans. If the home energy rating Provider‘s program provides for ratings by from plans, the rating be labeled as from plans. Such ratings may be used to demonstrate energy code compliance or programmatic qualification but must be confirmed through a field inspection upon completion of construction."
Posted @ Thursday, June 07, 2012 1:09 PM by David Butler
Builders can "put their money where their mouth is" by installing smaller HVAC units. How confident ARE you that it's insulated properly? Care to do 1,000 sqft per ton?
Posted @ Thursday, June 07, 2012 9:23 PM by Bob
At the recent NAHB Spring Board Meeting, the NAHB Research Center made a presentation to one of the subcommittees of the Construction Codes and Standards Committee on a cost benefit analysis of the 2009 IECC versus the 2006 IECC. Their conclusion was that it pays for itself within seven years and was therefore reasonable. Then they compared 2012 IECC versus 2009 and deemed the payback to be something like 20 years and therefore unacceptable. The point of the research was to provide ammo for those who may be trying to convince local and state code adopters that the 2012 IECC was a code too far. 
 
 
 
The problem with the NAHBRC model, was its "grossness". In an attempt at simplicity, they based their conclusions on an average house, in an average climate zone, in an average moisture zone, with average construction costs, average occupant loads, average utility costs, and on a prescriptive basis only. 
 
 
 
So when somone tries to use it as "proof" in any given locality, local administrators will be able to legitimately counter that the data does not represent local conditions, (unless they are truly "average"). And even then a builder could probably follow a creative performance path, get a HERS rating equivalent to the prescriptive path assumption, and bust the NAHBRC construction cost numbers. 
 
 
 
I offered the suggestion (as the Executive Officer Liaison to the committee) that perhaps RESNET should be solicited as a research partner. Having recently completed their millionth HERS rating, they should have the potential to glean and provide an immense amount of data for every climate zone, every size home and with every imagineable utility cost. Competent raters can also calculate the presumed energy cost in dollars, BtUs, therms, etc. 
 
 
 
RESNET cannot provide the cost of construction or energy efficiency upgrades, nor can they accurately predict occupant behavior, but they certainly could provide more accurancy and relevant data than the woefully inadequate conclusions reached by the NAHBRC. 
 
 
 
RESNET has its place as the dominant national measurement tool. Hopefully they will recognize their potential role as a national data collection service and begin to help influence local and national policy directives. 
 
 
 
Posted @ Friday, June 15, 2012 5:23 PM by kim shanahan
I have yet to have anyone explain how it is the the one millionth ENERGY STAR new home was certified in 2009 yet supposedly the one millionth HERS index was just calculated two months ago.
Posted @ Tuesday, June 19, 2012 1:51 PM by Matthew Cooper
Energy Star for homes preceded HERS ratings and thus had no requirement for a HERS rating at the beginning of the program.
Posted @ Tuesday, June 19, 2012 2:11 PM by kim shanahan
kim s.: Excellent points. If you want to see how cost effective a measure is, it helps to apply it in the correct climate zone and for the correct conditions. 
 
Matthew C.: I guess you didn't see my tweets on that topic this morning. The mathematical side of me rages against someone claiming to know which home was THE millionth home certified when there are so many open channels for certification. I think it's great to celebrate milestones, but to pick one house out of the thousands that were certified at about the same time is definitely a stretch.
Posted @ Tuesday, June 19, 2012 2:12 PM by Allison Bailes
Matthew C.: Oops. I had my hammer out and thought you had a nail. (I.e., I was addressing a different issue than the one you raised.) My guess on that discrepancy is that maybe they didn't count sampled homes as getting a real HERS Index, even though they do get a worst-case Index. I wasn't involved in the mid-'90s, so I don't know if and how many homes got the ENERGY STAR label without a HERS rating, as Kim suggested.
Posted @ Tuesday, June 19, 2012 2:17 PM by Allison Bailes
Matthew C.: I just recalled that part of the discrepancy is probably due to ENERGY STAR homes going through the prescriptive path (the Builder Option Package, or BOP) as well.
Posted @ Tuesday, June 19, 2012 2:19 PM by Allison Bailes
Matthew C wrote: 
> In many cases, they are... only rating their house plans and specs 
 
The implication is that these homes are not being confirmed through mandatory field inspections (see my previous comment). If so, there's a complaint procedure for situations like this. However, if you just meant these homes are not being DB/BD tested, then this is supported by the HERS Standard. The default leakage rate would apply. 
 
There seems to be a lot of confusion on this point. After hearing about homes in a western city that were not being tested, I studied the standard carefully and at best, it's ambiguous on this point. So I checked with several HERS providers and all said they require DB/BD testing (for a HERS certificate). However, none could point to such a requirement in the Standard. The fact that some providers (apparently) do not require DB/BD testing means that not everyone is playing by the same understanding of the rules. Not good. 
 
So I raised this question in the LinkedIn RESNET.US group last month and Steve Baden responded. He confirmed that the HERS Standard doesn't require leakage tests. But he added that most builders elect to have their homes tested since the default leakage rates impose a serious penalty on the HERS Index. More likely, it's because they nor their providers are aware it's optional. The reality is that for builders who are at the margin, the impact may be as small as 2 points, depending on the particulars. 
 
The pertinent chapter is currently undergoing revision for ANSI compliance, so hopefully this can be resolved. Steve Byers, who is a provider and is on the RESNET Board, is on top of this. 
Posted @ Friday, August 10, 2012 9:17 PM by David Butler
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