An Idea to Simplify the ENERGY STAR New Homes Program
In case you haven’t heard, version 3 of the ENERGY STAR new homes program requires homes to be more energy efficient and meet higher standards than version 2 of the program. That is as it should be. Energy codes and standard practices in the industry are improving, and an ENERGY STAR home is supposed to be better than a standard home.
In case you haven’t heard, version 3 of the ENERGY STAR new homes program requires homes to be more energy efficient and meet higher standards than version 2 of the program. That is as it should be. Energy codes and standard practices in the industry are improving, and an ENERGY STAR home is supposed to be better than a standard home.
Home builders and home energy raters haven’t exactly embraced the introduction of version 3, however. The market for homes is way down because of the economy, and new homes are still competing against a lot of foreclosures. Version 3 will cost the builders more. What seems to be the biggest problem, though, is the significantly increased complexity.
I love the ENERGY STAR homes program and want to see it sustain the momentum it’s achieved. With over a million new homes qualified since the program began and market share of 25% now, this program is definitely a success.
Here’s where I think they took a wrong turn. A builder can qualify their homes for the ENERGY STAR in one of two ways: the prescriptive path or the performance path. One of the big problems, in my opinion, is that the program administrators don’t really trust HERS raters and home builders to execute the performance path, so they’ve loaded it with prescriptive requirements.
What they call the peformance path isn’t a true performance path.
In fact, the performance path air sealing requirements are all prescriptive. Builders have to do all the items on the Thermal Enclosure Rater Checklist, but they don’t have to meet any particular threshold for air leakage if 
they’re using what ENERGY STAR calls the performance path. Checking off items on a checklist is prescriptive. Air sealing a house so that it meets a threshold when tested with a Blower Door is a performance measure.
I’ve already written about how I think the HVAC sizing issue could be fixed in a similar way. We could have a benchmark for sizing of air conditioners based on location. HVAC contractors can understand square feet per ton, so let’s tell them what their minimum is there and as long as they meet that, the HERS rater can approve it.
I think it’s time to hit the Reset button. We have this tool called a home energy rating, so let’s use it.
Finally, this seems a great time to recall one of Einstein’s famous quotes:
“Everything should be made as simple as possible, but not simpler.”
~ Albert Einstein
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“You say tomato, I say
“You say tomato, I say tomahto” is ES motto… 🙂
Would indeed be ironic if the
Would indeed be ironic if the industry came full circle and focused on sqft/ton. But you would be speaking to a broader audience, as what I call “the ignorant half” of the HVAC industry has been using that metric all along. Some do it openly, some hide behind fudged Manual J, but I get the message this is the language they think and speak.
+1, we need to raise the
+1, we need to raise the minimum standards for how many sq ft should be covered by each ton of A/C. While were at it hit the heat side too, putting a 40,000 BTU (smallest you can get from many manufacturers) in a 2000 sq ft house would scare most HVAC contractors. 40,000 BTU heat should be more than enough for a 2,000 sq ft energy star home in all but the coldest of climates. The oversize problem is even worse on the heat side since the cost of a 100k furnace is only a $200 more than a 40k furnace, makes it easy/cheap for the contractor to “play it safe”.
Armando:
Armando: Maybe so, but you say potato, I say potato. ;~)
M. Johnson: Yep!
Bob: In the other article, I suggested that 1000 sf/ton should be our baseline for energy efficient homes. And yes, that’s a good idea to do the same kind of thing with heating systems. These baselines would just be a threshold that the HVAC contractor has to meet, but they’d still need to do accurate load calculations.
I believe Allison makes a
I believe Allison makes a very good point. I believe the ES requirements and checklists could be greatly simplified. For example, instead of all the rules about how to install flex duct, simply state that flex duct (and many other building materials) be installed according to the manufacturers instructions and other established standards. The manufactures provide all the same details on installing flex duct.
I have long commented on the fact that foam seen at the penetrations does not mean they are sealed. The seal is easily tested with a blower door and IR camera. The presence of sealant is prescriptive, but the performance is what matters.
Let’s give this a few days and then summarize this blog and these comments and send them to energystarhomes@energystar.gov
Robert D.:
Robert D.: I’m glad I’m not the only one! Regarding ducts, since Version 3 requires testing and balancing to get proper air flow, that should eliminate the prescriptive requirements there. If the system is sized properly and gets the right amount of air flow, those performance measures should be adequate.
I like your idea about using thermal imaging. That’d be good to look for the reduced thermal bridging they’re asking for now, too. The only problem is getting enough ΔT in mild weather and houses that don’t have heating or cooling at final inspection.
The lack of trust of Raters
The lack of trust of Raters and others is a self-inflicted on the part of Energy Star. Basically ignoring QA for the entire life of the program inevitably results in abuse, failure and in some rare cases, even fraud. As we all like to say, “You get what you inspect, not what you expect.”
Steve B.:
Steve B.: That’s a good point. ENERGY STAR has relied completely on RESNET to provide Quality Assurance for their program, and the QA needs of ENERGY STAR really have gone beyond what the HERS Standards require. We’re trying to address that in the RESNET QA committee, but you’re right, it seems that ENERGY STAR should probably do some QA of their own.
Allison, thanks for telling
Allison, thanks for telling it like it is! Although I fully support the v2 TBC (there’s no way to test for these critical details in a pure performance approach), the new prescriptive air sealing requirements are unnecessary and are already causing problems in the field. These details should be recast as guidance for achieving a prescriptive blower door target. Period.
It is also my opinion that requiring Manual D proof is a waste of time. It’s only a piece of paper. LEED for Homes has already been struggling with this issue. If room airflow balance is verified (and I would add external static), it matters not how you get there.
David B.:
David B.: You’re welcome. This discrepancy about the program has bugged me for a while, and that discussion in the RESNET/BPI group on LinkedIn last night brought it to a head. I agree that checklists are good, but in the performance path, they mostly shouldn’t be mandatory. I added an Einstein quote to the end of the article that I think applies perfectly to this situation.
The Manual D is only one way the HVAC requirements have gotten out of hand.
Excuse my ignorance about
Excuse my ignorance about HVAC design, but how do you verify “room airflow balance” if you don’t have design air flows for each register determined by a Manual J and Manual D? Are you just waving your hand over a register and say yeah I can feel some air moving and it seems about right for this size room?
And suggesting a sq.ft per ton metric seems entirely self defeating. It would be telling the old school HVAC guys that they were right all along! I can’t believe we want to suggest that the floor area of a room has any significance to a HVAC load. We need to communicate that what really matters is the loads from windows and external walls ceilings and floors?! Builders actually undersadn this when I communicate this to them. However the HVAC guys may not want to think about it.They just want to oversize and run away.
I for one think there are a lot of good concepts in the V3 checklists. And if we can get HVAC Contractors to do their part, our lives will actually get easier.
For one example where the V3 HVAC Checklists would have helped, I tested some homes with HVAC systems that were entirely within the thermal boundary last week. The duct leakage to outside was beteen 1.5% and 3.5% of floor area in each home. The total leakage turned out to be about ten times greater. And 90% of it was now hidden behind drywall. I checked the static presure drop across the air handler with the duct blaster running and I found it to be 35 to 40 pa. So, I think this home will have a big HVAC problem and energy cost that would not have been caught by V2. The HVAC COmpany said they tested the ducts before the air handers were installed and the total leakage was 1% of floor area. They also said they looked inside the furance and air handler with a scope and found no blockage. And amazingly enough, they said they called the American Standard tech and he said a 40pa pressure drop was nothing – that sometimes it would be 120pa. I said the Rep must not understand how we test, but the HVAC Contractor was adamant that he did. So my final suggestion was to at least verify that they had adequate air flow at each register. But of course, they had no flow hood or design values to compare the flow to. Now if the HVAC Comapny had actaully self-verified the V3 HVAC checklist, I’m convinced this problem could have been identified before I got there and I would have saved myself and my client a ton of time sorting it all out.
I have been working hard with my builders to prepare for V3 and I am convinced that they can do it and that they will continue to set themselves apart from the rest and in doing so they will increase the value of the ENERGY STAR Homes Brand.
I do agree the training material and checklists need to be as simple as possible – and we certainly need to keep working on this – but let’s not dumb down ENERGY STAR and thereby decrease it’s value.
Keep educating folks!
Allison,I think you are
Allison,I think you are overstating the confusion between the Presciptive and Performance Paths.
You say “Guess what else is true. Just as the performance path has only prescriptive requirements for air sealing, the prescriptive path has only a performance requirement for air sealing. What?! This is almost Orwellian. Prescriptive is performance. Performance is prescriptive. War is peace.”
I think you are getting carried away with your own rhetoric.
When you say “the prescriptive path has only a performance requirement for air sealing,” this is clearly false. If you read the ES National Program Requirements you will see that both paths must meet the prescriptive measures in the Thermal Enclosure Rater Checklist.
Michael wrote: <
Michael wrote:
“…how do you verify room airflow balance if you don’t have design air flows…?”
Of course you need the design airflows. Air balancing is one of the new requirements under v3. Although the plus/minus 20% tolerance range is larger than I’d prefer, it’s definitely a move in the right direction. The problem of course is that many HVAC installers don’t have the training or tools required to do this.
Verify the proper airflow
Verify the proper airflow balance the same way a homeowner does. Stick a thermometer in each room and see if temps are within 2 degrees of each other.
Michael B.
Michael B.: Thanks for your comments! Let me see if I can help you understand what I’m thinking here.
First, the required room air flow comes out of Manual J, not Manual D. If you’ll go back and read my first article on the
square feet per ton benchmark for AC sizing, you’ll see that I said that there still needs to be a Manual J for actual sizing. The benchmark is just to simplify program qualification.
Second, yes, the checklists can be extremely helpful in getting builders and trade contractors to do things correctly, and I’m not suggesting abandoning them completely. What I am suggesting is to have performance goals in the performance path checklists and prescriptive requirements for the prescriptive path checklists. I think ENERGY STAR has muddled the distinction between the two paths.
Finally, you’re right about my getting carried away with my rhetoric on that part about the prescriptive path. I was wrong about that and have deleted that paragraph.
If you look at the other articles in our blog, you’ll see that I’m a big advocate of doing proper HVAC design and commissioning. As a HERS trainer and provider, though, I see the difficulty of loading up a program like ENERGY STAR with a lot of requirements that can’t be enforced well. In case you didn’t see it, I wrote an article earlier this year about my frustration with the HVAC industry: Why Won’t the HVAC Industry Do Things Right?.
Kudos to you for using the V3 guidelines to improve new homes in your area. What I’m hearing from our raters is that many builders aren’t going to stay in the program. I think RESNET sees this coming, too, and that’s why they’re pushing builders so hard to market the HERS Index.
David B.: Testing and balancing air flow is definitely a good thing, but you’re right that most HVAC contractors aren’t equipped to do it.
Bob: Well, I think that’s going a bit too far because you’d have to be there on hot day, cold days, and in-between days to make sure you got it right. Measuring air flow is easier, I think.
What do you recommend as
What do you recommend as baseline square ft per ton in an area such as Houston or similar climates?
Supernova:
Supernova: Houston’s climate is worse than Atlanta’s (I know because I was born there!), but you should still be able to build a house that’s efficient enough to reach 1000 square feet per ton or more. I like the number 1000, and if you can do it in Houston, you can do it almost anywhere.
One thing that’s easy to lose
One thing that’s easy to lose sight of… Even though Houston has almost twice the number of cooling degree days as Atlanta, the size of the AC, of course, depends on the cooling design temperature.
Atlanta’s design temp is 92F, whereas for Houston, the design temp ranges from 93F to 95F, depending on specific location. So there’s not much difference in what it takes to achieve 1000 sf per ton in Houston vs. Atlanta.
Just out of curiosity, I scanned the ASHRAE source for design temps and found these surprises:
94F
Boise ID
Lincoln NE
Grand Junction CO
95F
Medford OR
Pierre SD
98F
Wichita KS
DFW Intl, TX
That makes sense Allison. We
That makes sense Allison. We should strive to acheive that benchmark. And I do know about the design temperature. I was thinking it should be around 97 though.
@Supernova, forgive me if you
@Supernova, forgive me if you already know this, but the cooling design temp is the temperature at which only 1% of the hours is expected to exceed. Manual J refers to the ASHRAE tables, which are based on 30 years of climate data. The idea is that thermal lag will minimize the impact on indoor dry bulb when the ODB exceeds the design for a few hours.
It’s not unusual for HVAC contractors to use a higher design temp. It’s just one more way they pad their loads. But as long as the rest of the load is spot on, a couple of degrees isn’t that big of a deal. The real issue is egregious oversizing on high performance homes resulting from the contractor not taking the time to track down all the construction specs, and then rounding at every opportunity. Most contractors I’ve dealt with have no clue how badly oversized their systems are.
BTW, I’m David, not Allison.