Image Credit: US EPA
More Building Science
On the 1st of this month, the Energy Star new homes program moved fully (well, almost) into the much more rigorous set of guidelines called Version 3. There’s been a lot of discussion on the the transition for the past three years, when the Energy Star team at the U.S. EPA first started vetting the update with HERS raters and home builders. In case you’ve ignored or haven’t heard much about it yet, here’s a quick overview of what’s new:
- Version 2 had a fixed HERS Index requirement of 85 (or 80 in the far North); Version 3 has a variable HERS Index target, which is usually in the low 70s.
- Version 2 had one checklist for the HERS rater: Version 3 has 4 checklists: 2 for the HERS rater, 1 for the HVAC contractor, and 1 for the home builder.
- Large houses have to get to a lower HERS Index because of the new Size Adjustment Factor.
- All parts of the building envelope must have Grade I insulation or continuous insulation.
- All Version 3 homes must have mechanical ventilation systems that meet the requirements of ASHRAE 62.2.
Since the Energy Star team first released the Version 3 guidelines over two years ago, they made several revisions and have adjusted the implementation schedule. Currently, they’re up to Revision 5 of Version 3, and some items have been delayed, but Version 3 kicked in for good on Sunday. Really! If the house you’re hoping to qualify for Version 2.5 was permitted before 2012 and had its final inspection by the end of Saturday, 30 June 2012, you’re golden. If you’ve slopped over into July, it’s Version 3 for you!
I’ve included the Energy Star Version 3 implementation schedule graphic here, and you can see that since we’re now in July, it’s all Version 3, no matter when the house was permitted or finished.
What to watch out for
So, now that it’s really here, what are the big issues with qualifying new homes under Energy Star Version 3? There are a few, and they add up. We’ve qualified a lot of V2.5 homes and a few V3 homes through Energy Vanguard Energy Ratings, our HERS rating providership, and here are three obstacles that we’re seeing:
- Bath fans – Energy Star Version 3 requires bath fans to be able to exhaust 50 cubic feet per minute (cfm) of air. The HERS rater has to measure it, too, so when builders put in 50 cfm bath fans, they’re probably not going to pass. The typical bath fan moves only half its rated air flow, so a 50 cfm fan generally won’t cut it for Energy Star. One problem is the duct that makes an immediate 180° turn (as shown in the photo below), but there are other reasons bath fans underperform, too.
- HVAC contractors – Energy Star Version 3 expects a lot of HVAC contractors. On the whole, they had great difficulty with the minimal V2 program requirements (Manual J, properly sized cooling system, coils matched according to AHRI standards). Now they have to do full HVAC design and commissioning and get certified through the Quality Assurance program of the Air Conditioning Contractors of America (ACCA). The fees for that are over $1000 to get started and then about $820 per year (not including ACCA membership) to continue. Not many have done it yet. There are only 12 Georgia HVAC contractors listed on the ACCA website as of today. Even in Texas, which has probably had more homes qualify for Energy Star than any other state, only 63 HVAC contractors are listed.
- Cost – Energy Star has a document that shows their projections for the extra costs and savings (pdf) associated with qualifying a home for Version 3 versus having it meet the 2009 IECC. They say it will cost a home builder in the range of about $3500 to over $9000, depending on location, to qualify for Energy Star Version 3. The problem is that the builder doesn’t realize the savings; the homeowner does. Also, they’re comparing Version 3 costs to the costs to build to the 2009 IECC, which not everyone is doing yet.
Of course, these aren’t the only things that builders are balking at and getting stuck on. The requirement that all homes must have mechanical ventilation systems and Grade I insulation installation (or continuous insulation) are a couple of others.
So, now that the new guidelines are here, what happens next? Energy Star Version 3 is no longer an entry level energy efficiency program. Getting the Energy Star label on your home will be a lot more meaningful now that Version 3 is mandatory.
What are you seeing out in the field? Builders, are you sticking with the program? HVAC contractors, why aren’t you jumping in yet? HERS raters, what other hangups have you found?
Allison Bailes of Decatur, Georgia, is a RESNET-accredited energy consultant, trainer, and the author of the Energy Vanguard blog.
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9 Comments
Maybe...
In the last month or so, I've posted some pictures of horrible insulation and ductopus (I do like that word) installations that have been approved by ES verifiers; so why so much hoopla on switching versions if ES can assure that verifiers are doing their job... kind of a head scratcher, eh???
Bath Fans
Allison: If low-powered ceiling fans in the bathroom don't cut it, with their 180-degree turns and endless squiggly ducts, is this a reason to consider a wall fan, such as the 80cfm Panasonic WhisperWall? Or does an exterior wall fan like this involve too much of a break in the building envelope? Your thoughts please.
Cheater Idea for fans. Put in
Cheater Idea for fans. Put in what you want. Add an inline fan in the attic. Test. Pass test. Now if you don't want to be sucked out of your bathroom. remove inline fan. Reuse inline fan in next home.
I think ASHRAE 62.2 is for many homes way more air exchange than needed. Especially if no VOC loads exist in the home. I do think high levels of air exchange are needed for two years following completion. So leave the inline fan in for that period, dial up the fans to run long for two years. Then dial back as desired.
ASHRAE is a standard and is set to deal with all humans using a home in a zillion good and bad ways. With a bit of a brain, anyone should be able to vent less than the standard for many of the hours that their home is.
Rock paper scissors, err... PHDs common sense bananas... play on people
Response to Armando Cobo
Your point is a good one and it comes down to how good a job everyone does on the quality assurance process. QA providers are required to check the work of their raters (10% file review and 1% field review annually). RESNET does QA on providers. Do some raters and some providers get away with shoddy work? Yes. Do most raters and providers do a good job? I believe so. I'm on the RESNET QA committee, and we have biweekly conference calls during which we keep going through the HERS Standards and revising and refining our QA guidelines. Lately we've been spending all our time talking about probation and suspension of raters and providers, and those tools will become utilized more often, I believe.
I feel your pain, though, Armando. I go into a lot of houses that have a lot wrong with them. It's great for getting photos of how bad things are, but I think one of the things ENERGY STAR is trying to do with Version 3 is to raise the bar high enough that raters and providers can no longer say, "Well, you're close enough so we'll let it slide." I'm really glad that we're past Version 2.5 because now builders and HVAC contractors have to get serious if they want to stay in the program.
Response to Gordon Taylor
I'm not a fan (sorry!) of putting bath fans in walls that are part of the envelope. Ceiling fans can be completely covered up with insulation, but wall fans would compromise the performance of the building envelope. Yeah, you could come up with ways to overcome the problems, but the real issue, no matter where you put the fan, is making sure to install the proper fan with a good duct so that it moves enough air.
Required 50 cfm ?
What about the continious (low flow) approach. ?
We wont be getting 50 cfm out of the whole house ERV approach (per bathroom), though last time I checked, ASHRAE 62.2 had an allowable lower air flow for the continious approach.
For Example: My HERS reporting suggests that I would only need in the 66cfm range (for the whole house). So it might be obvious, that the 50 cfm is in regards to the on/off approach (and does not apply to the other method), but the continious approach is worth mentioning.
Response to matt berges
Yes, ENERGY STAR allows you to meet either the continuous (20 cfm) or intermittent (50 cfm) flow rate for bath fans. Most of the rating files we've seen so far for V2.5 and V3 are going the intermittent route, so that's why I didn't mention continuous flow rates. You can download the Version 3 checklists and more from the ENERGY STAR website, and they have all the details about the different ways to verify that the builder's meeting the guidelines.
PhDs, builders, and venting
PhDs, builders, and venting oh my... Oh my , oh my.
Energy star 3 taken to It's exponential limit. Whether tis entropy or exegy is the question thy certainly will ask of Teresa? No no does not rhyme, of thee... W/ tea, if from the "muddle" East.
Don't mind me, just meeting my daily ASHRAE venting quota. (Is there really a difference between sense and,,, nonsense? Really.)
To Allison Bailes
That was exactly the answer I expected. No exterior wall fans. Many thanks.
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