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Georgia Rocks! - New Energy Code Requires Blower Door Test


Blower Door testing is required in the new Georgia energy code.Starting on the 1st of January 2011, all new homes permitted in Georgia must have a Blower Door test! You heard, right? I've written about this twice before - last April, when the new Georgia state energy code was finalized and then again in July when the new energy code passed at the Department of Commuity Affairs.

Georgia is the first and only state to go this far with implementing 2009 International Energy Conservation Code (IECC). The IECC allows demonstrating compliance by either a Blower Door test or a visual inspection, and every other state so far has allowed the visual inspection.

You can get all the details by downloading the Georgia State Supplements and Amendments to the International Energy Conservation Code (pdf), which is based on the 2009 IECC. In that document, you'll find the qualifications necessary to become a Duct and Envelope Tightness (DET) Verifier. I'll save you the time and effort of having to download the pdf file and look it up, though. Here's the relevant section, from page 5:

CERTIFIED DUCT AND ENVELOPE TIGHTNESS (DET) VERIFIER. A certified DET verifier shall be a certified Home Energy Rating Systems (HERS) rater, or be a certified Home Performance with ENERGY STAR contractor, or be a Building Performance Institute (BPI) Analyst, or successfully complete a certified DET verifier course that is approved by the Georgia Department of Community Affairs.

That last section refers to a special class that will be offered just to teach people how to do Blower Door and duct leakage tests. The Georgia Environmental Finance Authority (GEFA) is about to issue a contract for statewide training to get more certified DET verifiers across the state. Six companies have put in proposals, and they'll choose one of those in the next two weeks. I'll provide more info here as I get it.

One question that's come up a number of times already is whether the testing must be done by a third party. The answer is no, builders can do the infiltration testing on their own houses, and HVAC contractors can test their own duct systems for leakage. Most likely, the majority of the testing will be done by third parties because most builders and HVAC contractors probably aren't going to rush out to get certified and buy Blower Doors and Duct Blasters.

This is great news for the people who end up buying those homes and great news for home energy raters and auditors who own Blower Doors and are certified to use them. I read in an article some time ago that there are three types of duct systems: Regular, sealed, and sealed and tested. This applies to homes, too, and it's the absolute truth. If it hasn't been tested, it's probably not as tight as the contractors think it is.


Georgia is doing this, but the last time I checked, a 1 story house meeting the 7 ACH50 criteria is going to require fresh air mechanical ventilation (ACHnat = 0.33). Two story folks get a pass (ACHnat > 0.35). Hmmm!
Posted @ Thursday, December 09, 2010 1:12 PM by Sam Young
The energy code doesn't specify mechanical ventilation, and I haven't looked at the IRC or IMC to see what they say. If it's in there, it's probably based on ASHRAE 62.2, though, which doesn't go by ACHnat. It's based on conditioned floor area and number of bedrooms. Can you point me to your reference?
Posted @ Thursday, December 09, 2010 1:31 PM by Allison Bailes
I'm looking at 2003 IMC 403.3, which references Table 404.3 for outdoor air for living areas of private dwellings. "0.35 air changes per hour or 15 cfm per person, whichever is greater." It doesn't say how to compute air changes per hour. I've interpreted this mean the conversion from ACH50 to ACHnat. I'm not aware of another method. 
What is weird is that the IMC doesn't apply to houses, except where the IRC is silent. There are holes in the IRC. This is one of them.
Posted @ Thursday, December 09, 2010 3:36 PM by Sam Young
"...HVAC contractors can test their own duct systems for leakage." 
Are duct also required to comply with 2009 IECC? You didn't explicity confirm this in your article.
Posted @ Thursday, December 09, 2010 4:29 PM by David Butler
David, yes, the duct tightness requirements in the Georgia energy code are pretty much identical to the 2009 IECC. I've read them side-by-side and see no difference. Are you hinting that the IECC requires third party testing? If so, I can't find that requirement in the IECC, and I know from the Georgia DCA that it's not written or implied in the Georgia code.
Posted @ Thursday, December 09, 2010 5:46 PM by Allison Bailes
No hint intended... My question was unclear. What I intended to ask is whether ducts must be tested for leakage under the new DCA regs (irrespective of who does the testing). You say that contractors can test their own duct systems but your article never says the new regs require duct leakage tests, only that blower door tests are required.
Posted @ Thursday, December 09, 2010 6:59 PM by David Butler
Ah, now I see what's going on. When I started the article, I intended to make it only about Blower Door testing because that's what sets Georgia apart from other states that have adopted the 2009 IECC. In the process, I brought up the DET verifier and that led to a mention of duct leakage testing, which then led to your confusion. In the article I wrote in July, I did discuss the requirement for duct leakage testing.  
I know you're not a fan of referencing duct leakage to conditioned floor area, David, and I totally understand your point on that. The IECC doesn't have oversizing limits yet, but I'm not sure if that alleviates any of your concern there. Ideally, it'd be nice to have the cfm25 referenced to both floor area and air handler flow, and it would have to be within certain limits for both.
Posted @ Thursday, December 09, 2010 7:35 PM by Allison Bailes
Yes, I recall that article, now that you mention it. I figured most states are going to ignore the duct leakage provision. Are you aware of other states that are or will be enforcing duct testing? 
Regarding duct leakage metric... 
Sigh. Hopefully the new BPI duct standard will begin to reverse the momentum.
Posted @ Thursday, December 09, 2010 7:58 PM by David Butler
The Florida Building Commission this week decided to leave in the duct testing requirement in the next version (2010) of the energy code. Maximum Qn of .03. We'll see if that stands.
Posted @ Friday, December 10, 2010 9:01 AM by Walter Stachowicz
Thanks for the good news from Florida, Walt. I hope it does stand.  
Now, it seems that FSEC/Energy Gauge has trained all you raters in down there to talk like engineers, but I believe that what you call Qn is shorthand for what I learned as 'percent duct leakage,' or cfm25 per 100 square feet of conditioned floor area. Right?
Posted @ Friday, December 10, 2010 1:26 PM by Allison Bailes
Allison, I was taught that the Qn is the normalized duct leakage, whereas the % leakage is the CFM25 divided by the rated air handler flow x 100. Energy Gauge calculates this for us. We've found that, generally, that a Qn of .09 is about 15%. But, hey - you're the professor!
Posted @ Sunday, December 12, 2010 8:14 AM by Walter Stachowicz
That's certainly a good way to do it, Walt, because the term 'percent duct leakage' is ambiguous now that it's been used the way I described above. When referenced to the floor area, it's not really a percentage - it's just a ratio, so I try to avoid calling the cfm25/CFA the percent duct leakage for that reason. I'm not crazy about the term Qn, though, because Q usually stands for heat flow. 
One reason I don't like referencing the duct leakage to the air handler flow is that in a home with a grossly oversized system (pretty much every non-ENERGY STAR house), you get a misleadingly low number. Is that 0.09 to 15% relation for correctly sized systems?
Posted @ Sunday, December 12, 2010 8:24 AM by Allison Bailes
Allison. I read the GA state supplements and amendments to the 20019 IECC relative to who can do the blower door testing and duct testing. Section C102 defines a Third Party Verifier as "An independent person or firm responsible for conducting inspections..." 
Section C103 goes on to qualify that third party verifier as one who "shall not be an employee of the Owner or BUilder or have a financial interest in the project." 
I cannot see a situation where a builder or HVAC company does not have a financial interest in the project if the failed testing will require them to do remedial work. It is in their interest to make sure the tests pass. 
Does this language not interpret to mean that the testing cannot be done by the foxes guarding the hen house?
Posted @ Monday, December 27, 2010 2:43 PM by howard feldman
Howard, you're absolutely right that that's in there and seems to be clear that builders & HVAC contractors can't test their own work. I got the following quote from someone on the task force, though: 
"As a compromise, we decided that you did not have to be a 3rd party to do the test but you DID have to know how to use the equipment. The idea being that the HVAC contractor can test their own ducts (and correct errors if found) parallels that of the plumber pressure testing their own pipes. 
"In an ideal scenario, it would be a 3rd party for duct and house testing but the notion would not have passed the committee. So we opted for the path that at least guarantees the tester is trained and knowledgeable." 
I realize that this contradicts what's written in the Georgia Supplements & Amendments, so I'll see what else I can find out and let you know.
Posted @ Monday, December 27, 2010 4:08 PM by Allison Bailes
Can someone please point me to where I can get involved as a 3rd person for training and education/costs involving these procedures. Send info to E-Mail above.I have 39yrs as Fireplace&Heater installer/repairman.
Posted @ Monday, January 31, 2011 2:23 PM by Leo Harrison
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