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3799 Main St. #87024
Atlanta, GA 30337
USA

773.398.5288

Advanced residential construction and home improvement consulting and owner's advocacy in Atlanta, using the latest building performance diagnostic and modeling techniques and tools. Airtightness, insulation, HVAC, ventilation, moisture, and air quality and EMF consulting for homeowners and building professionals alike.

Videos/Podcasts/Articles

Home performance articles and stories from the field with internationally respected building forensics guru Corbett Lunsford at the Building Performance Workshop. Hear new episodes of the Building Performance Podcast, see new videos from the Home Performance YouTube channel, and learn all about how diagnostic testing (more than an 'Energy Audit') can make home improvement and new home construction a proven process!

Filtering by Tag: hvac

OZONE: the Original Villain of Indoor Chemistry

Corbett Lunsford

Indoor Air Quality is being explored at breakneck speed with the HOMEChem Experiment, and not surprisingly, ozone (O3) is proving to be the original villain in the complex system of interactions that make the air we breathe much more worrisome than anyone guessed. Featuring HOMEChem scientists Marina Vance, Delphine Farmer, Charlie Weschler, and Richard Corsi.

More at: http://HomeDiagnosis.tv/homechem

Building Science Playground: the Test House of HOMEChem

Corbett Lunsford

Meet the Test House of HOMEChem at the University of Texas at Austin. More at: https://HomeDiagnosis.tv/homechem

Teaser for Home Diagnosis Season 1 (eps 3-6)

Corbett Lunsford

See bits of four episodes from Home Diagnosis Season 1! More at: https://HomeDiagnosis.tv

Combustion Testing the #TinyLab

Corbett Lunsford

Corbett checks the flue gas temperature, contaminant makeup, and efficiency of the tankless water heater in the #TinyLab with a new Wohler A450. Learn more and order this tool at: https://www.trutechtools.com/WohlerA450

How to Teach Home Performance to Home Owners

Corbett Lunsford

See how Corbett teaches home performance to the uninitiated after having given this presentation 214 times across the U.S. on the Proof Is Possible Tour. Special thanks to the tool companies and all other sponsors of the upcoming TV series 'Home Diagnosis' who have invested in making home performance a mainstream topic:

Review: EasyHood HVAC Diagnostic Tool $400

Corbett Lunsford

Corbett likes tools that are sexy and scary at the same time. This flow hood is both. Measure CFM, Drybulb, Wetbulb, Dewpoint, Velocity, and more with this very affordable tool that will help revolutionize the HVAC industry.

People I Follow (and hope you will too)

Corbett Lunsford

Corbett gives you 8 podcasts, video channels, and blogs you may not have heard of, all about home performance, HVAC, and building awesomeness:

Matt Moreman's Obsessed Garage channel: https://www.youtube.com/user/MattMoreman

Bryan Orr's HVAC School podcast and channel: http://hvacrschool.com/

HVAC with Stephen Rardon channel: https://www.youtube.com/user/jewvenile77

Neil Comparetto's HVAC channel: https://www.youtube.com/channel/UCICyuKv5NCGJu2gazjzgiGA/videos

Blake Reid's Terrawatt Home blog: http://www.terrawatthome.com/news/2017/10/23/keeping-things-dry-waimea-s-wet-side

Chris Laumer-Giddens' LG Squared channel: https://www.youtube.com/channel/UC2sJ6CQzqJ3DdeP7acjPRrg/videos

Adam Cohen's PassivHaus for Everyone channel: https://www.youtube.com/channel/UCmhV0KEJZWrMlmFHV0Je02Q

Stewart Brand's How Buildings Learn: https://www.youtube.com/watch?v=AvEqfg2sIH0

BPW on Lifetime TV 'Designing Spaces'

Grace McPhillips

On a recent episode of Lifetime Television's Designing Spaces, indoor air quality is discussed in depth by BPW founder Corbett Lunsford, joined by former 6-Week Mastermind student Ed Lammers of Honey Home Services. Thanks to Fantech for making this spotlight possible, and stay tuned for Grace and Corbett's own TV show coming up in 2018: Home Diagnosis!

DEAR CORBETT: HVAC Equipment Airflow Frustration

Corbett Lunsford

Dear Corbett,

I was going thru the videos in the training portal. Overall, I like your videos. However, every now and then, a portion of one leaves me less than satisfied with the answer. Usually, my disatisfaction is because you are rushing through and just skimming the details and explainations. I realize that your trying to limit the video's length and accept it.

However, I found one video that had something that you brought up, but didn't explain that frustrated me enough to write. The video is in the training portal, 'Mastermind Series Jan 2015' at 30:01 minutes in. Your talking about system airflows and you bring up NCI. You go to say how they add up supply airflows, return airflows, and compare it to what the airflow should be to get leakage. You say that that is wrong but don't explain. You finish by saying that system airflow needs to be measured at the blower. 

So, the question I have is: Are you objecting to comparing either the supply or return airflows to what the system airflow SHOULD be (i.e. not measured) or something else?

Would you agree with the following? 
(Equipment airflow) - (sum of supply register airflow) = (supply side leakage)
(Equipment airflow) - (sum of return register airflow) = (return side leakage)

Equipment airflow to be measured at or near the blower by one of the several methods. I am calling it equipment airflow and not system airflow just to be clear that it is what the fan actually produces.

Finally, are you doing full manual J's or just block load calculations to get ballpark numbers?

Thanks,
TJ

-_-_-

Dear TJ-

Great question, and I'm happy to clarify what I meant! Thanks for letting me know when my broad strokes don't actually answer your question and leave you frustrated- I always want to give a full picture of what home performance testing actually means.

My issue with measuring the supply airflows and return airflows, and inferring duct leakage from that is:

  1. How do you know what airflow the equipment is producing unless you measure the actual airflow at the equipment? You can use a calculation like 400cfm x tons of A/C, but what if it's heating season, 20 degrees outside, and the NEST thermostat won't let you disable the compressor's service disconnect and still run the air handler? Also, what if the installer targeted 350cfm per ton, or 450cfm?
  2. Even if you measure the equipment airflow, you won't be measuring the equipment cabinet air leakage, which is almost always there. In fact, the IECC duct leakage test assumes that 25% of all the duct leakage will be in the cabinet in new construction.
  3. The only way to measure duct leakage is to perform a duct tightness test, or for a quicker and more localized look, perform a pressure pan test during blower door testing.
  4. Measuring airflow is notoriously difficult. What tool and technique are we using? Pitot tube has high user error, passive flow hood (balometer) is not accurate for residential grilles and low flows, and anemometers need to be corrected for net free area of the grilles. Lots to scratch your head about, and it turns out the best way to measure airflow in the 21st century is still a plastic garbage bag.

To answer your final question, if all you need is a ballpark number, a block load is fine, but I always do a full room-by-room load calculation if I'm being paid to do an actual Manual J.

Hope that helps, and keep the questions coming!
Looking Forward,
Corbett

Best Home Improvement Showroom in the World: Sanders Home Services

Corbett Lunsford

Building performance testing expert Corbett Lunsford and Pete Sanders take you behind the curtain at the soon-to-be-opened Sanders Home Services showroom in Washington Township, New Jersey (outside Philadelphia). See the best hands-on demonstration of home performance outside the #TinyLab! Visit Sanders Home Services online at: http://www.sandershomeservices.com/

HVAC Pro Review of the Proof Is Possible Tour

Corbett Lunsford

Hear from Matt Adelman of Princeton Air Conditioning about the pro workshop portion of the Proof Is Possible Tour. Come study advanced techniques and tools for home performance diagnostics with Corbett Lunsford, the guy who wrote the book on it! http://ProofisPossible.com