I have reviewed, tested, studied, asked, and analyzed the many facets of whole house air leakage.  I am still somewhat unsure what constitutes a respectable level of air leakage to a home.  Newer homes built to higher standards are not a problem but when you get into older homes with varying degrees of air leakage depending on when they were built and by whom presents some interesting situations.  The recommended rates of leakage on older homes do not present the same situation as new homes as there are many areas of the home which are not accessible and to properly be able to reduce the leakage to ASHRAE guidelines would mean in many cases a major teardown and reconstruction to be able to seal the leakage to the "standards".  In addition, many of these homes were built on the premise that the leakage would keep the wood and structure dry, minimizing those types of problems.

If you have suggestions, references and guidelines, please let me know.  Thank you for your input. 

Roy Sakamoto

Views: 817

Reply to This

Replies to This Discussion

This jives with my experience trying to air seal a very small house - lots of caulk and foam and not much of a result (only a few hundred CFM after several hours of work).  Bigger homes seem easier to reduce in my experience.

This is definitely worth investigating if you are an air sealer and are forced to use the ACH50 metric.

First look at a 1500 ft2 ranch on a slab at 50'X30' with an 8' ceiling.  It has a volume of 12,000 ft3, and a surface area, all-in, of 4280 ft2.  If we divide the surface area by the volume, we get .36 - this is a measure of the number of square feet represented by each cubic foot of volume.

Then look at 3000 ft2 2-story on a basement at 50'X30' with 9' ceilings above grade.  It has a volume of 39,000 ft3 and a surface area of 7160 ft2.  Divide the surface area by the volume and we get .18.

So each cubic foot of the volume of the big house represents twice as much surface square footage as it does in the small house.  To reach the same 3 ACH50, each square foot of the smaller house must be 2 X as tight as the ones on the big house.  Or the way I like to phrase it, each square foot of the bigger house is allowed to by twice as leaky as that on the small house.

You can do the same exercise with that small house on a basement, with a house that is "U" shaped, with a long rectangle, with a square, etc.  And you can even see that the big house with 8' ceilings instead of 9' has a ratio of .19 - so just raising the ceiling a foot gives you a 5%+ advantage on the final air leakage number!

In MD that has had the '12 code for a year and 9 months, just last week I spoke with the head inspector of one of the counties.  He told me they still have a 30-40% failure rate and they are all houses under 2000 ft2.

Wrong metric.  

Hope we aren't hijacking the thread, but this applies to old houses as well as new.

RSS

Videos

  • Add Videos
  • View All

Twitter

Latest Activity

George Matthews commented on George Matthews's event Proof is Possible Tour by the Home Performance Workshop
"Here is the flyer for the Advanced Techniques and Tools in Home Performance Friday October 7th at…"
41 minutes ago
George Matthews posted an event

Proof is Possible Tour by the Home Performance Workshop at Truitt and White Lumber Conference Room

October 7, 2016 from 9am to 1pm
Building Energy Performance Testing is sponsoring the Proof is Possible Tour to come to the San…See More
1 hour ago
George Matthews replied to George Matthews's discussion Shortridge 8400 Flowhood for A/C airflow testing in the group Energy Auditing Equipment for Sale, Trade or to Purchase
"Here are the pics of the flowhood and airdata manometer"
Saturday
Sarah Holloway posted a photo
Friday
Joe Urycki added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase
Thumbnail

TEC blower door and UEI combustion analyzer for sale

For sale is one used TEC Minneapolis blower door system: Includes model 3 fan with rings A and B,…See More
Friday
John Nicholas replied to Kevin Emerson's discussion Studies re: radon mitigation and energy efficiency
"The Nay side is well represented with the links already posted. I presented a neutral side, with…"
Friday
Ray Lehman replied to Kevin Emerson's discussion Studies re: radon mitigation and energy efficiency
"Hey John, Thanks for the information.  Very good empirical data. While I agree that running…"
Friday
John Nicholas replied to Kevin Emerson's discussion Studies re: radon mitigation and energy efficiency
"I have no links, just some anecdotal evidence. I had several Blower Door Tests done on my own home.…"
Friday

© 2016   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service