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: 539

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

Home Energy Pros

Home Energy Pros was founded by the developers of Home Energy Saver Pro (sponsored by the U.S. Department of Energy,) and brought to you in partnership with Home Energy magazine.

Latest Activity

Hal Skinner replied to Richard Beyer's discussion Spontaneous Combustion and Flash Fire regarding Spray Foam Insulation
"Richard, here is something else that might be pertinent. In my hundreds of conversations with our…"
8 hours ago
Trip posted a discussion

Starting a Home Weatherization Business. Considering it...

I am considering starting a home weatherization business. (I live in Southeast Alabama)  Currently…See More
9 hours ago
Jim Gunshinan commented on Jim Gunshinan's blog post My Energy Upgrade California—The Numbers Are In
"To all, one thing I don't lack is advice from the experts! Thanks for the input, challenges,…"
10 hours ago
tedkidd commented on Jim Gunshinan's blog post My Energy Upgrade California—The Numbers Are In
"Jim, I'm glad you are open, that's great!  We all learn best when we are open! The…"
10 hours ago
David Eakin commented on Jim Gunshinan's blog post My Energy Upgrade California—The Numbers Are In
"Jim, Well, as the editor of Home Energy you should already know that the order of remediation is…"
10 hours ago
Greg Labbe posted a blog post

Technical Tape Desecration

Lets face it – building science is pushing the performance of adhesive tapes to a new levels and…See More
12 hours ago
Stacy Hunt posted an event

High Performance Enclosure Strategies: Part II, New Construction at Online

August 13, 2014 from 1pm to 2:30pm
Please join the Building America Program for our free webinar: High Performance Enclosure…See More
14 hours ago
Richard Beyer replied to Howard Katzman's discussion UV lights on filters
"Howard, There are numerous manufacturer's who swear these systems work and then you have the…"
22 hours ago
Christopher Morin posted a blog post

How do You Test a TXV?

  Thermostatic Expansion Valves (TEV or TXV), one of the most popular metering devices for…See More
yesterday
Howard Katzman posted a discussion

UV lights on filters

I recently saw UV bulb installations in 2 HVAC systems in a home. Each system had the Lennox…See More
yesterday
Don Fitchett joined Michael Stuart's group
Thumbnail

INFRARED THERMOGRAPHY USERS

This group is dedicated to knowledge sharing and discussion of infrared thermography for building…See More
yesterday
Don Fitchett commented on Diane Chojnowski's group Pinterest
"While most of our (BIN95.com) energy post and boards are industrial related, there are crossovers…"
yesterday

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service