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: 844

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

Latest Activity

Michael Woodham posted a photo

Shelves & Cabinets Maker - Spaceworks Design

Renovate your Home & Office by installing Shelves and Custom Cabinets!Stunning Home &…
8 hours ago
Thermodyne Boilers posted a discussion

Major problems which can cause troubles in Boilers

Most boilers come with a manufacturer’s warranty.…See More
8 hours ago
Kevin Daly added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase
Thumbnail

Minneapolis Blower Door Model 3 for sale

Selling minimally used Minneapolis Blower Door DG-700 model 3. Includes model 3 fan, DG-700…See More
13 hours ago
Profile IconDamon Morales, Thermodyne Boilers, Michael Woodham and 1 more joined Home Energy Pros
21 hours ago
marius gherman posted a video

Winter conditions, perfect operation - ROTEX / DAIKIN heat pump

FIAMMA company, ROTEX partner in Romania, offering turnkey packages to improve energy efficiency, from supply to installation. With an experience of over 25 ...
21 hours ago
Profile IconJeffery Liang and Ellen Phillips Soroka joined Home Energy Pros
Friday
Charles Cormany added a discussion to the group Job Board
Thumbnail

Energy Efficiency Incentive Program Manager - Efficiency First California (Berkeley)

Position Title: Program Manager Terms: Full time, available immediatelyAbout Efficiency First…See More
Thursday
Charles Cormany joined Diane Chojnowski's group
Thumbnail

Job Board

This group is for posting jobs related to all aspects of the home performance industry including…See More
Thursday

Home Energy Pros

Welcome to Home Energy Pros – the unique digital community by and for those who work in the home energy performance arena.

Home Energy Pros was founded by the developers of Home Energy Saver Pro (supported by the U.S. Department of Energy) and brought to you in partnership with Home Energy magazine.  Home Energy Pros is sponsored by the Better Buildings Residential Network. Please honor our Guidelines

© 2017   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service