I got into a discussion with a college the other day about testing the attic connection to the house.

When the house is depressurized to -50pa wrt outside, and the attic wrt house is -49pa, isn’t the attic more “outside” then “inside”? When the house was depressurized to -50pa I also looked at the attic wrt outside, and got just -2pa. My understanding is that if the Blower Door is putting -50pa on the house interior, and the attic only goes -2pa wrt the outside, the ceiling is pretty darn tight.

Any thoughts on this? We talked zonal pressures until my head got foggy. Any other ways to describe this testing process would be greatly appreciated. I may even get a lunch out of it if I can explain it better!

Views: 256

Replies to This Discussion

If I am understanding this correctly when the house is at 50Pa relative to outside and the attic is at 2Pa relative to outside then there is not much connection between those two zones. The 2Pa in the attic could even be due to stack. Sounds like they have a very tight ceiling.

 

Silvie Votrubova, Retrotec


Here are a couple of things to remember when measuring zonalpressures.  First is that you want tomeasure the change in pressure caused by the Blower Door, so you will need torecord a baseline attic to outside pressure. Secondly zonal pressures do not tell you the size of the leakage betweenthe house and the attic.  The zonalpressure tells you the leakage ratio between the house and attic compared tothe leakage between the attic and the outside. For example, if the attic to outside number is 25 pa, then the hole sizebetween the house and attic is the same as between the attic and outside.  If the attic to outside number is 2 pa, thenthe ratio is 1 to 8.  It is possible tohave a attic to outside zonal pressure of 2 pa on one house and 25 pa onanother house and have an equal hole size between the house and attic.

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

Juan Roca commented on Dale Stephens's blog post LED Lighting - Garage Door opener interference
"Hi,There is a real problem with remote controls and LED lights. However, there is a solution in the…"
17 minutes ago
Profile IconJuan Roca and Elizabeth Coe joined Home Energy Pros
10 hours ago
Casey Gesell posted videos
10 hours ago
Gerald Shechter posted videos
10 hours ago
Hal Skinner replied to Hal Skinner's discussion An example of what an RCC can do with no R- insulation in the walls.
"Bret,  here are the 2 reports I referred…"
13 hours ago
Craig Foley shared George Kopf's discussion on Twitter
13 hours ago
Jan Green replied to George Kopf's discussion Real Estate Professionals need our support - but how?
"Craig, I like your thinking!  With my new broker, I've been able to communicate more…"
14 hours ago
Craig Foley replied to George Kopf's discussion Real Estate Professionals need our support - but how?
"Thanks Jan, your insight, as always, is invaluable. Your suggestions regarding a top down approach…"
14 hours ago

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service