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: 451

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

Discussion Forum

Seeking a Flow Hood

Started by George Matthews Apr 10. 0 Replies

Affordable Manometers?

Started by Isaac Savage. Last reply by Pete Stoermer Feb 15, 2016. 3 Replies

Looking For A Retrotech Duct Tester ?

Started by Chris Schiewer. Last reply by Jamie Kaye Dec 16, 2015. 1 Reply

Buying Used Equipment

Started by Nick Semon May 18, 2015. 0 Replies

Used Blower Doors?

Started by Isaac Savage. Last reply by Cameron Millard Jan 16, 2014. 3 Replies

Latest Activity

Alfie Davis posted a blog post
Sep 19
Profile IconSam Compton, Cameron Home Insulation, Seth Shoneman and 2 more joined Home Energy Pros Forum
Sep 18
Home Energy Magazine's blog post was featured
Sep 18
Eric Kjelshus replied to Gregory Cisco's discussion Abandoning under-slab HVAC ductwork which fills with groundwater seasonally.
"In Kansas City a lot of "cardboard" for supply was used in slab on grade.  1950-1970…"
Sep 15
Richard L. Rue replied to Sonja Persram's discussion Energy Savings Guarantee for single family dwellings in cold climate??
"Try EnergyWise Structures (www.energywisestructures.com) They are a NASA spin-off company that has…"
Sep 15
Debra Little commented on Home Energy Magazine's blog post NREL Research Finds That 22% of New Homes Completed in the U.S. in 2016 Were HERS Rated
"The avg scores are interesting. Are there comparative numbers for previous years? I thought they…"
Sep 15
Home Energy Magazine posted a blog post
Sep 15
Robert Zockoff replied to Gregory Cisco's discussion Abandoning under-slab HVAC ductwork which fills with groundwater seasonally.
"Public water systems regularly "reline" the interior of existing 50 year old water mains…"
Sep 15

Photos

Loading…
  • Add Photos
  • View All

© 2017   Created by Home Performance Coalition (HPC)   Powered by

Badges  |  Report an Issue  |  Terms of Service