Greetings

First of all......

* As we upgrade and build new....

  I think it is time to eliminate atmospherically vented appliances from the breathing zones of our homes

* I realize that the effects of wind and mechanical equipment can and often do overwhelm Stack Effect.

 

My current favorite online resources for visualizing "Stack Effect" are.....

*John Straube's Article

http://www.buildingscience.com/documents/digests/bsd-014-air-flow-c...

 

*John Klote's Article

http://fire.nist.gov/bfrlpubs/fire91/PDF/f91013.pdf

 

*Bud Poll's Worksheet

http://myenergyworkshop.homestead.com/hot-air.html

 

I plan to post some Illustrations and see if you folks agree with my current thinking about the location of Neutral Pressure Planes

Meanwhile...

Does anyone else have suggestions for online links concerning  "Stack Effect"?

Views: 5516

Reply to This

Replies to This Discussion

An important element of the Klote report is that he uses a simplifying formula that only approximates the typical multiple vertical opening model.

"Analytic equations have been developed for the location of the neutral pressure plane for a few simple cases of leakage openings. However, the combinations of leakage openings in building shafts and compartments can be very complex... Analysis is simpler for horizontal openings, because the pressure difference across the opening does not vary with elevation. The analysis of this section is for horizontal openings…Vertical vents can be approximated by horizontal vents when the height of each vent is small compared to the height of the air column."

In a 2500 SF house with 1 ACH50 (about 350 CFM50), the Effective Leakage Area (ELA @ 4 Pa) is about 8 square inches. Since the blower door test is conducted with deliberate leaks sealed, this envelope leakage area is similar to what we might expect from dampered mechanical openings, making both deliberate and accidental leakage areas equally significant.

I'm still not sure what you're trying to accomplish by "controlling" the height of the NPP, especially given that - as you attest - the actual NPP will vary with both wind and mechanical effects.

Here's another link to an old article, CBD-23. Air Leakage in Buildings, from the National Research Council of Canada:

http://archive.nrc-cnrc.gc.ca/eng/ibp/irc/cbd/building-digest-23.html

RSS

Forum Discussions

How would you insulate this roof?

Started by David Butler in General Forum. Last reply by Bill Spikowski 14 minutes ago. 36 Replies

Home Energy Pros and #MeToo

Started by Mike Rogers in General Forum 15 hours ago. 0 Replies

Psychrometric Chart Training

Started by John Krochmalny in Training. Last reply by Mahendra Shah on Friday. 1 Reply

Latest Activity

Bill Spikowski replied to David Butler's discussion How would you insulate this roof?
"Brad Cook wrote: "Your ceiling is white and somewhat reflective on the inside, so your…"
14 minutes ago
Bill Spikowski replied to David Butler's discussion How would you insulate this roof?
"I may end up working from inside, a room or two at a time -- but my preference would be to do the…"
50 minutes ago
Blake Shurtz posted a discussion

Replacement for Energy Conservatory Flow-blaster

It's too bad that the flow-blaster is no longer being produced or technically supported. Does…See More
9 hours ago
Profile IconBrian Cizmar, Charles Allen, Charles Buell and 1 more joined Home Energy Pros Forum
12 hours ago
Mike Rogers posted a discussion

Home Energy Pros and #MeToo

If it doesn't seem obvious why a discussion of …See More
15 hours ago
David Butler replied to David Butler's discussion How would you insulate this roof?
"Sean Lintow proposed rails and clips (re: first comment in this discussion), but in the context of…"
yesterday
Brad Cook replied to David Butler's discussion How would you insulate this roof?
"I missed where the suggestion for rails came in. The plywood would not need any rails. 4+ inches is…"
yesterday
David Butler replied to David Butler's discussion How would you insulate this roof?
"I'm a little confused about the necessity and purpose of using support rails if working on…"
yesterday

Photos

  • Add Photos
  • View All

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

Badges  |  Report an Issue  |  Terms of Service