[Greenbuilding] insulation vs. air sealing

[Futureship]

Hello David,

Interesting results ... I am currently  doing Weatherization work. Air sealing
In attic top plate, plumbing and electrical penetrations, electrical ceiling 
Fixtures and any openings in ceiling 
Is required before blowing insulation.

I have a question with regard to 
Your results:

In the first case you described that "Results were 15% higher energy usage with 10% greater leakage."

How does a blower door measurement
Tell you 10% greater leakage? The 
Blower door measures holes in 
The building envelope . Assuming no
Air sealing was done the blower door 
Would not measure a 10% greater leakage. I would argue the increase in stack effect In this case caused an increase in pressure thru the same holes therefore causing more airflow thru the same holes. 

I ask again how do you measure that 
Increase in pressure thru the same holes?  I am missing a way to measure this increase in stack effect pressure With a blower door measurement? Maybe I just answered 
My own question? 

On Oct 2, 2010, at 3:24 PM, David <dpwentling at ymail.com> wrote:

> Ran weatherization program in Baltimore back in the '80s with sealed flat roofs. They cut holes in roof to spray insulation and seal holes with venting caps. Test before and after normalized energy bills and blower door. Results were 15% higher energy usage with 10% greater leakage. These were low income homes being assisted with federal funds. Revised program to cut hole in roof, send in crew to seal top plates and ballon frame chaseways, dense pack low area where could not reach to airseal. Blew R-40 over all other areas then applied sheet metal over the hole before we installed their standard vent cap. Results were 20% energy reduction and 15% airleakage for additional $150 per house installation cost. Other airseal measures were later added to increase savings.
> 
> Bottom line, seal top before insulation and no need to ventilate. Ventilation is to remove the moisture from the exfiltration air which was eliminated. 
> 
> Hope this helps.  
> 
> Sent from my iPhone
> 
> On Oct 2, 2010, at 10:49 AM, "Kathy Cochran" <kathys_old_house at goldrush.com> wrote:
> 
> Hi all,
> 
> I am getting ready to have insulation blown in to my attic.  What exactly is
> the "stack effect"
> 
> And, now in my county anyway, it is required to have roof caps that are
> ventilated.  So, how does this impact on sealing up all "leaks" in the
> attic?
> 
> Thanks,
> 
> Kathy Cochran
> 
> -----Original Message-----
> From: greenbuilding-bounces at lists.bioenergylists.org
> [mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of
> Futureship
> Sent: Saturday, October 02, 2010 7:03 AM
> To: Corwyn; Greenbuild List
> Cc: Greenbuilding
> Subject: Re: [Greenbuilding] insulation vs. air sealing
> 
> Corwyn and Nick,
> 
> Do you have a suggestion on
> How to test the stack effect ? 
> I could do a before and after. 
> My hunch is that the stack effect decreases if you air seal attic before
> blowing insulation and increases If you do not air seal the attic before
> blowing insulation.
> 
> Bob Jakaitis aka "Jake"
> 704-236-3574
> 
> 
> 
> On Sep 30 Corwyn wrote:
> 
> You certainly shouldn't take mine or Nick's word on it.  Perform an
> experiment for yourself.
> 
> Thank You Kindly,
> 
> Corwyn
> 
> --
> Topher Belknap
> Green Fret Consulting
> Kermit didn't know the half of it...
> http://www.greenfret.com/
> topher at greenfret.com
> (207) 882-7652
> 
> 
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