[Equest-users] Window replacement and infiltration rate changing

Peter Hillermann peterh at westallarchitects.com
Thu Sep 16 10:20:41 PDT 2010


I have a question along the line of infiltration through windows.

 

I know that there are methods of calculating infiltration and as an
architect we usually go with the crack method calculating the linear length
of all seams. I have read that air infiltration is not listed on NFRC labels
but needs to be obtained by manufacturers catalog.

 

My question is, how important is the infiltration when your building is
positively pressurized? Most of our buildings are designed that way, do you
still need to calculate that in your air exchange, since infiltration
through windows is typically an air exchange. My engineer told me not to
worry about it.

 

We also use metal panels on our PEMB buildings which our manufacturer says
has a lower infiltration rate than other metal panels. It’s how they set up
their gasket. So in the opinion of our engineer you would have to calculate
all the infiltration at all the seams. It’s like going down the rabbit hole.

 

Does your architect call for taped seams on tyvek? Does the architect call
for butyl at penetrations? Are you accounting for infiltration at doors?
ETC
 and believe me the list goes on because I almost went down it.

 

Thanks,

 

PETER HILLERMANN

 

peterh at westallarchitects.com

 

westall

architects

3404 pierce drive

chamblee, georgia 30341

 

o 770.458.4113

f  770.458.5352

c 678.898.2936

 

westallarchitects.com

e-signatureUSGBC-Logo

 

 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Chris Jones
Sent: Wednesday, September 15, 2010 7:07 PM
To: Alex Krickx
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Window replacement and infiltration rate
changing

 

ASHRAE 90.1-1989 prescribed the amount of infiltration to use in the design
and budget cases as 0.038 cfm/sq. ft. of gross exterior wall area.  I
believe that subsequent versions of 90.1 dropped any reference to modelling
infiltration rates.  The infiltration is "on" when the fans are off.  

The MNECB/CBIP in Canada uses 0.05 cfm/sq. ft of gross exterior wall area -
with a schedule on all of the time.

Who knows where those numbers came from and it doesn't really answer the
question of how much infiltration will be saved with new windows but it
gives a starting point.



At 06:16 PM 15/09/2010, Alex Krickx wrote:



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boundary="_005_B8B836A09111F041A16C8A3690FB3563AFF4FE9861EXVMBX0156exc_";
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Yeah, it does sound high, doesn’t it? But when compared to the maximum level
for new windows of 0.3, then it doesn’t sound as high
 new windows must be
3x less leaky than old ones – that sounds like the right reduction to me. 
 
The only link I could find on performance of old windows was this one:
http://www.bfrl.nist.gov/IAQanalysis/CONTAM/table00_arld.htm 
 
It gives leakage areas in “area per linear meter of seam”. A colleague
converted this to leakage area in CFM/SF at 75 pa. His number was 1.4 CFM/SF
based on the table (not sure which value he used). 
 
As a thought: perhaps 1 CFM/SF seems too high because we imagine it as the
infiltration for a whole wall, when in actuality it only applies to the
window? Assuming the wall has little infiltration, a 25% WWR would bring 1
CFM/SF (window) to around 0.25 CFM/SF (whole façade) – probably a little
higher if accounting for the wall leakage, but not significantly so. Does
that number still raise alarm bells? Not to me, but I don’t have as good a
feel for this as Carol does. 
 
I’ve definitely seen some leaky windows – unfortunately I’ve never tested
how leaky they are so I’m stuck with looking for industry papers and best
practice.  I definitely would like to learn more about this though. Typical
infiltration values of old windows seems to be a big question mark with
people I’ve asked
.
 
Regards,
Alex
 
 
From: Carol Gardner [ mailto:cmg750 at gmail.com <mailto:cmg750 at gmail.com> ] 
Sent: Wednesday, September 15, 2010 2:57 PM
To: Alex Krickx
Cc: YingQi Chen; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Window replacement and infiltration rate
changing
 
Wow! It seems like 1 cfm/sf for infiltration would be a lot. The people's
hair next to the windows would be blowing all around! That's the average
number I use for HVAC ventilation.

Carol
On Wed, Sep 15, 2010 at 2:36 PM, Alex Krickx < akrickx at seriousmaterials.com
<mailto:akrickx at seriousmaterials.com> > wrote:
Hi Yingqi,
 
I’m pretty sure eQUEST does not automatically adjust infiltration rates. 
 
If you search through the archives and look up “infiltration windows” you
can find some relevant posts. I’ve attached one email that was sent around
earlier this year describing one way to change the infiltration between
current and proposed cases.
 
I don’t think you can apply a percentage reduction without some more
information. I believe that the requirement to meet the DOE’s VPP for
windows is a maximum infiltration of 0.3 CFM/SF – this leads me to believe
that some new windows have more infiltration than this. My company
manufacturers windows with infiltrations as low as 0.01 CFM/SF. I’m having a
hard time finding a source, but I’m pretty sure I’ve heard of modeling
existing windows with infiltration as high as 1 CFM/SF. A building with a
large WWR and very leaky windows could substantially reduce whole-building
infiltration values.
 
Good luck!
Alex Krickx
 
 
Alex Krickx
Building Energy Specialist
email_sig
1250 Elko Dr, Sunnyvale, CA 94089
(t) 408.541.8124
 
Warning: The information contained in this e-mail may be privileged
attorney-client communications or attorney work product and/or proprietary
and confidential.  If the reader of this message is not the intended
recipient then you have received it in error and any review, distribution or
copying of this message is prohibited and you are to notify us immediately
by reply e-mail and delete the original message immediately.
 
 
 
From: equest-users-bounces at lists.onebuilding.org [
mailto:equest-users-bounces at lists.onebuilding.org
<mailto:equest-users-bounces at lists.onebuilding.org> ] On Behalf Of Carol
Gardner
Sent: Wednesday, September 15, 2010 2:19 PM
To: YingQi Chen
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Window replacement and infiltration rate
changing
 
If eQUEST changed the infiltration between the two cases you would be able
to see the change in your .inp deck. I'm not sure what the impact of doing
the change using the EEM Wizard vs. simply copying and renaming your input
deck and making the change in it's own .inp deck would be. You could
experiment and see if there's a difference. If it doesn't change your
infiltration I would lower the perimeter infiltration rate conservatively by
a fixed percent. You might Google infiltration rates on line and find some
information related to how much to expect for a single pane window to a
double pane window. Also, be sure to account for your frames, too. Are they
thermally broken? Does the frame material change, etc.

Carol
On Wed, Sep 15, 2010 at 2:05 PM, YingQi Chen <yingqi.chen at pertan.com >
wrote:
Dear eQuester:
 
I want to run a simulation by EEM wizard. I want to replace exiting single
pane, clear windows with double pane clear windows for a school building. 
 
I changed the class type form single pane clear to double pane clear
windows.  The energy saving doesn’t look good.  I have two following
questions need someone's guidance. 
 
Question 1:
 
My question is that this EEM will reduce perimeter infiltration rate of the
building. I am not quit sure if I need to reduce the perimeter infiltration
rate in the simulation. If, it does, how many percentage of infiltration
rate do I need to reduce? 
 
Question 2:
 
Does eQuest programmer has already considered this issue and changed the
perimeter infiltration rate automatically with changing window glass type
and insulation of the windows?
 
Yingqi Chen
 
The PERTAN Group
44 Main Street, Suite 
Champaign, IL 61820
 
217-356-1348 ext 205

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-- 
Carol Gardner PE


---------- Forwarded message ----------
From: Nick Caton <ncaton at smithboucher.com >
To: Alex Krickx < akrickx at seriousmaterials.com
<mailto:akrickx at seriousmaterials.com> >, "
equest-users at lists.onebuilding.org
<mailto:equest-users at lists.onebuilding.org> " <
equest-users at lists.onebuilding.org
<mailto:equest-users at lists.onebuilding.org> >
Date: Mon, 8 Mar 2010 16:47:48 -0800
Subject: RE: [Equest-users] Modeling Infiltration and Windows
I’ve done exactly that in the past for the exactly the same purpose!
 
The only difference is I believe I always punch in the differences in the
metric of ACH.  ASHRAE fundamentals provides some guidance regarding air
change rates to expect for various classes of construction as a function of
outdoor design temperature, and that was the best I could base my existing
construction off of from what info I had available.
 
Come up with a  “leakiness” for both you construction, old and new windows,
and do the weighted average jig =).
 
Kudos on your fancy facade spelling also ;)! 
 
~Nick
cid:489575314 at 22072009-0ABB
 
NICK CATON, E.I.T.
PROJECT ENGINEER
25501 west valley parkway
olathe ks 66061
direct 913 344.0036
fax 913 345.0617
Check out our new web-site @ www.smithboucher.com 
 
From: equest-users-bounces at lists.onebuilding.org [
mailto:equest-users-bounces at lists.onebuilding.org
<mailto:equest-users-bounces at lists.onebuilding.org> ] On Behalf Of Alex
Krickx
Sent: Monday, March 08, 2010 6:05 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Modeling Infiltration and Windows
 
Hello all,
 
I am interested in modeling the energy savings that occurs when windows are
replaced with lower-infiltration alternatives. In the wizard mode, the only
place that I see infiltration is under the “Building Envelope Constructions”
Screen. 
 
I’m hoping someone can confirm my methodology:
 
Can I input a weighted average of window and wall air infiltration here?  If
I’m looking at a building with 20% Window to Wall Ratio, and the windows
have 0.1 CFM/ft² while the walls have 0.04 CFM/ft²can I apply an area
weighted average into this box? I would take (20%*0.1+80%*0.04) as the
façade infiltration value.
 
That way I could use the same formula to determine the area weighted
infiltration of the façade if better windows were installed.
 
How do other people model this?
 
Thanks in advance!
 
Alex Krickx
 
 
Alex Krickx
Building Energy Specialist
email_sig
1250 Elko Dr, Sunnyvale, CA 94089
(t) 408.541.8124
 
Warning: The information contained in this e-mail may be privileged
attorney-client communications or attorney work product and/or proprietary
and confidential.  If the reader of this message is not the intended
recipient then you have received it in error and any review, distribution or
copying of this message is prohibited and you are to notify us immediately
by reply e-mail and delete the original message immediately.
 
 
 



-- 
Carol Gardner PE


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Chris Jones
14 Oneida Avenue
Toronto, ON M5J 2E3.
Tel.  416-203-7465
Fax. 416-946-1005

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