So maybe we can use what Alex said: new windows must be 3x less leaky than old ones. Since that is just the window, not the whole exposure leakage, I'd go ahead and pull a number from the table Alex sent that matched my window, reduce it by 3 and then do an area weighted average for the entire wall. As a guide you could use .038 cfm/sf or 0.05 cfm/sf for a wall of the same exposure as yours and with the same glass area as yours to figure out what the wall cfm/sf is, unless you happen to know it. As an example xx sf wall x wall cfm/sf + yy sf window x yy cfm/sf for your window = xx+yy sf x .038 cfm/sf, you know your xx and yy sf, you can pick a reasonable cfm/sf for your window, or ask Alex for one, and then solve for your wall cfm/sf. Assuming you aren't doing anything to improve your walls you then have your xx cfm/sf. Then reduce your yy cfm/sf by a factor of 3, plug all the numbers in and solve for your new xx+yy, or overall wall cfm/sf. Put that number in eQUEST, document your calcs for the LEED, or whoever, reviewer and you are good to go.<br>
<br>Carol<br><br><div class="gmail_quote">On Wed, Sep 15, 2010 at 4:07 PM, Chris Jones <span dir="ltr"><<a href="mailto:cj@enersave.ca">cj@enersave.ca</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div>
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. <br><br>
The MNECB/CBIP in Canada uses 0.05 cfm/sq. ft of gross exterior wall area
- with a schedule on all of the time.<br><br>
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.<br><br>
<br><br>
At 06:16 PM 15/09/2010, Alex Krickx wrote:<br>
<blockquote type="cite">Content-Language: en-US<br>
Content-Type: multipart/related;<br>
boundary="_005_B8B836A09111F041A16C8A3690FB3563AFF4FE9861EXVMBX0156exc_";<br>
type="multipart/alternative"<div><div></div><div class="h5"><br><br>
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. <br>
<br>
The only link I could find on performance of old windows was this one:
<a href="http://www.bfrl.nist.gov/IAQanalysis/CONTAM/table00_arld.htm" target="_blank">
http://www.bfrl.nist.gov/IAQanalysis/CONTAM/table00_arld.htm</a> <br>
<br>
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). <br>
<br>
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. <br>
<br>
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….<br>
<br>
Regards,<br>
Alex<br>
<br>
<br>
<b>From:</b> Carol Gardner
[<a href="mailto:cmg750@gmail.com" target="_blank">
mailto:cmg750@gmail.com</a>] <br>
<b>Sent:</b> Wednesday, September 15, 2010 2:57 PM<br>
<b>To:</b> Alex Krickx<br>
<b>Cc:</b> YingQi Chen; <a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> Re: [Equest-users] Window replacement and infiltration
rate changing<br>
<br>
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.<br><br>
Carol<br>
On Wed, Sep 15, 2010 at 2:36 PM, Alex Krickx
<<a href="mailto:akrickx@seriousmaterials.com" target="_blank">
akrickx@seriousmaterials.com</a>> wrote:<br>
Hi Yingqi,<br>
<br>
I’m pretty sure eQUEST does not automatically adjust infiltration rates.
<br>
<br>
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.<br>
<br>
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.<br>
<br>
Good luck!<br>
Alex Krickx<br>
<br>
<br>
Alex Krickx<br>
Building Energy Specialist<br>
<img src="" alt="email_sig" height="42" width="121">
<br>
1250 Elko Dr, Sunnyvale, CA 94089<br>
(t) 408.541.8124<br>
<br>
<b><i>Warning:</i></b> The information contained in this e-mail may be
privileged attorney-client communications or attorney work product and/or
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the intended recipient then you have received it in error and any review,
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<br>
<br>
<br>
<b>From:</b>
<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">
equest-users-bounces@lists.onebuilding.org</a>
[<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">
mailto:equest-users-bounces@lists.onebuilding.org</a>] <b>On Behalf Of
</b>Carol Gardner<br>
<b>Sent:</b> Wednesday, September 15, 2010 2:19 PM<br>
<b>To:</b> YingQi Chen<br>
<b>Cc:</b>
<a href="mailto:equest-users@lists.onebuilding.org" target="_blank">
equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> Re: [Equest-users] Window replacement and infiltration
rate changing<br>
<br>
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.<br><br>
Carol<br>
On Wed, Sep 15, 2010 at 2:05 PM, YingQi Chen
<<a href="mailto:yingqi.chen@pertan.com" target="_blank">yingqi.chen@pertan.com</a>
> wrote:<br>
Dear eQuester:<br>
<br>
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. <br>
<br>
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. <br>
<br>
<b>Question 1:<br>
</b> <br>
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? <br>
<br>
<b>Question 2:<br>
</b> <br>
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?<br>
<br>
Yingqi Chen<br>
<br>
The PERTAN Group<br>
44 Main Street, Suite <br>
Champaign, IL 61820<br>
<br>
217-356-1348 ext 205<br><br>
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<br><br>
-- <br>
Carol Gardner PE<br><br>
<br>
---------- Forwarded message ----------<br>
From: Nick Caton
<<a href="mailto:ncaton@smithboucher.com" target="_blank">ncaton@smithboucher.com</a>
><br>
To: Alex Krickx
<<a href="mailto:akrickx@seriousmaterials.com" target="_blank">
akrickx@seriousmaterials.com</a>>,
"<a href="mailto:equest-users@lists.onebuilding.org" target="_blank">
equest-users@lists.onebuilding.org</a>"
<<a href="mailto:equest-users@lists.onebuilding.org" target="_blank">
equest-users@lists.onebuilding.org</a>><br>
Date: Mon, 8 Mar 2010 16:47:48 -0800<br>
Subject: RE: [Equest-users] Modeling Infiltration and Windows<br>
I’ve done exactly that in the past for the exactly the same purpose!<br>
<br>
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.<br>
<br>
Come up with a “leakiness” for both you construction, old and new
windows, and do the weighted average jig =).<br>
<br>
Kudos on your fancy facade spelling also ;)! <br>
<br>
~Nick<br>
<img src="" alt="cid:489575314@22072009-0ABB" height="37" width="119">
<br>
<b> <br>
NICK CATON, E.I.T.<br>
</b>PROJECT ENGINEER<br>
25501 west valley parkway<br>
olathe ks 66061<br>
direct 913 344.0036<br>
fax 913 345.0617<br>
<i>Check out our new web-site @
</i><a href="http://www.smithboucher.com" target="_blank">www.smithboucher.com</a><u>
<br>
</u> <br>
<b>From:</b>
<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">
equest-users-bounces@lists.onebuilding.org</a>
[<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">
mailto:equest-users-bounces@lists.onebuilding.org</a>] <b>On Behalf Of
</b>Alex Krickx<br>
<b>Sent:</b> Monday, March 08, 2010 6:05 PM<br>
<b>To:</b>
<a href="mailto:equest-users@lists.onebuilding.org" target="_blank">
equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> [Equest-users] Modeling Infiltration and Windows<br>
<br>
Hello all,<br>
<br>
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. <br>
<br>
I’m hoping someone can confirm my methodology:<br>
<br>
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 <i>façade </i>infiltration value.<br>
<br>
That way I could use the same formula to determine the area weighted
infiltration of the façade if better windows were installed.<br>
<br>
How do other people model this?<br>
<br>
Thanks in advance!<br>
<br>
Alex Krickx<br>
<br>
<br>
Alex Krickx<br>
Building Energy Specialist<br>
<img src="" alt="email_sig" height="42" width="121">
<br>
1250 Elko Dr, Sunnyvale, CA 94089<br>
(t) 408.541.8124<br>
<br>
<b><i>Warning:</i></b> 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,
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notify us immediately by reply e-mail and delete the original message
immediately.<br>
<br>
<br>
<br><br>
<br><br>
-- <br>
Carol Gardner PE<br><br>
<br>
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<p>
<br>
Chris Jones<br>
14 Oneida Avenue<br>
Toronto, ON M5J 2E3.<br>
Tel. 416-203-7465<br>
Fax. 416-946-1005<br><br>
</p></div>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Carol Gardner PE<br>
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