[Equest-users] Modeling Window changes

[Lam, Linda]

I have come across that situation a couple times.  The conclusion I came
to for replacing windows with a "better" (lower) SHGC and "better"
(higher) U-value, and still getting more energy use, has to do with heat
balance.  
 
When a building is in a mild/cool climate, the outside air temp causes
room temperatuer to drop below setpoint (ie, 68F) during unoccupied
times.  (Heat is lost through the envelope from a higher temperature to
lower temperature.) This can also happen if your building schedule has
long periods of unoccupied times between events like in a conference
center.  In the morning, the the outside air temperature picks up and
solar radiation starts coming through the envelope. During these times,
the space wants to be brought up to an occupied temperature (72F) from
its unoccupied space temp (65F) and would actually benefit from a less
resistant envelope because a "poorer" performing envelope allows faster
heat gain in the space.  
 
I hope that kind of makes sense.
 
Linda Lam, LEED(r) AP
WSP FLACK+KURTZ
405 Howard St. San Francisco CA 94105
Direct  415.402.5813
 

________________________________

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of
Matutinovic, Luka
Sent: Friday, May 29, 2009 7:29 AM
To: jklikape at aol.com; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Modeling Window changes


John,
 
It's difficult to diagnose your issue without having the .inp and .pd2
files to review.  
 
What do you mean by "more energy efficient"?  If you are referring to
U-value, the result does seem counter-intuitive (unless the negative
result is actually a reduction in energy shown as a "negative").  If
however, you consider a reduction in the SHGC to be more energy
efficient, this may in fact lead to increased energy use in heating
dominated climates since less solar gain is available in the winter.  As
I said, seeing the simulation would be helpful.
 
Cheers,

Luka Matutinovic, B.A.Sc., LEED(r) AP

Green Building Consultant
 
T. 416.487.5257 ext. 317  
F. 416.487.9766  
Toll Free 1.888.425.7255
www.halsall.com 

HALSALL ASSOCIATES LTD. 
Toronto  Richmond Hill  Ottawa  Sudbury 
Burlington  Calgary  Vancouver  Dubai 

'Best Workplaces in Canada' 
2009 Globe and Mail
P Please consider the environment before printing this e-mail


________________________________

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of
jklikape at aol.com
Sent: Friday, May 29, 2009 10:23 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Modeling Window changes


Good Morning,
My associate and I are beginners on the E-Quest program and are feeling
our way around the program.  Among many other questions that we may have
we are in a quandry as to why, when we use a more energy efficient
window in the EEM module, the results show a negative effect in our
simulation.  Is there some basic fundimental we,re missing here? 

John Klika
KGZ Consulting Engineers, Ltd.
Joliet, Illinois 
815-714-2818 

________________________________

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