[BLDG-SIM] Simulations Insensitive to Glass Changes

[Vikram Sami]

Brandon,
Mysterious. 
 
What's you overall building use (BTU/sf)? Is the glazing are
significant? Where is this building located? (I have done a similar
study in Hawaii where I found that single glazing performs better than
double, because the weather was good for it. 
A good quick gut check  is to look at the LS-F reports and see what
percentage of the loads are coming from window conductance. 
 

Vikram Sami, LEED AP 
Direct Phone 404-253-1466 | Direct Fax 404-253-1366 

LORD, AECK & SARGENT ARCHITECTURE
1201 Peachtree Street NE, Suite 300, Atlanta, GA 30361 
Responsive Design * Technological Expertise * Exceptional Service 
www.lordaecksargent.com 

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________________________________

From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Brandon
Nichols
Sent: Monday, July 23, 2007 5:10 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Simulations Insensitive to Glass Changes


All,
 
I have a 3-story historic building, with circa-1920's windows on all
four exposures.  Big, beautiful, clear-glass single-pane architectural
masterpieces.  So while doing an optimization study, it became apparent
to me that substantially changing the U-value and infiltration
coefficients was having very little effect at all on the loads.
 
For example, varying the U-value from 1.27 to 0.55, 0.45 and at last
0.30 in the parametric runs using the 'simplified method' produced a
0.5% total (over all runs) change in the total energy consumption.
Selecting representative glass types using the 'library method' produced
essentially equivalent.  Superimposing upon either of these a change in
the infiltration coefficient from 1/4" to 1/8" to 1/16" to 1/32"
produced no additional effect at all (the INF-METHOD = CRACK keyword is
specified) on the annual energy consumption.
 
Lastly, I changed the baseline glass to "unglazed opening", again with a
mystifying zero net effect on the overall energy consumption.  It's as
if the glass is not being calculated at all, but I see no errors or
warnings in the SIM file.
 
Anyone have an idea on how to debug this?
 
Thanks in advance...
 
 
Brandon Nichols, PE
Mechanical
HARGIS ENGINEERS

600 Stewart Street

Suite 1000

Seattle, WA 98101

www.hargis.biz

 

d | 206.436.0400  c | 206.228.8707

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