[BLDG-SIM] Simulations Insensitive to Glass Changes

[Brandon Nichols]

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

o | 206.448.3376  f  | 206.448.4450

 
 


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