[BLDG-SIM] Simulations Insensitive to Glass Changes

[Graham Carter & Megan Lyall]

Try playing with night purge.  I suspect the lower U-Value is  
penalising you by trapping heat at night that is then retained for  
the morning to become an AC load.  If you look at peak loads and have  
simulated using a design day you should see an improvement in peak  
loads by lowering the U-Value.  A thermally massive building would  
make the % change between glasses appear even less.
G
On 24/07/2007, at 7:09 AM, Brandon Nichols wrote:

> 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
>
>
> ======================================================
> You received this e-mail because you are subscribed
> to the BLDG-SIM at GARD.COM mailing list.  To unsubscribe
> from this mailing list send a blank message to
> BLDG-SIM-UNSUBSCRIBE at GARD.COM
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20070727/3e3cbb62/attachment-0005.htm>