Re: [EnergyPlus_Support] Heat transmittance question

[Chris <chris@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

There is actually a substantial change in the U-factor when a window is 
tilted rather than vertical, due to changes in the convection patterns 
within the air space and outside air film.
Some typical results, based on WINDOW simulations, are presented in a 
paper in press, 
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V50-4VC10K5-1&_user=6583708&_coverDate=01%2F12%2F2009&_alid=867893182&_rdoc=3&_fmt=high&_orig=search&_cdi=5772&_docanchor=&view=c&_ct=31&_acct=C000047720&_version=1&_urlVersion=0&_userid=6583708&md5=b6e1dc352bb3bdbf15d7f466c683cb65
I don't know how E+ handles this, though.

Chris

>  The U value has got nothing to do with the position of the window. 
> The U value is always the same regardless of the position of the 
> window since it has got to do with the material of the glass pane and 
> the nature of the air gap of the window. The position of the window 
> though, has a different effect in the zone's heating or cooling demand 
> since it has an effect on the solar gains but apart from that the U 
> value is always the same. If you make a window the U value will be 
> stored from the EnergyPlus or DesignBuilder and the different 
> positions of this window mayindeed have a different effect in your 
> simulation but not due to the change in the U-value. 
>
> Regards
>
> Tasos
>


-- 
Chris A. Gueymard, PhD
Solar Consulting Services
P.O. Box 392
Colebrook, NH 03576, USA
Tel. (603) 237-8550
Fax  (603) 237-5314
http://www.SolarConsultingServices.com



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