[BLDG-SIM] energy consumption of low-E glazing , why the cooling energy increases

[nicole chen]

What I did is define a new glass type with simplied method in detailed
model. Then replace the old glass with the new defined one. Can this do? How
to avoid the defauls percolate through the program? I check again and find
that there was no wrong with the conduction heat and solar radiation through
window .But the load due to occupancy /lighting/euqipment of Glass Type II
is higher than Glass Type I . And the cooling energy of Glass type II is a
little highter. It make me confused. Why the load due to  due to occupancy
/lighting/euqipment  was different when Glass type changed.

And I doubt if the problem has something to do with OA load .


On 7/29/07, Karen Walkerman <kwalkerman at gmail.com> wrote:
>
> Hi nicole,
>
> I can't tell you why the heating energy of glass type II may be lower
> because of the better U-value.  With Shading Coefficients almost the
> same, there should be little change in heat gain from solar radiation
> between the two types.
>
> What method did you use to enter your data?  You should be careful of
> defaults that can percolate through the program.  For example, the
> window frame U-value may not be consistent, or the glass spacer-type
> may be different.
>
> Another good place to look for some feedback is the building and space
> peak loads summary.  Here, the solar gain (heat energy gained through
> radiation) and simple conditioning (energy transfered through the
> glass-same as walls), are broken out.  The heating design case will
> not take solar radiation into account.
>
> Hope this helps.
>
> ~karen~
>
> On 7/29/07, nicole chen <cloris.chen at gmail.com> wrote:
> > Dear all
> >
> > I have tried to compare the energy consumption between two different
> glass
> > types and got a curious result. The parameters of these two glasses are
> > listed below:
> >
> > 1) Coated U=2.5 SC=0.45
> >  2) low-e U=1.76 SC=0.44
> >
> > I thought the energy consumption of Glass Type II would be lower than
> that
> > of Glass Type I . But the result is the cooling energy of Glass Type II
> is
> > higher than  that of Glass Type I , and the heating energy lower than
> that
> > of Glass Type I.
> >
> > I have no idea of this. And I checked LS-F/ SS-D / BEPS and found some
> > points listed below
> >
> > 1) in LS-F annual sensible  cooling load of Glass Type II is lower than
> that
> > of Glass Type I , latent cooling load of Glass Type II is higher. The
> total
> > annual cooling load of Glass Type II is a little higher
> >
> > 2) in SS-D monthly cooling energy of Glass Type II is  higher
> >
> > 3) dencity and schedule of occupancy /lighting /euqipment are the same
> in
> > the two models , but cooling load and heating load due to these indoor
> > factors are different , why?
> >
> > 4) monthly schedule of occupancy /lighting /euqipment  is all the same
> > during the year, but cooling load and heating load due to these indoor
> > factors are different every month, why?
> >
> >
> >
> > --
> > Yours
> >  Nicole Chen
>
>
> --
> Karen Walkerman
> Second Law Consulting
> 802-238-0980
> kwalkerman at gmail.com
>



-- 
Yours
Nicole Chen


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