[BLDG-SIM] eQuest Dbl Skin Sim

[stvgates at pacbell.net]

See comments imbedded below ........

----- Original Message ----- 
From: "Kevin Krudwig" <kdk_71 at yahoo.com>
To: <BLDG-SIM at GARD.COM>
Sent: Saturday, January 24, 2004 8:26 PM
Subject: [BLDG-SIM] eQuest Dbl Skin Sim


> Hello,
> Can anyone tell me:
>
> Is it possible to simulate a double skin façade with
> eQuest?
> If so, how to?

I am not aware of an accurate way to simulate a double skin facade in
eQUEST, but a quick back-of-the-envelope analysis may suffice to draw
conclusions about this concept:

1.  Assume your building costs $150/sq.ft. to build, and that the
double-skin is 10% of that cost, or $15.
2.  Assume that energy for the building costs $1.25/sq.ft./year, and that
the double-skin saves 25% of the total energy budget, or $0.31/sq.ft./year.
(In many buildings, lights and plug loads comprise about half the energy
cost, and this analysis assumes the double-skin has no impact on either.  So
this guestimate is based on the double skin saving 50% of the HVAC costs,
which seems quite optimistic.)
3.  The simple payback is then $15/$0.31 = 48 years.  This assumes an
opportunity cost of 0%, and no additional operating and/or maintenance
costs. If the actual interest rate is 5%,
the annual interest cost is $15*0.05 = $0.75/year; or more than twice the
energy savings.  Given the interest cost, the double-skin would have to
eliminate ALL of the HVAC energy, and a portion of the lighting as well.

So, is a double-skin facade worthwhile?  Unless the assumed cost of the
double skin is high by a factor of at least 3, this concept does not appear
worth considering.

Does anyone have any better information on construction costs and energy
savings of an actual building using a double-skin facade?  To me, this
concept is so far out in left field that I don't understand why there is so
much interest in it.

>
> Is it possible to simulate a dynamic façade with
> eQuest?

I'm not sure what you mean by a dynamic facade.  In regards to dynamic
shading in eQUEST, you can define a schedule that modifies the transmittance
of a building shade.

> One that incorporates Photovoltaics?

Yes, eQUEST simulates photovoltaics.  The PV modules can be mounted
stand-alone, or incorporated as part of a building shade.  Be sure to use a
recent version, as the photovoltaic algorithms were upgraded last fall.
Study the PV-MODULE and ELEC-GENERATOR sections in the DOE-2.2 Dictionary.
>
> Thanks
> Kevin K.
>
>
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