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GBlist: calculating passive solar...




"Actually I might be interested in doing my own if it's not too complicated"

Hi Ed,

I don't know your background or skills, but here's some suggestions ranging
from simple to pretty damn tedious.  I'm posting this to the whole group
'cause there may be others interested and I spent a lot of time writing my
own programs and going through most of the available programs line by line.
 If you are using calculator or spreadsheet, I'd suggest you look for a copy
of Doug Balcomb's book on passive solar design.  It's a fairly simple method
that keeps the calculations to arithmetic.  If you program in BASIC, Fortran,
Pascal or C, and you are ok with collage level math, you could write your own
program.  Probably take you 100 hours to write and debug the program.  Maybe
a couple hundered lines of code.  I'd suggest doing calculations for the
average day of each month.  The solar radiation processor is the most tedious
thing to get working (lot's of transcendental functions).  Look at Duffy and
Beckman's Solar Engineering text.  I used Mike Rubins window transmission and
loss equations, but these days you can get a good estimate of window behavior
by calculating shading coefficients and u-vales in WINDOW from Dariush
Aresteh at LBL.  I like Barakat's mass-solar-internal gains model for
estimating the useful solar and internal gains.  For basement loss, there's a
good Canadian model (don't remember the fellows name but I've got the papers
in my files if you want them) or you can fit curves to the tables in ASHRAE
handbook of fundamentals.  For infiltration I'd stick with the LBL model
(Grimsrud and Sherman, not COMIS).  Definitely avoid the Shaw Tamura
infiltration model.  Danny Parkers Sunhouse uses the methods that I like
best.  Hotcan uses the same ones, but has no real radiation processor and a
pretty simple window calculation.  If you want to do hourly simulations, I'd
go for a second order Runge-Kutta method.  Let me know if you want to track
any of this stuff down. -Terry
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