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Night ventilation - Page 3

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Posted by daestrom on November 23, 2006, 3:17 pm

LIAR!  Or is the little smiley supposed to mean it's okay for you to make
mistakes and claim it's my fault?

I didn't miss it, you didn't put it in.  All you have is an overall
'conductance' between outside temperature and house temperature.  There's a
difference between admitting that you left something out, and claiming that
I overlooked it.  Identify the line of code that considers solar input in
your original listing.  Or admit that you omitted it.  Don't go around
implying that others are too ignorant to understand you when it is your

Another point; you've averaged the electrical heat gain over 24 hours.
Totally unrealistic for most folks.  This error causes your model to
underpredict the daily high indoor temperature, while overpredicting the
daily low.  Why not weight the electrical heat gain a bit differently to be
more realistic, say 1/2 the daily usage from 1400 to 2200 and 1/2 over the
other 16 hours?  Or you could claim that high-heat producing activities are
done between 0800 and 1200 (before the 'heat of the day' sets in).  But
regardless, it is totally unrealistic to claim that electrical heat gain at
0300 is the same as 1800 every day.  So the daily variations of indoor
temperature are useless.

If you're trying to calculate the hourly changes in temperature, you *have*
to consider the inputs on the same time scale.  In order to calculate house
temperature on an hourly basis, you must consider the heat gains/losses on
an hourly basis as well.  You've done this with the outdoor air temperature
(albeit out of phase by 6 hours because of the way you used the 'sin'
function), but you haven't done so with the electrical heat gain, nor human
heat inputs  (another input you've ignored).

Why ignore human/animal heat gain?  You've posted calculations in the past
claiming to heat an 8' cube in the winter with little more than human and
pet heat input.  So you've argued that those factors can be important heat
loads in a well designed home, but you selectively ignore them when it
doesn't suit your purpose?

Bottom line is, opening some conventional windows does a better job
controlling summer house temperatures in this climate than your
'ventilation' idea.

Folks like you that claim to have a lot of answers, and write shoddy code to
'prove' it, can be pretty annoying.  Junk science is all it is.  Yes heat
transfer and fluid flow is a mature, well respected science.  But applying
first-year formulas and simplifing to the point of garbage-in / garbage-out
and then holding it out for others to show them how 'smart' you are is
pretty lame.  The lay person may actually think your answers are meaningful
since you do use valid formulas.  Unfortunately, this is the 'junk
scientist' at his worst.  They have enough credibility using some basic
undergraduate level stuff to convince the 'masses' they know what they're
talking about, but they ignore so many factors (too hard for you??) that the
results are not much better than reading tea leaves.  And the poor layman
can't tell the difference and may actually build your systems; only to be

Consultants used the same sort of junk science in the late '70's to sell
solar systems to people after the energy crisis.  And when those systems
didn't perform anywhere near the claims of the consultants, solar got a lot
of bad press.  It's just recovering from that stigma, yet here you are
spouting the same junk science to a whole new generation.

So come on, clean up your act; do the calculations considering *all* the
significant factors; take the time to critique your own work pointing out
its limitations; -or- just admit your doing back-of-the-envelope guesses
that aren't really useful and be done with it.


Posted by nicksanspam on November 23, 2006, 3:34 pm

Can you say "unshaded windows"? :-)

Where should we stop on the way to infinite refinement? I did a TMY2
simulation for heating. Cooling is less interesting, on 70 F July days.

Would you have any evidence for this article of faith?


Posted by Solar Flare on November 24, 2006, 2:29 am
 Daestrom hasn't gotten laid for a few weeks I guess.

Posted by SJC on November 24, 2006, 2:46 am
 Or he might just be tired of people acting like they own Usenet cuz they do math.

Posted by Solar Flare on November 25, 2006, 2:39 am
 Or tired of people that know as much as he does.

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