| Phil Scott 2005-06-26, 4:25 am |
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"Robert Bonomi" <bonomi@host122.r-bonomi.com> wrote in message
news:11bs1lfok861n40@corp.supernews.com...
quote:
> In article <42BDB7E5.456E1146@Guy.com>, Some Guy
<Some@Guy.com> wrote:
quote:
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>
> Back in the days before ubiquitous A/C, and when 'skimpy'
insulation was
quote:
> commonplace, "watering the roof" was a _common_ method of
making things
quote:
> inside a bit more livable.
>
> The idea being to just wet down the roof, and have the water
_evaporate_
quote:
> to carry off the heat. evaporating water pulls off
hundreds of times as
quote:
> much heat energy as does just warming the water up does.
>
> 'Evaporative cooling' is one of the most energy efficient
cooling methods
quote:
> known. However, there are a whole bunch of limits as to how
much cooling
quote:
> you can get that way. The higher the ambient 'relative
humidity', the
quote:
> less cooling you can produce. The lower the temperature,
the less cooling
quote:
> you can produce. And, of course, you have to have a means
to 'discard'
quote:
> the 'used up' air.
>
> As a practical matter, you "don't care" how hot the attic
air is _near_the_
quote:
> _roof_, if the temperature just above the insulation to the
inhabited space
quote:
> stays rational. Decent 'convection' air-flow, possibly with
power-assist
quote:
> does a good job of _that_.
>
> Also, if you have 'good' insulation between the inhabited
space, and the
quote:
> attic, a 'spike down' in the attic temperatures will -not-
make a noticable
quote:
> difference in the inhabited space thermal load -- takes too
long for the
quote:
> change to 'penetrate' all that insulation.
>
>
> I'd try putting some temprature sensors at, or even a little
ways _into_
quote:
> the top of the insulation at the attic *floor*, and see how
bad the
quote:
> temperatures get there. And then try to optimize the
air-flow to get
quote:
> those readings close to 'in the shade' outdoor temperatures.
Thats good advice
Phil Scott
quote:
>
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