"rangerssuck" wrote in message
...
On Jul 27, 10:20 am, "Existential Angst" wrote:
Awl --

Recently, on one of these How They Do It ditties, they featured but more
Dubai profligacy, this time indoor skiing in the middle of the effing
desert.

The key to the insulation, they explained, was a huge air gap, asserting
that air -- caveat: trapped non-moving air -- was among the best
insulators.

First, is this true? Before I insulated my roof, that air would become
blisteringly hot, and it didn't seem to be moving much. That attic seemed
like a pretty good air gap to me, and it didn't seem to be doing much
insulating.

Second, I seem to remember one strategy where push/pull fans were used
with
air gaps in a roof-type situation, to keep air flowing, to reduce the
heating transfer, like what accumulated in my attic -- ie, the exact
opposite of static air.

Now mebbe air behaves differently in conduction vs. *radiant* heat from
roof-type situations that is making the attic so hot, not hot air
itself --
if the two can be distinguished wrt air.

iirc, the Dubai ditty used reflection, insulation, AND that big air
gap.....

But I've read about this insulating property of air before, so I'm
wondering
how it might be employed in a house.
It would seem that if air itself was so good, solid insulation wouldn't be
so high a priority

I wonder what mooslims think about Dubai.....
--
EA

You've got a bunch of apples and oranges mixed up in your fruit salad.
In your attic, you have a roof which is being heated by the sun. Then
you have convection, which mixes up the attic air and brings it in
contact with the lower floor's ceiling. The object of insulation
material is to keep the air still, to (virtually) eliminate the
convection.
================================================== ==

If I saw/understood correctly, the air gap space in this Dubai skiing thing
was the size of an airplane hangar.
=======



a properly vented attic space should have a considerably lower
temperature. Air is drawn into the soffit vents and expelled through
the ridge vent. Even better is a powered ventilator or, the push-pull
fans you mentioned. In the ventilated space, the sun-heated air is
replaced with cooler ambient outside air. This has nothing to do with
the insulation value of the air, just its temperature.

Besides the house cooling issues, it is generally a good thing for the
logevity of the roofing materials to keep the inside attic temperature
as close as possible to the outside temperature.
================================================== =====

Yeah, I've heard that too.
I've got a slate roof, I wonder if insulated the rafter space was the best
move.
--
EA









A reflective roof would make a huge difference. I don't understand the
fascination with black (or othr dark color) roofing shingles.