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re: best reflective surface for skylight shaft?
31 jul 2004
michael daly wrote:
>> ...i'm looking at a table that says white paint has 80% reflectance,
>> vs 86% for aluminum foil and 92% for aluminized mylar.
>
>considering you can see through aluminized mylar, i have my doubts about this
>claim.
full sun is about 10,000 footcandles. we can see in 0.1 fc,
ie we can "see through" something that's 99.999% reflective.
>consider what they cover telescope observatories with. the domes are almost
>always painted white with a high-titanium content paint. they are trying to
>reflect as much heat and light as possible in order to keep the observatory
>from heating up during the day. when have you ever seen them cover it with
>a mirror finish?
that's not easy to do.
>> the mirrorlike mylar can minimize the number of bounces in the shaft,
>> compared to diffuse white paint, further increasing the intensity at
>> the bottom.
>only if you can get it nice and smooth.
i disagree. wrinkles make little difference.
nick
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