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Re: Blinds?

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Posted by Josepi on June 27, 2010, 7:36 pm
Some have foil layers inside but I have not seen any that can be turned
backwards or would want to turn backwards.

All ours have top down bottom up features for privacy while maintaining a
view. This may work to block / reflect sun at the bottom while maintaining
more light and a view at the top.

These guys beat HD and all the blinds stores by about half the price. We
bought the Bali brand as we also saw them at our local Lowes store and could
compare quality with most other top brands. They run much cheaper than the
Levellor with 20% off, Hunter Douglas , also, in the stores and the online
gives you much less than that also.


Delivery was 6 days and 7 days (incl long weekend) from Texas to Ontario and
taxes were all paid up front to avoid border crossing delays and charges.
Very nice quality! Hung in about 3 min each!

I am not affiliated with blinds.cxx in anyway, only a recent satisfied

Does anyone make window blinds that can be turned one way to reflect heat
back out in the summer, and the other way to absorb heat into the home in

- Jane Galt

Posted by Jim Wilkins on June 27, 2010, 10:23 pm

If the blinds are open in winter the room will absorb any heat that
radiates in.


Posted by Jane Galt on June 28, 2010, 1:07 am

Good point, but what if you want them closed for privacy. The black on one
side could still absorb heat.

- Jane Galt

Posted by Jim Wilkins on June 28, 2010, 1:44 pm
That is a good idea, but...

A hot surface next to the window will also radiate back out, though at
a longer wavelength that the glass may absorb (and conduct out). The
warmer it is the more it loses, proportional to the fourth power of
its absolute temperature. This is why the floor absorbs heat more

When I made my insulated window inserts I was working for a brilliant
engineer with a Ph.D in physics, who calculated the radiative heat
gain and loss through them in his head. The result was low enough that
I simply made aluminized cloth liners for the curtains and open them
in the day, close them at night or if I want privacy. There are very
few times when I would want both solar heat and privacy.

That's typical for me, finding an answer so simple I can't make any
money from it. The sink spray hose in the shower is another one. They
do get me R&D jobs sometimes, which may be the most gain for the least

If you want to experiment you could hang two sets of curtains, the
aluminized ones close to the glass to block convection and the dark
ones further back to allow it.

In theatre we use a sheet of white gauze called a scrim which is
opaque when illuminated, otherwise transparent. You can see a good
example in the musical "Chicago" when the back wall of the warden's
office dissolves to show inmates chanting We Want Billy. All the
effects in that movie are standard stage practice. You could attach
gauze to a curtain roller to make a one-way daytime privacy window, at
least to experiment. Aluminum window screens help when the sun is out.

I measure surface temperatures in experiments by reading black tape or
Magic Marker patches with an infrared thermometer. Otherwise
differences in emissivity distort the values.

Look at the energy savings vs the nuisance and distraction cost as
well. How many extra morning chores can you stand? To use this type of
free energy savings you have to watch and remember the weather report
and pay attention to indoor and outdoor temperatures, and in the
summer the dew point.


Posted by Jane Galt on June 28, 2010, 1:06 am

Like regular slat window blinds, where you can close them either one way or
the other? Only these would have black on one side and reflective material on
the other.

Surely someone has done that?

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