Date: Wed, 20 Jul 2005 23:59:08 -0700
Reply-To: Doug in Calif <vanagon@ASTOUND.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Doug in Calif <vanagon@ASTOUND.NET>
Subject: Re: Window Tinting - What Really Works? - cooling, shades,
curtains, solar gain
Content-Type: text/plain; charset="iso-8859-1"
Group,
All of my reading and testing with various window tints has all taught me
that dark tints super heat
the glass and thereby super heat the air inside the van.
The reason a car heats up in the sun is due to a process called "solar gain"
The car windows act as one way valves to allow sunlight through and once it
strikes a dark object inside the vehicle it is absorbed and the energy wave
changes into heat.
The heat is no longer a "light wave" of energy and can no longer pass back
out through glass, so the build up continues.
When sunlight strikes a dark colored object the heat energy is absorbed, a
light color will reflect the sunlight and not absorb it or convert it to
heat.
This is why the body of a white car sitting in the sun will be the same as
the air temp when you put your hand on it and a black car right next to it
can literally fry an egg. A light colored curtain in the window or a foil
type windshield sun shade reflects the "light" back out as "light" not
allowing it to be absorbed. If everything inside of your car was bright
white or a foil fabric it could reflect most or all of the light back out of
the glass and it would not have much "solar gain".
The problem with dark tints is even though they do stop the light from
entering the vehicle they ABSORB the light at the surface of the glass like
the paint on a black car does, because the glass is now a dark color. The
glass itself also has a great deal of thermal mass, its heavy and dense so
it can store lots of heat, like a black rock or hunk of black steel vs. a
black piece of wood in sitting in the sun. This even means once your AC
cools the air inside your van, you still have the weight of the glass to
cool down which takes far more energy than if the fabric on your seat (which
has little thermal mass) stopped the light, . There is so much glass in the
vanagon that it does a pretty good job of making an oven out of your bus.
An easy and effective solution while parked is a light colored (white
curtain) or mirror (bubble foil)
to reflect the heat back out the glass.
This does not allow anything inside the van to absorb the sunlight, even if
there are some dark colors in the curtain it has little thermal mass.
The glass will stay at a much lower temp.
Mirrored tint helps to a degree but they add dark pigments to it and the
dark pigments absorb heat.
I have personally tinted several of my vanagon windows with both dark limo
tint and even mirrored bronze and gold tints, and removed them every time
because they heat the glass too much for me with no AC.
True silver mirrored tint would absorb less or none but looks like mirrors.
Ceramic tints though expensive do the best job of not allowing the heat wave
energy to penetrate the glass and being a ceramic don't hold or absorb heat.
They are by far the best to see out clear glass and reject solar gain.
A light colored curtain in the window works extremely well but you cant see
out.
My first van an 85 sunroof was painted factory dark navy blue and had no
factory AC.
It was such an oven on hot sunny days that I eventually painted the whole
van white on the outside which made a huge difference.
I tried every kind of tint I could find and ended up making my own custom
shades to block the heat and gain privacy.
I ended up making shades out of Plexiglas and painting 50% of it white to
create a venetian blind effect.
It worked pretty well at blocking the heat, (and cold btw). Here's a couple
pics of the 85 with the custom the shades.
http://users.ca.astound.net/dougfayne/85sunroofvanagonpic3.JPG
http://users.ca.astound.net/dougfayne/85sunroofvanagonpic1.JPG
Currently on my 87 syncro which also has no factory AC and is the Dove blue
color (still hot in the sun) I made custom shades using a screen fabric
material called Suntex. It is developed solar heat rejection for homes and
RVs. It usually goes outside the glass. http://www.phifer.com/suntex.htm
It comes in various colors I chose the gray color and painted white stripes
on the outside with Krylon.
I attach it with snaps on all the windows during the summer. I also have the
westy curtains because at night you can see right through into the van when
lights are on.
It also adds insulation from the glass when its cold outside.
Here's some pics
http://users.ca.astound.net/dougfayne/SuntexFabriccantseein.JPG
http://users.ca.astound.net/dougfayne/Suntexlookingoutslider.JPG
http://users.ca.astound.net/dougfayne/Suntexpoptopup.JPG
http://users.ca.astound.net/dougfayne/Suntexlookingoutrearhatch.JPG
http://users.ca.astound.net/dougfayne/SuntexandDpillarsliders.JPG
Doug
----- Original Message -----
From: "Matthew C. Huntley" <matthew.huntley@STRATHBOGIE.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, July 20, 2005 8:58 PM
Subject: Window Tinting - What Really Works?
> I am looking into tinting the windows on my '86GL.
> I Really want to cut the amount of heat that the car retains during the
> day.
> I have have heard 2 stories on tinting the windows, Either it helps cut
> down the heat, or the tint picks up the heat, and radiates it into the
> car.
>
> which one is true?
>
> Thanks All,
> Matt