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I got a van and I want to use reflectix on the windows to stop heat exchange.  I can't use reflectix on the walls/ceiling/floor because I'm going to install sound deadening material there.

So my question is; How much heat exchange happens at the windows compared to the rest of the van?
Here is a snipet that might help you determine things about 'heat exchange'

"The R-value is a measure of an insulation sample's ability to reduce the rate of heat flow under specified test conditions. The primary mode of heat transfer impeded by insulation is conduction, but insulation also reduces heat loss by all three heat transfer modes: conduction, convection, and radiation."

See also: https://en.wikipedia.org/wiki/R-value_(insulation)
Why do you think that sound dampening materials excludes the option of also adding insulation?

What kind of sound dampening materials will you be using?
If they are full-covering, they might provide the same insulation R-value as reflectix  does. As the R-value (conduction insulation) of reflectix is quite low.
And here is some information about heat exchange properties of windows: http://www.gjerdessolarshield.com/2016/1...nsulation/
(04-26-2019, 04:56 AM)MrAlvinDude Wrote: [ -> ]Here is a snipet that might help you determine things about 'heat exchange'

"The R-value is a measure of an insulation sample's ability to reduce the rate of heat flow under specified test conditions. The primary mode of heat transfer impeded by insulation is conduction, but insulation also reduces heat loss by all three heat transfer modes: conduction, convection, and radiation."

See also: https://en.wikipedia.org/wiki/R-value_(insulation)

Thanks for the information.
(04-26-2019, 05:03 AM)MrAlvinDude Wrote: [ -> ]Why do you think that sound dampening materials excludes the option of also adding insulation?

What kind of sound dampening materials will you be using?
If they are full-covering, they might provide the same insulation R-value as reflectix  does. As the R-value (conduction insulation) of reflectix is quite low.

I'm not sure what sound dampening material to use, but it would be good if it had a high R-value then I could use it for both purposes.

I thought reflectix is the best for avoiding heat exchange through the windows??
reflectix works great for the windows especially to block sunlight and canceling the greenhouse effect. but for anything else it's pretty useless. highdesertranger
Have to disagree that for anything else reflectix is pretty useless.

It's only useless if it's not installed properly - ie with a dead air space between it and the vehicle metal wall.

I have nothing but reflectix/dead air space in the van - no sound deadening and no insulation.

IMO anyone who thinks they can make a van as quiet as a high end car by putting sound deadening material throughout is wasting time and money. A van quiets down to some extent when you put an interior in it but you'll never get it to ride like a Caddie, nor be quiet inside like one...it's inherent in the beast.

I didn't insulate the van because 1/2"polyiso wasn't even available in Ontario when I was building out the interior and I wasn't willing to wait until I was stateside to do the inside. I needed it livable (by my standards) before I left for the southwest.

After almost 4 years of living in the van full-time I can attest to the usefulness of reflectix as a radiant heat barrier. The van stays way cooler inside even in direct sunlight. I've had to open the doors first thing in the morning to let warm air inside because the van is not heating up as fast as the outside air once the sun rises. The temperatures have equalized overnight leaving the inside at night time temps while the outdoors is heating up nicely - a definite sign that the reflectix indeed is doing it's job.

The problem with most installations of reflectix is that it is done without regard to proper installation techniques.
(04-26-2019, 11:28 AM)poot_traveller Wrote: [ -> ]I thought reflectix is the best for avoiding heat exchange through the windows??

Of the three types of heat exchange (conduction, convection, and radiation) then reflectix works (some) on all three, but it is best about convection and radiation. And radiation being the main thing to think about for windows. So for windows reflectix can be quite useful.

But because it is a quite thin material, the conduction limiting properties (R-value) of reflectix is quite low. I think the official value is R-1.
So to get as optimal use of reflectix as possible, in walls and ceilings, one needs to make sure there is an air gap (which improves the conduction limitation quite a bit = raises the combined R-value), just like 'Almost There' has already mentioned.  And then reflectix can also be useful in wall and ceilings.
(04-26-2019, 05:06 AM)MrAlvinDude Wrote: [ -> ]And here is some information about heat exchange properties of windows: http://www.gjerdessolarshield.com/2016/1...nsulation/

This isa sales pitch, sorry. If you wnt a coating it needs to be on the inside of the outside pane. Argon gas will leak out in a few years as it has a tiny tube to stabalize the inner window going over the mountains or the glass would explode. We sold Hued windows with an R value of 7. 1" glass with a plastic sheet in the center but like I've seen on Airstreams the plastic didn't last. You'll get about 2-2.5R.
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