Date:         Fri, 12 Jun 2015 13:18:15 -0400
Reply-To:     Marc Perdue <mcperdue@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Marc Perdue <mcperdue@GMAIL.COM>
Subject:      Re: how to cool a poptop?
In-Reply-To:  <CAFdLW6m+JtvY84DQ9w7OqLKVkz=_Vt5cMKCc60pJF9+eiirCTg@mail.gmail.com>
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Alistair,

The surface of a dark poptop will be hotter. A darker surface can't
conduct the heat absorbed by the dark surface fast enough so it
reradiates it back to the exterior and feels hotter on the surface.
How much of the heat gets through to the interior depends on the
conductivity of the fiberglass. This strikes me as odd too, and I
didn't get it till I attended a solar engineering conference years
ago. A presentation by the masonry institute showed that lighter
colors for mass storage walls were more efficient because their
ability to conduct the heat collected on the surface to the interior
of the mass was better matched to the ability of their surface to
absorb incoming solar radiation, or insolation. What they also found
was that amount of mass wasn't as important as the surface area
exposed to the incoming solar radiation. What that means to us is park
in the shade.

As others have noted, your windows are the bigger problem. Their high
transmissivity allows much of the insolation to pass through, where it
gets converted to heat, which doesn't pass back out of the window as
easily. If you further insulate the inside of your van without
reducing the insolation, you're basically creating a passive solar
collector or oven.


Patti,

I had my van tinted after camping at my first festival shortly after I
bought it. It is significantly cooler now, though I don't have actual
measurements to back that statement up. The guys that did my van were
able to do the window behind the linen closet without taking the
window out. Same with the sliders, though one of them is peeling back
some from the seal at the leading edge of the window. I should take it
back to them; they gave me a lifetime warranty on their work.

Marc Perdue

On Fri, Jun 12, 2015 at 10:41 AM, Dan N <dn92610@gmail.com> wrote:
> the Easy-Up canopy is way to go... but quite heavy... about the same weight
> as full size awning
>
> On Fri, Jun 12, 2015 at 7:13 AM, Steve Williams <sbw@sbw.org> wrote:
>
>> I'm told at Burning Man folks rely on shade structures over their vans
>> and other dwellings.  Not feasible for parking at work, maybe, but if
>> planning to camp where no shade is available, it might be worth carrying
>> a collapsible shade structure.
>>