Date: Thu, 11 Jun 2015 19:38:07 -0700
Reply-To: Bill Gibson <bill.bgibson@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Bill Gibson <bill.bgibson@GMAIL.COM>
Subject: Re: how to cool a poptop?
In-Reply-To: <911C422A-C506-44CE-A7C5-E5DBBAD8D82C@shaw.ca>
Content-Type: text/plain; charset=UTF-8
I deal with it all the time. It's a pretty common misconception: the
difference between heat and temperature. We are actually not as sensitive
to differences in temperature as we are to the loss or gain of heat from
our skin. Too much, and we burn, from heat or cold! Paint color does have
an effect, but not as much as we think. Heat can move 3 ways: radiation,
convection, or conduction. How much of each takes a pretty sophisticated
technique to measure. Nothing beats shade, except refrigeration.
On Thu, Jun 11, 2015 at 5:44 PM, Alistair Bell <albell@shaw.ca> wrote:
> I really should have pure my hand on the inside of the pop top int he
> comparison.
>
> But crikey Bill, that blue top was scorching hot. I'd be really surprised
> if the interior of the pop top wasn't hotter than the interior of my white
> top.
>
> But then again, I'm still able to be surprised by things :-)
>
> Alistair
>
>
>
> On Jun 11, 2015, at 2:29 PM, Bill Gibson <bill.bgibson@gmail.com> wrote:
>
> There is much less effect from light or dark paint than most people
> assume. Black paint will get hotter than white paint, but the mass of the
> paint is so small that it does not contribute very much to interior
> heating, even though you can touch white painted surfaces more easily than
> black painted surfaces. The glass creates a strong greenhouse effect, and
> that does raise the inside temps when the windows are closed. Simple
> ventilation prevents the greenhouse effect to a large degree, but tinting
> or reflective insulation, best outside, not inside glass, is better yet.
> Think shade, or space satellite style. Beep Beep.
>
> My stock, no air conditioning 84 Westphalia in southern Arizona has a
> white top, and Twinkie yellow cream paint, doesn't have tinted glass, but
> leaving windows slightly open and using interior sunshades when parked
> makes it possible to touch the steering wheel, etc. this time of year
> (June). It just gets dusty.
>
> On Thu, Jun 11, 2015 at 12:55 PM, Alistair Bell <albell@shaw.ca> wrote:
>
>> I can tell you from direct experience that I could not keep my hand on
>> the blue (darkish blue) pop top on my friends westy. Whereas the white pop
>> top on my van parked beside it was just warm to the touch.
>>
>> Alistair
>>
>>
>>
>> > On Jun 11, 2015, at 11:02 AM, PB <pbrattan@GMAIL.COM> wrote:
>> >
>> > The "paint guy," where I took my Westy for an estimate, seemed to think
>> > that a white poptop would not make a difference during hot weather.
>> Where
>> > I live it can go up to 110 degrees or more, but there are usually only
>> > about 20 or less of these days per year, and usually spread out in
>> August
>> > and September. If it's 108 degrees outside, I can't see how a white
>> rooftop
>> > could reduce the inside temp by more than 2 or 3 degrees, which would
>> still
>> > result in a sizzling 105 degrees.
>> >
>> > I'm wondering if there's any feasible or "creative" way to install
>> > Reflectix or any other type of insulation *inside* the poptop, or would
>> > there happen to be some kind of "paint on" insulation for the
>> exterior...
>> >
>> > Patti
>> > 90 Westy Automatic
>> > North Hollywood, CA
>> >
>> > *♪♫**♥**♫♪♪♫**♥**♫♪♪♫**♥**♫♪♪♫**♥**♫♪*
>> > If it's not on my Smart Phone, it doesn't exist...
>> > ●▬▬▬▬▬▬ஜ۩۞۩ஜ▬▬♥▬▬▬ஜ۩۞۩ஜ▬▬▬▬▬●
>>
>
>
>
> --
> Bill Gibson
> Tempe, Arizona, USA
>
>
--
Bill Gibson
Tempe, Arizona, USA
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