How much heat does a Westy poptop transmit to the interior?

aguabonita

Hey folks,

Just wondering if you think it is worth it to paint the top of a Westy white in order to avoid transmitting too much solar heat to the occupants? Thinking out loud here, but it seems like the darker greys, blues, and burgundies would absorb a lot more energy than a white top. The question, in my mind, is whether that heat is then transmitted to the occupants via conduction.

For example, I have a Wolfram Grey westy that is getting painted and originally I was going to paint the top grey to match the body. But I'm sitting outside on a hot day and thinking to myself that it might be a better idea to paint it off white so that my kids and I don't fry when driving on hot days.

I'm sure there are a couple of factors that affect how much solar energy is transmitted to the interior (e.g. tinted window being one of them) so I guess I am just wondering what amount of that is attributed to the poptop.

Any thoughts and ideas appreciated.

Thanks!
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'87 Westfalia, GW 2.2, and some other goodies
'90 Volvo 245

PDXWesty · Posted: Mon Jun 20, 2011 11:44 am Post subject:

I had mine paiinted dark to match the body and I have not noticed the difference.
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89 Westy 2.1 Auto

randywebb · Posted: Mon Jun 20, 2011 11:58 am Post subject:

more than a couple of factors

but, the big deal is solar radiation thru the windows that then gets trapped inside the Van (it is re-radiated as IR, which cannot "get out" thru the glass)
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1986 2.1L Westy 2wd Auto Trans.

Jake de Villiers

Ahwahnee · Posted: Mon Jun 20, 2011 1:03 pm Post subject:

I actually like the original white top on my 84 but the later colors and body trimmings seem to look better with the body-color tops.

What you might think about is just painting the very top surface white, leaving the sides of the fibreglass pop-up in body color. I think school buses are often painted this way (or maybe it's just the school buses in desert cities).

randywebb · Posted: Mon Jun 20, 2011 1:15 pm Post subject:

if you only care about heat reflectance and not aesthetics, then use a high metallic content light silver color

solar radiation is usually divided into two wavebands - short (SW) and long wave (LW)
[not exactly the same as infrared]

almost everything in nature acts like a blackbody (perfect absorber and emitter) of LW rad. no matter what the "color" (yes, all humans are black in the LW spectrum)

the exceptions are metals, esp. polished or bright metal surfaces - they reflect LW

so a very metallic paint will reflect both SW and LW radiation and the light color will reflect SW

I'd go for window tint or shades first, but if every bit helps then...
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1986 2.1L Westy 2wd Auto Trans.

PDXWesty · Posted: Mon Jun 20, 2011 1:19 pm Post subject:

I guess that's why I haven't noticed it because it was painted a grey metallic color. But then again, I don't sleep up top. I don't think anything would help though in 95+ heat if you're in the direct sun.
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89 Westy 2.1 Auto

dobryan · Posted: Mon Jun 20, 2011 1:28 pm Post subject:

kamzcab86

dobryan

aguabonita · Posted: Mon Jun 20, 2011 10:12 pm Post subject:

Noganav T3 · Posted: Mon Jun 20, 2011 10:32 pm Post subject:

You can buy a temp guns pretty inexpensively these days HF has them on sale for around twenty bucks. Great for getting to the bottom of questions like this.

Bright white = much cooler top - huge.

randywebb · Posted: Mon Jun 20, 2011 11:01 pm Post subject:

re: lack of heat dissipation

note that a metallic color will also have lower emissivity -- i.e. it will not radiate away heat as well
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1986 2.1L Westy 2wd Auto Trans.


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