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aguabonita Samba Member
Joined: November 27, 2005 Posts: 267 Location: Monterey, CA
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Posted: Mon Jun 20, 2011 11:42 am Post subject: How much heat does a Westy poptop transmit to the interior? |
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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! _________________ '87 Westfalia, GW 2.2, and some other goodies
'90 Volvo 245 |
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PDXWesty Samba Member
Joined: April 11, 2006 Posts: 6247 Location: Portland OR
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Posted: Mon Jun 20, 2011 11:44 am Post subject: |
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I had mine paiinted dark to match the body and I have not noticed the difference. _________________ 89 Westy 2.1 Auto |
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randywebb Samba Member
Joined: February 15, 2005 Posts: 3815 Location: Greater Metropolitan Nimrod, Orygun
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Posted: Mon Jun 20, 2011 11:58 am Post subject: |
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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) _________________ 1986 2.1L Westy 2wd Auto Trans. |
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Jake de Villiers Samba Member
Joined: October 24, 2007 Posts: 5911 Location: Tsawwassen, BC
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Posted: Mon Jun 20, 2011 12:07 pm Post subject: Re: How much heat does a Westy poptop transmit to the interi |
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aguabonita wrote: |
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! |
We borrowed my Mom's Bordeaux Red Metallic Westy a couple of times before we got our Pastel White van and the dark top is a solar collector of the first order! Sleeping upstairs, we were awoken shortly after first light by the massive heat radiating from the raised roof. The white is MUCH better!
YMMV etc. _________________ '84 Vanagon GL 1.9 WBX
'86 Westy Weekender Poptop/2.5 Subaru/5 Speed Posi/Audi Front Brakes/16 x 7 Mercedes Wheels - answers to 'Dixie'
@jakedevilliersmusic1
http://sites.google.com/site/subyjake/mydixiedarlin%27
www.crescentbeachguitar.com
www.thebassspa.com |
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Ahwahnee Samba Member
Joined: June 05, 2010 Posts: 9810 Location: Mt Lemmon, AZ
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Posted: Mon Jun 20, 2011 1:03 pm Post subject: |
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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). |
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randywebb Samba Member
Joined: February 15, 2005 Posts: 3815 Location: Greater Metropolitan Nimrod, Orygun
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Posted: Mon Jun 20, 2011 1:15 pm Post subject: |
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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... _________________ 1986 2.1L Westy 2wd Auto Trans. |
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PDXWesty Samba Member
Joined: April 11, 2006 Posts: 6247 Location: Portland OR
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Posted: Mon Jun 20, 2011 1:19 pm Post subject: |
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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. _________________ 89 Westy 2.1 Auto |
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dobryan Samba Member
Joined: March 24, 2006 Posts: 16504 Location: Brookeville, MD
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Posted: Mon Jun 20, 2011 1:28 pm Post subject: |
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Ahwahnee wrote: |
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). |
I did exactly this when I repainted my Titian Red Westy. White top with red sides (the red overlaps two inches onto the top so you cannot tell from the ground). HUGE difference in heat transfer. Before it was like an oven in the sun with heat coming through the top, after it was much less. _________________ Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD
"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson
MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646
Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371
The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794 |
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kamzcab86 Samba Moderator
Joined: July 26, 2008 Posts: 7923 Location: Arizona
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Posted: Mon Jun 20, 2011 1:32 pm Post subject: Re: How much heat does a Westy poptop transmit to the interi |
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aguabonita wrote: |
...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. |
Is your concern for only when driving? Because driving my Orly Blue van across the desert area of I-40 last summer, it wasn't the roof roasting us it was the 95-degree air blasting in through the windows and dash.
Being parked is a different story; with no insulation, that fiberglass roof heats up right quick when the sun hits it in the morning (nice in the winter, sucks in the summer). Parked = no airflow to dissipate heat build-up. _________________ ~Kamz
1986 Cabriolet: www.Cabby-Info.com
1990 Vanagon Westfalia: Old Blue's Blog
2016 Golf GTI S
"Real knowledge is to know the extent of one's ignorance." - 孔子 |
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dobryan Samba Member
Joined: March 24, 2006 Posts: 16504 Location: Brookeville, MD
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Posted: Mon Jun 20, 2011 1:35 pm Post subject: Re: How much heat does a Westy poptop transmit to the interi |
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kamzcab86 wrote: |
aguabonita wrote: |
...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. |
Is your concern for only when driving? Because driving my Orly Blue van across the desert area of I-40 last summer, it wasn't the roof roasting us it was the 95-degree air blasting in through the windows and dash.
Being parked is a different story; with no insulation, that fiberglass roof heats up right quick when the sun hits it in the morning (nice in the winter, sucks in the summer). Parked = no airflow to dissipate heat build-up. |
I agree. It was when parked with the top popped that we notice the difference the most. _________________ Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD
"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson
MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646
Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371
The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794 |
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aguabonita Samba Member
Joined: November 27, 2005 Posts: 267 Location: Monterey, CA
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Posted: Mon Jun 20, 2011 10:12 pm Post subject: |
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dobryan wrote: |
Ahwahnee wrote: |
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). |
I did exactly this when I repainted my Titian Red Westy. White top with red sides (the red overlaps two inches onto the top so you cannot tell from the ground). HUGE difference in heat transfer. Before it was like an oven in the sun with heat coming through the top, after it was much less. |
Interesting ideas. The lack of heat dissipation when the van is stationary really resonates with me.
Dobryan, I would love it if you posted a pic of you poptop. I had that same thought a while back and I would like to see what it looks like implemented. Did you fade it from red to white?
Gracias a todos,
Kebean _________________ '87 Westfalia, GW 2.2, and some other goodies
'90 Volvo 245 |
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Noganav T3 Samba Member
Joined: August 11, 2010 Posts: 101 Location: California
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Posted: Mon Jun 20, 2011 10:32 pm Post subject: |
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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. |
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randywebb Samba Member
Joined: February 15, 2005 Posts: 3815 Location: Greater Metropolitan Nimrod, Orygun
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Posted: Mon Jun 20, 2011 11:01 pm Post subject: |
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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 _________________ 1986 2.1L Westy 2wd Auto Trans. |
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