Heat Reflective Paint for black van roof

[Gobi King]

It gets really really hot in the van, I have factory dual a/c but having a black roof it is HOT inside.

Color - I will go with white paint.

Farm Equipment paint is the one I picked and I will use a 4 inch roller to get it done.

First I need to wash the darn roof.

[Midway Tommy]

First I need to wash the darn roof.

Yep, and then you need to rough up the clear coat and prime it prior to repanting. If you don't it will just peel.

You might want to look into white RV roof coating. It actually has some slight insulation and sound proofing qualities.

[Alan Matsuno]

White roof, black body; might look like law enforcement.

[thrasher]

Had a buddy paint his cargo van with Kool Seal that you can get from Home Depot or Lowes but White on a nice black van like yours might look funny. His van was already white and a lot older than yours. Maybe try that thermal board stuff that you use on garage doors on the inside of the van.

[Alan Matsuno]

I have used both Kool Seal and Henry's on travel trailer roofs.  Thick stuff, will not be as smooth as paint.

[Finest Kind]

I had an 85' Ford pick up, dark blue. When the paint was sun blasted ten years later I brushed a coat of Rustoleum gloss white on the roof. Made a difference temp wise and looked great.

[jurelometer]

Don't think that you are going to get what you want with some paint.

The biggest contribution to the high internal temperature is probably coming from the windows.  When you are parked, the paint color might contribute some, but I bet much less when the car is moving.  Here is why:

Those giant windows turn the van into a very effective solar oven.  Energy can get in easily in the form of light, but once the light hits the interior, much of it is absorbed, generating heat.    But since it is not light energy any more, this infrared (heat) energy can't get back out through the glass nearly as efficiently.

The metal skin on the roof has to be heated by the sun, and then has to pass the heat through insulation /headliner, so much less efficient, and not that much more surface area than the windows.  Not a good way to design an oven.  But when the skin  is hot, it will be less effective at conducting heat out of the interior, and if hot enough, will even conduct a bit back in.

If you have ever parked a car on a sunny cold day, you can witness this effect.  The interior of the car can be warmer the the metal skin, especially on a windy day.  Which brings me to my next point.

Once  the van is moving for a bit of time, the skin temperature is reduced by convection from the continuous passage of cooler air molecules.  But those windows are cooking away the same as when parked.

All those tests on paint job color and heat are performed on parked cars.

I would look into window tinting, which would probably help more (especially while driving), and wouldn't damage resale value or make it look like you parked the van under some crows' favorite nesting spot.

If we get to gamble on the white roof project outcome, I would place my money on "ending up regretting".  I would even offer some pretty decent odds

-J

[Gobi King]

First I need to wash the darn roof.

Yep, and then you need to rough up the clear coat and prime it prior to repanting. If you don't it will just peel.

You might want to look into white RV roof coating. It actually has some slight insulation and sound proofing qualities.

I have used both Kool Seal and Henry's on travel trailer roofs.  Thick stuff, will not be as smooth as paint.

The white RV roofing stuff is some sorta rubberized sealing ...
my roof is good, the reason I bought it with dual factory A/C and heat is that I don't want any holes in the roof and associated maint.

Also over time of the rubber adhesion fails I might get moisture underneath and might get rust/holes in the roof.

[Gobi King]

White roof, black body; might look like law enforcement.

Not with the "Free Fishing Tackle" sticker the back ;-)

hmm, dual color, I might have to check with my local PD if I need to do any paperwork for changing my roof color.

If I get time later in the summer, I might put

AT.com on the roof :-)

it is big I mean tall van, not sure if anyone will assume it is police van, on contrary I did have people ask if I work for Amazon.

[Gobi King]

Had a buddy paint his cargo van with Kool Seal that you can get from Home Depot or Lowes but White on a nice black van like yours might look funny. His van was already white and a lot older than yours. Maybe try that thermal board stuff that you use on garage doors on the inside of the van.

It is  passenger van, so has a headliner and side airbags,
At some point I might take off the head liner and side panels and add thinsulate batting to add to the insulation.
Yeah, it will look funky but staying kool is important, we plan to head out more during summer and right now it is bit warm for this dad, who is the one to stay back and sit in the van while the girls are out stretching their legs.

[Gobi King]

I had an 85' Ford pick up, dark blue. When the paint was sun blasted ten years later I brushed a coat of Rustoleum gloss white on the roof. Made a difference temp wise and looked great.

Exactly what I am planning, good to get confirmation that it made a diff in temp.

[Gobi King]

Don't think that you are going to get what you want with some paint.

The biggest contribution to the high internal temperature is probably coming from the windows.  When you are parked, the paint color might contribute some, but I bet much less when the car is moving.  Here is why:

Those giant windows turn the van into a very effective solar oven.  Energy can get in easily in the form of light, but once the light hits the interior, much of it is absorbed, generating heat.    But since it is not light energy any more, this infrared (heat) energy can't get back out through the glass nearly as efficiently.

The metal skin on the roof has to be heated by the sun, and then has to pass the heat through insulation /headliner, so much less efficient, and not that much more surface area than the windows.  Not a good way to design an oven.  But when the skin  is hot, it will be less effective at conducting heat out of the interior, and if hot enough, will even conduct a bit back in.

If you have ever parked a car on a sunny cold day, you can witness this effect.  The interior of the car can be warmer the the metal skin, especially on a windy day.  Which brings me to my next point.

Once  the van is moving for a bit of time, the skin temperature is reduced by convection from the continuous passage of cooler air molecules.  But those windows are cooking away the same as when parked.

All those tests on paint job color and heat are performed on parked cars.

I would look into window tinting, which would probably help more (especially while driving), and wouldn't damage resale value or make it look like you parked the van under some crows' favorite nesting spot.

If we get to gamble on the white roof project outcome, I would place my money on "ending up regretting".  I would even offer some pretty decent odds

-J

Jurelometer,

The van came with factory tinted windows, all but the front side windows, I plan to double tint the 2nd big side windows and I have added shiny bubble insulation in the rear 2 side windows.
Most of the time when we make stops are around a late lunch hour when the sun is right overhead.

So 10 am ish we start 2 pmish we stop and long break and girls step out for some retail therapy or and dessert, while I stay back and take a break, snooze.
I have a reflective shade for the front windshield (not big enough).

The skin temp of the roof rises to around 160F, I will take my heat gun and measure later today before I start washing roof.

to alleviate the funky look issue, I might have the front of the roof painted white too.

to be continued.....

Part Deux:

Here is my strategy:
Heat Ingress Mitigation - windows
Side Windows - rear add Shiny bubble insulation and 5% limo heat reflective tint to windows behind driver/pass doors.
Tint Back windows - after trip with 5% limo tint
Roof - Back section paint white for this trip, Front section paint white next summer
Exhaust under vehicle - add heat shield (??) need to research this

I agree that the windows will make the most difference, 
next one is the roof and I spoke to a few transit owners who went that route and it did help a little with heat.

Here is a study result from Concordia Univ
https://www.usatoday.com/videos/money/business/2020/02/19/ups-trucks-have-white-roofs-do-you-know-why/638426000/

I have a week left, not sure I will time to give the roof a thorough was and mask off and paint before I leave next week.

[JasonGotaProblem]

Upgrade to mirror tint. Bam!

[foakes]

Hi Gobi —-

Since you have a High-Top van with tinted windows already —- I assume it has a front A/C unit that also ducted to the rear passenger area?

Painting the roof will help slightly —- but this is a passive remedy that will likely not do much to reduce the heat inside your van.  Same with additional window tinting.

It is important to remember that there is a LOT of cubic foot area to cool down.

I would look into a 12 Volt rooftop mounted RV A/C unit that puts out around 6500 to 7000 BTU's.

A complete system runs between $1000 to $2500.

I think if you use a digital laser temperature gun on the inside of your unit —- with the A/C on, and in the sun —- you will be able to test the temperature.

These units have remote control —- can operate off your onboard batteries when driving —- and will handle the issue.

Your vehicle's alternator will keep the batteries charged up.

Simple to install —- and this is what is generally used to keep the interior cool.

Best, Fred

[funhog]

how about a white "wrap " application?