silver vs white for heat gain?

[tobyd]

Hi Folks,

Just wondering if people have knowledge if there is much of a difference in solar heat gain in silver vs white campers. Living in Colorado sun is strong out here.

Sure there'll be a huge difference between, say, white and black, but I'm only considering silver and white.

Thanks,
Toby.

[Aguyfromohio]

Bright white is better
The building trades sometimes seek LEED certification ratings for large buildings to prove energy efficiency, and one factor is the Solar Reflectivity Index (SRI) of materials on exterior walls and roofs.

White is better than silver on that index.
Here's a link with a table http://www.deansteelbuildings.com/produ ... -by-color/

Optical efficiency like for a headlight or lamp is a slightly different situation than bouncing off sunlight to reduce heating, that's why lamps have mirror polished silver reflectors but white is still better for avoiding solar gain.

[tobyd]

That's really interesting, thank you! At least if I equate "silver" to Alu Zinc in that table then white is streets ahead.

[QueticoBill]

I was trying to figure out if bright aluminum without any finish was in this list.

[Aguyfromohio]

I was trying to figure out if bright aluminum without any finish was in this list.

I couldn't find much in a two minute google. Below is a a table from Lawrence Berkeley National Lab that includes aluminum but does not mention the surface finish.
I don't really understand the physics of all this deeply. But it does involve the emmisivity of the surface.
Most materials emit and absorb the same amount at any given wavelength, but that changes with changes in wavelength.

Stainless steel and aluminum actually do corrode, though only a tiny microscopic layer of oxide is present right at the surface.
And that tiny layer might as well be a mile deep to a photon -that microscopic oxide layer what is really running the show for solar absorption.
That oxide layer has different emmisivity and SRI than the actual pure metal, which is why surface treatment matters.
If the bulk metal is sealed under a layer of anodizing or clear coat or car wax it behaves differently than if it's polished and allowed to naturally develop a protective oxide layer.

I'm on the edge of Appalachia, and as a hillbilly I guess if I really wanted to know I would lay two little test panels out in the front yard on a sunny day and see which one burned my finger worse.

As I