white metal roof vs traditional silver metal
 

i'm thinking of putting a metal roof on my house and i dont know which color would be more efficient as far as keeping the house cool WHITE or SILVER? thanks troy p.s. i just installed a quadrafire wood stove for heat and man is it awesome!

joesgot4 -

I vote white with an elastomeric paint/coating.

CarloSW2

There are companies that offer special reflective pigments in their metal roofing paint to further reflect light. I'd check that out.

I would go with silver as it's going to be cheaper and zinc oxide white, if I remember right has this nifty property where it is able to reflect light and heat and also radiate heat faster then other colors, and over time that silver galvanized metal is going to turn gray from the zinc turning to an oxide.
It's also a classic and if you are going to buy a roof that will last 100 years go with a classic, either way the paint is not designed to last 100 years.

Unless you absolutely need to redo the roof, wouldn't a radiant barrier stapled in the attic be the cheapest solution?

Most of the roof colors have the same efficiency. Check the company you are going to use to see if the roofing is energystar rated, if it is the colors will be the same and there is a tax credit.

That is pretty far from true, light colors reflect alot more heat then dark colors, in the summer this keeps the roof and the attic cool, allowing the insulation to stay cooler, in the winter dark colors let the snow melt sooner, snow acts as extra insulation, yes, snow can be insulation as it's better to have your attic just below freezing then it is to have it -20F.

"Englert’s Ultra-Cool metal roof coatings dramatically increase the reflectivity of medium to darker color roofs, meeting Energy Star specifications for cool roofs. Consequently, architects and builders can enhance the appearance of their projects with the use of medium and darker colors and save warm weather energy costs because reflectivity keeps the roof and interior spaces cooler. In addition, the use of Englert’s Ultra-Cool metal roof coatings has several positive impacts on the roof, its structure and the environment. Heat is reflected away from the building, urban smog is reduced when environmental temperatures are reduced, the life expectancy of the roof increases due to less expansion and contraction and public monetary incentives are available for using reflective roofing products. Englert standing seam metal roofs are available in a wide variety of Ultra-Cool colors including dark bronze, charcoal gray and matte black."

My neighbor is a dealer for Englert. This is from thier site.

jmf -

Yes, but those are also the "normal" colors that meet aesthetic expectations of what people want to buy. I went here :

Englert: Ultra-Cool Coatings are available in the following popular colors
http://ecomodder.com/forum/member-cf...oof-colors.jpg

In the above you can see that the white has a better Solar Reflectivity Index ...

Atlanta Roofing | Cool Roofs | Green Roofs | LEED Certified Roofs | Solar Roofing in Atlanta | Green Wave Forever
CarloSW2

not necessarily. there is enamels/urethanes that keep dark colors cool, just by a high uv rating...it needs to accept uv to accept heat, and then be able to give it away again.

a roof should get hot, there is organic and gases in the house that need out, and other physics that just needs up, unless you have a common sensed air circulation?

making a dirty old barn out of the house ...ewww.

My neighbor has a silver metal roof. Damn thing is like the sun shining in my front door at 12 noon.

All else being equal white will be much cooler than silver. Low-e coatings can be incorporated into coatings design. Like somebody pointed out earlier, roofing companies list the solar index of their products. If it's not listed they might just be embarrassed by it.

This guy knows EXACTLY what he's talking about. I put elasomeric paint on my mobile home roof and the roof went from scorching hot on a mild summer day to ice cold on the hottest days. I swear, the stuff is like magic.

Could you put elastomeric paint on a car?

MadisonMPG -

I am guessing yes, but I will let the smarter-than-mes chime in. Depending on the brand, I think they also can have "grainy" characteristics (using super teeny ceramic or glass bubbles that help to increase the insulation value), so there *might* (BIG might) be an aero-benefit to doing that.

CarloSW2

hmmmm.... elastomeric coating on roof on car.
interesting idea.

Might make it a bit cooler when you get in.

The local hardware store had a neat display going--- two plywood boxes w/ a glass front and thermometer inside.

each had the same zinc/steel roofing over it. One was painted w/ a white roofing paint, the other was ... zinc colored. The temperature difference inside the two on a sunny day was dozens of degrees. I don't recall exact numbers, but on an approx 100* degree day (its hot here) in the sun, the plain roofed box was over 150* and the painted one was down by 120-130*. I don't recall how well sealed the boxes were nor if there was breeze that day. That's a pretty big difference. I suspect that the effect is even stronger as you get a larger surface (ie: the little box radiates a lot of heat and is thus closer to ambient temps vs. an entire house roof)

I actually thought about painting a car myself. But it is about $70 for 5 gallons of the stuff.

I bet it would make a car very cool in the summer though!

Sort of related to some of the above items...

One other option is an additional roof to form an air space between the new roof and the existing one.
The top roof exposed to the sun heats up and the air flows between that roof and the one below keeping it cooler than it would otherwise be.
This is sometimes called a "fly roof" , tropical roof , false roof etc and was an option fitted to Land Rover vehicles heading to the hot areas. The colour was normally white powder coated aluminium in that case.

Pete.

Pete -

That would be my ideal house configuration. I always imagine erecting one of those steel and currugated metal versions over my (flat roofed) house. I'm sure the neighbors would have a hissy fit.

CarloSW2

I need to redo my roof this summer and have been thinking about colors. I want to go metal. Black would be nice, since Michigan only gets nice and warm maybe 1 week out of the year. The whole rest of the year I need to capture as much heat as possible.

When the sun does shine, it's not going to get hot enough to catch the underlying wood on fire?