@Skaperen: Easier said than done in many parts of the country now.

@mrearly2: Most houses could be better insulated, but that's not entirely accurate.

On a clear summer day a dark-colored roof can absorb enough heat to raise the roof surface temperature 50 or more degrees higher than the ambient air temperature. Heat transfer is partly affected by the temperature differential you are trying to maintain. If your desired indoor air temperature is 70 degrees and it's 90 degrees outside you could have a difference of 70 degrees from the outside surface of your dark roof to the inside. Even if you had modern roof insulation of R-38 or greater you would still get a substantial amount of heat conducted or radiated through the roof.

Save on heating costs by installing a black roof!

The difference in reflectivity between a light-colored asphalt shingle and a dark-colored one is actually not that big. They both still have asphalt substrates so they both still absorb a lot of heat relative to other types of roofing.

If you want a cool roof for your house a metal roof is a good option. Its reflectivity is 2x-3x greater than a white asphalt shingle. It's also likely to be more durable and architecturally appropriate than other solutions, like white coatings. Metal roofing typically comes in panels, but there are metal shingles as well. On the downside, a metal roof can also cost 2x-3x more than a shingle job.

Another option is to use a reflective roofing underlayment. These are usually either a plastic sheet with a metallic coating or a flexible reinforced metal foil and are surprisingly effective at blocking radiant heat gains. The only tricky thing with these is that most of them are not vapor permeable and can create condensation problems, depending upon your climate and where the underlayment is in the roof assembly.

It's why we'll never go HOA again.

@zegolf: My HOA would have a conniption if I tried this.

I was wondering about this; so many HOAs are power-mad when it comes to the slightest thing that they consider 'different' from all the other units in the neighborhood. How many of them would force the homeowner to revert the roof back to the original?

[www.flickr.com]

If you're replacing a roof, it certainly makes sense to calculate the payoff period for improvements such as this or having solar panels installed. Nothing but the economic costs are likely to matter, and the costs and benefits will accrue to individual households. We could turn every road, rood, and parking lot white and still cover less than 2% of the surface area of our land.

@eyebrows_etc The one in my current house was installed by a pro and is almost silent. The one in my old house was installed by my now ex mechanical engineer husband and sounded like a jet engine. Trust the pro installer, not the MSME.

@Trai_Dep: That's probably the case. They did a sloppy job on other parts of the building, so it fits the pattern.

@Eyebrows McGee (now with more baby!): Like those "Sunsetter Retractable Awnings" commercials, which show happy old folk drinking lemonade and clicking the remote control for the awning - LOL. They just need a giant one for the roof.

The recent threads here have gotten me really interested in reflective roofs/radiant barriers. It takes me a while to research and save for a big spend anyway, and this would give me a good five years to prep for a more heat-resistant roof approach.

@ztoop: Did you just solve global warming?

@Damocles57: I thought the second law of thermodynamics was "do not talk about thermodynamics"

Of course you are correct.

[www.roofcalc.com]

Even in more northerly climes where heating-degree-days far outnumber cooling-degree-days, more-reflective roofs still provide advantages. Due the the low angle of the sun during winter and shorter days, 6 months of "good" wintertime heat gain amounts to less than less than 3 months of "bad" summertime heat gain.

My husband used to rent the house we now own, and he said he couldn't get the former owner to chose light-colored shingles when it was re-roofed about 10 years ago. According to the above calculator, that would have made a difference of about $150/year for us. Not a ton of money, but if you're reroofing anyhow, it's better than a stick in the eye.

@RevRagnarok:
@econobiker:
@winshape:

I had a "water lint trap" from the hardware store, it was a small bucket you keep water in, and it caught some of the lint and condensed a little of the moisture. It had to be emptied and refilled after each load. But only a tiny amount of lint was captured, it got throughout the house. So I started putting old pantyhose legs over the end of the flexible tube vent (whenver one gets a run in it and I can't wear it anymore, I designate it for the dryer vent.) I attach it with a rubber band. It catches lint really well, but I have to change it very often so it does not build up the lint. That way the lint does not get into the air of my house.

The easiest thing for me to do is pretend we don't have a washer and dryer and go to the laundrymat. But it's so tempting to use them instead of the laundrymat, because I'm a busy working mom with lots of laundry. Maybe I should look into a wash and fold service.

Yes, the builder of our condos was an idiot to put the non-venting dryer set up inside a utility closet of a condo. We have had lots of other problems too, 10 years of condo drama with leaks and such. They are doing renovations now. When the renovations are done, we hope to sell when the market picks up and get a "normal" house with a dryer that vents outdoors, and without the other problems we've had. Heck, I might even just rent a house. At least that way if there is a major problem, I can move when the lease is up!

(Also, ours is crazy loud. But a newer model would fix that, I'm sure.)

The awning guys could totally branch out into roof shades!

Now, my roof is an east/west exposure; it has no Southern face. I don't particularly notice the southern face of the house is warmer in the winter, either, but because that side is partly shaded by my neighbor's house, that may not be a fair test.

In the winter, there doesn't seem to be any particular heat gain from the roof, though, again, the sun is very low in the sky and my roof has no southern face. My biggest winter heat GAIN (and it's quite minimal) is probably from the red brick western side of my house in the afternoon (which is shaded by trees in summer), my biggest winter heat loss is far and away the windows. I truly don't think painting the roof white would have much effect on my winter heating.

And as someone else pointed out, my roof is frequently covered with snow in the winter ... although snow itself is insulating. :)

Also, the white roof reflects sunlight back out of the earth, and so has a net cooling effect on the whole earth. If every home had a white roof, this can have an impact on the total amount of heat for the whole earth.

Maybe I should get a white roof and, in the winter, paint all the snow black?

Duh.

@mechteach: Good point about thermal mass, I hadn't thought about that. I guess that's why most roofs in my area (Chicago area: hot in the summer, cold in the winter) are grey - some absorption in the winter, and some deflection in the summer ;-)

@florapost: Probably a good idea in any case. You should have access to the attic spaces to check for rotting in your roof joists and plywood sheeting. If your roof has a small leak, over time the wood will rot out and it's hideously expensise to replace that on top of paying for the shingles.

It's a liquid ceramic insulation that you apply on top of roofs that will cut your energy bill in both summer and winter about 20-25 percent.

I put it in my attic since I didn't want a white roof and it's saved me about 15% on my cooling costs this summer. Plus, they're a local company. Big up South Eastern Louisiana.

Judging by what the article says, Iowa's in the zone that could still benefit, especially if you're in town. It sounds like the winter factor is pretty negligible, actually, and that the real issue is how much electricity you use in summer to cool yourself down. If you're in a region where you don't run the A/C anyway, it's not going to help you much, but if you've got hot enough summers that you power-cool through it, it doesn't matter that the winters are cold, you'll still benefit. (That's what it sounds like, anyway.)

Neither the article referred to nor the intro by Consumerist is advocating tearing out perfectly good roofs just to install white reflective roofs. The message is that if you are going to reroof or are building new and need to roof anyway, white might be something to consider.

There are variables beyond the color of your roof in your area: amount of sun that actually hits your roof (trees or other shade), slope of the property, number and types of windows and curtains, comfort levels, amount of insulation in your building envelope, natural ventilation, cost of utilities in your area, varying amounts of local, state or federal "encouragement", etc.

As with everything, it is prudent to look at your specific circumstances, do some research and crunch some numbers.

As I previously commented, where I grew up on the NJ shore 30 years ago white/grey (and some other colors green/red/blue) roofs were common. This probably ended due to home fashion and the extra expense to purchase lighter colored roofing materials versus materials which tended toward the darker colors of petroleum products.

White roofing HAS to be able to help in some areas. When flying into Dallas TX in the summer, you see the desert like environment and then thousands of dark roofed homes just baking away in the sun. Surely white or grey roofing would help reduce cooling costs incrementally much like CFL bulbs help reduce engergy use.

The only other issue that people have brought up about white roofing in southern climes is green mold that is not killed by cold temps during the winter...

@Julia789: Maybe you could use one of those interior lint traps to help capture some of the water...

@TheBursar:

The second law of thermodynamics states that heat flows from areas of high heat to areas of low heat. In the summer, the high heat is outside, on the roof, and in the attic with the cooler (hopefully) area in the house. Heat will flow into the cooler house making it hotter trying to reach equilibrium.

In the winter, the area of higher heat is in the house with the world outside the house being cooler. The flow of heat from a marginally warm roof in the winter will flow away from the house.

I'm sure that there is some code against that somewhere.

@Saboth: You should invent them. They already make children's toys that change color in hot or cold temperature. Why not roof shingles?

Or just a big retractable white roof shade for summer LOL.

this actually does work very well. my wife's great grandmother has a porch that has a metal roof. in the summer time the porch would be almost unbearable. we painted the roof white and installed some white styrofoam in between the roof supports. now the porch is nice and cool.

@punkrawka: Probably depends on what area of the country you live in, and how cold your winters are. Big difference between New York and Arizona, for example.

It does seem like it makes sense though. It's basic middle-school Science. Darker colors absorb more heat, ergo a darker roof would make a house hotter. Sort of makes you wonder why we've been installing dark shingles for years and years.

Eye sore.

@TheBursar: We have sort of a similar problem - something that is handy during one season but a problem in the other. Our condo was built during the energy crisis, so they designed the laundry room/utility closet with no vent for the dryer. Back in the late 70's early 80's some builders thought it was good to have clothes dryers blowing back inside the house, helping to heat it in winter.

This is only "handy" and energy efficient during the coldest dead of winter in low humidity.

Problem is, the clothes dryer dumps two gallons of water into the air every load of laundry. This equals sticky wet house. I had to buy an "industrial strength" dehumidifier to run every time I run the dryer. I also have to run the central air fan every time I run the dryer, to get the heat dispersed throughtout the house or it gets to almost 90º in the laundry room. In the spring and summer I skip the central air fan, and just run the A/C full blast. Sometimes I go to the laundrymat instead but I hate it. I'm not sure what is more expensive; the higher electric bill from running the A/C and dehumidifier, or the couple dollars per load I have to pay at the laundrymat and the waste of hours of my time sitting with really strange people.

We inquired about installing a vent, but due to the location of the laundry/utility room in the "very middle" of the condo, not near any exterior walls, it is not feasible the construction guys said. (We offered to pay for it during renovations they were doing on the building.) Dryer vents have to be short and direct, they said. If they are too long or snake through walls they collect lint and catch fire.

I'm with you on the insulation, though. Just weather-stripping my doorframes was phenomenally helpful, and I'm looking into getting a genuine access hatch cut into the attic so I can revamp the insulation properly up there (right now it can only have blown in since there's no human access).

I don't know if they're actually commercially available or if they were just experiments.

Of course, if you have leaky doors/windows/walls, this point is moot. The whole insulation industry really needs better PR - insulation ain't sexy, but it is relatively cheap, and has one of the best energy payback times.

> [consumerist.com]

Of course that assumes you also have very good insulation under that metal roof to maximize the sun reflection.

@TheBursar: I guess it would depend on how your house / apartment is built with respect to the roof. In my case, I have a roof then immediately under the roof structure is a walk-up attic, followed by a tri-split level below that. If the roof absorbs heat, it will pass that heat down to the attic at best (remember heat rises).

I suppose if your living space is immediately under a roof, you would benefit from having the roof absorb heat, thus a black (or dark) roof. Otherwise, I can't think of any heating benefit.

I'm sure something like a tarp would just look hideous (and probably muck with property values) However there's gotta be a way to make something like this cost effective AND easy to install as well as remove & store.