I think that white roofs are definitely worth experimenting with.

My rowhouse has a flat black "rubbber" roof. It will need replacement in, let's say, five to seven years (it was new in 2004).

I have some questions:

1. Will I have a cooler house in the winter if I install a white roof? Will increases in heating offset any reduction in cooling expense? I tend to fun my (gas-fired hot-water radiator) heat much more than I do my window A/C units, by the way....

2. What are my options, either before I replace my roof or when I do? That is, should I investigate any (white) coating to my rubber roof? And are contractors prepared with white "rubber" replacement rooves? What is known about durability of white vs. black roofing materials?

3. Finally, would I be doing this for my own local/personal advantage or more "for the greater good"?

TW: Good questions, BankStreet. Anyone know the answers offhand? On #3, I can say proponents of white roofs have suggested they will provide individual as well as community benefits - i.e., cooler interiors, reduced air conditioning costs. This study seems to suggest how much benefit depends on where you are and the particulars of your home - type of roof, insulation etc.

I just had a new shingle roof put on my home and used white shingles. I expect to save a few percent on cooling this summer. I also get a 30% tax credit for the material cost.

S&K Roofing did the job and did a wonderful job at that.

Is there a special paint that you have to use to paint the roof? And like one of the posts asked, would it make the home cooler in the winter also? I would rather be warm in the winter than hot in the summer, and if the dark roof helps to capture warmth from the sun during the winter months, I would rather do that.

The posts questioning the value of the white roof during the winter are valid. Anyone who has lived in an Balto rowhome during the heat of our summer can figure out the advantages of having a white roof. Would you want to be under that same white roof when we hit the bitterest part of winter? A classic six of one and a half-dozen of another....

This is Adam Rothstein from Civic Works. I have a couple comments to add to the discussion.

On the topic of energy efficiency, while cool roofs will significantly cut your summertime cooling costs (a 20% savings according to this NYTimes article, http://bit.ly/1pcs2), you will also end up using a bit more energy to heat your home in the winter. However, a cool roof is not a purely altruistic investment. For most areas of the country, including Baltimore, the net effect will be significant energy savings (for an analysis of the costs and benefits, see this article from the EPA, http://bit.ly/bJJBfw).

You probably will not recover your entire investment in energy savings, which is why we recommend cool roofs for people already considering replacing their existing roof. Above the energy efficiency benefits, what makes our cool roofs truly cost effective is their durability, lightweight and low-cost maintenance. We apply a layered system of acrylic coatings with an imbedded layer of woven synthetic fabric to the existing roof. This repairs existing leaks and prevents future leaks, which we backup with a 10 year warranty. The system can be applied on any existing low-slope roof, whether tar, rubber or asphalt.

Unlike a conventional tar roof that has to be fully replaced every 10-20 years because the accumulated weight of each additional layer will cause structural damage to the house, cool roofs are lightweight and never have to be torn off. At the end of the 10 year warranty, we simply apply a single low-cost maintenance coat every 5 years.

For more information, please contact me at energysolutions@civicworks.com or (410) 366-8533 Ext. 209.

Also to calculate the potential energy savings for your own roof, check out this cool roof energy calculator from the Department of Energy (http://bit.ly/2yFDgM). To gauge the efficiency of our cool roofs, use a solar reflectance of 83 and an infrared emmitance of 94.

TW: Thanks, Adam!

BankStreet - in my personal experience with my Baltimore rowhouse, the window A/C units are far less efficient than the gas furnace, so even if heating costs would increase in the winter, it would probably not offset the savings in A/C cost.

Also- FYI, I paid about $4K to have a new furnace and A/C installed to replace the window units, and my summer electric bill decreased almot $200/month, and my winter bill went down too. You would also qualify for BGE's PeakRewards, to save add'l money. Just something to think about.

TW: Thanks to you, too, glsever!

White roofs are good, but green roofs are much better.

I painted my rowhome roof white last year, I bought the paint from Home Depot, it was called Solar Flex I believe. Anyway, as an experiment, to brought a meat thermometer up on the roof one 90 degree day. My roof was about 112 degrees, I then put the thermometer on my neighbor's black rooftop and it read 128 degrees, so yes, this stuff really works!!!

I live in a rowhouse and switched from a black asphalt roof to a silver-coated roof a few years back. From a personal finance and comfort perspective, the difference is negligible in my opinion. The upper floor is still extremely hot in the summer and doesn't seem noticeably colder in the winter. One of the benefits that sold me on it is that the surface is supposed to last longer since it doesn't get as hot.

I could see white roofs reducing the heat island effect if implemented on a large scale, but if you're looking to save $ on utility bills and be more comfortable in hot weather, better insulation and a more efficient A/C system would probably be more effective.

White roofs do nothing to alter the ratio of impervious surfaces to non-impervious surfaces, so they do nothing to affect our management of storm water. Green roofs with rain gardens and other water-absorbent technology allows us to attack two problems at once: reduce the heat island effect and reduce polluted storm water runoff.

As a roof consultant for the past twenty years I have a few comments:
1. Painting a black asphalt roof white or aluminum will lower the temperature of the roof surface somewhat, but it is considered a "maintenance" item, and will have to be repeated every five to seven years at a pretty good expense. No coating on the market will be effective longer than that because they degrade over time (depending upon quality), and white roofs get dirty fast from airborne pollution.
2. I suggest that a homeowner who wants to cool down their attic hire a reputable Baltimore roofer who can install a white membrane roof, either a single ply TPO or PVC, or even better, a 2-ply white modified bitumen roof with an white elastomeric coating applied to the finished surface. In addition, I would add 2 layers of 2-inch polyisocyanurate insulation- each layer staggered to avoid gaps, as additional thermal insulation. The additional thermal insulation is what will keep the attic cooler combined with the white surface.
3. The key to getting your money's worth is hiring the reputable contractor. Do the usual checking with BBB and other sources, and get more than one quote.
4. Finally, don't ever put a new roof over an older wet roof. If the old roof is wet, have the roofer tear it off first. It adds to the expense, but will make the new roof last much longer.

There is a source for white roof supplies right here in Baltimore:

http://www.conservationtechnology.com/waterproofing_acrylic.html

(full disclosure, I work for CT).

I'm oversimplifying and this is merely an educated guess, but I would imagine the gain in summer cooling would more than offset the loss in winter heating because of the angle of the sun.

Make it White! Great study from Geophysical Research Letters on the value of painting roofs white. With reduced air-conditioning costs because of the reflected sunlight and benefits for the planet, this is a great idea for businesses and home owners.

Researching how to make your company, product, or next project more Green? Go to http://www.greencollareconomy.com for sustainability white papers and the largest b2b green directory on the web.