Wednesday, September 10, 2008

Green White Roofs

Ten years ago, upon moving into a townhouse, I was slightly disappointed to discover that the Homeowners Association had already made plans to replace the roofs on all the units in the complex. I thought it was unfortunate that no one had considered the possibility of installing solar panels. We do live in southern California and there is no dearth of sunshine; in fact 73% of our days are sunny every year. Imagine the energy savings over the last decade if the Board had been a bit more forward-thinking.

But it's not just solar panels that can make a difference. I've discussed green roofs on several occasions in the past, but for many people, the structural reinforcements necessary for a green roof can rule out that option. What if there was a simpler way not only to lower energy costs but also slow down global warming?

It turns out that simply having a highly reflective, white roof on the average home, rather than the conventional dark roof, can prevent 10 metric tons of planet-heating carbon dioxide emissions from entering the atmosphere. And, because a white roof never gets more than a few degrees warmer than the ambient temperature, the need for air-conditioning is substantially reduced -- as much as 40% in some commercial buildings.

The LA Times reported today:

"Since 2005, the Golden State has required that flat commercial structures have white roofs. Next year, new and retrofitted residential and commercial buildings, with both flat and sloped roofs, will have to install heat-reflecting roofing, as part of an energy-efficient building code."

If, in addition to white roofs, the 100 biggest cities in the world also began using reflective materials for pavement, "the global cooling effect would be massive, according to data released Tuesday at California's annual Climate Change Research Conference in Sacramento."

The Atlanta Business Chronicle pointed out that "several years ago, [Georgia] became the first state to amend its building code to recognize the benefits of reflective material. The 'White Roofing Amendment' became part of the Georgia State Minimum Code for Construction."

The Chronicle also notes, "White roofs also reduce the heat island effect in an urban area, a potentially critical boon for Atlanta, which famously suffers from a lot of bad-air days. Studies have shown that cities are often three to eight degrees warmer on hot days than outlying rural areas. The effect in Atlanta has been measured as high as 12 degrees. And heat is a major contributing factor to the formation of ozone." Anyone who's ever ventured into downtown LA on a hot, smoggy summer day knows how miserable that heat island effect can be.

Naturally, the EPA has taken a positive position on cool roofing materials:

"Cool roof systems with high reflectance and emittance stay up to 70°F (39°C) cooler than traditional materials during peak summer weather. Benefits of cool roofs include reduced building heat-gain and saving on summertime air conditioning expenditures. By minimizing energy use, cool roofs do more than save money – they reduce the demand for electric power and resulting air pollution and greenhouse gas emissions."

If you've traveled to the Mediterranean countries or seen photographs of towns and cities in those areas, you've probably noticed the consistent use of white on the buildings, both residential and commercial. Well, it doesn't just look beautiful, obviously it's smart, too. Good for the consumer, good for the environment. A very thoughtful choice.


© 2008 Cynthia Friedlob


Michele said...

I wish I had known about white roofs when we re-roofed in 2006. We were in a bit of a rush to get our place into liveable condition though, and did not have time to fully research all our options. Our attic has almost no ventilation and feels like an oven. We are in the process of adding some vents now.

Cynthia Friedlob said...

White roofs were news to me, too, and they would have been perfect for the flat roofs of our townhouses.

Don't know what your budget is, but you might want to check out the
Roof Coating Manufacturers Association to get information on white roof coatings to use at some time in the future.

Thanks for commenting!

eeny said...

I thought this was my own idea and was wondering how to persuade the world that it's doable! It makes more sense than most of the wild 'science' ideas put forward to stop the temperature going up.
Just surfing to get a few more facts and figures, I found your article which tells me what I needed to know - and that there's always someone who's thought of it before me.

Cynthia Friedlob said...

Thanks for your comment, Eeny.

This does seem like such a simple and relatively inexpensive solution for both residential and commercial properties. I was very pleased to see that California has mandated its use.

I think more people need to be made aware of this technique. Not everyone will figure it out on their own like you did. You get three cheers for that!

Roof Coatings said...

Nice post, is white roofs better than metal roofs and if i replace my one roof which is 20/15, how much the cost will be? and should i replace it with metal roof or white which will be best for me, i live in Florida please give me any suggestion for that.

Cynthia Friedlob said...

Roof Coatings: There are incentives in Florida if you install a white roof, so it's a good idea to investigate the possibility of doing so.

I don't have specific cost information, so I'd suggest that you look in your local phone book for companies that sell white roofs to get an estimate for your property. Also, here's a link to the Roof Coating Manufacturers Association which has a couple of members in Florida.

Good luck and thanks for commenting.