There’s no reason to restrict cool roofs only in America, in Chu’s thinking. At a Nobel laureate symposium in London, he suggested that the world’s roofs should all be painted white as part of the effort to control the climate. He described climate change as a “crisis situation,” calling also for “wind, wave and solar” to supply energy for the globe. His own Energy Department has compiled statistics showing the lack of promise for such renewable energy sources at any time in the calculable future.

The Sunday London Times also reported that Chu said building regulations “should insist that all flat roofs [be] painted white,” and visible tilted roofs could be painted with “cool-colored” paints which absorbed much less heat than conventional dark surfaces. He also recommended that roads could be lightened to a concrete color so they would not dazzle drivers in bright sunlight. “I think with flat-type roofs…yes, I think you should regulate.” Spoken like a true-blue patron of bureaucratic control.

In his passion for cool roofs on government buildings, Secretary Chu directed all Energy Department offices to install white roofs during new construction, when replacing old roofs and whenever an installation is cost-effective over the lifetime of the roof, The New York Times reported in January. In a news release July 19 he urged other federal agencies to follow suit. The Energy Department (DOE) has 10,500 buildings. The Federal government owns or leases 500,000 buildings. That’s a lot of white paint.

At the same time, the coating prolongs the life of the roof system because temperature changes are smaller, spokesman Bill Bero said.

NEW YORK, N.Y. — Herb Van Gent points his infrared gun at a square of still unpainted grey shingle and clicks the trigger. He gets an immediate temperature reading: 143 F and rising. Then he aims it about a metre and a half away to a square of roof I have just painted: 98 F and decreasing.

He smiles.

“A 45-degree difference and we’re only on the first coat,” he says. That means it also will be cooler inside the building, he says, saving energy.

Its 11 a.m. and we are on the roof of a New York retirement home, rolling out a thick, shiny white paint. Van Gent is one of a volunteer group that has come up here to paint the roof as part of a city-sponsored “cool roof” program.
The idea of painting roofs white is catching on across the country; Energy Secretary Steven Chu has said it could contribute to the fight against global warming.

“Cool roofs are one of the quickest and lowest-cost ways we can reduce our global carbon emissions and begin the hard work of slowing climate change,” said Chu in July, while announcing that Department of Energy buildings would be painted white wherever possible.

While white roofs keep homes cool in summer by letting less heat in, they have little impact on winter heating bills, according to the Cool Roof Rating Council, a non-profit group created in 1998 to research and implement the technology. That’s generally because the sun is less intense in winter, the group said, and less important as a heat source. The roofs do not let any more heat escape than other roofs, it said.

In Arizona, cool roofs are mandatory for state and state-funded buildings, while Philadelphia has an ambitious green energy plan that put cool roofs at its centre.

In New York, with Mayor Michael Bloomberg’s blessing, the Department of Buildings and other public and private groups have vowed to paint almost 93,000 square metres of roof on city-sponsored community buildings. Organizers have advertised on Craigslist for volunteers, promising that the painting is rewarding and fun.

I decided to give it a try.

There were half a dozen volunteers on the roof that day from Wayne, N.J.-based GAF Materials, which supplied the reflective white paint. Among them was technical specialist Steve Hecht, who showed me how to spread the paint.

“This should bring the temperature down 50 or 60 degrees,” Hecht said as I rolled a coat onto one small part of the roof.

Proponents say the idea is as sound for private homes as it is for big, residential apartment buildings.

Philadelphia recently held a “cool roofs for free” competition, and a block of row houses won.

“The biggest difference is definitely when we wake up in the morning,” said Terry Jack, who organized her block’s winning entry. “I noticed the difference the very next morning after they painted the roof. It was a good 15 degrees cooler inside; it was much more livable.”

Workers are painting the roofs on both sides of her street with reflective white paint, and also insulating the houses. City officials hope to show that a white roof will reduce the amount of air conditioning used, saving energy and reducing electricity bills.

According to former California energy commissioner Arthur Rosenfeld, an average, 93-square-metre roof painted white can save about 10 tonnes of carbon dioxide, the equivalent of emissions from one car for about 2½ years. On a national scale, turning roofs cool could eliminate two billion tonnes of carbon dioxide, roughly the same as taking 20 million cars off the road for 20 years, according to Rosenfeld, who carried out his experiments with Hashem Akbari at the Lawrence Berkeley National Laboratory, in California.

So far, many cities have been limited in their response. New York has a “very, very, very, conservative target,” said Akbari, who advised the city on its NYC Cool Roofs project.

“When you consider that a large box store or mall can have a roof of 200,000 square feet (18,500 square metres), the entire New York program is the equivalent of painting five of those stores,” he said.

But Akbari stressed it’s not just about white paint.

“Certainly, the white colour helps, especially if it’s special reflective paint, but ultimately we want to see people using cool roof material when they have to change their roofs,” he said. “There are a whole range of materials that can reflect the heat.”
Sophisticated white roofing material can lie underneath a roof’s visible surface, he said, reflecting the sun’s heat while allowing a wider choice of colours on the surface.

“Definitely, esthetics has held back the cool roof movement until now, but that is changing. You have a longer lasting roof without having to look bad,” said Akbari.

According to the Department of Energy, there are no federal tax credits for roof coatings, but there is a tax credit for using cool materials when replacing a roof.