After green roofs, white ones !


You perhaps remember the article I published last year on green roofs and how they enable to reduce greenhouse gases emissions and energy consumption.

Now come white roofs, which according to Fortune and other sources, just provide the same advantages. However, these ones won’t purify the air of cities, as their counterparts do.

As 90 % of all roofs in the US are dark, a recent study showed that painting them white would enable the country to save a billion Dollars in air conditioning costs.

According to Green Wombat, a blog by Fortune Magazine :

(…) a new study from the University of California’s Lawrence Berkeley National Laboratory shows that simply installing white roofs on homes and commercial buildings – to reflect the sun’s rays rather than absorb them – can reduce air-conditioning costs by 20% and could save $1 billion a year in energy outlays in the United States.

Switch to cool sidewalks and roads and the savings rise to $2 billion annually, according to the study by scientists Hashem Akbari and Surabi Menon and California Energy Commissioner Art Rosenfeld to be published in the journal Climate Change.

The scientists calculated that a global white roofs and roads effort would offset 44 billion metric tons of greenhouse gas emissions, or more than a year’s worth of carbon, and help stablize future C02 emission increases.

“The 44 Gt CO2-equivalent offset potential for cool roofs and cool pavements would counteract the effect of the growth in CO2-equivalent emission rates for 11 years,” according to the authors.

Such emission reductions, of course, can be securitized into tradable carbon credits, which the study estimates would be worth $1.1 trillion. Regulated carbon market exist in places like Europe but securities based on cool roofs have not yet been created.

A global cool roofs agreement could avoid the pitfalls of Kyoto-style accords, the scientists note. “Installing cool roofs and cool pavements in cities worldwide does not need delicate negotiations between nations in terms of curbing each country’s CO2 emission rates.”

It’s one of those low-tech, commonsense solutions to both energy use and global warming – one used for thousands of years in the regions like the Mediterranean; those picturesque villages overlooking the sea are white-washed for a reason.

(…) But there’s another, albeit much more expensive solution, to hot roofs: Cover them with solar panels.

To learn out more on this, please check this interesting article by Treehugger : White Roofs to Fight Global Warming

And you what do you think we should do with all our roofs ? Should be plant them ? Should we paint them white (something the Rolling Stones wouldn’t appreciate) ? Or should we install massive amounts of solar panels, both photovoltaic and thermal ?

In a couple a words : Are you more in favor of white, green or blue roofs ?

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