Zen Center roof painted white

"I see a black roof and I want to paint it white."
(apologies to the Rolling Stones)

This from Michael (Chuna Guan) of the Zen Center:

For the past week, Jian-Xie shifu led a group of volunteers painting
Zen Center’s roof white. This effort is one action of Zen Center’s
overall SunnyZen Green Initiatives.

A pale colored roof would help to contain climate change both by
reflecting more solar radiation into space and by reducing the amount
of energy needed to keep buildings cool by air-conditioning. It also
has the potential of increasing the efficiency of solar panels.

We used a surface thermometer to measure the temperature of two areas,
side by side, of our tar roof. One area is painted white while another
is not. The difference in temperature is about 40F degrees (please see
the posted photos in Files section). Using the rule of thumb that
“1000 square feet would offsets 10 tons of CO2 emission; our action
would offset about 160 tons of CO2 or more. For comparison purposes, a
typical US house emits about 10 tons of CO2 per year. The average
world car emits about 4 tons of CO2 each year. “

There is a winter penalty of a white roof as more heating is needed.
The penalty is about 5 to 15%. There is no specific data for
California, but it would be on the lower end of the scale. “In the
winter, the sun is low and sees mainly the south wall. As long as the
south wall of the building is in dark color” that should compensate
the penalty to great extent.

California has an ordinance, since 2005, that requires all flat roofs
on new commercial buildings to be white. This ordinance is the brain
child of Dr. Art Rosenfeld, a member of the California Energy
Commission. In 2008, Dr Rosenfeld and two colleagues from the Lawrence
Berkeley National Laboratory in California, Hashem Akbari and Surabi
Menon, calculated that changing surface colors in 100 of the world’s
largest cities could save the equivalent of 44 billion tons of carbon
dioxide — about as much as global carbon emissions are expected to
rise by over the next decade.

Dr, Rosenfeld’s research result influenced Steven Chu, the Nobel prize-
winning physicist appointed by President Obama as Energy Secretary. On
May 26th of 2009, Dr, Chu announced a global initiative to change the
color of roofs, roads and pavements in containing global warming.

Please see following links for more information:
http://www.loe.org/shows/segments.htm?programID=09-P13-00007&segmentID=7
A link to an interview with California energy commissioner Arthur
Rosenfeld on the reasons to paint our roof white. It also commented on
the CO2 emission and economy of this action.

http://www.loe.org/images/090213/White%20Roofs%20Cool%20the%20World.pdf
A non-technical summary of this action.

http://www.loe.org/images/090213/Global%20cooling.pdf
A technical summary of this action.