In fact, several high-rises around the country have been built according to Leadership in Energy and Environmental Design certification standards, which demand energy and resource efficiency.

But Calvin Welch, a local housing activist, said it is "virtually impossible to conceive a green-materials building of any sort" that would meet the seismic requirements of high-rises in San Francisco. These include the use of "heroic construction techniques" involving extraenforced foundations to build on "Bay Area mud," high-tinsel steel, which is packed with carbon and takes loads of energy to produce (often using coal or gas ovens), and thousands of gallons of diesel for the transportation of materials to the city center.

"This is one of the most disastrous building techniques of mankind," Welch said of high-rise housing, noting that "the environmental debt, even if compensated by solar panels, etc., is too great." *

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