Enterprise Community Partners, Inc., has found a new way to help finance green buildings. The nonprofit organization's Green Communities Offset Fund is already making funding commitments, starting with Silver Gardens here. This 66-unit green affordable housing community is expected to receive $6,600 to upgrade the wind turbine system planned for its roof.

"It's not a lot, but it's real money," said Dana Bourland, senior director of Enterprise's Green Communities initiative.

The Offset Fund is modeled on formal "cap and trade" or "carbon trading" systems used in other countries that require large utilities to either cap their own carbon emissions or to offset those emissions by funding emissions-reduction activities. In countries that follow the protocols of the Kyoto Treaty, which the United States does not, carbon trading is already a huge business-$64 billion in trades were made in 2007, according to the World Bank.

Experts expect the United States to eventually create its own formal, government- regulated carbon trading system. Until then, the Offset Fund uses voluntary contributions from individuals and organizations seeking to shrink their own carbon footprints. Those contributions are then reinvested in housing developments to make them more energy-efficient. Thanks to the green design of Silver Gardens, carbon dioxide emissions will be reduced by at least 330 tons over a five-year period. That's how much would be produced to heat and light a comparable building designed to meet the local building code, according to calculations by Enterprise. The investors on the other side of this transaction were the Urban Land Institute and the U.S. Green Building Council, which paid $20 per ton to purchase offsets for the carbon emissions created by their conferences held this year in Miami and Boston.

Prices for carbon offsets on the voluntary market range from $1 to $100 per ton, said Bourland, who expects prices to become higher and less volatile if carbon trading becomes the law in the United States.

Enterprise charged no fee to structure the deal, so the $6,600 in carbon offset money went straight to the developers, the Supportive Housing Coalition of New Mexico, Inc., and Romero Rose, LLC. They plan to use the funds to upgrade Silver Gardens' planned wind turbine from a $20,000 model with a 2 to 3 kilowatt capacity, or about enough electricity to power a small house, to an 11-kilowatt model.

Construction is planned to begin this December on the $13.4 million midrise. The project will also use $8.4 million from the sale of a $9.7 million reservation of low-income housing tax credits to Enterprise Community Investment.

In addition, the property received a $2.5 million loan from the New Mexico Mortgage Finance Authority and $1.8 million from the city's Workforce Housing Fund. Participating in the Offset Fund helps Silver Gardens distinguish itself from the flood of other green affordable housing properties being built to meet the Leadership in Energy and Environmental Design standards set by the U.S. Green Building Council, said Homer Robinson, project manager for Romero Rose.