FACTBOX-U.S. "green tech" by the numbers

July 30 (Reuters) - Here is a look at U.S. clean-energy investments by the numbers.

It is based on an analysis by economists at the University of Massachusetts, Amherst, and by the Center for American Progress, a Washington-based think tank, of the economic stimulus package and climate-change legislation pending in Congress.

* Federal environmental spending in the stimulus bill alone amounts to about $100 billion, most of which goes to developing renewable energy, increased conservation, expansion of mass transit and upgrades in the electrical power grid.

* Matching grants, loan guarantees, tax incentives and bond financing in the bill are expected to generate as much as $180 billion in additional investments by state, local and private sources for "green-tech" projects.

* The Congressional Budget Office assumes the bulk of federal stimulus dollars for green tech will be spent between 2010 and 2014.

* The stimulus bill and pending climate-change legislation, the Clean Energy and Security Act, would together generate about $150 billion a year in clean-energy investments over the next decade, mostly from the private sector, translating into the creation of 1.7 million jobs annually.

* The potential market for energy efficiency retrofits of homes and other buildings in the United States is roughly $80 billion a year over the next decade, which would account for the single biggest share of combined green investments.

* A related study found clean-energy investments generated roughly three times more jobs than an equivalent amount of money spent on carbon-based fuels.

* Net job gains of 1.7 million a year in clean energy would be enough to reduce U.S. unemployment by about one full percentage point, even after factoring in corresponding job losses in the conventional fossil fuels sector. (Editing by Peter Cooney)