Politicians have applied a fiscal stimulus and, to keep housing finance flowing, relaxed prudential controls on government-sponsored mortgage lenders.

ECONOMIST: America's housing

The figures come from The Global Trends in Renewable Energy Investment 2012 report, a UN Environment Program backed study that has tracked the finance flowing into green energy across the world since 2004.

CNN: Who's funding the green energy revolution?

That may have to wait, if mortgage finance is to keep flowing.

ECONOMIST: America's housing bill