Pike Research just released its Q1 2012 report on "Zero Energy Buildings". It's very comprehensive and forecasts this market will grow to $1.3 trillion by 2035.
The EU, of course, is leading with its Energy Performance of Buildings Directive which requires zero energy construction for nearly all public buildings by 2019 and in all new construction by 2021. You can puruse it here: http://www.epbd-ca.eu/
(psssst! This is exactly the kind of legislation the USA needs.)
In Pike's report, note key players such as commercial property firms (Jones Lang Lasalle, CB Richard Ellis), tech companies (like Honeywell, Siemens, Schneider, Johnson Controls), and others, including MASDAR (the green city in the UAE).
The report is pricey but worth it.