ACEEE, Report Number F1401, Feb. 2014.
http://www.aceee.org/sites/default/files/publications/researchreports/f1401.pdf  (free registration required to access)

"On October 18, 2013, the American Council for an Energy-Efficient Economy (ACEEE) and Energi Insurance Services, with support from the National Renewable Energy Laboratory (NREL), Argonne National Laboratory, and the U.S. Department of Energy (DOE) convened a group of key stakeholders to discuss opportunities for augmenting small bank and lender activity in the energy efficiency space.

This white paper captures key findings from the convening and places them within the context of current research and experience. It goes on to make recommendations to entities within the energy efficiency community to help increase small to mid-size lender activity in the market for energy efficiency financing."