PACE (Property Assessed Clean Energy) financing is an ingenious tool to overcoming the major barrier to investments in significant building retrofits.
Its a win, win, win, win and if you count all the life on earth and our future generations, the wins continue.

PACE financing details are somewhat complex. IN a nutshell, towns and cities provide low interest, long term financing for energy efficiency or renewable energy investments. The opt-in financing is tied to the building, not the owner. Houses get retrofitted and occupants live healthier, and more comfortable lives, less CO2 emitted, more durable and valuable homes.

From www.PACEnow.org:

Our Nation:
Significant job creation
Accelerates movement toward energy independence & reduces GHG emissions
Very low fiscal cost & high probability of success

Property Owner:
Lower energy bills and substantially reduced upfront costs for energy retrofits
Improved return on investment/positive cash flow on retrofits (annual savings > cost)

States, Cities & Municipalities:
Immediate job creation
No credit or general obligation risk
Obligation is liability of real estate owner
Greenhouse gas reductions/energy independence
Opt in: Only those real estate owners who opt in pay for it

Existing Mortgage Lenders:
Borrowers cash flow/credit profile improves (energy savings > annual tax cost)
Property/collateral value increases

Lender:
Virtually no risk of loss as property tax liens are senior to mortgage debt
97% of property taxes are current & losses are less than 1%