More doom-and-gloomery in the battle to save Property Assessed Clean Energy (PACE), a once-popular finance tool that helped homeowners cut energy waste and add rooftop solar panels: The mortgage giants Fannie Mae and Freddie Mac issued letters today saying that homeowners must pay off PACE assessments before refinancing their mortgages, if they have sufficient equity.

That doesn’t change things for the large majority of PACE programs that were suspended or canceled before launch because of Fannie and Freddie’s opposition (backstory here). But it could make life harder for the comparatively few homeowners who have already used local PACE programs to finance energy-efficiency retrofits.

“To mitigate the risk posed by PACE obligations that take lien priority over the mortgage, Fannie Mae is requiring that borrowers with sufficient equity pay off the existing PACE obligation as a condition to obtaining a new mortgage loan,” Fannie’s guidance states.

Homeowners without enough equity to pay off the lien can refinance with the PACE assessment still in place.

The continued antagonism from Fannie and Freddie isn’t surprising; they’ve stuck to their attack on PACE assessments despite criticism from building contractors, local leaders, governors, members of Congress, and the Obama administration. Last week, their regulator, the Federal Housing Finance Agency, doubled down on its opposition to PACE by rejecting the possibility of a pilot program that would test whether PACE really threatens lenders, as it alleges.

Todd Woody has more at the New York Times‘ Green blog.