US looking for new ways to fund RE and EE

As Brad Plumer of the New Republic reported recently, some communities in the US are looking for ways to help people invest in renewable energy and energy efficiency - things like solar roofs and weatherization. The problem is that Americans tend to move every six or seven years on the average, and their investments in upgrades to property are then "stranded" because the value of these investments lasts for 20 or 30 years.

The idea, which the New York Times has also covered, is that local communities will provide upfront funding, which will then be repaid through property taxes. In that case, if you move and have to sell your house, you can pass on the debt easily to the buyer:

The debt typically stays with the property, rather than the individual, so homeowners who reckon they’d be selling their homes inside of a 30-year repayment period aren’t dissuaded from participating.

It is true that the mobility of Americans is an obstacle to such investments. I don't have the figures for the average number of years it takes for Germans to move, but a city official here in Freiburg told me last year that none of the 58 units in Freiburg's "Solar Settlement" have come up for sale at all, and I believe they have all been up for roughly 10 years now.

Having said that, I still do not see what the benefits of this new idea in the US are. Why is it not possible to simply add on the value of whatever improvements are made to the house when the house is appraised? And is it really that hard for Americans to get a low-interest loan for such things?